CROSSLINKING AND COMPATIBILIZATION IN BLENDS OF POLYSTYRENE AND POLYETHYLENE

This paper investigated the influences of butadiene rubber (BR) and dicumylperoxide (DCP) on thermal and rheological behaviour, morphology and mechanical proper-ties of PS/LLDPE/SBS blend. Addition of DCP alone was found to decrease the mechanicalproperties of PS/LLDPE/SBS blend due to the decomposition of PS. When BR was addedtogether with DCP, it is found that the co-crosslinking of BR, SBS and PE takes place,and the decomposition of PS is reduced simultaneously because of the consumption of thefree radicals in the crosslinking process. Synergism was thus realised which resulted in theimprovement of the ductility of blend.     

乙丙橡胶/聚丙烯共混体系的界面相互渗透

本文用X射线衍射仪、差热分析仪、动态力学扭摆仪和测定有效网链密度等方法,研究了乙丙橡胶/聚丙烯(EPDM/PP)共混体系中PP的非晶部分和EPDM的相互渗透。EPDM和PP不具有互溶性,但PP的非晶部分和EPDM两相界面处有较强的相互渗透,即部分互容性。有效链密度和性能间关系的数据表明,共混体系不一定存在硫化胶那样的对应关系。     

聚氯乙烯缺口冲击断面粗糙度定量分析

聚氯乙烯缺口冲击断面粗糙度定量分析于杰（贵州工学院材料中心，贵阳，５５０００３）金志浩，周惠久（西安交通大学材料系，西安，７１００４９）关键词分形，冲击强度，温度，聚氯乙烯实际材料的断裂表面是一种近似的或统计意义上的分形模型．分形维数是断面粗糙度的定...     

STUDY ON THE MORPHOLOGY OF POLYVINYL CHLORIDE/POLYSTYRENE BLENDS BY ELECTRON MICROPROBE ANALYSIS*

The morphology of polyvinyl chloride/polystyrene (PVC/PS) blend samples with different mass ratios, preparedby means of solution casting and melt mixing, have been successfully examined by electron microprobe analysis (EMP). Thisexperiment was performed in a scanning electron microscope attached to an energy dispersive X-ray analyzer. Differentialscanning calorimetry was also used to investigate the phase separation of the blends. The results show that PVC and PS areincompatible and the blends have sea-islands phase structures. Blends prepared via melt mixing have finer phase-dispersionthan those prepared via solution casting.     

极低密度聚乙烯与其它聚乙烯的共混

从结构角度，用ＤＳＣ，ＷＡＸＤ，ＳＡＸＳ研究了聚乙烯（ＰＥ）家族中极低密度聚乙烯（ＶＬＤＰＥ）与其它ＰＥ的互容性．ＨＤＰＥ／ＶＬＤＰＥ是共晶互容的，以其大量无规部分“溶解”了ＨＤＰＥ的结晶缺陷部分，提高了ＨＤＰＥ的Ｔｃ，Ｔｍ，Ｘｃ，结晶峰半高宽变窄，晶胞参数随组成而有最低值．ＶＬＤＰＥ与ＬＬＤＰＥ结构极为相似，ＤＳＣ及ＷＡＸＤ证明其共混物是共晶相容体系．ＬＤＰＥ／ＶＬＤＰＥ的结晶度符合按组成的计算值，但晶胞参数ａ，ｂ以及晶粒尺寸增大，ＤＳＣ上有分别相应于两组份的两个Ｔｍ；ＶＬＤＰＥ的Ｔｃ，Ｔｍ峰高之和高于按组份的计算值，ＬＤＰＥ的Ｔｍ，Ｔｃ则低于计算值．认为是正如ＬＬＤＰＥ／ＬＤＰＥ，ＬＤＰＥ向充满整个体积的ＶＬＤＰＥ中不断填入，以ＶＬＤＰＥ为晶核而结晶，形成相分离的不相容体系．     

聚氯乙烯膜在玻璃化转变温度区域的傅里叶变换红外光谱研究

本文用傅里叶变换红外光谱(FTIR)研究了从高弹态缓冷、高弹态淬火以及其后在低于T_g温度热处理的三种不同热历史聚氯乙烯膜的结构差异。在升温在位FTIR测量中,发现经低于T_g温度热处理的样品在与示差扫描量热(DSC)热焓吸收牛相对应的温度区间有构象突变发生,并用高分子链缠结的观点加以解释。     

PTHF-b-PMMA/PVC共混体系的相容性和结晶行为

研究了具有焓效应的聚四氢呋喃-聚甲基丙烯酸甲酯两嵌段共聚物与聚氯乙烯PTHF-b-PMMA/PVC)共混体系的相容性和结晶行为. 结果表明, 其相容性比AB/A型嵌段共聚物共混体系的相容性要好得多; 与PTHF部分相容的PVC对PTHF微区的结晶行为可产生很大的影响. 应用有关理论和模型很好地解释了结晶行为的这种变化.     

天然橡胶/聚乙烯共混体相容性的研究

本工作首先对橡胶/聚乙烯共混体系的相容性进行了计算,推测聚乙烯的非晶部分和橡胶间有一定的互容性,提出了橡胶和聚乙烯相互作用模型。然后用动态力学方法、有效网链密度测定、密度测定和广角X-射线衍射方法对天然橡胶分别未交联和交联的天然橡胶(NR)/低密度聚乙烯(LDPE)共混体系的相容性进行了验证。实验结果表明,LDPE非晶部分和NR之间存在一定的相互渗透。     

顺丁橡胶／低密度聚乙烯的共混

比较了未交联和动态交联不同组成PB/LDPE共混物的力学性能。共混物的T_g、T_m和T_d不随组成而变化,表明PB和LDPE不具有相容性。但共混物中PE的γ转变向高温方向位移,说明PE非晶部分的分子短链和PB有界面相互作用。形态研究表明,未交联体系中量多的组份形成连续相,动态交联体系在PB/LDPE≤70/30时,PE呈连续相,交联的PB为分散相。     

聚氯乙烯树脂的不饱和度和热稳定性的关系

用紫外 可见光谱法表征了不同来源的聚氯乙烯树脂（ＰＶＣ）的热稳定性，用一氯化碘加成法测量了ＰＶＣ的总的双键含量，用红外光谱法测量了ＰＶＣ的孤立双键和共轭双键的相对含量．结果表明，ＰＶＣ在加工期间的初期着色行为和长期热稳定性并不直接相关，前者取决于ＰＶＣ分子链中共轭双键的含量，而后者则和孤立双键的含量有关     

聚氯乙烯多乙烯多胺树脂催化合成硫氰酸苄酯

在含有聚氯乙烯-多乙烯多胺树脂的乙醇中，氯化苄在78℃与硫氰酸钾反应5小时，得到97．3%收率的硫氰酸苄酯，此法操作简便，催化剂容易分离并能重复使用。     

共混过程中EPDM/PP共混热塑弹性体的结构、形态和性能的变化

用SEM,TEM,DSC,WAXD和有效网链密度(v_e)测定,研究了共混时间长短和返炼对EPDM/PP共混物结构和性能的影响。两相分散随共混时间和返炼而更趋均匀。随共混时间,PP结晶度(x_c)先行降低然后升高,抗张强度正相反,v_e则降低x_e和v_e返炼后总是较一次共混降低。影响强度的因素主要是两相分散均匀和两相界面的相互渗透。     

线性低密度聚乙烯/橡胶共混体系的相容性研究

本文用FTIR-ATR方法考察了线性低密度聚乙烯与天然橡胶(NR)及丁苯橡胶(SBR)两个共混体系,发现NR的835cm~(-1)和SBR的964cm~(-1)两个吸收峰因与聚乙烯共混而增高变窄,说明聚乙烯的非晶链段和橡胶分子之间存在一定程度的相互作用。     

EFFECTS OF COMPATIBILIZERS ON THE MECHANICAL PROPERTIES OF LOW DENSITY POLYETHYLENE/LIGNIN BLENDS

Low density polyethylene(LDPE)/lignin blends were prepared using melt blending.Two kinds of compatibilizers, ethylene-vinylacetate(EVA) which is softer than LDPE and polyethylene grafted with maleic anhydride(PE-g-MA) which is harder than LDPE were used to improve the interfacial adhesion.Scanning electron microscope(SEM) was used to investigate the dispersion of lignin in LDPE matrix.The results showed that both of the compatibilizers could improve the interaction between the low density polyethylene an...     

PREPARATION OF HIGHLY BRANCHED POLYETHYLENE WITH ACENAPHTHENEDIIMINE NICKEL CHLORIDE/DIETHYLALUMINUM CHLORIDE CATALYST

The homogeneous catalyst system [ArN = C(Nap)- C(Nap)= Nar]NiCl2 (Nap = 1,8-naphthdiyl, Ar = 2,6-diisopropylphenyl)/AlEt2Cl has been prepared and examined for ethylene polymerization. Polymerization conditions such as cocatalyst, Al/Ni molar ratio and polymerization temperature (Tp) have a great effect on catalytic activity and properties of polyethylenes (PE). The activity of 5.1 × 105g PE/mol Ni. H was obtained by the catalyst, activated with AlEt2Cl at 120 of Al/Ni ratio and 30℃. Especially, Tp had a pronounced influence on branches and molecular weight of PE. Branching degree of PE increased with increasing temperature whereas their molecular weight decreased correspondingly. At Tp lower than about 70℃, the resultant PE was an elastic material. When Tp was higher than 70℃, the product was a viscous oil. The resultant PE was confirmed by 13C-NMR to contain significant amounts of not only methyl but also ethyl, propyl, butyl,amyl, and longer branches (longer than six carbons). According to gel permeation chromatographic measurement, the weightaverage molecular weights of the polymers obtained ranged from 3.6 × 103 to 2.3 × 105.     

氯化聚氯乙烯/氯化聚乙烯共混体的流变性能

<正> 氯化聚氯乙烯(CPVC)是聚氯乙烯(PVC)的氯化产物。它具有优良的耐化学腐蚀、耐油、隔氧等性能。它的使用温度、抗张和弯曲强度与PVC相比有很大提高。这些特性加上氯元素资源丰富、价格便宜,使CPVC可望成为具有吸引力的热塑性工程塑料。有关CPVC共混体系的研究已有不少报道。然而多数的研究范围较窄,尤其是关于CPVC共混体系流变性研究很少见。本文首次广泛研究了不同组成的CPVC/CPE共混     

剪切作用下纳米粘土对LDPE熔体粘弹响应的影响

以LDPE/EVA/纳米粘土复合体系为研究模型,考察了剪切作用下,分散良好的纳米粘土对聚合物基体熔体稳态及瞬态粘弹响应的影响.发现剪切作用下,纳米粘土增加了聚合物熔体粘弹特性对剪切速率、剪切应变及剪切作用史的依赖性,改变了相应的依赖关系.稳态剪切时,纳米粘土的加入使体系第一法向应力差(N1)在低剪切速率区变为负值,而在高剪切速率区N1与粘土的含量无关;同时就瞬态剪切应力及N1的应变依赖关系而言,复合体系明显不同于聚合物基体;预剪切对聚合物基体瞬态粘弹响应几乎没有影响,而当纳米粘土的加入量大于3wt%后,与未经预剪切的样品相比较,经预剪切的复合体系的瞬态剪切应力值、应力过冲程度以及稳态剪切应力值均明显下降,且预剪切前后复合体系达到稳态时其瞬态剪切应力差值随纳米粘土含量的增高而线性增加.此外,纳米粘土的添加对聚合物熔体受剪切作用的非线性粘弹响应存在影响.复合体系熔体呈现特异非线性粘弹响应,其缘由被认为是由于纳米粘土在聚合物基体中剥离分散,或聚合物分子链插层于粘土片层间,形成局部有序结构,受剪切作用而排列取向.     

IMPROVED PROPERTIES OF METALLOCENE-CATALYZED LINEAR LOW-DENSITY POLYETHYLENE/POLYPROPYLENE BLENDS DURING ULTRASONIC EXTRUSION

Metallocene-catalyzed linear low-density polyethylene/polypropylene （mLLDPE/PP） blends were prepared by ultrasonic extrusion in this work. Their extrusion processing behaviors were estimated by online measured data, such as the die pressure and flow rate. Crystallization and mechanical properties of the blends were also investigated. The results show that the addition of PP improves the processing behaviors of mLLDPE, but has little effect on its mechanical properties. On the other hand, the addition of mLLDPE improves the impact strength of PP, but has little effect on its processing behavior. The processing behaviors and mechanical properties of mLLDPE/PP blends get further improved due to the presence of ultrasonic oscillation during extrusion. Compared with PP-rich blends, the apparent viscosity drop of mLLDPE-rich blends is more sensitive to ultrasonic oscillation. The ultrasonic oscillation affects the crystal nucleation, while barely the other crystalline behaviors of the blends.     

聚乙烯醇与硬脂酸酯化反应及性能的研究

聚乙烯醇 (ＰＶＡ)具有良好的成纤成膜性能 ,膜的阻氧性、透明性、抗静电性、韧性、印刷性和耐化学性能优异 ,用途广泛 .ＰＶＡ的缺点是吸湿性大 ,耐水性差 ,熔融加工困难和热稳定性低 .吸湿后 ,ＰＶＡ的强度仅为其干强度的 55%～ 60 % ,膜的阻氧性下降 .ＰＶＡ在 1 60℃开始分子内脱水 ,2 30℃时开始分子间脱水变脆 .由于分子内和分子间有大量氢键存在 ,ＰＶＡ熔融温度高 ,不能熔融加工 ,而溶液成型工艺复杂、成本高、难于制备厚壁和形状复杂的制品 .降低熔融温度、提高热稳定性能是实现ＰＶＡ熔融加工成型的必要条件 .国内外在采用马来酸…     

TIME-TEMPERATURE-MISCIBILITY AND MORPHOLOGY OF POLYOLEFIN BLENDS

Miscibility and crystallization have been studied for polypropylene-polyethylene and polyethylene-polyethyleneblends. In the case of the polypropylene blends the composition of interest is 20% polypropylene. At this composition thepolypropylene has been found to be soluble in linear low density polyethylene but insoluble in high, low and very lowdensity polyethylenes. The miscibility has been concluded from the crystallization kinetics and polarised optical microscopywith a hot stage. Polyethylene-polyethylene blends have been formed from polymers with similar average branching contentbut where they have different melting temperatures. Important consequences are to introduce long branches into apolyethylene that only has short branches, and to modify the morphology of a polyethylenes so that haze, gloss and strainhardening are improved. Polyethylene blends must be developed after careful consideration of the branch content anddistribution within each of the constituents. It is not sufficient to simply blend polyethylenes, with the desired range ofproperties, without regard to the miscibility of the blend composition.