Question 1: Are polyethylene and polypropylene both plastics? What is the difference between the two? Polyethylene and polypropylene are both plastics. When polyethylene is not colored, it is milky white, translucent, and waxy; use your hands to The product feels smooth when touched, soft and pliable; it can be slightly stretched. Generally, low-density polyethylene is softer and has better transparency; high-density polyethylene is harder. Polypropylene is white, translucent and waxy when uncolored; polyethylene is light. The transparency is also better than polyethylene and harder than polyethylene.
Question 2: The difference between plastic and PP PP is a kind of plastic in the broad sense.
Plastic is a general term for chemically synthesized materials. After breaking the molecular bonds, the molecules are held hand in hand to form large molecular clusters with similar structures.
For example: PE polyethylene, ABS engineering plastics, PC polycarbonate, PVC polyvinyl chloride, as well as polyurethane, polystyrene, PET, etc. are all different chemical compositions.
These plastics with different materials and different structures have very different physical properties. Some are high temperature resistant, some are acid resistant, some are flame retardant, and some have high hardness.
These can be collectively referred to as plastics, but if you need to know the composition of the ingot particles, you must give the specific name.
Just like you and I are both human beings, but to distinguish them we need names.
Question 3: What is polypropylene? Polypropylene (PP) is a semi-crystalline thermoplastic. It has high impact resistance, strong mechanical properties, and is resistant to various organic solvents and acid and alkali corrosion. It is widely used in industry and is one of the common polymer materials. Australian coins are also made from polypropylene.
The repeating units of polypropylene are composed of three carbon atoms. Two of the carbon atoms are in the main chain, and one carbon atom exists in the form of a branch chain. The structure of polypropylene is close to that of polyethylene, so many of its properties are similar to polyethylene. However, due to the presence of a methyl side branch, polypropylene is more susceptible to oxidative degradation under the action of ultraviolet light and heat energy.
Question 4: Is there any difference between polypropylene engineering plastics and polypropylene? Polypropylene PP is a raw material without any characteristics. Polypropylene engineering plastic has undergone some performance changes, adding glass fiber, flame retardant, etc. to enhance its own performance and meet the material needs of various mold designs!
Question 5: Why can polypropylene be used as both a hard plastic and an elastomer? 5 points Polypropylene itself is a hard plastic, but the vast majority of elastomers are made of propylene and ethylene. As the main component, polypropylene can also be the main component of elastomer.
Polypropylene hard plastic: homopolypropylene and polypropylene
Polypropylene elastomers are modified by adding polyethylene or rubber components. For elastomers. For example: SEBS/TPE. Polypropylene elastomer is softer than polypropylene hard plastic, but has much higher impact resistance. General polypropylene hard plastic can only withstand 4kJ impact, but elastomers can withstand more than 20KJ.
Polypropylene is a thermoplastic resin made from the polymerization of propylene. According to the arrangement position of the methyl groups, it is divided into three types: isotactic polypropylene (isotactic polypropylene), atactic polypropylene (atactic polypropylene) and syndiotactic polypropylene (syndiotactic polypropylene).
When the methyl groups are arranged on the same side of the main chain of the molecule, it is called isotactic polypropylene. If the methyl groups are arranged randomly on both sides of the main chain of the molecule, it is called atactic polypropylene. When the methyl groups are arranged alternately on the molecule Both sides of the main chain are called syndiotactic polypropylene. In general industrially produced polypropylene resin, the isotactic structure content is about 95%, and the rest is atactic or syndiotactic polypropylene. Industrial products contain isoforms as main components. Polypropylene also includes polymers of propylene and a small amount of ethylene. It is usually a translucent colorless solid, odorless and non-toxic.
Due to its regular structure and high degree of crystallization, its melting point can be as high as 167°C. Heat resistance and corrosion resistance, and the products can be sterilized by steam are its outstanding advantages. It has low density and is the lightest general-purpose plastic. The disadvantages are poor low-temperature impact resistance and easy aging, but these can be overcome through modification.
Polymer PP material has a lower heat distortion temperature (100°C), low transparency, low gloss, and low rigidity, but has stronger impact strength, and the impact of PP Strength increases with increasing ethylene content. The Vicat softening temperature of PP is 150°C. Due to its high degree of crystallinity, this material has good surface stiffness and scratch resistance. PP does not have environmental stress cracking problems.
The melt mass flow rate (MFR) of PP is usually between 1 and 100. Low MFR PP materials have better impact resistance but lower ductility. For materials with the same MFR, the impact strength of the polymer type is higher than that of the homopolymer type. Due to crystallization, the shrinkage rate of PP is quite high, generally 1.6~2.0.
Question 6: What are the characteristics of polypropylene material? Polyethylene (PE for short)
It is a thermoplastic resin obtained by polymerizing ethylene. In industry, it also includes polymers of ethylene and a small amount of α-olefins. Polyethylene is odorless, non-toxic, feels like wax, has excellent low temperature resistance, good chemical stability, and is resistant to most acids and alkalis. It is insoluble in general solvents at room temperature, has low water absorption and excellent electrical insulation properties. Polyethylene is a typical thermoplastic and is an odorless, tasteless, non-toxic flammable white powder. The molded PE resin is extruded and granulated waxy pellets, with a milky white appearance. Its molecular weight is in the range of 10,000 to 10,000 loa. Those with a molecular weight of more than 100,000 are ultra-high molecular weight polyethylene f UHMWPE3. The higher the molecular weight, the better the physical and mechanical properties, and the closer they are to the required level of engineering materials. However, the higher the molecular weight, the more difficult it is to process. The melting point of polyethylene is 10---130C. It has excellent low temperature resistance. It can still maintain good mechanical properties at -60℃, but the use temperature is between 80~110℃.
Polyethylene has good chemical stability and can withstand dilute nitric acid, dilute sulfuric acid and any concentration of hydrochloric acid, hydrofluoric acid, phosphoric acid, formic acid, acetic acid, ammonia, amines, hydrogen peroxide, and hydrogen at room temperature. Sodium oxide, potassium hydroxide and other solutions. But it is not resistant to strong oxidizing corrosion, such as fuming sulfuric acid? A mixture of concentrated nitric acid, chromic acid and sulfuric acid. At room temperature, the above solvents will slowly corrode polyethylene, but at 90---100°C, concentrated sulfuric acid and concentrated nitric acid will quickly corrode polyethylene, causing it to be damaged or decomposed.
Under the influence of atmosphere, sunlight and oxygen, polyethylene will age, discolor, crack, become brittle or pulverized, and lose its mechanical properties. At the molding processing temperature, the melt strength will also decrease due to oxidation, causing discoloration and streaks. Therefore, attention should be paid to the molding process and use process or when selecting materials. Because polyethylene has the above characteristics and is easy to process and shape, the recycling of polyethylene has far-reaching value. Properties 1. Polyethylene has excellent chemical stability and is resistant to corrosion by hydrochloric acid, hydrofluoric acid, phosphoric acid, formic acid, amines, sodium hydroxide, potassium hydroxide and other chemical substances at room temperature. However, nitric acid and sulfuric acid are harmful to polyethylene. Strong destructive effect; 2. Polyethylene is prone to photo-oxidation, thermal oxidation, ozone decomposition, and degradation under the action of ultraviolet rays. Carbon black has excellent light-shielding effect on polyethylene. After exposure to radiation, reactions such as cross-linking, chain scission, and the formation of unsaturated groups may occur. A milky white, translucent thermoplastic produced by homopolymerization of ethylene and polymerization with a small amount of α-olefin. Density is 0.86~0.96g/cm3. According to density, there are low density polyethylene (also including linear low density polyethylene), ultra-low density polyethylene, etc. Odorless and non-toxic. Resistant to chemicals and insoluble in solvents at room temperature. Resistant to low temperatures, the lowest operating temperature is -70~-100℃. Good electrical insulation and low water absorption. Physical and mechanical properties vary with density. Industrially, low-density polyethylene mainly adopts high-pressure (110~200MPa) and high-temperature (150~300℃) free radical polymerization.
Others use low-pressure coordination polymerization. Sometimes the same set of equipment can produce polyethylene products with a density of 0.87 to 0.96g/cm3, which is called full-density polyethylene process technology. Polyethylene can be processed into films, wire and cable sheaths, pipes, various hollow products, injection molded products, fibers, etc. Widely used in agriculture, packaging, electronic and electrical, machinery, automobiles, daily necessities, etc.
Polypropylene is a thermoplastic resin made from the polymerization of propylene. According to the arrangement position of the methyl groups, it is divided into three types: isotactic polypropylene (isotactic polypropylene), atactic polypropylene (atactic polypropylene) and syndiotatic polypropylene. It is non-toxic, odorless, has low density, has better strength, stiffness, hardness and heat resistance than low-pressure polyethylene, and can be used at around 100°C. It has good electrical properties and high-frequency insulation and is not affected by humidity, but it becomes brittle at low temperatures, is not wear-resistant, and is prone to aging. Suitable for making general mechanical parts, corrosion-resistant parts and insulating parts. Common organic solvents such as acids and alkalis have little effect on it and can be used in tableware.
Polypropylene has many excellent properties: 1. The relative density is small, only 0.89-0.91, making it one of the lightest varieties of plastics. 2. Good mechanical properties. Except for impact resistance, other mechanical properties are better than polyethylene, and the molding and processing performance is good. 3. It has high heat resistance, and the continuous use temperature can reach 110-1...gt;gt;
Question 7: What is polypropylene? Propylene, PP, is a thermoplastic resin made by polymerizing propylene. Polypropylene is a non-toxic, odorless, tasteless, milky white, highly crystalline polymer with a density of only 0.90--0.91g/cm3. It is one of the lightest varieties of all plastics currently. It is particularly stable to water, its water absorption rate in water is only 0.01, and its molecular weight is about 80,000 to 150,000. The formability is good, but due to the large shrinkage rate (1~2.5), thick-walled products are easy to dent, and it is difficult to meet the requirements for some parts with high dimensional accuracy, and the surface gloss of the product is good. The polymer-type PP material has a low heat distortion temperature (100°C), low transparency, low gloss, and low rigidity, but has stronger impact strength. The impact strength of PP increases with the increase of ethylene content. And increase. The Vicat softening temperature of PP is 150°C. Due to its high degree of crystallinity, this material has good surface stiffness and scratch resistance. PP does not have environmental stress cracking problems.
Question 8: What is polypropylene used for? What is PP? There are two types of pp materials, one is for blow molding and the other is for extrusion