Polymer PhysicsPolymer Physics高分子物理高分子物理

王苓College of Material Science &

Engineering

《《An Introduction An Introduction to Polymer Physicsto Polymer Physics》》

By David I. Bower

CAMBRIGDE University Press

1. Introduction2. Molecular sizes and shapes and ordered structure3. Regular chain and crystallinity4. Morphology and motion5. Mechanical properties I – time-independent

elasticity6. Mechanical properties II – linear viscoelasticity7. Yield and fracture of polymers8. Polymer blends, copolymers and liquid-crystal

polymers

Contents

Charpter 1 Introduction

1.1 Polymers and the scope of the book1.2 A brief history of the development of synthetic polymers1.3 The chemical nature of polymers

1.3.1 Introduction1.3.2 The classification of polymers1.3.3 Newer polymers and polymerization processes

1.4 Properties and application1.5 Polymer processing

1.5.1 Introduction1.5.2 Additives and composites1.5.3 Processing methods

1.6 Further reading

1.1 Polymer and scope of the book

1. What is polymers?

polymers are all around us in everyday use:

In rubber, in plastics, in resins, in adhesives and in adhesive tapes 粘胶带.

Extraordinarily versatile class of material

with properties of a given type often having enormously different values

for different polymers even sometimes for the same polymer in

different physical states.

Young’s modulus: for a typical rubber 10 MPafor a fibre of a LCP 350 GPa

Conductivity 导电性:the best insulating polymer 10-18Ω-1 m-1

polyacetylene with suitable donor 104Ω-1 m-1

聚乙炔 杂质

For example:

Synthetic polymers 合成聚合物– produced by chemical industry• substitutes for the natural polymers• long outgrown to be a substitute• become a important material

Biopolymer - produced by living system and are used with little or no modification• textile fibres (silk, wool and linen)• wood• natural rubber

type of polymers 聚合物的类型

2. The scope of this book

synthetic polymersPolymer in the solid state

structure –conformation 构象, Configuration 构型, morphology 聚集态

propertiesmolecular motion

纤维素的化学结构

1930 – polystyrene （聚苯乙烯） in Germany1936 – commercial poly(methyl methacrylate) （聚甲基丙烯

酸甲酯）was produced by ICI in UKthen polyethylene （聚乙烯）afterwards

1932 – aliphatic polyesters 脂肪族聚酯was in produced 1938 – nylon-6,6 was in production by Du Pont1939 – poly(vinyl chloride) or PVC（聚氯乙烯）was largely

produced in Germany then USA1939-41 poly(ethylene terephthalate) (聚对苯二甲酸乙二酯)

as an example of the deliberate design of a polymerfor special purpose - the production of fibres

1.2 A brief history of the development of synthetic polymers

1941 – polyurethane （聚氨酯）in Germany1945 – silicon rubber （硅橡胶）which can withstander

much higher temperature1950 – polyolefin (CnH2n) （聚烯烃）

• 1953 – polyethylene produced at low pressure by Ziegler• 1954 – successful polymerization of polyethylene with high molar mass• 1962 – stereospecific （有规立构的）polymerisationof polypropylene and produced in large volume (by Natta)

1960 – linear thermoplastic polycarbonate （聚碳酸酯）as made in 1953 and brought into commercialproduction in 1960

1970 – Kevlar fibre commercially manufactured which wastheoretical prediction by Onsager and Flory

1980s- thermoplastic co-polyester ( rigid main chain liquidcrystal polymers) was manufactured

1987 – blending of polymers (高聚物共混）reasons:

1) reducing cost of new type of polymer;2) products with properties which were acombination of the constituent polymer

1970s – 1980s started to develop the interesting60-70% of polyolefin + 23 % other polymers

The important way to form new materials

With less expense to develop new polymer – influencing their properties

• by variours physical treatments:

annealing – improve mechanical properties fornon-crystalline polymers crystalline polymers stretching – improve the tensile strength of

polymer fibres

15世纪 美洲玛雅人用天然橡胶做容器，雨具等生活用品。

1839 美国人古德伊尔(Charles Goodyear)发现天然橡胶与硫

磺共热后明显地改变了性能，使它从硬度较低、遇热发粘软化、遇冷发脆断裂的不实用的性质，变为富有弹性、可塑性的材料。

1869 美国的海厄特(John Wesley Hyatt,1837-1920)把硝化纤

维、樟脑和乙醇的混合物在高压下共热，制造出了第一种人工合成塑料“赛璐珞”(cellulose)。

1887 Count Hilaire de Chardonnet用硝化纤维素的溶液进行

纺丝，制得了第一种人造丝。

高分子材料发展史大事记

1909 美国人贝克兰(Leo Baekeland)用苯酚与甲醛反应制造出第一种完全人工合成的塑料--酚醛树酯。

1920 施陶丁格(Hermann Staudinger)发表了"关于聚合反应"(Uber Polymerization)的论文提出：高分子物质是由具有相同化学结构的单体经过化学反应(聚合)，通过化学键连

接在一起的大分子化合物，高分子或聚合物一词即源于此。

1926 瑞典化学家斯维德贝格等人设计出一种超离心机，

用它测量出蛋白质的分子量：证明高分子的分子量的确是从几万到几百万。

1926 美国化学家Waldo Semon合成了聚氯乙烯，并于1927年实现了工业化生产。

1930 聚苯乙烯(PS)发明。

1932 施陶丁格(Hermann Staudinger)总结了自己的大分子

理论，出版了划时代的巨著《高分子有机化合物》成为高分子化学作为一门新兴学科建立的标志。

1935 杜邦公司基础化学研究所有机化学部的卡罗瑟斯(Wallace H. Carothers，1896-1937)合成出聚酰胺66，即尼龙。尼龙在1938年实现工业化生产。

1930 德国人用金属钠作为催化剂，用丁二烯合成出丁钠

橡胶和丁苯橡胶。

1940 英国人温费尔德(T.R.Whinfield,1901-1966)合成出聚酯纤维(PET)。

1940s Peter Debye 发明了通过光散射测定高分子物质分子量

的方法。

1948 Paul Flory 建立了高分子长链结构的数学理论。

1950s 德国人齐格勒(Karl Ziegler)与意大利人纳塔(GiulioNatta)分别用金属络合催化剂合成了聚乙烯与聚丙烯。

1955 美国人利用齐格勒-纳塔催化剂聚合异戊二烯，首次用

人工方法合成了结构与天然橡胶基本一样的合成天然橡胶。

1971 S.L Wolek 发明可耐300oC高温的Kevlar。

1.3.1 Definitions

1. polymer – a particular class of macromolecules consisting• a set of regularly repeated chemical units of the same

type, • possibly of a very limited numbers of different types

(usually only two) joined end to end• sometime in more complicated ways, to form a chain

molecules.

1.3 The chemical nature of polymers

Homopolymer – only one type of chemical unit in the macromolecules consistingCopolymer – more than one type of chemical unit in the macro-molecules consisting

2. monomer or monomer unit – chemical repeat unit

the small molecule which polymerizes to give the polymer

3. distribution of molecular masses (M) – molecular weight and corresponding molar masses M

the molecules of polymer are not all identical

4. backbone bond – the covalent bonds to link monomer units together to form a polymer chain.

Fig. 1.2 Structure of the repeating units of some common polymers.

聚异丁烯

聚甲醛

聚甲基丙烯酸甲酯(有机玻璃)

聚对苯二甲酸乙二酯

1.3.2 The classification of polymers

1) Based on structure:

• Linear (线型）• Branched （支化型）• Network （交联型）

Fig. 1.3 Schematic representations of (a) a linear polymer, (b) a branched polymer and (c) a network polymer. The symbol represents a cross-link point, i.e. a place where two chains are chemically bonded together.

2) Based on properties:

• Thermoplastics （热塑性塑料）-structure: linear or branched polymerproperty: they melt when heated – can be moulded

they may form a glass on cooling - Tgthey may crystallize

• Rubbers (elastomers) -（橡胶）structure: network polymer – lightly crosslinkedproperty: reversibly stretchable to high extension

fairly tightly randomly coiled moleculesthe cross link prevent molecules from flowing past each other when stretchedon cooling they become glassy or crystallisepartiallyon heating they can not melt in conventional sense (due to crosslink)

• Thermosets- （热固性塑料）Structure: network polymer (due to heavily crosslink)Property: they are normally rigid

on heating they can not melt, when T is high enough they decompose

• main chain LCPs 主链液晶聚合物– linear rod like such as Kevlar：stiff material will withstanding hightemperature have high molecular orientation

• side-chain LCPs 侧链 – non linear optical materialpossible to incorporate into the polymer as chemically linked side-chains. 液晶原连接在侧链上

Liquid crystal polymers (LCPs) 液晶聚合物– subset of thermoplastics

property: in some temperature range molecules tend to line up parallel to each other

1.3.3 Classical polymerisation processes经典的聚合反应过程

1）Polymerization – monomer units react to give polymer molecules.

e.g. ethylene —> polyethylene

2）Addition polymerization 加成聚合-- there are three stages

• Initiation step 引发阶段 –a free radical from an initiator added to the system,将带有自由基的引发剂加入系统attacks and opens the double bond of a molecule of the monomer, producing a new activated species.单体分子的双键断开，形成新的活性物

• Propagation step 传播阶段–this species adds on a monomer unit which becomes the new site of activation and adds on another monomer unit in turn.

• Termination step 终止阶段 –normally occurs by one of a variety of specific chain-terminating reactions, which lead to a corresponding variety of the end groups.

3）Step-growth polymerisation 逐步聚合 -

Repeat process of joining together smaller moleculeswhich are usually of two different kinds at the begining

Condensation polymer are an important class of step-growth polymers formed by the common condensation reactions of organic chemistry.缩合聚合物是重要的一类逐步聚合高分子，通过有机化学普通缩合反应形成的。

1.3.4 Newer polymers and polymerisation processes

Newer processes have been and being developed with a variety of aims in mind. These involve:

production of novel polymer topologies 新颖的聚合物拓扑学

precise control over chain length and over monomer sequences in copolymer 共聚高分子单体顺序及链长的精确控制

control of isomerism 同分异构控制production of polymers with special reactive end

groups, the so-called telechelic polymer 遥爪聚合物的制备production of specially designed thermally stable

polymers and liquid crystal polymers with a variety of different structure and properties

遥爪聚合物在其链的一端或两端带有活性功能基的聚合物，常由

活性聚合反应制成的。遥爪聚合物常用来制备嵌段共聚物，制备星形或树枝状聚合物或形成网状结构（由末端键合）。

production of polymers with very precisely defined molar masses

production of networks with defined chain lengths between entanglements

or made stiff rather than flexible chain

1.4 Properties and application

Why the properties of polymer make them so important for a wide variety of application?

aluminium has a density roughly twicecopper & steel have densities of order six times

poly(ethylene terephthalate) PET is used not only as a textile fibre

but also as a packaging material in the form of film and bottle

low densities

the versatility of polymers （多功能性）

polymer can be used as plastics, rubbers, fibres, coatings, adhesives, foams .

ability to be cast or moulded into complex shapes, reduce machining & assembly cost

poly(vinyl chloride) PVC is used not only as a rigid material for making mouldings but also in elasticized form, for making flexible tubing and artificial leather

many of their use are combination of propertiesHigh strength-to-weight ratioHigh stiffness-to-weight ratioHigh resistance to chemical attack Resistance to chemical attack combined with high electrical resistanceFlexibility combined with toughness

Medical use include:

• tooth fillings• components for hip-joint replacement• contact and implant lenses

Non-medical speciality uses include

• conducting polymers for rechargeable batteries• polymer sensors for many applications• high-density information storage, CD or holographic devices• smart windows that can react to levels of light• liquid crystal displays

1.5 Polymer processing

1.5.1 Introduction

• giving a brief introduction to the processing of polymers• to understand polymeric materials in actual use are not simple

additiveshow to ease processinghow to improve performance

1.5.2 Additives and composites

Classification of additives:

fillers(充填物)– to produce cheaper product or to improve properties

anti-oxidants (抗氧化剂) – to prevent degradation of polymer

stabiliser (稳定剂) – to prevent the inferior effect of environment conditions

plasticisers (塑化剂)– to give a plasticity to a polymerfire retardants (阻燃剂)- to prevent or retard polymer

to be fired pigments (色素)– to give a colour to a polymer productlubricants (润滑剂)– to prevent adhesion of the

polymer to the processing equipment

Composites: there is a second component added into a polymer.

• is a filler • is a reinforcement to increase the strength and stiffness of products

1.5.3 Processing methods

The principal processing methods are:

• injection moulding （注塑） -• extrusion（挤出）• below moulding （吹塑成型）• calendering（压延）• thermoforming（热成型）• reaction moulding

diescreen

gearbox

hopper

melting and pumping pumping

solids conveying

polymer out

die heaters

screw barrel screen

pellets in

Diagram of an extruder.