具有负泊松比效应的聚烯烃共混物

实验证实用共混法制备的特殊聚烯烃共混物是一种拉伸膨胀材料 (Auxetic) ,测试发现共混物具有明显的负泊松比效应 ,所获得的最稳定体系可以获得 -1 4的泊松比值 ,比目前文献报道的数据减小了 2 0 0 %.采用SEM观察了共混体物拉伸前后的微观结构 ,推断负泊松比效应的产生是由于材料内部发生了空化作用的结果 ,与提出的理论模型基本一致     

聚合物共混：Ⅰ.聚合物共混物的制备方法

本讲主要介绍聚合物共混物的制备方法,其中包括熔融共混、溶液共混、胶乳共混、冷冻干燥共混、接技共聚共混、互穿聚合物网络、就地反应型共混、分子共混等.     

离聚物共混研究进展

综述了十 多年来。人们旨在提高相容性及其它一些性能，将离聚物引人共混体系所展开的系列研究。总结出，离聚物共混体系中，离聚物起增容作用的根本原因是在共混休整 系中引入了一些特殊的离子相互作用：离子－离子作用，离子－偶极作用，过渡金属离子的配位作用，介绍了目前研究离聚物共混的主要方法。     

聚合物共混物的原位成纤复合

综述了近年来原位成纤复合材料的研究成果，简要论述了原位成纤机理，介绍了原位复合材料的流变性能、力学性能、形态及形态分布、结晶熔融行为以及影响形态、性能的因素。     

聚烯烃功能化研究进展

在烃烃聚合中，聚烯烃的功能化是受到人们普遍关注的问题之一。本文综述国内外用溶液法，等进行的后功能化研究，重点介绍了新型的中介物的功能化研究进展，并扼要介绍了功能化聚烯烃的应用情况。     

聚合物共混物的相容性及相分离

综述了聚合物共混物相容性和相分离的研究现状。介绍了聚合物共混物的相容性理论,影响相容性的因素及改善和相容性的方法和表征相容性的手段。聚合物共混物的相分离机理制约着材料的性能,旋节分离和成核－增长相分离分别形成不同的形态结构。旋节分离和成核－增长相分离所对应的动力学过程是不同的,散射光强与相分离时间分别满足指数和幂指数关系。     

聚合物共混物脆韧转变性能研究：II.准韧性聚合物共混物脆韧转变的几何模型

给出了分散相粒间基体层厚度Ｔ与分散相粒径（ｄ）、粒径分散度（σ）和分散相体积分数（φ）的定量关系式。发现σ对Ｔ的影响与φ有关，不仅Ｔ随σ的增大而增大，而且φ越大，这种影响越显著。用计算机图像分析仪直接测定了聚氯乙烯／丁腈橡胶、聚丙烯（ＰＰ）／三元乙丙橡胶、ＰＰ／乙烯－醋酸乙烯酯共聚物共混物的Ｔ，发现这三种共混物的Ｔ近似于对数正态分布，理论预示与实验结果很好符合。     

POM／EVA共混物的研究

用力学测试、扫描电镜（ＳＥＭ）、热分析（ＤＳＣ）等手段研究了聚甲醛（ＰＯＭ）与乙烯－醋酸乙烯酯共聚物（ＥＶＡ）共混物（ＰＯＭ／ＥＶＡ）的力学性能及其微同形态；用聚甲醛与马来酸二丁酯（ＤＢＭ）的接枝物（ＰＯＭ－ｇ－ＤＢＭ）作相溶剂，能改变共的两相间的粘结力，从而提出了共混物的力学性能，ＳＥＭ观察表明接枝物的加入改变了ＰＯＭ／ＥＶＡ共混物的断裂方式，微观形态及结晶性能，对其热性能影响不大；通过改变ＰＯ     

聚丙烯／聚烯烃弹性体共混体系的结构-性能关联

聚丙烯是目前应用最广泛的通用塑料之一。为了克服聚丙烯脆性大的弱点,人们发展了多种方法来增韧聚丙烯,其中聚丙烯和聚烯烃弹性体共混是常用的改性聚丙烯的方法。本文介绍了聚丙烯／聚烯烃弹性体共混物相容性的研究方法和较为普遍接受的增韧理论,并对近年来国内外聚烯烃弹性体增韧聚丙烯的研究进展做了介绍。     

增塑剂法研究高分子共混物的相平衡曲线

经共聚改性的聚苯乙烯PS(OH)与聚甲基丙烯酸丁酯PBMA形成的互溶体系具有LCST行为。由于体系的玻璃化温度较高。分相温度与玻璃化温度接近。使分相时的浊点温度受升温速率影响很大,以致浊点曲线与相平衡曲线有一定的差距。本文以邻苯二甲酸二丁酯DBP为增塑剂加入PS(OH)/PBMA共混体系中,在一定的升温速率下测浊点温度,并对增塑剂作零浓度的外推,由此得到的浊点曲线与相平衡曲线完全一致。证实了增塑剂法的可靠性。加入增塑剂后浊点温度随升温速率变化平缓,更接近相平衡点,显示了增塑剂法的有效性。     

升温淋洗分级技术在聚乙烯研究中的应用

升温淋洗分级技术是根据结晶性聚合物的结晶度进行分级和表征的一项分析和制备技术，在聚烯烃非均匀性的表征和窄组成分布样品的制备中有重要应用。本文主要介绍升温淋洗分级原理、热力学模型、装置技术特点、分析方法以及在聚乙烯研究中最新应用进展。     

Polyolefin analysis by single‐step crystallization fractionation

Temperature rising elution fractionation (TREF) fractionates polymer chains with respect to their crystallizability, independently of molecular weight effects. In order to achieve a good fractionation, TREF requires a time‐consuming polymer deposition step over an inert support before the elution step. A single‐step crystallization fractionation method has been developed recently,^1,2 Crystallization Analysis Fractionation (CRYSTAF), in which the chemical composition (or short chain branching) distribution of olefin copolymers can be measured by monitoring on‐line polymer concentration in solution at decreasing temperatures. For the present experimental investigation, a CRYSTAF‐prototype has been assembled and used to fractionate several linear low‐density polyethylene (LLDPE) samples. These results were compared to the ones measured by the commercial CRYSTAF apparatus from Polymer ChAR. Additionally, CRYSTAF results from Polymer ChAR were compared to analytical TREF results. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 539–552, 1999     

The effect of molecular composition and heterogeneity on the environmental stress cracking resistance (ESCR) of propylene impact copolymers

The ESCR of three propylene impact copolymers in the presence of isopropanol was investigated and the variation in stress crack resistance was evaluated in terms of polymer characteristics. The effect of removing both soluble and crystalline material from the copolymers on the ESCR was evaluated. The stress crack resistance appears to be dependent on the crystallinity of the materials, but not solely so. The amount and distribution of the rubbery copolymer in these materials appears to play a role as well.     

等规聚丙烯/聚丁烯-1釜内合金的结构与性能

高分子材料的组成、 组分分布及链结构与宏观性能紧密相关. 因此, 分析多组分釜内合金材料的链结构特点与性能之间的关系至关重要. 采用升温淋洗分级的方法对两种采用序贯两段聚合原位合成的等规聚丙烯/聚丁烯-1(iPP/iPB)釜内合金在-30 ℃~140 ℃温度范围进行分级, 采用核磁共振波谱仪、 傅里叶变换红外光谱仪、 差示扫描量热仪和凝胶渗透色谱仪等表征了级分的链结构及序列分布、 热行为、 分子量(M_w)及分子量分布(M_w/M_n)等. 结果表明iPP/iPB合金主要由5种级分组成, 高等规聚丁烯(iPB)为主要组分, 同时含有少量的丁烯-丙烯嵌段共聚物(PB-b-PP)和等规聚丙烯(iPP)等. 随淋洗温度升高, PB-b-PP级分中PP嵌段长度逐渐增加, PB嵌段长度逐渐减小; 在相同的淋洗温度, 合金B的嵌段共聚物级分中PP嵌段较长且结晶较完善; 合金B中iPB组分及嵌段共聚物组分含量较高, 使得合金B具有较高的拉伸强度、 弯曲强度、 优异的抗冲击性能、 较高的维卡软化温度及较快的晶型转变速率.     

Analysis of microstructure of ethylene–1-hexene copolymer prepared over thermally pretreated MgCl2/THF/TiCl4bimetallic catalyst

Thermally pretreated catalysts were prepared by heating MgCl₂/THF/TiCl₄ (TT-0) at 80°C for 5 min (TT-1) and 60 min (TT-2), and at 108°C for 5 min (TT-3) and 60 min (TT-4). Ethylene–1-hexene copolymers were prepared with these catalysts. The TT-1 catalyst produced more blocky and higher 1-hexene content polymer than TT-0, 2, 3, and 4. Temperature rising elution fractionation (TREF) analysis was used to investigate the chemical composition distribution of the ethylene–1-hexene copolymer, exhibiting bimodal distribution for TT-0 and trimodal for TT-1, 2, 3, and 4. A portion of higher hexene content of the copolymer markedly increased when the copolymerization was performed with TT-1, indicating that copolymerization active sites were newly generated. Portion of homopolyethylene increased drastically when the copolymerization was performed with TT-4, indicating that ethylene homopolymerization active sites were increased. Gel permeation chromatography (GPC) also revealed that three kinds of active sites existed on the catalyst. ¹³C-NMR spectrum of each fraction after TREF analysis suggested that the isospecific active site could polymerize 1-hexene well, resulting in random and alternating copolymers. A scheme for generation of the active site and change of its nature during thermal treatment of bimetallic complex catalyst is proposed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 291–300, 1998     

结晶分级技术在支化聚乙烯研究中的应用

介绍了近年发展起来的几种结晶分级技术及其在支化聚乙烯结构表征及性能研究方面的应用。利用升温淋洗分级技术(TREF),可根据结晶特性的不同将高分子分离成多个分布较窄的级份,通过分别表征各级份的链结构,从而可获得高分子链结构方面较为准确的信息。基于差示扫描量热技术(DSC)发展起来的两类热分级技术,主要包括逐步结晶热分级(SC)和连续自成核退火分级(SSA)技术,虽然不能从物理上对高分子进行分级,但通过选择适当的操作参数,也能得到一系列与升温淋洗分级实验类似的链结构信息,并且具有设备简单、操作方便、样品用量少、耗时短等优点。本文结合我们自己的工作,对各种分级技术的原理、实验操作及应用进行了系统综述,并展望了结晶分级技术发展的某些可能趋势。     

Crystallization Elution Fractionation of LLDPEs Made with Metallocene Catalysts

Summary: Temperature rising elution fractionation (TREF) and crystallization analysis fractionation (CRYSTAF) fractionate semicrystalline polymers according to their crystallizabilities from dilute solution and have been widely used to measure the CCD of LLDPE. A new fractionation technique, known as crystallization elution fractionation (CEF), has been developed recently. The main difference between CEF and TREF and CRYSTAF is that the crystallization cycle in CEF is performed dynamically under solvent flow in a long column that contains an inert support material. In this paper, several metallocene-LLDPE resins have been analyzed by CEF to investigate the effect of cooling cycle parameters, comonomer fraction, polymer molecular weight, and blend cocrystallization on the fractionation. This new technique can be used to obtain CCDs with better resolution and in shorter times than TREF and CRYSTAF.     

聚烯烃的化学接枝改性

综述了化学接枝改性聚烯烃的三种方法,即溶液法,熔融法及固定相法,并讨论了接枝单体的选择,接枝机理和接枝物的性能表征。     

Mathematical modeling of crystallization analysis fractionation (Crystaf) of polyethylene

Four polyethylene samples (PE) with different molecular weight distributions (MWD) were analyzed by crystallization analysis fractionation (Crystaf) at several cooling rates to investigate the effect of MWD and cooling rate on their Crystaf profiles. Using these results, we developed a mathematical model for Crystaf that considers crystallization kinetic effects, which are ignored in all previous Crystaf models. The Crystaf model we proposed can fit the experimental Crystaf profiles of the 4 polyethylene resins very well. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2749–2759, 2006     

医用聚烯烃材料的开发及应用进展

伴随着塑料工业、医学技术和生物技术的不断发展以及人们对健康的日益关注,医用塑料应用领域已变得越来越广泛。聚烯烃材料由于其安全无毒的特点,已经越来越多地应用在医用领域。迄今为止,聚氯乙烯在国内仍是广泛用作医用材料。基于人体健康和环境安全的考虑,采用更安全、环保的替代品是大势所趋。采用其它更安全环保的聚烯烃材料替代PVC材料的研究将是本领域的一个重要研究方向。本文综述了医用聚烯烃材料的开发和应用现状,阐述了各类聚烯烃材料的主要特点和用途,重点介绍了各类聚烯烃材料研究和开发进展,展望了医用聚烯烃材料的某些可能发展方向。