Category Manufacturer, Supplier and Distributor of Solvents and Chemicals

As the largest manufacturer of n-Heptane in China, we feel it necessary to provide you with professional product introduction, so that you can more directly understand our products. Please follow my steps to learn about our products.

Heptane, a chemical substance, may be less exposed in our life, because it is mainly used as a standard substance for determining octane number, as well as as as a raw material for anesthetics, solvents and organic synthesis, and the preparation of experimental reagents.

What we need to know is that the main component of this product is pure, and its appearance and properties: colorless and volatile liquid. Solubility: insoluble in water, soluble in alcohol, miscible in ether and chloroform.

This chemical substance is a high-risk product with anesthetic effect and irritation. In case of acute poisoning, inhalation of this product vapor can cause dizziness, nausea, anorexia, euphoria, staggering gait, and even loss of consciousness and numbness. It is slightly irritating to the skin. Chronic effects can lead to long-term exposure, which can cause neurasthenia syndrome. A few people have mild neutropenia and dyspepsia.

Therefore, before contact, we should fully understand this chemical substance and make full preparations to ensure the safe use of products.
In case of skin contact, the contaminated clothes should be removed immediately, and the skin must be washed with soapy water and clear water. Eye contact: lift the eyelids and rinse with flowing water or normal saline. See a doctor.

In case of inhalation, leave the site quickly to a place with fresh air. Keep the respiratory tract unobstructed. If breathing is difficult, give oxygen. If breathing stops, give artificial respiration immediately. See a doctor. When eating, you should drink enough warm water to induce vomiting. See a doctor.

As a manufacturer of n-heptane, we remind you that you should pay attention to every chemical substance, so as to understand and prevent it, so as to ensure safe use.

Cyclopentane, as a foaming agent and solvent, has brought many conveniences to our life. Cyclopentane can replace freon and be widely used in refrigerators, insulation materials for freezers and foaming agents for hard PU foam. It can also be used as a solvent for solution polymerization such as polyisoprene rubber and a solvent for cellulose ether. Cyclopentane, as a blowing agent in Polyurethane (PU) foams, is the most important raw material for high-performance insulation in refrigerators. It allows for a high energy efficiency, CO2 reduction and cost savings. At the same time, Cyclopentanes enable a particularly thin insulation for maximum volume utilisation.

Foaming technology is common in every refrigerator, and foaming materials are also very important, which are reflected in heat preservation, noise reduction, more constant box temperature and faster freezing time. There are only four kinds of foaming material technologies used in a refrigerator. The first is monochloroethane, which is the most primitive foaming process. Up to now, it can also be said to be a relatively backward foaming process. The thermal insulation performance of this foaming material is actually good. But there are two obvious shortcomings. One pollutes the atmosphere, the other is easy to crack. Therefore, internationally, the Montreal agreement clearly requires developed countries to completely ban it in 2010. Developing countries are allowed to use it until 2040. Our country has made it clear that the total phase out will be completed ten years ahead of schedule by 2030.

The second kind of Cyclopentane foaming, as a second-generation foaming technology, is used to replace monofluorodichloroethane, which is very good in environmental protection and is not easy to crack.

The third is 245fa mixed foaming agent, which initially aims to solve the problem of the lack of thermal insulation performance of cyclopentane foaming technology, and makes a balance between thermal insulation performance and environmental protection, which belongs to a transitional stage.

The fourth is HFO foaming agent, which is excellent in thermal insulation and environmental protection, and is not easy to crack. It is a luxury to use in refrigerators.

Cyclopentane is commonly used in household appliance foaming materials, and the GWP value of cyclopentane is very small. Halogen free, short life in the atmosphere, easy to decompose safely, and will not destroy the ozone layer. The thermal conductivity of gas phase is small. It can meet the technical requirements of most household appliances for thermal insulation performance.

Cyclopentane is flammable and explosive, with an explosion limit of (1.4-8.0)%. It is listed as a class a class B fire-fighting object in fire fighting. Cyclopentane is also a volatile organic compound, with a volatile amount of 8.5kg/m per hour, with a faint pungent smell. Therefore, there are strict requirements for production equipment, workshops, transportation and storage, as well as higher requirements for the quality and safety of enterprise employees.

Cyclopentane itself has low toxicity and deasterification function. Once it contacts the skin or splashes into the eyes, it should be immediately cleaned with clean water. Once cyclopentane leaks, it should be diluted and dispersed with inert gas nitrogen immediately. The above is the knowledge sharing on cyclopentane foaming process sorted out by Junyuan Petroleum Group and I hope it will be helpful to you!

Refrigerant refrigerant, also known as refrigerant, snow kind. In the refrigeration system, it is vaporized by the energy absorbed by the cooling medium in the evaporator, and the heat is transferred to air and water in the condenser to condense. The increasing consumption of refrigerants in China also drives the demand for refrigerants. Another point is that the state promotes fluorite to be a strategic resource for protective development. Combined with these reasons, the price of refrigerants is gradually rising.

At present, there are more than 80 kinds of substances used as refrigerants, including ammonia, freon-12, Freon-22, R-134a, r-404a refrigerant, R-410A refrigerant, azeotropic refrigerant and hydrocarbon refrigerant. Previously, with regard to the impact on the ozone layer, the production of CFC substances such as R11, R12, R113, R114, r115, R502 and R22 in Freon was restricted.

In the early days, most refrigerants were flammable or toxic, and some accidents often occurred due to high pressure. The history of isobutane R600a refrigerant development appeared in the middle of the 19th century. Mechanical refrigeration, using ether as refrigerant, is a steam compression system. Carbon dioxide (CO2) and ammonia (NH3) were first used as refrigerants in 1866 and 1873, respectively. Other chemicals include chemical cyanogens (petroleum ether and naphtha), sulfur dioxide (r-764) and methyl ether, which have been used as refrigerants for vapor compression. Its application is limited to industrial processes. Most foods are still preserved with ice collected in winter or prepared industrially.

R290 refrigerant and propane refrigerant are hydrocarbon refrigerants, which have no damage to the ozone layer and have a very small greenhouse effect. They are today’s environmentally friendly refrigerants. From the perspective of environmental protection, almost all countries in the world have no restrictions on the use of R290 refrigerant in the initial installation of new refrigeration equipment and after-sales maintenance. The product is mainly used to replace R22 and R502 refrigerants in low-temperature refrigeration equipment; Because R290 is flammable, it is usually only used in low-temperature refrigeration equipment with less liquid filling, or as a component of low-temperature mixed refrigerant; R290 is compatible with traditional lubricants. R290 refrigerant cylinders for storage and transportation are pressurized containers, which are flammable and explosive. They should be stored away from kindling and heat sources to avoid direct exposure to the sun. They are usually stored in a cool, dry and ventilated warehouse; Handle with care to prevent damage to steel cylinders, valves and other accessories. Matching refrigerant oil for the refrigerant oil used with R290 refrigerant, it should follow the recommendations of the refrigeration compressor and refrigeration (air conditioning) equipment manufacturers, or determine to use the refrigerator lubricating oil with the same design requirements according to the specific conditions of the refrigeration compressor and refrigeration equipment, that is, select the equivalent refrigerant oil.

The refrigerant in the refrigerator is fluorinated quantitatively. Use a quantitative liquid dispenser to add fluorine according to the marked amount. When adding fluorine, feel whether the air return pipe feels cool by hand. The air return pipe is very cold or slightly dewy, and the evaporator is basically hung with frost. When filling, first add less fluorine than the original amount, let it run, wait until the evaporator is full of frost, and finally add it until the return pipe only condenses. In general, the steps of adding fluorine to the refrigerator are very simple. Vacuum, draw out the air inside, add fluorine after pumping, and then seal it.

The use of new environmentally friendly refrigerants does not destroy the ozone layer, and the refrigeration efficiency is higher than before. The international community has also begun to use emerging hydrocarbon refrigerants, which fully meet the international standards for energy conservation, environmental protection and emission reduction. They are currently the international ideal refrigerants.

Physical Properties The boiling points of the pentane isomers range from about 9 to 36 °C. As is the case for other alkanes, the more branched isomers tend to have lower boiling points.

Usually, n-Pentane is used as a refrigeration or air conditioning substance, effectively replacing substances such as fluorinated hydrocarbons and ammonia. Here are some of its potential uses: refrigerant R601, non-polar solvent polyethylene process medium, how to use Isopentane? Isopentane is widely used. Firstly, it is an important refrigerant, which is used as the mixed refrigerant component of condensation inducer and LNG in LLDPE unit of olefin plant; Used for blending octane number of oil products;

Usage: isopentane is widely used. First, it is an important refrigerant of olefin unit, condensation inducer of LLDPE unit and LNG mixed refrigerant components; Used for blending oil octane number; It is widely used in organic synthesis reactions and the separation and purification of organic compounds; Secondly, isopentane dehydrogenation can be made of isoprene and isoprene, and isopentanol is obtained by chlorination and hydrolysis. It is also an important raw material for organic synthesis. Isopentane can also be used with n-pentane in EPS (expandable polystyrene) blowing agent, or with cyclopentane as rigid polyurethane blowing agent. It is mainly used in organic synthesis and also as a solvent.

Cyclopentane, as a blowing agent in Polyurethane (PU) foams, is the most important raw material for high-performance insulation in refrigerators. 

Pentane, C₅H_12, is a clear colorless liquid with a petroleum-like odor. It belongs to the organic class alkanes, and is naturally present in crude oils and condensates. It is a component of some fuels and is employed as a specialty solvent in the laboratory.

The boling point 36°C/97°F, and the vapors are heavier than air. Both the liquid an the vapor are flammable.

The phase diagram of pentane is shown below the table.

Chemical, physical and thermal properties of pentane:
Values are given for liquid at 25^oC /77^oF / 298 K and 1 bara, if not other phase, temperature or pressure given.

Density and specific weight of liquid pentane at varying temperature and atmospheric pressure, SI and Imperial units:

Density units conversion of Pentane:

kilogram/cubic meter [kg/m³] = gram/liter [g/l], kilogram/liter [kg/l] = gram/cubic centimeter [g/cm³]= ton(metric)/cubic meter [t/m³], once/gallon(US liquid) [oz/gal(US liq)] pound/cubic inch [lb/in³], pound/cubic foot [lb/ft³], pound/gallon(UK) [lb/gal(UK)], pound/gallon(US liquid) [lb/gal(US liq)], slug/cubic foot [sl/ft³], ton(short)/cubic yard [ton(short)/yd³], ton(long)/cubic yard [yd³]

• 1 g/cm³ = 1 kg/l = 1000 kg/m³ = 62.428 lb/ft³ = 0.03613 lb/in³ = 1.9403 sl/ft³ = 10.0224 lb/gal(UK) = 8.3454 lb/gal(US liq) = 0.5780 oz/in³ = 0.7525 ton(long)/yr³
• 1 g/l = 1 kg/m³ = 0.001 kg/l = 0.000001 kg/cm³ = 0.001 g/cm³ = 0.99885 oz/ft³  = 0.0005780 oz/in³ = 0.16036 oz/gal(UK) = 0.1335 oz/gal(US liq) = 0.06243 lb/ft³ = 3.6127×10-5 lb/in³ = 1.6856 lb/yd³ = 0.010022 lb/gal(UK) = 0.0083454 lb/gal(US liq) = 0.0007525 ton(long)/yd³ = 0.0008428 ton(short)/yd³
• 1 kg/l = 1 g/cm³ = 1000 kg/m³ = 62.428 lb/ft³ = 0.03613 lb/in³ = 1.9403 sl/ft³ = 8.3454 lb/gal(US liq) = 0.5780 oz/in³ = 0.7525 ton(long)/yr³
• 1 kg/m³ = 1 g/l = 0.001 kg/l = 0.000001 kg/cm³ = 0.001 g/cm³ = 0.99885 oz/ft³  = 0.0005780 oz/in³ = 0.16036 oz/gal(UK) = 0.1335 oz/gal(US liq) = 0.06243 lb/ft³ = 3.6127×10-5 lb/in³ = 1.6856 lb/yd³ = 0.010022 lb/gal(UK) = 0.008345 lb/gal(US liq) = 0.0007525 ton(long)/yd³  = 0.0008428 ton(short)/yd³ 
• 1 lb/ft³ = 27 lb/yd³ = 0.009259 oz/in³ = 0.0005787 lb/in³ = 16.01845 kg/m³ = 0.01602 g/cm³  = 0.1605 lb/gal(UK) = 0.1349 lb/gal(US liq) = 2.5687 oz/gal(UK) = 2.1389 oz/gal(US liq) = 0.01205 ton(long)/yd³ = 0.0135 ton(short)/yd³
• 1 lb/gal(UK) = 0.8327 lb/gal(US liq) = 16 oz/gal(UK) = 13.323 oz/gal(US liq) = 168.179 lb/yd³ = 6.2288 lb/ft³ = 0.003605 lb/in3 = 0.05767 oz/in³  = 99.7764 kg/m³ = 0.09977 g/cm³  = 0.07508 ton(long)/yd³ = 0.08409 ton(short)/yd³
• 1 lb/gal(US liq) = 1.2009 lb/gal(UK) = 19.215 oz/gal(UK) = 16 oz/gal(US liq) = 201.97 lb/yd³ = 7.4805 lb/ft³ = 0.004329 lb/in3 = 0.06926 oz/in³  = 119.826 kg/m³ = 0.1198 g/cm³  = 0.09017 ton(long)/yd³ = 0.1010 ton(short)/yd³
• 1 lb/in³ = 1728 lb/ft³ = 46656 lb/yd³ = 16 oz/in³ = 27680 kg/m³ = 27.680 g/cm³  = 277.419 lb/gal(UK) = 231 lb/gal(US liq) =4438.7 oz/gal(UK) = 3696 oz/gal(US liq) = 20.8286 ton(long)/yd³ = 23.3280 ton(short)/yd³
• 1 oz/gal(UK) =  0.8327 oz/gal(US liq) = 6.2360 kg/m³ = 6.2288 oz/ft³ = 0.3893 lb/ft³ = 10.5112 lb/yd³
• 1 oz/gal(US liq) = 1.2009 oz/gal(UK) = 7.4892 kg/m³ = 7.4805 oz/ft³ = 0.4675 lb/ft³ = 12.6234 lb/yd³
• 1 sl/ft³ = 515.3788 kg/m³ = 514.7848 oz/ft³ = 0.2979 oz/in³ = 32.1741 lb/ft³ = 82.645 oz/gal(UK) = 68.817 oz/gal(US liq) 
• 1 ton(long)/yd³ = 1.12 ton(short)/yd³ = 1328.94 kg/m³ = 0.7682 oz/in³ = 82.963 lb/ft³ = 2240 lb/yd³ = 2.5786 sl/ft³ = 13.319 lb/gal(UK) = 11.0905 lb/gal(US liq)
• 1 ton(short)/yd³ = 0.8929 ton(long)/yd³ = 1186.55 kg/m³ = 0.6859 oz/in³ = 74.074 lb/ft³ = 2000 lb/yd³ = 2.3023 sl/ft³ = 11.8921 lb/gal(UK) = 9.9023 lb/gal(US liq)

Pentane Phase Digaram

When it comes to Isohexane, I believe many chemical workers know it well, but as people who have not been in this industry, they are very strange. In fact, hexane can be found in cleaning and aerosol used in our life. Isohexane is closely related to our life. Now let’s take a look at Isohexane.
Isohexane, also known as dimethylpentane, is a commonly used chemical raw material. Its chemical properties are mainly soluble in ethanol, ether, benzene and other organic solvents. It is precisely with one property that Isohexane is used in various industries.

Here are some examples of Isohexane closely related to our daily life

1. Cleaning industry

Isohexane is an alkane solvent oil. Through hydrofining process, it has the characteristics of low aromaticity, low distillation, narrow process, colorless and non-toxic. In the cleaning agent industry, Isohexane is mainly used for cleaning precision instruments, such as circuit boards, mobile phones and other electronic products, as well as clothing cleaning agents. Isohexane will not be absorbed into the human body through the respiratory tract, skin and gastrointestinal tract, resulting in dizziness and anesthesia.

2. Use of aerosol

Aerosol is a kind of aerosol commodity produced in modern fine chemical industry. It is small, easy to carry, simple to use, and the ejected materials are very fine and evenly distributed, which can give full play to the application effect. Among them, the raw material for making aerosol contains Isohexane.

3. Gas chromatography analysis

Gas chromatography analyzer uses a high-efficiency physical separation technology, which is used in analytical chemistry and combined with appropriate detection means to become chromatographic analysis. The separation principle of chromatography is to separate various substances by using the difference of distribution coefficient, adsorption capacity and other affinity in two phases. Among them, Isohexane is used to detect the gas chromatographic analysis standard.

4. Coating industry

Isohexane is widely used in the paint industry, mainly as an extraction diluent because of its good performance, good solubility and good safety
Through the above introduction to you, you may have a further understanding of Isohexane. In fact, there are many roles that Isohexane plays in our life, which are closely related to our life.

Show Ambition, Forge Ahead with Innovation, Review and Forge Ahead

>From July 15 to 17, Junyuan Petroleum Group’s 2022 semi annual work report meeting was held in Qingdao. The meeting was presided over by Qichunxiao, General Manager of Junyuan Petroleum Group of companies, and attended by more than 30 people, including Chairman Miao Guangfa, members of the company’s leading group, senior managers, department head level managers, and model worker representatives. All staff of Xinjiang Liangxin Petrochemical attended the meeting via video network.

At the meeting, general manager Qichunxiao, senior leaders and department heads made work reports respectively, and leaders in charge of each department made comments. The meeting comprehensively summarized the work of the first half of the year, studied and analyzed the problems in production and operation, and further clarified the work objectives of the second half of the year. Finally, Miao Guangfa, chairman of Junyuan Petroleum Group of Companies, made an important speech.

Miao Guangfa, chairman of the board, pointed out in his speech that 2022 is a year of breakthrough development for the company. In the first half of the year, we withstood the pressure of shrinking traditional businesses and declining economic benefits, withstood the pressure of safety and environmental protection inspections at all levels, overcame the impact of many unstable factors brought about by the “COVID-19” and the “economic crisis”, maintained the bottom line, stabilized the overall situation, and made steady progress in all work. In 2022, facing the new normal of economic development, we adhered to the project construction as the basic path of development, completed the construction and put into use of new power boilers, completed the construction and put into use of important facilities such as central control room, laboratory, power distribution room and fire pump room, completed the overall relocation of office buildings and dormitory buildings, completed the overall improvement of the company’s environment, and completed the construction of several technological transformation projects, Constantly inject new vitality into the development of the company and usher in a broader development space. The second half of the year is the key period for the project to “blossom and bear fruit” and “mature melon and land”. We must effectively integrate the ideas and measures of various work into the overall planning of the company’s development, integrate our energy and focus into the specific arrangement of work, see action and results in key work, and strive to create a new situation of leapfrog development.

Qi Chunxiao, the general manager, pointed out at the meeting that we should find gaps and fill in weaknesses through reporting on our work, and be soberly aware of our imperfections compared with the development situation of the company, the development situation of the industry, and the expectations of the majority of employees; We should summarize good experience and practices, find out problems and deficiencies, conduct comprehensive and objective analysis and summary, and constantly identify gaps and learn from each other. Through reporting on work, we should increase vitality and motivation, further strengthen the development consensus, glow the enthusiasm of officers, and earnestly achieve unity of purpose, the same direction of goals, and the same efforts of all staff; We should play a game of chess together, with no division of labor. We should always keep one voice and one pace, and think and work hard in one place. We should enhance the awareness of shouldering heavy responsibilities through reporting on work. As the backbone, leading cadres are the decisive factor, and we should bear the responsibility in the spirit of “nailing nails, bearing burdens, and buttoning”. We should strengthen the systematic concept through reporting, comprehensively analyze and summarize the work ideas, methods and requirements, and use the systematic concept and innovative thinking to plan and promote the work, so as to realize the transformation from “ten fingers exerting force” to “gathering fingers into fists”, and from “fighting alone” to “coordinated combat”.

Qi Chunxiao required that all departments should earnestly follow the work objectives at the beginning of this year, change their thoughts, cheer up, perform their duties and missions with the several requirements put forward by the chairman, refresh themselves, speed up, concentrate, and devote themselves to work with a new spirit and work style.

The market scale of n-Pentane continues to expand, and the separation and purification cost of the industry is high. n-Pentane, with the chemical formula C5H12, has a colorless liquid appearance and a slight mint flavor. n-Pentane has stable chemical properties. It does not react with acids and bases under normal temperature and pressure. It is insoluble in water and soluble in ethanol, ether, acetone, chloroform and other organic solvents. It can be burned. Mixing with air, it has explosion risk, and burning emits carbon dioxide and water.

n-Pentane is widely used as a solvent, foaming agent, electronic cleaning agent, chemical raw materials, etc. As a solvent, n-Pentane can be used to produce artificial ice, anesthetics, fuels, etc; As foaming agent, n-Pentane can be used to produce polystyrene foam and other foamed plastics; As a chemical raw material, n-Pentane can be used to produce isopentane, pentanol, butane, propylene, butene, isobutene and other chemicals; In addition, n-Pentane can also be used as a reference liquid for gas chromatography, for preparing standard gas and correction gas, and as a molecular sieve desorption agent.

There are many preparation processes for n-Pentane, mainly using C5 fraction obtained from catalytic cracking of petroleum as raw material, through hydrogenation, rectification, separation and other processes. n-Pentane is a kind of pentane. Pentane has three isomers, namely n-Pentane, isopentane and neopentane. In C5 fraction, pentane content is about 15%. In pentane, the content of n-Pentane is high. However, due to the small boiling point difference between n-Pentane and Isopentane, it is difficult to separate and purify n-Pentane, so the production cost of n-Pentane is high.

According to the report on the development prospects of China’s n-Pentane industry and suggestions on investment risk avoidance from 2021 to 2025 released by the New World Chemical Research Center, in China and the global market, n-Pentane producers are mainly Shell, Junyuan Petroleum Group, ExxonMobil, Phillips 66, TREC, etc. these well-known producers are large petrochemical enterprises, with perfect upstream and downstream layout of the industrial chain, with scale, capital, technology Cost control and other advantages.

Xiuwen Yang, sales director at Junyuan Petroleum Group, said that n-Pentane is an organic compound, which belongs to alkanes. It can be widely used in the downstream and can produce a variety of chemical products. However, the separation and purification of n-Pentane are difficult and the production cost is high. In the future, the industry needs to continue to improve the production process and energy consumption, so as to reduce the production cost and further expand its application range. In the global market, the leading production enterprises in the n-Pentane industry are mainly petrochemical enterprises with large scale, complete industrial chain layout and high technical level, which are difficult to compete with other relatively small enterprises.

In order to ensure that the fire sprinkler equipment can be put into operation in good condition, on the morning of July 9, all the staff of the storage and transportation team of the quality control operation center carried out fire sprinkler inspection and dredging of sprinkler heads for the 3# Spherical storage tank area and the East-West loading and unloading station. With the arrival of hot summer, the production work is facing greater tests. The materials stored in the spherical tank area of the company are liquid hydrocarbons with light density and high pressure.

Chemical solvent storage tank is a container for storing solvent products. It is the main equipment of petrochemical enterprises. It is mainly used to store pentane, hexane, heptane, petroleum ether and other chemicals and solvents. The tank farm fire has the characteristics of high explosion risk, easy to form large-area combustion, fast combustion speed, great difficulty in extinguishing and great loss. Fire, explosion, poisoning, asphyxiation and other accidents are very likely to occur during the inspection and maintenance of oil tanks. The oil storage tank farm is a typical major industrial hazard source, so it is necessary to conduct a safety analysis on the hot work maintenance of the oil storage tank and put forward corresponding safety measures. Because the safety situation of the tank farm directly affects the safety production and environmental protection of enterprises.

As the temperature rises, the pressure in the storage tank also rises, which has a lot of impact on production safety. In order to ensure the safety of high temperature operation in summer, it is necessary to use fire sprinkler to spray water to cool the spherical storage tank with high pressure. The fire sprinkler inspection and dredging work created conditions for the cooling work of the device and ensured the safe production in summer.

Xiaoqing Zhang, Quality Control and Transportation Center

Polyurethane foam is derived from a mixture comprising a crude isocyanate component and a polyol component which contains all or some of the following products in a homogeneous mixture: polyols, catalysts, surfactants, water, flame-retardants, expanding agents, fillers, colourings, and pigments, in which the expanding agents comprise a pentane component associated with a diethanolamide derived from substances of vegetable origin. Polyurethane (PU) is a polymer that is made of different organic molecules (polyols and polyisocynates) that are bonded by urethane linkages. It can be either thermoplastic polyurethane (TPU) or thermosetting polyurethane. Pentanes are mainly known as blowing agents for insulation materials. But they can do even more: the three isomers n-Pentane, Isopentane and Cyclopentane can each show their advantages in a wide variety of applications, either on their own or as a blend. In this article you can read about the differences between the three Pentane isomers and the applications in which they have proven to be particularly useful.

1. Hydroxyl value: the amount of hydroxyl (-oh) contained in 1g polymer polyol is equivalent to the milligram of KOH, in mgkoh/g.
2. Equivalent: the average molecular weight of a functional group.
3. Isocyanate content: isocyanate content in the molecule
4. Isocyanate index: indicates the degree of excess isocyanate in polyurethane formula, usually represented by the letter R.
5. Chain extender: refers to low molecular weight alcohols and amines that can extend, expand or form spatial network crosslinks.
6. Hard segment: the segment on the main chain of polyurethane molecule formed by the reaction of isocyanate, chain extender and crosslinker. These groups have large cohesive energy, large space volume and large rigidity.
7. Soft segment: carbon carbon main chain polymer polyol with good flexibility. It is a flexible segment in the polyurethane main chain.
8. One step method: it refers to the method that oligomer polyol, diisocyanate, chain extender and catalyst are mixed at the same time, and then directly injected into the mold, and cured at a certain temperature.
9. Prepolymer method: the oligomeric polyol and diisocyanate are prepolymerized to form NCO terminated polyurethane prepolymer, and then the prepolymer is reacted with chain extender during pouring to prepare polyurethane elastomer, which is called prepolymer method.
10. Semi prepolymer method: the difference between semi prepolymer method and prepolymer method is that some polyester polyols or polyether polyols, chain extenders and catalysts are added to the prepolymer in the form of mixtures.
11. Reaction injection molding: also known as reaction injection molding (RIM), it is a process in which oligomers with small molecular weight are measured in liquid form, mixed instantaneously and injected into the mold at the same time, which react rapidly in the mold cavity, the molecular weight of the material increases rapidly, and a brand-new polymer containing new characteristic group structure is generated at an extremely fast speed.
12. Foaming index: that is, the number of parts of water equivalent to 100 parts of polyether is defined as foaming index (if).
13. Foaming reaction: generally refers to the reaction in which water reacts with isocyanate to generate substituted urea and release CO2.
14. Gel reaction: generally refers to the formation reaction of carbamate.
15. Gel time: the time required for liquid substances to form gel under certain conditions.
16. Opacification time: at the end of zone I, opacification occurs in the liquid-phase polyurethane mixed materials. This time is called cream time in the formation of polyurethane foam.
17. Chain extension coefficient: refers to the ratio of the amount of amino group and hydroxyl group (unit: mo1) in the chain extender component (including mixed chain extender) to the amount of NCO in the prepolymer, that is, the ratio of the molar number (equivalent number) of active hydrogen group to NCO.
18. Low unsaturation polyether: it is mainly developed for PTMG. The price of PPG is reduced to 0.05mol/kg, which is close to the performance of PTMG. DMC catalyst is used, mainly Bayer acclaim series products.
19. Urethane grade solvent: the solvent selected for the production of polyurethane should consider the solubility and volatilization rate, but the solvent used for the production of polyurethane should focus on the heavy nc0 group in polyurethane. Solvents such as alcohols, ethers and alcohols that react with NCO groups cannot be selected. The solvent shall not contain water, alcohol and other impurities, nor alkali substances, which will deteriorate the polyurethane.
Ester solvents are not allowed to contain water, free acids and alcohols, which will react with NCO groups. The ester solvent used for polyurethane shall be “urethane grade solvent” with high purity. That is, the solvent reacts with excess isocyanate, and then the amount of unreacted isocyanate is determined with dibutylamine to test whether it is suitable. The principle is that the one that consumes more isocyanates is not applicable, because it indicates that the water, alcohol and acid in the ester will consume the total value of isocyanates. If it is expressed in grams of solvent required to consume leqnco group, the higher the value, the better the stability.
Isocyanate equivalent less than 2500 shall not be used as polyurethane solvent.
The polarity of the solvent has a great influence on the reaction of the resin. The greater the polarity, the slower the reaction. For example, the difference between toluene and methyl ethyl ketone is 24 times. The polarity of this solvent molecule is large, and it can form hydrogen bond with the hydroxyl group of alcohol to slow the reaction.
Aromatic solvents are better for polychlorinated esters, and their reaction speed is faster than that of esters and ketones, such as xylene. The use of ester and ketone solvents can prolong the service life of the polyurethane In the production of coatings, the “urethane grade solvent” mentioned earlier in the film selection is beneficial to the stable parts stored.
Ester solvents have strong solubility, moderate volatilization rate, low toxicity and are used more. Cyclohexanone is also used more. Hydrocarbon solvents have low solid solubility and are rarely used alone. They are often used in combination with other solvents.
20. Physical foaming agent: physical foaming agent means that foam pores are formed through the change of physical form of a substance, that is, through the expansion of compressed gas, the volatilization of liquid or the dissolution of solid.
21. Chemical blowing agent: chemical blowing agent is a compound that can release carbon dioxide, nitrogen and other gases after heating and decomposition, and form fine pores in the polymer composition.
22. Physical crosslinking: there are some hard chains in the polymer soft chain, and the hard chain has the same physical properties as the vulcanized rubber after chemical crosslinking at the temperature below the softening point or melting point.
23. Chemical crosslinking: refers to the process in which macromolecular chains are connected by chemical bonds under the action of light, heat, high-energy radiation, mechanical force, ultrasound and crosslinking agent to form a network or body structure polymer.
24. Foaming index: the number of parts of water equivalent to 100 parts of polyether is defined as foaming index (if).
25. what are the commonly used isocyanates in terms of structure?
Answer: aliphatic: HDI, alicyclic: IPDI, htdi, hmdi, aromatic: TDI, MDI, Papi, PPDI, NDI.
26. what kinds of isocyanates are commonly used? Write the structure
Answer: toluene diisocyanate (TDI), diphenylmethane-4,4 ‘- diisocyanate (MDI), polyphenylmethane polyisocyanate (Papi), liquefied MDI, hexamethylene diisocyanate (HDI).
27. What are the meanings of tdi-100 and tdi-80?
Answer: tdi-100 refers to toluene diisocyanate with 2,4 structure; Tdi-80 refers to a mixture composed of 80% toluene diisocyanate with 2,4 structure and 20% 2,6 structure.
28. What are the characteristics of TDI and MDI in the synthesis of polyurethane materials?
A: for the reactivity of 2,4-TDI and 2,6-TDI. The reaction activity of 2,4-TDI is several times higher than that of 2,6-TDI, because the NCO at position 4 in 2,4-TDI is far away from the NCO at position 2 and methyl group, and there is almost no steric hindrance, while the NCO of 2,6-TDI is greatly affected by the steric hindrance effect of ortho methyl group, so the reaction activity is affected.
The two NCO groups of MDI are far away from each other, and there are no substituents around, so the activities of these two NCOs are large. Even if one NCO participates in the reaction, the activities of the remaining NCOs are reduced, and the overall activity is still large. Therefore, the reaction activity of MDI polyurethane prepolymer is greater than that of TDI prepolymer.
29. Which of HDI, IPDI, MDI, TDI and NDI has better yellowing resistance?
Answer: HDI (belonging to invariant yellow aliphatic diisocyanate) and IPDI (the polyurethane resin made has excellent optical stability and chemical resistance, and is generally used to manufacture high-grade non discolored polyurethane resin).
30. Purpose of MDI modification and common modification methods
A: Liquefied MDI: modification purpose: Liquefied pure MDI is a kind of MDI modified by liquefaction. It overcomes some defects of pure MDI (solid at room temperature, melting when used, and the performance is affected by repeated heating). It also provides a basis for large-scale modification to improve the performance of MDI based polyurethane materials.
method:
① Urethane modified liquefied MDI.
② Carbodiimide and uretonimine modified liquefied MDI.
31. what types of polymer polyols are commonly used?
Answer: polyester polyol, polyether polyol
32. how many industrial production methods are there for polyester polyols?
Answer: A. vacuum melting method B. carrier gas melting method C. azeotropic distillation method
33. what are the special structures on the molecular backbone of polyester and polyether polyols?
Answer: polyester polyol: a macromolecular alcohol compound containing ester group on the main chain and hydroxyl (-oh) on the end group. Polyether polyol: polymer or oligomer containing ether bond (-o-) and terminal group (-oh) or amino group (-nh2) in the molecular main chain structure.
34. according to the characteristics, polyether polyols are divided into several categories?
Answer: high activity polyether polyol, grafted polyether polyol, flame retardant polyether polyol, heterocyclic modified polyether polyol, polytetrahydrofuran polyol.
35. how many kinds of ordinary polyether are there according to the initiator?
Answer: polyoxypropylene glycol, polyoxypropylene triol, hard foam polyether polyol, low unsaturation polyether polyol.
36. what is the difference between hydroxyl terminated polyether and amino terminated polyether?
Amine terminated polyether is a polyoxypropylene ether whose hydroxyl end is substituted by amino group.
37. what types of polyurethane catalysts are commonly used? Which common varieties are included?
Answer: the common types of tertiary amine catalysts are: triethylenediamine, dimethyl ethanolamine, N-methyl morphorphine, N, N-dimethyl cyclohexylamine
Metal alkyl compounds, common varieties are: organotin catalysts, which can be divided into stannous octanoate, stannous oleate, dibutyltin dilaurate.
38. what are the commonly used polyurethane chain extenders or crosslinkers?
Answer: Polyols (1,4-butanediol), alicyclic alcohols, aromatic alcohols, diamines, alcohol amines (ethanolamine, diethanolamine)
39. reaction mechanism of isocyanate
Answer: the reaction between isocyanate and active hydrogen compound is caused by the nucleophilic center in the active hydrogen compound molecule attacking the carbon atom of NCO group. The reaction mechanism is as follows:
40. how does the isocyanate structure affect the reactivity of NCO groups?
Answer: electronegativity of A.R group: if R group is electron absorbing group, the electron cloud density of C atom in -nco group will be lower and more vulnerable to attack by nucleophiles, that is, it is easier to conduct nucleophilic reaction with alcohols, amines and other compounds. If R is an electron donor group, the electron cloud density of C atom in -nco group will increase through electron cloud transmission, making it less vulnerable to attack by nucleophiles, and its reaction ability with compounds containing active hydrogen will decrease. B. Induction effect: because the aromatic diisocyanate contains two NCO groups, when the first NCO gene participates in the reaction, due to the conjugation effect of the aromatic ring, the -nco group that does not participate in the reaction will play the role of electron withdrawing group and enhance the reaction activity of the first NCO group, which is the induction effect. C. Steric hindrance effect: in the aromatic diisocyanate molecule, if two -nco groups are on an aromatic ring at the same time, the influence of one NCO group on the reaction activity of the other NCO group is often significant. However, when two NCO groups are located on different aromatic rings in the same molecule, or they are separated by hydrocarbon chains or aromatic rings, the interaction between them is small, and decreases with the increase of the length of chain hydrocarbons or the number of aromatic rings.
41. types of active hydrogen compounds and NCO reactivity
Answer: aliphatic nh2> aromatic nh2> primary oh> water > secondary oh> phenolic oh> carboxyl group > substituted urea > amide > carbamate. (if the electron cloud density of nucleophilic center is higher, its electronegativity is stronger, and its reaction activity with isocyanate is higher, and the reaction speed is faster; otherwise, its activity is lower.)
42. effect of hydroxyl compounds on their reactivity with isocyanates
Answer: the reactivity of active hydrogen compounds (Roh or rnh2) is related to the properties of R. when R is an electron withdrawing group (with low electronegativity), it is difficult to transfer hydrogen atoms, and the reaction between active hydrogen compounds and NCO is more difficult; If R is an electron donor substituent, the reactivity of active hydrogen compounds with NCO can be improved.
43. what is the purpose of the reaction of isocyanate with water
Answer: it is one of the basic reactions for preparing polyurethane foam. The reaction between them first generates unstable carbamic acid, and then decomposes into CO2 and amine. If the isocyanate is excessive, the generated amine will react with the isocyanate to generate urea.
44. during the preparation of polyurethane elastomers, the water content of polymer polyols shall be strictly controlled
Answer: no bubbles are required in elastomers, coatings and fibers, so the water content in raw materials must be strictly controlled, usually less than 0.05%.
45. difference of catalytic effect of amine and tin catalysts on isocyanate reaction
Answer: tertiary amine catalysts have high catalytic efficiency for the reaction of isocyanate with water, while tin catalysts have high catalytic efficiency for the reaction of isocyanate with hydroxyl.
46. why can polyurethane resin be regarded as a block polymer? What are the characteristics of the chain segment structure?
Answer: the chain segment of polyurethane resin is composed of hard segment and soft segment. The hard segment refers to the chain segment formed by the reaction of isocyanate, chain extender and crosslinker on the main chain of polyurethane molecule. These groups have large cohesive energy, large space volume and large rigidity. The soft segment refers to the carbon carbon main chain polymer polyol, which has good flexibility and is a flexible segment in the polyurethane main chain.
47. what are the factors that affect the properties of polyurethane materials?
Answer: cohesive energy of group, hydrogen bond, crystallinity, crosslinking degree, molecular weight, hard segment and soft segment
48. what are the raw materials for the soft and hard segments of the main chain of polyurethane materials
Answer: the soft segment is composed of oligomer Polyols (polyester, polyether glycol, etc.), and the hard segment is composed of polyisocyanate or its small molecule chain extender.
49. how do the soft and hard segments affect the performance of polyurethane materials?
Answer: soft segment: (1) molecular weight of soft segment: assuming that the molecular weight of polyurethane is the same, if the soft segment is polyester, the strength of polyurethane will increase with the increase of molecular weight of polyester glycol; If the soft segment is polyether, the strength of polyurethane decreases with the increase of molecular weight of polyether glycol, but the elongation increases. (2) Crystallinity of soft segment: it contributes greatly to the crystallinity of linear polyurethane segment. Generally speaking, crystallinity is beneficial to improve the performance of polyurethane products, but sometimes crystallization will reduce the low-temperature flexibility of materials, and crystalline polymers are often opaque.
Hard segment: the hard segment usually affects the softening melting temperature and high temperature performance of the polymer. The polyurethane prepared by aromatic isocyanate has a rigid aromatic ring in its hard segment, so its hard segment cohesion strength increases. The material strength is generally greater than that of aliphatic isocyanate polyurethane, but its UV degradation resistance is poor and it is easy to yellowing. Aliphatic polyurethane will not turn yellow.
50. classification of polyurethane foam
Answer: (1) hard foam and soft foam; (2) high density and low density foam; (3) polyester and polyether foam; (4) TDI and MDI foam; (5) polyurethane foam and polyisocyanurate foam; (6) one-step and prepolymerization production; (7) continuous and intermittent production; and (8) block foam and molded foam.
51. basic reaction of foam preparation
Answer: it refers to the reaction between -nco and -oh, -nh2 and H2O. When it reacts with polyols, the “gel reaction” in the foaming process generally refers to the formation reaction of carbamate. Because the foam raw material uses multi-functional raw materials, the crosslinked network is obtained, which makes the foaming system quickly gel.
Foaming reaction occurs in the foaming system with water. The so-called “foaming reaction” generally refers to the reaction in which water reacts with isocyanate to generate substituted urea and release CO2.

52. nucleation mechanism of bubbles
The raw material reacts in the liquid or depends on the temperature of reaction production to produce gaseous substances and volatilize the gases. With the progress of the reaction and the large amount of reaction heat, the amount of gaseous substances and volatilization is increasing. When the gas concentration increases beyond the saturation concentration, the maintained bubbles begin to form in the solution phase and rise.
53. the role of foam stabilizer in the preparation of polyurethane foam
Answer: it has emulsification function, which enhances the mutual solubility of each component of foam material; After adding silicone surfactant, the surface tension of the liquid is greatly reduced γ ， The increased free energy required for gas dispersion is reduced, which makes the air dispersed in the raw material easier to nucleate in the mixing process, helps to produce small bubbles and improves the stability of foam.
54. stability mechanism of foam
Answer: the addition of appropriate surfactant is conducive to the formation of fine bubble dispersion.
55. formation mechanism of open cell foam and closed cell foam
Answer: formation mechanism of open cell foam: in most cases, when the maximum pressure is generated in the bubble, the strength of the bubble wall formed by the gel reaction is not high, and it cannot withstand the wall membrane tension caused by the increase of gas pressure. The bubble wall membrane is pulled and broken, and the gas escapes from the rupture to form open cell foam.
Formation mechanism of closed cell foam: for hard foam system, due to the reaction of polyether polyols with multi-functional and low molecular weight with polyisocyanate, the gel speed is relatively fast, and the gas in the cell can not break the cell wall, thus forming a closed cell foam.
56. foaming mechanism of physical foaming agent and chemical foaming agent
Answer: physical foaming agent: physical foaming agent means that foam pores are formed through the change of physical form of a substance, that is, through the expansion of compressed gas, the volatilization of liquid or the dissolution of solid.
Chemical blowing agent: chemical blowing agent is a compound that can release carbon dioxide, nitrogen and other gases after heating and decomposition, and form fine pores in the polymer composition.
57. preparation method of flexible polyurethane foam
Answer: one step and prepolymer method
Prepolymer method: the prepolymer containing free NCO group is prepared by the reaction of polyether polyol and excess TDI, and then mixed with water, catalyst, stabilizer, etc. to make foam.. One step method: various raw materials are directly mixed in the mixing head through calculation to produce foamed plastics in one step, which can be divided into continuous type and intermittent type.
58. characteristics of horizontal foaming and vertical foaming
Answer: characteristics of horizontal foaming: side film lifting method: this method adds an upward traction side paper device on the basis of the original horizontal foaming machine to make the edge and middle of foam rise and foam synchronously, so as to make a foam block close to the flat top. Balanced pressing plate method: it is characterized by the use of top paper and top cover plate. Overflow trough method: characterized by the use of overflow trough and conveyor belt landing plate.
Vertical foaming features: large cross-sectional area of foam blocks can be obtained with a small flow rate, while the horizontal foaming machine is usually used to obtain blocks with the same cross-section, and the horizontal flow rate is 3 ~ 5 times larger than the vertical foaming; Because the cross section of the foam block is large, there is no upper and lower skin, and the side skin is thin, so the cutting loss is greatly reduced; The equipment covers a small area, the plant height is about 12 ~ 13m, and the investment cost of plant and equipment is lower than that of horizontal foaming process; The cylindrical or rectangular foam body can be produced conveniently by changing the hopper and model, especially the round block foam blank for rotary cutting.
59. basic points of raw material selection for soft foam preparation
Answer: polyols: polyether polyols used for ordinary block foam, with a molecular weight of 3000 ~ 4000, mainly polyether triols. High resilience foam mostly uses polyether triol with molecular weight of 4500 ~ 6000. When the molecular weight increased, the tensile strength, elongation and resilience of foam increased; The reactivity of the same polyether decreased. When the functionality of polyether is increased, the reaction is relatively accelerated, the crosslinking degree of polyurethane is increased, the hardness of foam is increased, and the elongation is decreased. Isocyanate: toluene diisocyanate (tdi-80) is the main Isocyanate Raw Material of polyurethane soft block foam. Tdi-65 with relatively low activity is only used for polyester polyurethane foam or special polyether foam. Catalysts: the catalysts used for block soft foam foaming can be roughly divided into two categories: one is organometallic compounds, of which stannous octanoate is the most commonly used; The other is tertiary amine, commonly used as bis (dimethylaminoethyl) ether. Foam stabilizer: the polyester type polyurethane block foam is mainly composed of non silicon surfactants, and the polyether type block foam is mainly composed of silicone olefin oxide copolymers. Foaming agent: generally, when manufacturing polyurethane soft block foam with a density greater than 21 kg / m3, only water is used as foaming agent; Only low boiling point compounds such as methylene chloride (MC) are used as auxiliary blowing agents in low-density formulations.
60. influence of environmental conditions on physical properties of block foam
Answer: influence of temperature: the foaming reaction of polyurethane accelerates with the rise of material temperature, which will cause the risk of core burning and fire in sensitive formulas. Influence of air humidity: with the increase of humidity, the hardness of foam decreases and the elongation increases because the isocyanate group in foam reacts with the moisture in the air; The tensile strength of foam increased due to the increase of urea group. Effect of atmospheric pressure: for the same formula, when foaming at a higher altitude, the density decreases significantly.
61. main differences of raw material system between cold molded soft foam and hot molded foam
Answer: the raw materials used for cold curing molding have high reactivity. During curing, there is no need for external heating. Depending on the heat generated by the system, the curing reaction can be basically completed in a short time, and the raw materials can be demoulded within a few minutes after injection molding. The raw material reaction activity of heat curing molding foam is low. After the reaction mixture is foamed in the mold, it needs to be heated together with the mold. The foam products can be demoulded only after they are completely cured in the drying channel.
62. what are the characteristics of cold molded soft foam compared with hot molded foam
Answer: ① there is no need to provide external heat in the production process, which can save a lot of heat energy; ② High sag coefficient and good comfort; ③ High rebound rate; ④ Foam without flame retardant also has certain flame retardancy; ⑤ The production cycle is short, which can save the mold and cost.
63. characteristics and applications of soft foam and hard foam
Answer: characteristics of soft foam: the cell structure of polyurethane soft foam is mostly open cell. Generally, it has the properties of low density, good elastic recovery, sound absorption, ventilation, heat preservation, etc. Application: mainly used as furniture, cushion material, vehicle seat cushion material, various soft cushion laminated composite materials. In industry and civil use, soft foam is also used as filter material, sound insulation material, shockproof material, decorative material, packaging material, heat insulation material, etc.
Characteristics of rigid foam: polyurethane foam has light weight, high specific strength and good dimensional stability; Polyurethane rigid foam has superior thermal insulation performance; Strong adhesion; Good aging performance and long thermal insulation service life; The reaction mixture has good fluidity and can smoothly fill the mold cavity or space with complex shapes; The raw materials for the production of polyurethane rigid foam are highly reactive, which can realize rapid curing, and can realize high-efficiency and mass production in the factory.
Uses: used as insulation materials for refrigerators, freezers, refrigerated containers, cold storages, etc., insulation layers for oil transmission pipelines and hot water transmission pipelines, insulation layers for building walls and roofs, insulation sandwich panels, etc.
64. key points of hard foam formula design
Answer: polyols: polyether polyols used in hard foam formulation are generally polyoxypropylene polyols with high functionality and high hydroxyl value (low molecular weight); Isocyanate: at present, the isocyanate used for hard foam is mainly polymethylene polyphenyl polyisocyanate (commonly known as Papi), i.e. crude MDI and polymerized MDI; Blowing agent: (1) CFC blowing agent (2) HCFC and HFC blowing agent (3) pentane blowing agent (4) water; Foam stabilizer: the foam stabilizer used for polyurethane rigid foam formulation is generally a block polymer of polydimethylsiloxane and polyolefin. At present, most foam stabilizers are mainly Si-C type; Catalyst: the catalyst of hard foam formula is mainly tertiary amine, and organotin catalyst can be used in special occasions; Other additives: according to the requirements and needs of different uses of polyurethane rigid foam products, flame retardant, pore opening agent, smoke inhibitor, antioxidant, mildew inhibitor, toughening agent and other additives can also be added to the formula.
65. preparation principle of whole skin molded foam
Answer: integral skin foam (ISF), also known as self skinning foam, is a kind of foam that produces a dense skin during manufacturing.
66. characteristics and applications of polyurethane microporous elastomer
A: characteristics: polyurethane elastomer is a block polymer, which generally consists of oligomer polyol flexible long chain to form soft segment, diisocyanate and chain extender to form hard segment, and hard segment and soft segment are arranged alternately to form repeated structural units. In addition to containing urethane groups, polyurethane can form hydrogen bonds within and between molecules, and the soft and hard segments can form microphase regions and generate microphase separation.
67. what are the main performance characteristics of polyurethane elastomer
Answer: performance characteristics: 1. High strength and elasticity, which can maintain high elasticity in a wide hardness range (Shore A10 ~ shore d75); Generally, the required low hardness can be achieved without plasticizer, so there is no problem caused by plasticizer migration; 2. Under the same hardness, the bearing capacity is higher than that of other elastomers; 3. Excellent wear resistance, its wear resistance is 2 ~ 10 times that of natural rubber; 4. Excellent oil and chemical resistance; Aromatic polyurethane radiation resistance; Excellent oxygen resistance and ozone resistance; 5. High impact resistance, fatigue resistance and vibration resistance, suitable for high-frequency flexure applications; 6. Good low temperature flexibility; 7. Ordinary polyurethane can not be used above 100 ℃, but it can withstand 140 ℃ high temperature with special formula; 8. Molding and processing costs are relatively low.
68. polyurethane elastomers are classified according to polyols, isocyanates, manufacturing processes, etc
Answer: 1 According to the raw materials of oligomer polyols, polyurethane elastomers can be divided into polyester type, polyether type, polyolefin type, polycarbonate type, etc. the polyether type can be divided into polytetrahydrofuran type, polyoxypropylene type, etc. according to specific varieties; 2. according to different diisocyanates, they can be divided into aliphatic and aromatic elastomers, which can be subdivided into TDI, MDI, IPDI, NDI and other types; In terms of manufacturing process, polyurethane elastomers are traditionally divided into three categories: casting type (CPU), thermoplastic type (TPU) and mixing type (MPU).
69. from the perspective of molecular structure, what are the factors that affect the properties of polyurethane elastomers?
Answer: from the perspective of molecular structure, polyurethane elastomer is a block polymer. Generally, the soft segment is composed of oligomer polyol flexible long chain, and the hard segment is composed of diisocyanate and chain extender. The hard segment and soft segment are arranged alternately to form repeated structural units. In addition to containing urethane groups, polyurethane can form hydrogen bonds within and between molecules, and the soft and hard segments can form microphase regions and generate microphase separation. These structural characteristics make polyurethane elastomer have excellent wear resistance and toughness, and it is known as “wear-resistant rubber”.
70. performance difference between ordinary polyester type and polytetrahydrofuran ether type elastomers
Answer: Polyester molecules contain more polar ester groups (-coo-), which can form strong intramolecular hydrogen bonds. Therefore, polyester polyurethane has high strength, wear resistance and oil resistance.
The elastomer prepared from polyether polyol has good hydrolytic stability, weather resistance, low temperature flexibility and mold resistance.

Where do Pentanes come from?
Pentanes are all saturated hydrocarbons that have five carbon atoms. n-Pentane and iso-Pentane occur naturally in crude oil and as a by-product of natural gas production. Cyclopentane, a ring-shaped molecule much sought after by the industry, is found more in naphtha (crude petrol), which is obtained in refineries from so-called cracking processes.

Naphtha contains varying amounts of Pentanes, depending on the origin of the crude oil, the construction of the refinery and the management of the processes. They are the first hydrocarbons to be liquid at room temperature.

Isopentane has the lowest boiling point at 29 °C, followed by n (35 °C) and Cyclopentane (49 °C). Due to the low boiling points and the large interval between them, the three isomers of Pentane can be easily separated from each other.

Pentane production: What are the differences between n-Pentane, Isopentane and Cyclopentane?
Due to their property profile, Isopentane, n and Cyclopentane can show their advantages in a wide variety of applications. Moreover, the three isomers can be mixed with each other or with other chemical components. In this way, it is possible to create Pentane blends that fulfil the desired requirement profile in the best possible way.

Application area Isopentane
Isopentane is almost insoluble in water, but shows very good solubility or unlimited miscibility with many organic solvents such as paraffins, ethers, esters, aromatics or chlorinated hydrocarbons. Therefore, the product is suitable for a wide range of applications:

Personal care products such as shaving foam and shower gel
Working medium in geothermal plants
Non-polar solvent with very high volatility
Process medium for polyethylene (PE, LLDPE) and polypropylene (PP)

Cyclopentane, also known as pentamethylene, is a kind of hydrocarbon. It is used to replace freon as a foaming agent for refrigerator freezer insulation materials and hard PU foam. It is used as a solvent for solution polymerization of polyisoprene rubber and cellulose ether. Isopentane is one of the components of petroleum ether. It is obtained through the recombination of isopentane under the action of platinum. It has a broad market prospect. High purity industrial grade requires high cyclopentane itself, so it is of great significance to strengthen the research on purification technology of high purity cyclopentane.
Cyclopentane has low thermal conductivity, good anti-aging performance, no damage to the ozone layer, and many advantages in solubility in polyols. At present, cyclopentane production mainly relies on petrochemical raw materials, mainly petrochemical C5 fraction. Cyclopentane is a component of petroleum ether in the boiling point range of 30-60 ℃, and its content is generally 5%-10%. It is distilled under normal pressure in a 8m high tower with a reflux ratio of 60:1. Isopentane and n-pentane are first evaporated, and then fractionated to obtain cyclopentane with a purity of more than 98%. Cyclopentane can also be prepared by reduction of Cyclopentanone or catalytic hydrogenation of cyclopentadiene.

Cyclopentane Blowing Agent

The spontaneous combustion temperature of cyclopentane blowing agent is about 380 ℃. The normal temperature of 50 ℃ will not cause spontaneous combustion. Harmful effects of cyclopentane inhalation of high concentrations of cyclopentane can cause central nervous system depression, although its acute toxicity is low. The symptoms caused by acute exposure are first excitement, then imbalance, even numbness and coma. Rarely die of respiratory failure. It has been reported that this product was given orally to animals, resulting in severe diarrhea, heart, lung and liver vascular collapse and brain degeneration.

Cyclopentane and Freon are both substances that are easy to liquefy and vaporize. They should absorb heat during vaporization and release heat during liquefaction; Liquid cyclopentane flows in the pipe. When it flows to the freezer, it will vaporize and absorb heat, absorbing the heat in the refrigerator and reducing the temperature in the refrigerator; When it flows into the condenser, it will be compressed and liquefied, and the absorbed heat will be released to achieve the purpose of refrigeration.
In the past, most of the traditional water tank insulation materials in the solar industry used polyurethane foaming technology. This material has many disadvantages, such as consuming oil resources, destroying the ozone layer with HCFC-141b foaming agent, and “white pollution” caused by waste foam. It does not meet the environmental protection requirements. Cyclopentane, as a new environmentally friendly foaming agent, has brought greater improvement to our environment and life, but cyclopentane is flammable and volatile, It is easy to cause combustion and explosion in case of open fire. Pay special attention to safety during use.

Junyuan Petroleum Group is a new chemical enterprise integrating R & D, production and marketing. The company’s products cover four major fields: refrigerant, carbon hydride, fluoride and chemical raw materials. Its main products are n-pentane and isopentane Pentane blowing agent, n-hexane, isohexane, n-heptane, n-octane, petroleum ether, isobutane R600a, n-butane R600, propane R290, propylene R1270, n-pentane r601, isopentane r601a, cyclopentane, isobutene, ethylene R1150, R22, R23, r507, ethane R170, methane, freon, dimethyl ether, isooctane, n-heptane, propylene butane, n-hexane, n-hexene, n-butene and other blowing agents, aerosols and solvents; The company is committed to science and technology and environmental protection industries. Its products are widely used in refrigeration, energy, electronics, pharmaceutical intermediates, scientific research, laser technology, aerospace technology, metal smelting, low-temperature refrigeration and other fields. Its customers radiate in Europe, America, the Middle East and Southeast Asia.