PVC/EVA共混物的研究

本文研究了混炼温度和时间对PVC/EVA共混物抗冲性能的影响,发现加入聚乙烯,共混体系的抗冲击强度能进一步提高.用TEM观察了PVC/EVA的形态结构,采用Brabender塑化仪和毛细管流变仪研究了共混物的塑化和熔体流变行为.通过计算机对实验结果进行二元线性回归,建立了共混物的熔体粘度与剪切应力和温度相关联的数学模型.     

类苯乙烯对PVC性能的影响研究

采用双辊混炼机将类苯乙烯与聚氯乙烯(PVC)熔融共混,制备类苯乙烯/PVC共混物,考察了不同含量类苯乙烯对PVC的透明性、低温性能、微观形态结构、力学性能、塑化温度及动态黏弹性等的影响。研究表明,类苯乙烯/PVC共混物具有良好的透明性,类苯乙烯可使PVC的低温冲击强度提高1.6倍,脆性温度降低12℃,使PVC的塑化温度、储能模量和损耗模量降低。     

PVC／PE共混体系的研究—ELVALOY741,EVA对PVC／LLDPE共混物的增容作用

本文采用 ELvaloy741、EVA 作为 PVC/LLDPE 共混物的增容剂,用机械共混法制样,研究了增容剂含量对共混物的力学性能、熔体流动性能及相态结构的影响。实验结果表明,增容剂含量对共混物的上述三种性能影响呈现一定的规律性,增容剂含量适当,能不同程度地改善共混体系的力学和加工性能。     

PVC/EVA形状记忆管材的制备及性能研究

采用双螺杆挤出制备了聚氯乙烯/乙烯-醋酸乙烯共聚物(PVC/EVA)共混物管材,考察了EVA含量对PVC塑料管材的流变性能、热力学性能、形状记忆等性能的影响。研究发现,EVA弹性体能够显著增加材料的韧性和降低材料的维卡软化温度,缩短材料的塑化时间;制备的PVC/EVA共混物具有较佳的形状记忆效应,且形变回复后管材的环刚度、拉伸强度、断裂伸长率等力学性能没有明显降低,满足国标PVC管材要求。     

PP/EVA/COPET共混物流变性能的研究

采用CFT-500型毛细管流变仪研究了聚丙烯/乙烯-醋酸乙烯酯/碱溶性聚酯(PP/EVA/COPET)共混物的流变性能。结果表明:PP/EVA/COPET共混物出现剪切变稀现象,非牛顿指数小于1,熔体为假塑性流体;熔体表观粘度随EVA含量的增加呈现先减小后增大趋势,并随温度的上升而下降;EVA质量分数为15%的共混物的表观粘度最低,粘流活化能最小。     

超支化聚（酰胺-酯）对聚丙烯／聚氯乙烯／苯乙烯-甲基丙烯酸甲酯共聚物接枝聚丙烯共混体系的增容作用

研究了超支化聚(酰胺-酯)(HBP))对聚丙烯/聚氯乙烯/苯乙烯-甲基丙烯酸甲酯共聚物接枝聚丙烯共混体系[PP/PVC/PP-g-(St-co-MMA)]的增容作用。讨论了HBP的用量对PP/PVC(80/20)共混物力学性能的影响；研究了剪切应力、剪切速率和温度对PP/PVC(80/20)共混物熔体黏度的影响。实验结果表明在PP/PVC/PP-g-(St-co-MMA)(80/20/6)共混物中加入1份HBP时，就可以很好改善共混体系的相容性，使共混物拉伸强度达到最大值，同时使熔体表观黏度达到较小值。该共混物熔体属于假塑性流体。扫描电子显微镜(SEM)研究结果证明了HBP增强了PP/PVC/PP-g-(St-co-MMA)的界面粘结作用，减小了共混体系的相分离程度。     

CPVC／PVC／CPE三元共混改性的应用

研究了CPVC/PVC/CPE三元共混物的物理力学性能和流变性能。结果表明 :共混物的维卡软化温度、拉伸屈服强度和熔体粘度随CPVC用量的增加而明显增加 ;CPE的用量为 4～ 8份时可明显改善共混物的冲击强度     

影响NBR/PVC共混硫化胶性能因素的研究

系统研究了影响丁腈橡胶/聚氯乙烯(NBR/PVC)共混胶性能的主要因素,包括PVC塑化温度、增塑剂用量、橡塑比、PVC的聚合度、NBR的丙烯腈质量分数。研究结果表明,塑化温度在160℃、增塑剂用量为20份、橡塑比为60/40~70/30时,NBR/PVC共混硫化胶综合性能较好。随着PVC聚合度的提高,NBR/PVC共混硫化胶力学性能得到提高;NBR中丙烯腈含量的增大有利于NBR/PVC共混硫化胶性能的提高。     

EVA熔体流动速率对PLA/EVA共混物性能的影响

通过熔融共混法制备了聚乳酸（PLA）/乙烯-乙酸乙烯酯共聚物（EVA）共混物,采用SEM、DSC、旋转流变仪等研究了VA质量分数为28%,熔体流动速率（MFR）不同的EVA对PLA/EVA共混物性能的影响。结果表明,EVA熔体流动速率越小,其在PLA基体中分散越均匀,EVA颗粒粒径也越小。共混物的结晶度随EVA熔体流动速率的增大而增大,但PLA的玻璃化转变温度（Tg）基本不受EVA的影响。PLA/EVA共混物的复数黏度和储能模量均随EVA的熔体流动速率的增高而减小。力学性能测试结果表明,当EVA的质量分数为15%时,PLA的断裂伸长率明显升高,冲击强度约是纯PLA的2倍。     

PVC-C/PVC共混材料的性能研究

采用氯化聚乙烯（CPE）对氯化聚氯乙烯（PVC—C）进行抗冲改性，将改性后的PVC—C与PVC进行共混，研究了PVC-C／PVC配比对PVC-C／PVC共混物力学性能、耐热性能及流变形能的影响。结果表明，PVC—C／PVC共混物的维卡软化点随PVC—C的用量增加而上升，在50／50（质量比）处有一拐点，大于50／50时上升更快些。共混物的拉伸强度、弯曲强度和熔体黏度随PVC—C用量的增加而提高；混物中随PVC—C用量增加，塑化时间缩短，塑化能力增强，而冲击强度和断裂伸长率却随PVC—C用量增加而下降。共平衡转矩增加。     

Rheological Behavior and Mechanical Properties of Blends of Poly(vinyl chloride) with CP-POSS

In this work, a polyhedral oligomeric silsesquioxane which contains 3-chloropropyl groups (CP-POSS) was synthesized. The rheological behavior of CP-POSS/PVC blends was investigated by torque rheometer and capillary rheometer. Mechanical properties were investigated by electronic material tester. Influences of blending composition, shear rate and shear stress on melt apparent viscosity and non-Newtonian index (n) were discussed. The results show that the plastic time decreases and melt viscosity increases with increasing content of CP-POSS. CP-POSS has a good compatibility with PVC. The blend has the best impact strength when the content of CP-POSS is 7 wt%. The CP-POSS can be used as a processing aid and impact-resistant aid for PVC.     

聚羟基烷酸酯改性聚氯乙烯的研究

通过熔融共混的方法分别制备了聚氯乙烯/邻苯二甲酸二辛酯/聚羟基烷酸酯（PVC/DOP/PHA）和PVC/PHA共混物。研究了PHA逐步代替DOP对共混物力学性能和熔体流动性能的影响规律,利用扫描电子显微镜对所制备的试样进行微观结构分析。结果表明,随着共混体系中PHA用量的增加和DOP的等量减少,与PVC/DOP共混物相比,PVC/DOP/PHA共混物的拉伸强度由21 MPa提高至42 MPa,断裂伸长率先增加而后降低,在PHA含量为10.7 %(质量分数,下同)时出现极大值(350 %);在PVC/PHA体系中,PHA含量增加,PVC/PHA共混物的力学性能及熔体流动速率都显著提高,说明PHA可以作为PVC的一种有效的绿色增塑剂和增韧剂。     

茂金属聚乙烯（mPE）／高压聚乙烯（LDPE）共混熔体的流变学

研究了不同比例共混的茂金属聚乙烯（mPE)和高压聚乙烯（LDPE）熔体的流变行为,讨论了共混物组成、剪切速率和剪切应力以及温度对熔体流变曲线、熔体粘度和膨胀比的影响,mPE的加工提供了理论依据。不同共混比的熔体均为假塑性流体,且熔体假塑性随LDPE含量增大而增强。熔体流动活化能随LDPE组成的增加逐渐增大,粘度对温度的敏感性增强,共混物的非牛顿指数随LDPE的增加而降低,改善了mPE的加工性能。     

Melt rheology of HDPE/EVA blends: The effects of blend ratio,compatibilization, and dynamic vulcanization

The melt rheological behavior of high‐density polyethylene (HDPE)/ethylene vinyl acetate (EVA) blends has been examined with reference to the effect of blend ratio, shear stress, and temperature. The HDPE/EVA blends exhibit pseudoplastic behavior, and the observed rheological behavior of the blends was correlated with the extrudate morphology. The experimental values of the viscosity were compared with the theoretical models. The effect of maleic‐ and phenolic‐modified PE compatibilizers on the viscosity of H₇₀ blend was analyzed and found that compatibilization did not significantly increase the viscosity. The effect of dynamic vulcanization and temperature on the viscosity was also analyzed. The activation energy of the system decreased with increase in EVA content in the system. The phase continuity and phase inversion points of the blends were theoretically predicted and compared with the experimental values. The melt flow index (MFI) values of the blends were also determined and found that the MFI values decreased with increase in EVA content in the system. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Ethylene copolymers as sintering enhancers and impact modifiers for rotational molding of polyethylene

The objective of this work was to evaluate the effect of blending minor amounts of ethylene styrene Interpolymer or ethylene vinyl acetate (EVA) with polyethylene on cycle times and impact strength in rotational molding. The blends sintered significantly faster than polyethylene. The sintering rates were primarily influenced by the melting points of the minor blend components, and not by differences in melt viscosity and/or elasticity at low shear rate. Blending Interpolymer or EVA with polyethylene resulted in improved environmental stress crack resistance and decreased flexural modulus. In rotational molding, blending Interpolymer or EVA with polyethylene generally resulted in faster bubble removal, more uniform thickness and shorter cycle times. Ductile failure was generally observed at the peak mean failure energy (MFE). The blend containing Interpolymer yielded significantly increased MFE, possibly because the Interpolymer was compatible with polyethylene and was very well dispersed.     

Studies on the polyblends of poly(vinyl chloride) with various methacrylate copolymers,melt rheological properties. II

Studies have been made on the melt rheological properties of poly(vinyl chloride) (PVC) with copolymers of methyl methacrylate (MMA) and methyl acrylate (MA), ethyl acrylate (EA), butyl acrylate (BA), and 2-ethyl hexyl acrylate (EHA) at a blending ratio of 80:20. Effect of blend composition on shear stress–shear rate, melt viscosity, melt elasticity, and extrudate distortion have been studied. A significant decrease in the melt viscosity is observed on incorporation of low T_g, acrylate copolymers such as those with BA and EHA, thereby reducing the processing temperature. First normal stress and die swell ratio also decreases with an increase in the side chains of acrylate copolymer. PVC blended with P(MMA-co-BA) and P(MMA-co-EHA) is sensitive to both temperature and shear stress.     

Melt flow behavior of blends from poly(vinyl chloride) and epoxidized natural rubber

Blends from poly(vinyl chloride) (PVC) and epoxidized natural rubber (ENR) were prepared in a Brabender plasticorder by the melt blending technique. The melt flow behavior of these blends with respect to blend ratio and temperature has been examined using a melt flow indexer and capillary rheometer. ENR decreases the Brabender torque, increases the melt flow index (MFI), and decreases the melt viscosity of PVC in the blends. Arrhenius plots were used to study the effect of temperature on melt flow index (MFI) and viscosity. Moreover, the flow behavior index (n′) obtained from capillary rheometer data was found to be dependent on temperature and blend ratio.     

聚乳酸/聚丁二酸丁二醇酯共混物的研究

通过熔融共混制备了聚乳酸(PLA)/聚丁二酸丁二醇酯(PBS)共混物,采用扫描电子显微镜、差示扫描量热仪、旋转流变仪对其相容性、热性能和黏度等进行了研究,并研究了PBS的加入对PLA力学性能的影响。结果表明,PLA和PBS之间是部分相容的,PBS的少量添加并不影响PLA的拉伸强度,且其冲击强度随着PBS含量的增加呈先上升后下降的趋势,当PBS含量为10份时,共混物的冲击强度最好;与纯PLA相比,共混物的黏度有所增加,且随着PBS含量的增加,共混物的黏度逐渐增大;PBS的添加起到异相成核作用,促进了PLA的结晶。