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Characteristics of common plastic materials

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What are the characteristics of commonly used plastic materials

I. polycarbonate (PC /bulletproof glass adhesive) is a highly transparent, non crystalline thermoplastic

advantages: 1. It has high mechanical strength, impact resistance, fatigue resistance, good toughness and cowardice resistance; 2. High transparency, non-toxic, tasteless and easy to dye; 3. Good weather resistance, heat resistance and insulation; 4. Low forming shrinkage (0.5% ~ 0.7%) and good dimensional stability

disadvantages: 1. Poor solvent resistance; 2. There is stress cracking; 3. Long term immersion in boiling water is easy to hydrolyze; 4. Poor fatigue strength

II. Polyvinyl chloride (PVC) is transparent. Before plasticizer is added, PVC is a hard plastic with good moisture resistance, but it is also decomposed by ketone and ester solvents

advantages: 1. Good dimensional stability; 2. Low cost; 3. Good weather resistance; 4. Adding different proportion of plasticizer can easily adjust the soft hardness

disadvantages: 1. Poor chemical resistance; 2. Poor temperature resistance; 3. The density is higher than that of general plastics; 4. Hydrogen chloride will be produced after thermal decomposition

III. polymethylmethacrylate (PMMA) is highly transparent, amorphous polymer, 92% light penetration, and the thermal denaturation temperature is between 74 ° C and 102 ° C

advantages: 1. High optical transparency; 2. Good weather resistance, hard and easy to dye

disadvantages: 1. Poor chemical resistance; 2. The maximum long-term service temperature is 93 ° C; 3. Fragility at stress concentration

IV. polystyrene (psgps hard glue) is transparent and amorphous polymer. The shrinkage after molding is less than 0.6. The low-density characteristics make the output greater than 20% to 30% of the general material

advantages: 1. Low cost; 2. Transparent and colorable; 3. Dimensional stability characteristics; 4. High rigidity, good water and drug resistance and good insulation

disadvantages: 1. It is not resistant to impact and is easy to break; 2. Temperature tolerance

v. liquid crystal polyester (LCP) is a semi aromatic polyester with high strength, high elasticity and low linear expansion

advantages: 1. High fluidity 2. Good dimensional stability 3. Solvent resistance 4. High mechanical strength 5. Flame retardant

disadvantages: poor mechanical and physical properties perpendicular to the flow direction

extended data:

plastic material characteristics

<1> chemical corrosion resistance

<2> shiny, partially transparent or translucent

<3> most of them are good insulators

<4> light and strong

<5> easy to process, low price

<6) wide use, multiple effects, easy to color Some high temperature resistant

reference: Baidu Encyclopedia – Plastics

I. acrylonitrile butadiene styrene (ABS) (milky white translucent)

advantages:

1. Good mechanical and thermal properties, milky white translucent, high hardness and easy metal plating on the surface

2. High fatigue and stress cracking resistance and impact strength

3. Resistance to chemical corrosion such as acid and alkali

4. Easy processing and modification

disadvantages:

1. Poor weather resistance

2. The heat resistance is not ideal

3. Low tensile rate

main application scope: machine cover, cover, instrument shell, electric drill shell, fan impeller, shell of radio, telephone and television, some electrical parts, automobile parts, machinery and conventional weapon parts

II. Polyethylene (PE)

advantages:

1. Soft, non-toxic, transparent and easy to dye

2. Impact resistance, drug resistance and good insulation

disadvantages:

1. It is not easy to press out and fit

2. High coefficient of thermal expansion

3. Poor temperature resistance

purpose:

water pipe, gas pipe, industrial chemical container, heavy packaging bag and shopping bag, shampoo bottle, etc

III. polypropylene (PP)

advantages:

1. Translucent, rigid and tough High bending strength, fatigue resistance and stress cracking resistance

2. Light weight, non-toxic, tasteless, high temperature resistance and good insulation

disadvantages:

1. It is easy to become brittle and difficult to join below 0 ℃

2. Poor weather resistance, easy to be decomposed and oxidized by ultraviolet light

It is used to make parts with high precision (P> 3%) and poor stability

purpose:

chemical containers, washbasins, pipes, pump impellers, joints, ropes, packing belts, transparent bottles, insulating materials and auto parts

IV. nylon 66 (PA66)

advantages:

1. It still has high strength, toughness, rigidity and low friction coefficient in a wide temperature range

2. Good wear resistance, self lubrication and self extinguishing

3. Oil resistance and many chemical reagents and solvents (excluding sulfuric acid)

disadvantages:

1. High moisture absorption

2. The impact strength decreases in dry environment

3. The processing and forming process is not easy to control

purpose:

electronic and electrical appliances: connector, reel, timer, cover breaker, switch housing base

automobile: cooling fan, door handle, fuel tank cover, air inlet grille, water tank cover, lamp holder

industrial parts: gear, cam, worm gear, shaft sleeve, bearing bush, chair seat, bicycle transmission frame, skate base, pedal and sliding transmission

v. Polyoxymethylene (POM)

is a crystalline thermoplastic plastic with an obvious melting point of 165 ~ 175 ℃, which is the closest to metal. It is generally called plastic steel

advantages:

1. It has high mechanical strength, rigidity, environmental resistance and repeated impact

2. Good dimensional stability, elasticity, self lubrication and wear resistance

3. Good temperature resistance (- 40 ℃ ~ 120 ℃), good dielectric and good resistance to organic solvents

disadvantages:

1. It is easy to decompose under high temperature for a long time

2, no self extinguishing and poor acid resistance

3. Large forming shrinkage

purpose:

electronic appliances: washing machine, juice machine parts, timer components

automobile: handlebar parts, electric window parts

industrial parts: mechanical parts, gears, handles, toys, screws

data expansion:

1. Most plastics are light, chemically stable and will not rust

2. Good impact resistance

3. It has good transparency and wear resistance

4. Good insulation and low thermal conductivity

5. Generally good formability and coloring, and low processing cost

6. Most plastics have poor heat resistance, high thermal expansion rate and easy combustion

7. Poor dimensional stability and easy deformation

8. Most plastics have poor low temperature resistance, become brittle at low temperature and are easy to age

9. Some plastics are easily soluble in solvents

10. Plastics can be divided into thermosetting and thermoplastic. The former cannot be reshaped and used, and the latter can be produced repeatedly. Thermal plasticity has a large physical elongation, generally 50% ~ 500%. The force does not change linearly at different elongation

reference: Baidu Encyclopedia – Plastics


light weight: the density of plastic is generally between 0.9-2.3g/ml, about half of aluminum and 1 /6 of copper

2. Higher specific strength and stiffness

3. Good chemical stability: good corrosion resistance to chemical substances such as acid and alkali

< p>4. Good electrical insulation: plastic has excellent electrical insulation and arc resistance

5. Good durability and performance

6. Good noise elimination and shock absorption performance

7. Good self lubrication

material properties

<1> chemical corrosion resistance

<2> glossy, partially transparent or translucent

<3> most of them are good insulators

<4> light and solid

<5) easy to process, mass production and low price

<6) wide use, multi-purpose, easy coloring and high temperature resistance

advantages

1. Most plastics have strong corrosion resistance and are not related to acids Alkali reaction

2. Low manufacturing cost of plastics

3. Durable, waterproof and light

4. Easy to be molded into different shapes

5. It is a good insulator

6. Plastics can be used to prepare fuel oil and fuel gas, which can reduce crude oil consumption

disadvantages

1 When recycling waste plastics, classification is very difficult and uneconomical

2. When plastic burns, it is easy to produce toxic gases. For example, toluene is produced when polystyrene is burned. A small amount of this substance will lead to blindness, vomiting and other symptoms when inhaled. PVC combustion will also produce hydrogen chloride toxic gas. In addition to combustion, it is a high-temperature environment, which will lead to the decomposition of plastic into toxic components, such as benzene

3. Plastics are made from petroleum refined products, and petroleum resources are limited

4. Plastic will not rot if it is buried underground for hundreds, thousands or even tens of thousands of years

5. The heat resistance of plastics is poor and easy to aging

6. Due to the non natural degradability of plastic, it has become the first enemy of mankind and has led to the tragedy of many animal deaths. For example, monkeys, pelicans, dolphins and other animals in the zoo will swallow the No. 1 plastic bottle thrown by tourists by mistake, and finally die painfully due to indigestion; Looking at the beautiful and pure sea surface and looking closer, in fact, it is filled with all kinds of plastic garbage that cannot be accommodated by the sea. In the intestines of many dead seabird samples, all kinds of plastic that cannot be digested have been found

reference: Baidu Encyclopedia of plastics

characteristics of common plastic materials:

Properties of polyethylene plastics : Polyethylene refers to the polymer polymerized by ethylene monomer free radical, which is called PE for short in English. The synthetic raw material of PE comes from petroleum and has been ranking first in the output of plastic resin in the world since 1965

at present, the quality of polyethylene mainly includes the following :

low density polyethylene (LDPE)

high density polyethylene (HDPE)

linear low density polyethylene (LLDPE)

(ultra high molecular weight polyethylene) (UHMWPE)

metallocene polyethylene (m-PE)

there are also its modified varieties: ethylene vinyl acetate (EVA), chlorinated polyethylene (CPE)

expanded data:

plastics are classified into general plastics, engineering plastics and special engineering plastics according to the scope of application

general plastic, a kind of plastic with large output, wide application and low price. It mainly includes PE (polyethylene), PP (polypropylene), PVC (polyvinyl chloride), PS (polystyrene), PF (phenolic plastic) and amino plastic. Their total output accounts for more than 75% of the total plastic output. Many products used in people’s daily life are made of these general plastics

engineering plastics, long-term use temperature is 100-150 degrees. It can bear certain external force, has good mechanical properties and dimensional stability, and can maintain its excellent performance at high and low temperature. It can be used as a plastic for engineering structural parts

because of their high mechanical strength or special properties such as high temperature resistance, corrosion resistance and radiation resistance, they can replace metals for some loading and unloading components or other special purposes. Commonly used are PC (polycarbonate), PA (polyamide), POM (polyoxymethylene), PSF (polysulfone), ABS, PPS (polyphenylene sulfide), CP (chlorinated polyether), pet (polyethylene terephthalate), PBT (polybutylene terephthalate), UHMWPE (ultra high relative molecular weight polyethylene), EP (epoxy resin), phenolic epoxy resin and PU (polyurethane). The tensile strength of Engineering (and special) plastics is generally more than 50MPa, and the bending modulus is more than 2gpa

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