Phase behavior studies of the system polystyrene-polybutadiene-chloroform. II. Modification of the Flory-Huggins theory

Phase behavior of polymer-polymer-solvent systems can be determined using gel permeation chromatography. This technique enables one to generate the binodal curve and tie lines relating coexisting phases, to locate the critical point and, through the use of an appropriate solution theory, to calculate interaction parameters. Previous studies of the incompatible polystyrene-polybutadiene-chloroform system indicated that the classical Flory-Huggins theory yields an anomalous behavior of negative interaction parameters. Probable causes are specific interactions due to the polar nature of chloroform plus failure to account for the concentration dependence of the polystyrene-chloroform interaction. A modified version of the Flory-Huggins theory incorporating concentration dependence of polymer-solvent interaction was used to reevaluate the polystyrene-polybutadiene-chloroform system. This approach yields positive interaction parameters for the incompatible system polystyrene and polybutadiene.     

Application of flory-erman theory to rubber in biaxial strain

The modified statistical theory of rubber elasticity introduced by Flory ⁵ is designed to take into account the constraints on the fluctuations of network junction points arising from spatial occupancy of neighbouring chains. This theory has been applied by Erman ² with some success to the rather limited experimental data of Jones and Treloar ⁶ for natural rubber subjected to biaxial strains of the most general type. However, when applied to the more extensive data of Vangerko and Treloar ¹² he theory is found to be seriously inadequate in the high-strain region. This inadequancy is thought to be due primarily to the neglect of the limited extensibility of the network chains, though straininduced cystallisation may also play some part.     

The theory of rubber elasticity

It is argued that one can envisage two extreme regimes in rubber. The first is a dilute regime, where crosslinks are the only significant interaction between chains, and is the conventional model. The other extreme is one in which a very entangled situation exists where the chain statistics under deformation are remote from free Gaussian statistics. This latter case is studied and it is argued that the entropy per crosslink takes the form where α and β are independent of deformation but depend on temperature and density, and J² is the usual first invariant. The dilute regime is α = β = 0.     

Molecular theory of rubber elasticity

Theories of rubber elasticity are reviewed and compared. Principal differences centre on the connection between the locations of network junctions and the macroscopic strain. Constraints on junctions imposed by surrounding chains have been postulated to be responsible for departures of experiments from the theory for idealized ‘phantom’ networks. Experimental evidence in support of theory developed using this hypothesis is discussed.     

硅橡胶在电力系统外绝缘中的应用

通过试验数据分别分析了在输变电设备上使用的室温硫化硅橡胶和热硫化硅橡胶（HTV）的运行特性，着重介绍了运行条件对HTV硅橡胶憎水性能的影响、运行HTV硅橡胶的耐漏电起痕及电蚀损性能、机械性能和积污特性。认为因老化引起的憎水性、机械强度、积污性能下降以及材料劣化均影响着其长期工作的可靠性，需改进配方，以满足外绝缘材料长期运行的要求；并比较了3种硅橡胶材料的老化试验方法：斜面法、1000h盐雾法及5000h老化试验方法的试验条件、试验程序、试验现象、试验结果和试验评定的差异。     

芳纶纤维在胶管胶布制品中的应用

芳纶纤维作为一种新型纤维增强材料，其应用受到人们的高度重视，本文介绍了芳纶纤维优良的物理机械性能及其与橡胶粘着的处理与加工方法，并对芳纶纤维在软管和胶布制品方面的应用作了评述。     

Bound rubber theory and experiment

Adsorption of polymer on filler from bulk is known to result in a partial loss of polymer solubility (“bound rubber”). The existing theories of this phenomenon were critically examined, and the random adsorption model suggested by the author was found to provide the most complete explanation of available experimental data. Theory based on this model and containing one adjustable parameter (filler surface area per adsorption site) correctly predicts the change of molar mass distribution with adsorption on filler and satisfactorily describes the experimental dependence of fraction B of the filler-bound polymer on filler concentration and surface area and on M _w of the polymer, in both narrow and very broad molar mass distributions. No distinct effect on B of a moderate degree of branching of EPM, EPDM chains could be detected. It is concluded that the modification of the random adsorption model suggested by Shiga is not warranted, neither theoretically nor experimentally. © 1993 John Wiley & Sons, Inc.     

有关Flory—Huggins理论的教学点滴

根据高分子的特点,我们从Boltzmnn熵定理出发,来理解Flory-Huggins晶格模型理论中推导混合熵（△SM）的思路。教学过程中突出高分子溶液中由于高分子相对分子质量大（x个链段）,造成高分子的△SM比小分子大得多的结果Hory-Huggins理论与实际情况的偏差;让学生学会用Hory-Hug—gins参数X1,值判断高分子溶液中溶剂的优劣性。     

Network topology and the theory of rubber elasticity

The earliest investigations on rubber elasticity, commencing in the 19th century, were necessarily limited to phenomenological interpretations. The realisation that polymers consist of very long molecular chains. commencing c. 1930, gave impetus to the molecular theory of rubber elasticity (1932-). according to which the high deformability of an elastomer, and the elastic force generated by deformation, stem from the configurations accessible to long molecular chains. Theories of rubber elasticity put forward from 1934-1946 relied on the assumption that the junctions of the rubber network undergo displacements that are affine in macroscopic strain. The theory of James and Guth (1947) dispensed with this premise, and demonstrated instead that the mean positions of the junctions of a ‘phantom’ network consisting of Gaussian chains devoid of material properties are affine in the strain. The vital significance of the distinction between the actual distribution of chain vectors in a network and their distribution if the junctions would be fixed at their mean positions went unnoticed for nearly 30 years. Experimental investigations, commencing with the incisive work of Gee in 1946. revealed large departures from the relationship of stress to strain predicted by the theories cited. This discrepancy prompted extensive studies, theoretical and experimental, during succeeding years. Inquiry into the fundamentals of polymer networks, formed for example by interlinking very long polymer molecules, exposed the need to take account of network imperfections, typically consisting of chains attached at only one end to a network junction. Various means were advocated to make corrections for these imperfections. The cycle rank ζ of the network has been shown (1976) to be the fundamental measure of its connectivity, regardless of the junction functionality and pattern of imperfections. Often overlooked is the copious interpenetration of the chains comprising typical elastomeric networks. Theories that attempt to represent such networks on a lattice are incompatible with this universal feature. Moreover, the dense interpenetration of chains may limit the ability of junctions in real networks to accommodate the fluctuations envisaged in the theory of phantom networks. It was suggested in 1975 that departures from the form predicted for the elastic equation of state are due to constraints on the fluctuations of junctions whose effect diminishes with deformation and with dilation. Formulation of a self-consistent theory based on this suggestion required recognition of the non-affine connection between the chain vector distribution function and the macroscopic strain in a real network, which may partake of characteristics of a phantom network in some degree. Implementation of the idea was achieved through postulation of domains of constraint affecting the equilibrium distribution of fluctuations of network junctions from their mean positions. This led in due course to a theory that accounts for the relationship of stress to strain virtually throughout the ranges of strain accessible to measurement. The theory establishes connections between structure and elastic properties. This is achieved with utmost frugality in arbitrary parameters.     

神经网络在橡胶配方设计中的应用

在实验数据的基础上，利用人工神经网络建立了表示NR胶料配方成分与硫化胶物理性能对应关系的数学模型，并用该数学模型对不同配方硫化胶的物理性能进行了预测，预测结果与实验数值相符，利用这种方法还可定量分析相同硫化胶物理性能条件下各配方成分间的相互作用。     

硅藻土在氟橡胶中的应用

研究了硅藻土等5种填料对氟橡胶硫化特性、力学性能及老化性能的影响。试验结果表明,添加进口硅藻土MW-25对氟橡胶强度提高最为明显,且具有良好的老化、硫化性能,优异的回弹性、低压缩永久变形性能及良好的加工性。     

A modification of rubber elasticity theory

Summary Based on a reconsideration of the packing conditions in amorphous polymers, a modification of the statistical theory of rubber elasticity is derived. The main assumption is, that the mean square end-to-end distance of a free chain in the bulk state depends on the dimensions of the surrounding chains. The theory describes quite well the deformation behaviour of real elastomeric networks.     

沉淀法白炭黑在橡胶产品中的应用

介绍了沉淀法白炭黑在橡胶产品中的应用情况，沉淀法白炭黑作为活性补强填料，具有高比表面积，高活性，特殊的表面特性和颗粒形态结构及独特的物理化学特性，在白色和浅色填料中补强性能和表面活性优异，广泛用于橡胶鞋底，轮胎，胶管，胶带、胶辊、橡胶密封件等产品。白炭黑发展方向是高分散性，精细化、造粒化和表面改性。     

硅橡胶在电气绝缘方面的应用进展

简述了国内外硅橡胶(高温硫化型硅橡胶、室温硫化型硅橡胶、液体硅橡胶等)在电气绝缘方面的应用情况。     

分散助剂AtsinR-50在橡胶并用体系中的应用

<正>在橡胶制品生产中,为了适应不同的工况环境和获得良好的加工性能,往往需要多种橡胶进行并用。但在橡胶并用时,往往不能使不同橡胶之间很好地融合,特别是极性不同的橡胶由于溶解度参数相差较大,相互之间更难以混合均匀。为了解决上述问题,作者在配方中添加部分均匀分散助剂AtsinR-50。     

橡胶机械在胶磁制造中的应用

介绍了胶磁产品的制造工艺,以及制造设备(包括混料设备、破碎机、出片机、卷取机、压延机等)的特点和要求。总结出胶磁制造设备和普通橡胶设备的主要区别在于设备表面耐磨硬化处理要求更高。     

橡胶材料学基础理论的新假说

橡胶硫化产生交联键和直链硫键。无机材料增强橡胶有一增强临界粒径(约100nm)和临界比表面原子数(约2％)。无机金属氧化物与橡胶间是物理作用,并屏蔽部分硫化交联反应,加入偶联剂后以化学作用为主。炭黑与NR间是以化学作用为主,而与SBR则以物理作用为主。硫化胶疲劳过程的力化学表观动力学反应级数为三级,有自愈合能力。硫化胶蠕变寿命与拉伸强度呈正和负的相关性。     

橡胶海绵在胶鞋中的应用

橡胶海绵既承袭了橡胶的弹性体特质。又具有海绵样的柔软、微孔结构。在胶鞋制造上用作胶鞋的中（内）底材料。具体应用有三种：第一种是作为低档胶鞋的内底,与其他部件贴合成型后一次完成硫化,故称一次硫化海绵,因含胶率低、大量掺用再生胶,所以成本低廉而被广泛采用：第二种要经过两次硫化,第一次经平板机大面积硫化、裁切,然后和其他部件贴合成型为整鞋,再进硫化罐硫化。因为海绵前后经历两次硫化,故称二次硫化海绵：第三种是用模具定型,经过发泡、硫化而得到活络海绵插底,穿用中可随时穿、脱,也称海绵模压单元底,常与高档运动鞋配套。海绵制造中,因工艺没有严格把好关而导致整鞋废次的例子屡见不鲜．特别以海绵质量引发的大底鼓泡最具代表性。     

橡胶型氯化聚乙烯在矿用喷砂管外层胶中的应用

采用CM135B为基体胶种，根据要求优化选择了硫化体系、增塑体系、填充补强体系、阻燃体系的种类及用量，通过性能测试最终确定配方（质量份）为CM135B 100，DOP 10，氯化石蜡5，MgO 10，炭黑N330 20，超导炭黑15，碳酸钙50，复合阻燃剂20，DCP5，TAIC 3，其它配合剂15。此时，胶料的力学性能、阻燃性能和抗静电性能均达到了矿用喷砂管外层胶的要求。     

胶鞋制造与合成胶应用

文章概述了我国胶鞋工业应用合成胶的现状,包括数量与品种,对各品种的优势和缺陷加以研讨,并提出如何在胶鞋制造中扩大ＳＲ应用面,提高使用比的建议。