高分子材料英文-塑料PE

• The increase of molecular weight results in the increase of the entanglement and the attraction between macromolecular chains, and most of the mechanical properties are improved.
3. Properties
Odorless、non-poisonous; Density: 0.91-0.96g/cm3 ; Milk white waxy solid, the material is translucent or opaque（半透明或不透 明）, transparent (透明的), with the increase in the degree of crystallinity transparency is decreased; Permeability to water(透水) is low, permeability to gas(透气) is large, suitable for moisture proof packaging(防潮包装); Flammable, the oxygen index of 17.4, low smoke when burning, a small amount of melt dripping（熔滴）, paraffin (石蜡) smell.
Polyethylene film
3.1 Mechanical properties
▪ General mechanical properties（机械性能一般）,low strength, low hardness and rigidity;
Polyethylene barrel
▪ Soft and tough（软而韧）, strong creep （强的蠕变） under persistent force, high impact strength （冲击强度） as well as low friction（低摩擦）; ▪ Factors affecting mechanical properties 1) Crystallinity 2) molecular weight
塑化
冷却硬化-热塑性塑料
Fra Baidu bibliotek交联固化-热固性塑料
Plastics▪Classification
PE (Polyethylene)聚乙烯
PP(polypropylene)聚丙烯
PS(polystyrene)聚苯乙烯 PVC(polyvinyl chloride)聚氯乙烯 Other general plastics（commodity plastics）通 用塑料 Engineering plastics 工 程塑料
2.3 Molecular weight of PE
2.3.1 Representation of molecular weight
Melt flow rate (MFR熔体流动速率): the mass of PE melt heated to 190 degrees under 21.2N pressure from a hole in a certain pore size every 10 minutes, g/10min
•The degree of crystallinity is related to the degree of branching of the macromolecular chain, and the degree of branching depends on the polymerization method. HDPE with low degree of branching ,high crystallinity, high density, high mechanical properties and poor toughness. LDPE with high degree of branching,low crystallinity, low density, low mechanical property and good impact performance.
industry 、Agriculture etc.
2. Structure
2.1 Structure of PE
• Linear polymer ，Linear long chain 线性聚合物 • Nonpolar group, Small intermolecular forces 非极性基团 • Spatial arrangement- Planar zigzag (平面锯齿) • The molecular chain-good flexibility and regularity(良好柔顺性规整
Polymer Materials
----Plastic
I‘m surrounded by plastic!
What is the plastic ?
A. resin
base 基础材料---树脂 material B. Add proper polymeric additive 高分子助剂
C. With the aid of 成型设备 molding facility D. Certain temperature and pressure plasticizing shape and size E. Cooling and hardening ---thermoplastics Cross-linking and Solidity-thermosets
3.2 Thermal properties
Not high heat resistance, low thermal deformation temperature, improved with the increase of molecular weight and crystallinity ;
20-30 branches of per 1000 carbon atoms
LDPE
not only contains ethyl, butyl short branched chain, but also contains a long chain, may be as long as the main chain
性); Can be repeatedly folded and stacked to form a crystal
• Molecular chains contain short methyl groups and long alkyl chains.
Polyethylene
• Both the crystalline structure, and amorphous structure exist
The greater the MFR, the better the liquidity, the higher the melt viscosity.
Numberaverage Molecular Weight MFR g/10min Melt Viscosity Pa· s (190℃)
19,000 21,000 24,000 28,000 32,000 48,000 53,000
Synthesis method
High- pressure method Temperature：150～300℃ Pressure：150～300MPa
Polymerization mode
homopolymer monomer:ethylene
HDPE
1953
Germany，Ziegler(齐格勒)， Low- pressure、medium-pressure homopolymer Temperature：85～100℃ US, Phillips Petroleum monomer:ethylene Company(美国菲利浦石油 Pressure：ordinary pressure～ 化学公司) 2MPa Low pressure gas phase method Temperature：75～90℃ Pressure：1.4～2.1 MPa copolymer monomer：ethylene 、 α-olefin(α-烯烃)
PE (聚乙烯)
1. Overview
2. Structure 3. Properties 4. Applications
1. Overview 概述
• molecular formula：—[CH2—CH2]n—
• monomer：ethylene • Synthesis method：free radical polymerization(自由基聚合)、coordination polymerization(配位聚合) • Synthesis materials：petroleum; Ethylene monomer was obtained from petroleum cracking • Production：Since the middle of 1960s, has been the highest in the first place, accounting for 1/3 of the total amount of plastic • Characteristics ：light quality、non-poisonous、Excellent chemical resistance、 Electrical insulation、Low temperature resistance, Easy processing and forming • Application：Appliance（家用电器）、Chemistry、Food、Machine building
170 70 21 6.4 1.8 0.25 0.005
45 110 360 1,200 4,200 30,000 1,500,000
2.3.2 Effect of PE molecular weight on mechanical properties
The higher the molecular weight, the greater the entanglement and the attraction between macromolecular chains. Tensile strength 、 surface hardness、Abrasion resistance、 creep resistance、aging resistance、solvent resistance are improved.
LLDPE
1970
HDPE
about 5 short branches per 1000 carbon atoms;
LLDPE
substantially linear polymer (polyethylene), with significant numbers of short branches
The effects of crystallinity and molecular weight
•The crystallinity increases, and the mechanical properties increase except for the impact strength.
2.2 Classification of PE
Polyethylene can be classified by its density: LDPE(低密度聚乙烯)、HDPE(高密度 聚乙烯)、LLDPE(线性低密度聚乙烯).
Year
LDPE 1933
Companies
UK，Imperial Chemical Industries Ltd（ICI）