范文一：高分子材料与工程专业英语课文

UNIT 22 Mechanical Properties of Polymers

聚合物的力学性能

The mechanical properties of polymers are of interest in all applications where polymers are used as structural materials. Mechanical behavior involves the deformation of a material under the influence of applied forces.

聚合物的力学性能感兴趣的所有应用中聚合物被用作结构材料。机械行为涉及材

料形变的影响下，施加的力。

The most important and most characteristic mechanical properties are called moduli. A modulus is the ratio between the applied stress and the corresponding deformation. The re-ciprocals of the moduli are called compliances. The nature of the modulus depends on the na-ture of the deformation. The three most important elementary modes of deformation and the moduli (and compliances) derived from them are given in Table 22.1, where the definitions of the elastic parameters are also given. ? Other very important, but more complicated, de-formations are bending and torsion. From the bending or flexural deformation the tensile modulus can be derived. The torsion is determined by the rigidity.

最重要和最具特色的机械特性被称为模。一个模之间的比例应力和相应的变形。

该re-ciprocals的称为弹性模量。性质的模量取决于钠?真实的变形。三个最重

要的基本模式和变形模量(和依从性)来自他们在表22.1中给出的定义，给出

了弹性参数。?其他非常重要，但更为复杂，de-formations是弯曲和扭转。从弯

曲或弯曲变形，拉伸模量可导出。扭转是由僵硬。

Cross-linked elastomers are a special case. Due to the cross-links this polymer class shows hardly any flow behavior. The kinetic theory of rubber elasticity was developed by Kuhn , Guth, James, Mark, Flory, Gee and Treloar. It leads, for Young's modulus at low strains, to the following equation s

交联弹性体是一种特殊情况。由于这类的交联聚合物显示几乎没有任何流动行

为。橡胶弹性动力学理论是由库恩，杰姆斯，马克，古思，弗洛里，吉和特雷洛

尔。它的领导，为杨氏模量低的菌株，对以下方程

E=3RTp/Mcrl = 3zcrlRT/V=3C0

The paragraphs above dealt with purely elastic deformations, i. e. deformations in which the strain was assumed to be a time-independent function of the stress. In reality, materials are never purely elastic: under certain circumstances they have nonelastic properties. This is especially true of polymers, which may show nonelastic deformation under circum-stances in which metals may be regarded as purely elastic. ? It is customary to use the ex-pression viscoelastic deformations that are not purely elastic. Literally the term viscoelastic means the combinations of viscous and elastic properties. As the stress-strain relationship in viscous deformations is time-dependent, viscoelastic phenomena always involve the change of properties with time. Measurement of the response in deformation of a viscoelastic material to periodic

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forces, for instance during forced vjbration, shows that stress and strain are not in phase; the strain lags behind the stress by a phase angle 8, the loss angle. So the moduli of the materials, the complex moduli, include the storage moduli which determine the amount of recoverable energy stored as elastic energy, and the loss moduli which determine the dissipation of energy as heat when the material is deformed.

以上段落处理纯粹的弹性变形，即变形，应变假定时间独立功能的应力。在现实中，材料是

不纯粹的弹性:在某些情况下他们的非弹性性能。这是特别真实的聚合物，这可能表明非弹

性变形情况下，金属可能被视为纯粹的弹性。?通常使用粘弹性变形的表达式，并不是纯粹

的弹性。粘弹性是指粘性和弹性性能的结合。由于应力应变关系的粘性变形的时间依赖性，

粘弹现象总是涉及的性能随着时间的变化。测量反应在变形的粘弹性材料定期部队，例如在

被迫vjbration，表明应力和应变不阶段;应变滞后的压力的相位角8，损耗角。因此，模量

的材料，复模量，包括储存模量的确定数额的可恢复能源存储弹性能量，和损失模量确定能

耗的热量时，材料的变形

UNIT 23 Thermal Properties of Polymer

热性能的聚合物

The heat stability is closely related to the transition and decomposition temperature, i. e. to intrinsic properties. By heat stability is exclusively understood the stability (or re-tention) of properties (weight, strength, insulating capacity, etc. ) under the influence of heat. The melting point or the decomposition temperature invariably form the upper limit; the "use temperature" may be appreciably lower.

热稳定性是密切相关的过渡和分解温度，即内在特性。热稳定性是完全理解的稳

定性(或re-tention)性能(体重，强度，绝缘能力，在热的影响等。)。熔点

或分解温度总是形式的上限;“使用温度可明显降低。

The way in which a polymer degrades under the influence of thermal energy in an inert atmosphere is determined, on the one hand, by the chemical structure of the polymer itself, on the other hand, by the presence of traces of unstable structures.

方式，聚合物降解的影响下，热能在惰性气氛是确定的，一方面，通过化学结构

的聚合物本身，另一方面，存在的痕迹不稳定结构。

Thermal degradation does not occur until the temperature is so high that primary chemi-cal bonds are separated. For many polymers thermal degradation is characterized by the breaking of the weakest bond and is consequently determined by a bond dissociation energy. Since the change in entropy is of the same order of magnitude in almost all dissociation reac-tions, it may be assumed that also the activation entropy will be approximately the same. This means that, in principle, the bond dissociation energy determines the phenomenon. So it may be expected that the temperature at which the same degree of conversion is reached will be virtually proportional to this bond dissociation energy. ?

热降解不会发生，直到温度较高，主要化学债券分离。对许多聚合物热降解的特

点是打破最薄弱的债券，从而确定一个键的离解能。由于熵的变化是相同的数量

级在几乎所有的解离反应，可以假定，同样的活化熵是大致相同的。这意味着，

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在原则上，键离解能确定的现象。因此可以预计，温度在相同转化率达到将几乎

成正比这个键离解能。?

The process of thermal decomposition or pyrolysis is characterized by a number of ex-perimental indices, such as the temperature of initial decomposition, the temperature of half decomposition, the temperature of the maximum rate of decomposition, and the average en-ergy of activation. The heat resistance of a polymer may be characterized by its "initial" and "half" decomposition.

热分解过程或裂解的特点是一些试验指标，如初始分解温度，温度的分解温度的

一半，最大分解速率，和平均能量活化。耐热聚合物的特点是其“初始”和“半”分

解。

There are two types of thermal decomposition: chain depolymerization and random de-composition. The former is the successive release of monomer units from a chain end or at a weak link, which is essentially the reverse of chain polymerization; ? it is often called deprop-agation or unzippering. This depolymerization begins at the ceiling temperature. Random degradation occurs by chain rupture at random points along the chain, giving a disperse mix-ture of fragments which are usually large compared with the monomer unit. The two types of thermal degradation may occur separately or in combination; the latter case is rather nor-mal. Chain depolymerization is often the dominant degradation process in vinyl polymers, whereas the degradation of condensation polymers is mainly due to random chain rupture. 有2种热分解:链式解聚和随机分解。前者是连续释放单体单位从一个链或薄弱

的一个环节，其本质是反链聚合;?常被称为deprop-agation或unzippering。

这解开始在上限温度。随机降解发生链断裂随机点沿链，使分散混合片段，通常

是比较大的单体单元。不同类型的热降解可能发生单独或合并;后者是相当

nor-mal.链式解聚往往是主要降解过程中的乙烯基聚合物，而退化的缩合聚合物

主要是由于随机链断裂。

The overall mechanism of thermal decomposition of polymers has been studied by Wolfs et al. The basic mechanism of pyrolysis is sketched in Fig. 23.1.

整体热分解机理聚合物研究了狼等人。基本机制的热解是绘在图23.1。

In the first stage of pyrolysis (<550?c) a="" disproportionation="" takes="" place.="" part="" of="" the="" de-composing="" materials="" is="" enriched="" in="" hydrogen="" and="" evaporated="" as="" tor="" and="" primary="" gas,="" the="" rest="" forming="" the="" primary="" char.="" in="" the="" second="" phase="" (="">550?C) the primary char is further decom-posed, i. e. mainly dehydrogenated, forming the secondary gas and final char. During the disproportionation reaction, hydrogen atoms of the aliphatic parts of the structural units are "shifted" to saturate" part of the aromatic radicals. The hydrogen shift during dispropor-tionation is highly influenced by the nature of the structural groups.

在第一阶段的热解(<>

丰富的氢气和蒸发作为主要气体，其余形成的主要特征。在二期(>550?丙)的

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主要特征是进一步decom-posed，即主要脱氢，形成二次气体和焦炭。在歧化

反应，氢原子的脂肪部分的结构单位”转向“饱和”一部分的芳香自由基。氢转移过

程中dispropor-tionation高度影响的性质的结构组。

Reading Materials

Requirements for Heat Resistance

Heat resistance is the capacity of a material to retain useful properties for a stated period of time at elevated temperatures (?230?C) under defined conditions, such as pressure or vacuum,

mechanical load, radiation, and chemical or electrical influences at temperatures ranging from cryogenic to above 500?C. Both reversible and irreversible changes can occur. In a reversible change, for example, as a polymer under load approaches the glass-transition temperature Tg, deformation occurs without change in chemical structure. Reversible changes occur primarily as & function of Tg, which for the purposes of this article, i. e. , for high temperature structural polymers, must be above 230?C. The maximum-use temperature for an amorphous or semicrystalline structural resin usually depends on Tg rather than the crystalline melt temperature Tm. A semicrystalline polymer can exhibit substantial loss of mechanical properties near the Tg, depending upon the degree of crystallinity. The Tm is usually so high that in its vicinity chemical degradation occurs. Irreversible changes alter the chemical structure. For example, exceeding the thermal stability results in bond breaking.

The chemical factors which influence heat resistance include primary bond strength, secondary or van der Waals bonding forces, hydrogen bonding, resonance stabilization, mechanism of bond cleavage, molecular symmetry (structure regularity), rigid intrachain structure, and cross-Unking and branching. The physical factors include molecular weight and molecular weight distribution, close packing (crystallinity ), molecular (dipolar) interac-tions, and purity.

The primary bond strength is the single most important influence contributing to heat resistance. The bond dissociation energy of a carbon-carbon single bond is ~ 350 kj/mol (83.6 kcal/mol), and that of a carbon-carbon double bond is ~610kJ/mol (145.8 kcal/ mol). In aromatic systems, the latter is even higher. Known as resonance stabilization, this phenomenon adds 164~287kJ/mol (39. 2—86. 6 kcal/mol). As a result, aromatic and hete-rocyclic rings are widely used in thermally stable polymers.

Secondary or van der Waals bonding forces provide additional strength and thermal stability. Dipole-dipole interaction and H bonding contribute 25 ~ 41 kj/mol (6.0 ~ 9.8 kcal/mol)toward molecular stability and affect the cohesion energy density* which influences the stiffness , Tg, melting point , and solubility. Thus , beat-resistant polymers often contain polar groups, e.g. , —CO—, —S02—, that participate in strong intermolecular associa-tion. Polymers containing electron-withdrawing groups, e. g., —CO—, as connecting groups are generally more

stable than those containing electron-donating groups, e. g. . —O—.

The mechanism of bond cleavage also influences thermal stability. In polysiloxanes, for example, the energy of the silicon-oxygen single bond is ~445kJ/mol (106. 4kcal/mol), and that of the silicon-carbon single bond ~328kJ/mol (78. 4kcal/mol). Although the Si—C bond would be

expected to cleave at high temperatures more readily than the Si—O bond, the latter breaks at high

temperatures to form low molecular weight cyclic siloxanes because this degradation route is energetically favored.

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Molecular symmetry or regularity of the chemical structure arises when moieties are joined in the same position in each repeat unit. The presence of isomers lowers Te. Rigid in-trachain structure refers to substitution of the aromatic or heterocyclic ring. Although para-oriented polymers have the highest thermal stability and Tg, they have the lowest solubility and processability.

Cross-linking improves heat resistance of a polymer primarily because more bonds must be cleaved in the same vicinity for the polymer to exhibit a weight loss or reduction in mechanical properties. Crystalline regions in a polymer serve as cross-links. Branching in a polymer tends to lower the thermal stability.

Molecular weight and molecular-weight distribution influence mechanical and physical properties. Higher molecular-weight polymers are more heat resistant than lower molecular-weight materials because of more entanglements and the ability to accommodate more chain cleavage without significant property reduction. Low molecular-weight polymers exhibit lower Tgs.

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范文二：高分子材料与工程

高分子材料与工程

Macromolecular Materials & Engineering

一、专业特色

根据高分子学科的基本特色，本专业按如下三个方向开展本科教学工作：高分子材料的合成、加工和改性、各种功能的高分子材料、复合材料和特种橡胶。近年来，在专业建设上，坚持基础理论研究与应用研究并重，高分子合成、改性与物理性能研究并重的特色。 二、培养目标

培养具有高分子材料与工程专业的基础知识，了解材料科学与工程领域相关的基础知识，能在高分子材料领域从事科学研究、教学、技术开发、工艺设计、生产及经营管理等方面工作，有较强的计算机应用能力和语言表达能力；身心健康并富有创新精神的高素质研究应用型专门人才。 三、培养要求

本专业学生主要学习四大化学、高分子化学和物理、高分子成型加工原理和设备、高分子功能材料、复合材料、高分子材料研究方法、高分子材料配方设计以及计算机在高分子材料中的应用等基本理论和基本技能，掌握高分子材料的成型加工和改性工艺和方法，掌握新型高分子材料的研究方法，具备对高分子材料合成、改性、加工以及功能化过程进行技术经济分析、研究开发和经营管理的基本能力。

毕业生应获得以下几方面的知识和能力： 1．具备扎实的物理、化学、化工基础知识；

2．掌握高分子化学、高分子物理、材料科学与工程的基本理论； 3．掌握高分子材料合成、改性和性能评价的方法； 4．掌握高分子材料的组成、结构与性能之间的关系；

5．掌握高分子加工流变学、成型加工工艺和加工设备的基本理论和基本技能； 6．具有对高分子材料进行改性、加工工艺研究、设计和分析测试的能力； 7．具有对新型高分子材料及功能高分子材料设计及制备的能力； 8．具有应用计算机对高分子材料进行配方设计的能力；

9．具有对高分子材料合成、改性、加工以及功能化过程进行技术经济分析、研究开发和管理的综合能力。 四、学制与学位

标准学制：四年 修业年限：三至六年 授予学位：工学学士 五、主干学科、主干学科、交叉学科

主干学科：材料科学与工程 交叉学科：化学、物理学 六、主要课程

有机化学、物理化学、化工原理、高分子化学、高分子物理、材料物理基础、高分子材

料研究方法、材料成型原理与工艺、高分子材料配方设计、高分子成型设备与模具、功能高分子材料、复合材料学、橡胶材料学等。 七、集中实践教学环节

军事训练、金工实习、VB课程设计、化工原理课程实习、化学综合实验、高分子基础实验、高分子制备课程设计、高分子成型综合实验、生产实习、毕业设计。 八、课程体系结构及学分比例

课程类别

通识教育基础课

General Education Courses 学科基础课

Basic Courses of Disciplines 专业课

Specialized Courses 学科选修课

Disciplines Electives 集中实践教学环节 Practical Training 第二课堂

The Second Classroom

合 计 Total

学 分 72 47.5 15 10 30 4 178.5

学分比例 40.34% 26.61% 8.40% 5.60% 16.81% 2.24% 100%

九、学习进程拓扑图

具体内容见附表。 十、教学计划进程表

具体内容见附表。 十一、十一、其他

高分子材料与工程专业2008级教学计划进程表

表1 基础课

课

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