介绍了大分子布朗运动的特点。从布朗运动与大分子链柔顺性的关系、分子热运动与分子间相互作用的竞争、分子热运动与熵致相变的关系等方面论述布朗热运动在现代高分子物理学中的重要地位,指出深入研究布朗运动及其影响对于更好理解聚合物（包括其它软物质）的结构、性能特征具有深刻意义。

给出用恒速型毛细管流变仪研究熔体挤出畸变时,计算熔体壁滑速率和外推滑移长度的原理和方法,采用2种聚合物样品HDPE(高密度聚乙烯)和EPDM(三元乙丙橡胶)验证计算方法.求得样品的壁滑速率在每秒几厘米的量级,临界外推滑移长度在毫米数量级.由此进一步探讨壁滑的分子机理和界面机理,指出发生显著熔体壁滑、压力振荡和挤出物表面畸变的前提条件是,熔体具有线形分子链且发生强缠结以及熔体/模壁间具有强吸附边界.

根据对熔体挤出整体畸变和熔体破裂机理的分析,设计一系列方法减轻和消除畸变.采用原位成纤复合法和纤维流动取向效应改善无规共聚聚丙烯(PP-R)熔体在口模入口区的流动稳定性,消除环向次级流动,减轻螺纹畸变.添加一定质量的炭黑或白炭黑,利用炭黑形成三维网络结构改善溶聚丁苯橡胶(SSBR)的挤出畸变和熔体破裂行为.改变口模尺寸,适当增大口模长径比,有利于挤出过程稳定.

采用恒速型毛细管流变仪研究分子量双峰分布聚乙烯PE-SP2520的高速挤出性能.结果表明:因分子量分布的特殊性,PE-SP2520的结晶度和熔峰温度均低于对比样品LLDPE-7047.高速挤出时PE-SP2520剪切黏度较高,非牛顿流动性较弱,入口压力降和熔体强度较高.与对比样品比较,PE-SP2520挤出稳定性好:挤出压力稳定,流动曲线连续,挤出畸变主要为鲨鱼皮畸变.流动稳定性提高的重要原因在于分子量双峰分布使分子链缠结能力下降,熔体/管壁边界应力集中效应弱.

The extrusion flow stability of reactive degraded polypropylene (PP) samples was studied by a double capillary rheometer. The results indicate that the extrusion pressure of basic resin PP-2401 increases stably and step by step with the rise in the shear rate, but the extrusion pressure of the degraded PP samples is irregular undulated by higher shear rate. Such pressure instability of degraded PP with low relative molecular mass happens mainly at the entrance area of die. The causes of this instability are related to the chain structure of PP, larger Weissenberg number and Reynolds number of melts at the entrance area of die.

The non-linear rheological properties of polypropylene (PP) prepared by reactive extrusion degradation with different molecular structure parameters were studied by a double capillary rheometer. The results show that PP prepared by reactive extrusion degradation is pseudoplastic fluid. The shear viscosity of PP melts decreases with the degradation, but the non-Newtonian index increases, indicating the PP samples with lower relative molecular mass has low viscosity-shear sensitivity. The viscosity of the PP samples with different relative molecular mass decreases with the rise in the temperature. The viscous flow activation energy of the PP samples with lower relative molecular mass is slightly higher, which may be related to the lesser conformation entropy of shorter molecular chains. The inlet pressure drop (as characterization of melt elasticity) of the PP melts decreases with the degradation of PP, and moreover the curves of inlet pressure drop versus extrusion rate of the PP samples with lower relative molecular mass were irregular, which means that the PP melts flowing through the area of capillary entrance was unstable.

In this work the features and influences of entropy in the lytropic condensation of macromolecules were discussed.In an irregular condensation,in that the amorphous polymers were generated,just the entropy increase causes a decrease of Helmholtz's free energy,and so that the condensation process can go on.In a regular condensation,in that the crystalline polymers were generated,the change of entropy induces very complex effects for polymer crystallization.Due to the competition between entropy and internal energy,a folded chain lamellae with loose structure was prior generated in the lytropic crystal process;and a two phases structure with crystal and amorphous region was generated in the crystal process from polymer melts.Two different change's ways of entropy were distinguished: a jump change of entropy can induce a thermodynamic phase transition-entropy induced phase transition;but a gradual change of entropy can change only the mechanical property or initiate a mechanical state transition of polymers.

The scaling concepts and the scaling laws were introduced from the self similarity and the fractal of macromolecular chains.With several examples the basic concepts,thinking and methods of scaling theory were presented for description of the intrinsic properties and complex behaviors of polymeric materials.It is indicated that with scaling theory the research fields of polymer science were widened and deepened.The more important is the scaling theory is also a new expanding in methodology for polymer science to substitute the mean field approximation.The universal statistic laws and behaviors of polymers and of other soft matters were clearly described with more compendious concepts and expressions in a new approach.This constitutes a very important contribution for the development of modern sciences.

The relationship between extrusion pressure and extrudate distortions of melts was studied by a double-capillary rheometer.The results show that by high speed extrusion the extrusion pressure oscillations occures when the flow stress concentrations are strong.The pressure oscillations can be divided into two types:inlet pressure oscillation and capillary pressure oscillation.The flow stress concentrations of polymer melts with various structures are different,therefore the places and natures of pressure oscillations are also very different.The signals and strength of the pressure oscillations are directly related to the features of extrusion distortions.

依据对挤出畸变的指纹识别,分析了引发挤出畸变的流场扰动源位置和扰动性质.结果表明:畸变发生在口模外,扰动源却在口模内.具体扰动位置有口模入口区、出口区及熔体-模壁边界处;扰动性质按流体动力学方程分为剪切流扰动、拉伸流扰动及压力流扰动.建立了不同类型畸变与扰动源位置、扰动性质的对应关系.

The relationships between rheological curves and extrudate distortions of polymer melts were discussed by a capillary rheometer.The results show that for some melts with linear chains,the adsorption between melts and wall is strong,a flow stress concentration occurres at boundary by high speed extrusion,it leads to melts desorption from wall,the stress-shear rate curves break,and accordingly some regular distortions at surface of extrudate.For some melts with long branched chains,the melts elasticity is strong,then a strong flow stress concentration occurres at die inlet by high speed extrusion,it leads to the inlet drawing flow unstability,and accordingly an integral irregular distortion or melts fracture.

Each mature science contains inevitably a paradigm,it gives expression to the special structure, the basic theoretical frame and the study range of this science. But a paradigm for the condensed matter physics of polymers is so far not formed. In this paper the important successes of condensed matter physics of polymers in recent 20 similar to 30 years were summarized; a series of notions e. g. soft matter, self similarity, fractal, scaling laws, correlative effect, lyotropic condensation, entropy induced phase transition, Brownian movement, multi-body effects, symmetry breaking and their importance were interpreted and emphasized. And it is indicated, that the summarizing of paradigm of condensed matter physics of polymers becomes already an urgent work for polymer physicists.

Using constant rate and constant pressure rheometer,the effects of the lanthanides stearate / PE wax on the extrusion rheological properties of HDPE6098 were researched.The results showed that the extrusion properties of HDPE6098 were improved by lanthanides stearate and PE wax.Especially,after the addition of compounds containing 1.5 phr lanthanum stearate and 2 phr PE wax or 3.5 phr cerium stearate and 3 phr PE wax,the shear rate were enhanced from 4 770 s-1 to 14 039 s-1 and 21 271 s-1,which increasing about 190%and 346%,respectively.

根据对熔体挤出表面畸变现象和机理的理解,采用多种方法减轻和消除畸变.结果表明:在口模内壁涂敷含氟加工助剂能有效克服线性低密度聚乙烯(LLDPE)的鲨鱼皮畸变和黏-滑畸变;在高密度聚乙烯(HDPE)中混入少量低密度聚乙烯(LDPE)、聚丙烯(PP)等聚合物,有效减弱了HDPE熔体高速挤出时的压力波动现象;相对分子质量双峰分布的聚乙烯(PE)比普通HDPE的加工性能优越;调节口模区温度可减轻LLDPE熔体的鲨鱼皮畸变.

A database to study the extrudate distortions of polymer melts at high extrusion speed was constructed.The extrudate distortions are very complex.But these phenomena can be generally divided into two classes:surface distortion and integral distortion.The surface distortions include rough surface,sharkskin,slip-stick distortion etc.The integral distortions include slight warp,integral warp,serious kinking etc.Both surface distortion and integral distortion can come up simultaneously,which is called as gross melts fracture.The extrudate distortions of polymer melts with different topological structure are very various,so the polymers can be fingerprinted according to the extrusion behaviors.

The extrudate distortion behavior and its mechanism of the raw rubber and compound of solution polymerized styrene-butadiene rubbers(SSBR-T2003 and SSBR-2305) having different structure were investigated.In raw rubber extrusion,extrudate distortion occurred for both SSBR-T2003 and SSBR-2305 and the distortion of SSBR-2305 was worse due to higher molecular weight and branched structure.The distortion was caused by unstable extensional flow at the die entrance.With the addition of carbon black,the rheological property of compound could be improved,the entropy elasticity of compound was reduced and the flow field at the die entrance was stabilized.Therefore,the overall distortion was reduced.The smooth surface of extruded SSBR-2305 compound could also be obtained under high shear speed.

按照现代高分子凝聚态物理学观点,高分子溶液按浓度分为:极稀溶液、稀溶液、亚浓溶液、浓溶液、极浓溶液5个层次,各层次间的分界浓度分别称为动态接触浓度、接触浓度、缠结浓度和全高斯链浓度,其中全高斯链浓度由本文作者命名.文中给出各分界浓度的定义,介绍各分界浓度的物理意义,特别说明命名全高斯链浓度的依据.同时详细讨论了不同浓度溶液中大分子链的构象及其变化、链间相互作用的本质和微观图像、以及溶液浓度变化对溶液性质的影响.

The study of macromolecular chains condensation will be beneficial with the discussion about polymer solutions.The transitions from dilute solution to semi-dilute and to concentrated solution were in nature the process of interlace,entanglement and condensation of a lot of isolated single chains.This can be known as lyotropic condensation.The types of chains lyotropic condensation are varied,e.g.condensed to amorphous state,to crystal state,and sol-gel transition etc.The characters of these processes were discussed.The basic physical problems in lyotropic condensation: e.g.many-body effects,correlations,mean field approximation,critical index and the new study method——scaling laws were brief introduced.

The effects of carbon black amount on the rheological properties of solution polymerized styrene-butadiene rubber(SSBR T 2003 and 2305) were studied by a constant speed double-capillary rheometer.The results showed that the extrudate appearance of the compounds of T 2003 and 2305 was apparently improved after filling carbon black,because carbon black could not only stabilize the flow field at the die entrance,but also relieve the interaction between melt and pipe wall.The flow curves of the 2305 compounds discontinued at the critical shear rate,and the curve gradient changed,which indicated that the interface state changed suddenly.The second smooth extrusion zone occurred at high shear rate when the 2305 compound was filled with 30 phr or 50 phr carbon black.With the increase of carbon black amount,both die swell ratios of SSBR T 2003 and 2305 compounds decreased,while the network contents both increased

In this work the macromolecular chain＇s conformations in dilute, semidilute,concentrated and extra concentrated polymer solutions were discussed respectively, at the same time the interactions between macromolecules, the complex correlative effects and the changes of macromolecular sizes were explained in detail, and the definition of excluded volume and several concepts, thermic correlation, long-range correlation and full Gaussian concentration were introduced. It is indicated that the conformations at different chain＇s size ranges are different in the solutions of different concentrations, and that the single chain＇s size happened contraction in lytrooic condensation process of macromolecules, from Flory size RF to unperturbed chain dimension Ro.This is a specialty of lytrooic condensation of macromolecules.