高分子材料英文-塑料PE.pptx

Polymer Materials ----Plastic;;What is the plastic ?;Plastics?Classification;PE (聚乙烯);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 industry 、Agriculture etc. ;2. Structure ;2.2 Classification of PE;HDPE;2.3 Molecular weight of PE;3. Properties;3.1 Mechanical properties ; The effects of crystallinity and molecular weight;3.2 Thermal properties;1) Polyethylene consists of nonpolar, saturated, high molecular weight hydrocarbons; 2) Because of their symmetric molecular structure, they tend to crystallize; 3) Overall polyethylene is partially crystalline. Higher crystallinity increases density and mechanical and chemical stability. 4) Polyethylene absorbs almost no water. The gas and water vapor permeability (only polar gases) is lower than for most plastics; oxygen, carbon dioxide and flavorings（调味品） on the other hand can pass it easily.;Polyethylene anticorrosive tape;;3.4 Electrical properties;PE can become brittle when exposed to sunlight. Carbon black is usually used as a UV stabilizer（紫外线稳定剂）; ;3.6 Processability ; Comparison of structure and properties of three kinds of polyethylene; （1）Ultra high molecular weight polyethylene（UHMW-PE）（3.5 and 7.5 million） ;4. Applications;Low molecular weight polyethylene;Exercises