纳米CaCO3／PP／PS复合材料的结晶与熔融行为

熔融方法制备了纳米CaCO3／PP／PS复合材料，DSC研究了PP／PS、增容PP／PS共混物及其纳米CaCO3填充共混物的结晶与熔融行为。研究结果表明加入PS对PP结晶行为影响不大，但导致PP熔点下降，熔融峰从单峰变为双峰。纳米CaCO3和增容剂对PP／PS共混物中PP结晶存在异相成核作用，提高PP结晶温度和熔点，PP—g—MA和PP—g—AA的异相成核作用比CaCO3的大。PP—g—MA增容的PP／PS共混物和CaCO3填充共混物有利于PP形成β晶，但CaCO3填充共混物、PP—g—AA的增容PP／PS共混物和CaCO3填充共混物无β晶形成。     

马来酸酐混合单体改性PP/PS共混物的结晶与动态力学性能

用熔融法制备了马来酸酐（MAH）及其与苯乙烯（St）混合单体改性PP／PS共混物,以及MAH、St改性聚丙烯（原住形成PP／PS共混物）。用DSC、DMA和FT—IR研究了改性共混物的结晶与熔融行为、动态力学性能和接枝产物。结果表明,MAH加入对PP／PS共混物中PP的结晶温度影响不大,但其与St混合单体对共混物中PP的结晶温度影响明显,原位生成PP／PS的结晶温度也有较大提高。改性对共混物中PP的熔融温度影响不大,但熔融峰形变化明显。改性PP／PS共混物具有高的E′和E″强度。     

官能团化聚丙烯改性Mg(OH)2/PP中PP结晶的异相成核作用

用DSC研究了外加官能团化聚烯烃(FPP)、接枝单体和原位形成FPP改性Mg(OH)2／聚丙烯中的异相成核作用。Mg(OH)2表面的异相成核作用使聚丙烯(PP)结晶温度提高;外加FPP使PP结晶温度进一步提高,接枝单体加入也使复合材料中PP结晶温度提高,但原位形成FPP使PP结晶温度、熔点和结晶度降低。认为在改性复合材料中存在Mg(OH)2表面异相成核作用和FPP活化Mg(OH)2表面异相成核的协同作用。     

从β-聚丙烯到β-聚丙烯共混物

相对于聚丙烯(PP)共混物,β-PP共混物研究很少。文中对本实验室近几年开展的β-成核PP与聚苯乙烯(PS)、丙烯腈-苯乙烯共聚物(AS)、丙烯腈-丁二烯-苯乙烯共聚物(ABS)、尼龙(PA)、对苯二甲酸乙二醇酯(PET)共混物的制备、结构与性能进行了总结。重点讨论了不同第二组分及其用量、结晶度与极性,增容和制备方法等对PP共混物的β-成核作用的影响。观察到PS、AS和ABS对β-成核作用影响很小,可获得高β-晶含量的PP共混物。β-成核PP与PA、PET共混物的β-成核作用取决于制备方法,降低PET结晶度的方法和加入相容剂有利于共混物β-晶的形成。第二组分极性并不是影响共混物β-成核作用的主要因素。     

PP/PC/PP-g-GMA共混物的结晶和相形态

采用偏光和相差显微镜详细研究了聚丙烯(PP)/聚碳酸酯(PC)不相容聚合物共混体系和PP/PC/PP-g-GMA增容共混体系的结晶和相形态.研究结果表明,PP/PC共混体系中增容剂PP-g-GMA中甲基丙烯酸缩水甘油酯(GMA)支链起到成核剂的作用,促进PP结晶异相成核,使得PP有效晶核密度增加,球晶尺寸减小;PC分散...     

相容剂对聚丙烯/聚乙醇酸共混物结构与性能的影响

采用熔融共混法制备了聚丙烯/聚乙醇酸共混物(PP/PGA),研究了相容剂聚丙烯接枝马来酸酐(PP-gMAH)用量对共混物力学性能、熔融结晶行为、流变行为和断面形貌的影响。结果表明:PP-g-MAH的加入能明显改善共混体系的相容性,共混物的力学性能得到提升。PP-g-MAH对PGA结晶具有异相成核作用,且先结晶的PGA又可作为PP结晶的异相成核剂。随相容剂用量增大,PGA结晶温度升高,结晶完善程度降低,甚至不结晶,PP的结晶温度先降低后升高,且复数黏度呈先增大后减小的趋势。     

原位交联改性PP/POE共混物的等温结晶行为

采用热塑性聚烯烃弹性体(POE)作为增韧材料,以过氧化二异丙苯(DCP)为交联剂制备了PP/POE共混物。利用差示扫描量热仪(DSC)和偏光显微镜(PLM)研究了PP/POE共混物等温结晶行为,并用Avrami方程分析了PP/POE共混物结晶动力学。结果表明,POE的加入能起到异相成核的作用,加快了PP的结晶成核速率。Avrami指数在1.93～3.09,DCP的引入对聚丙烯(PP)的成核与生长机理影响不大,但其原位交联作用阻碍了PP分子链的运动,使得PP结晶速率降低,结晶时间延长。     

PP/POE共混物的热行为与晶态结构

采用双螺杆挤出机熔融共混制备了不同组成的聚丙烯(PP)/乙烯-辛烯弹性体(POE)共混物,利用差示扫描量热仪、偏光显微镜和广角X射线衍射系统研究了共混物的热行为与晶态结构。结果表明PP与POE之间具有一定的相容性,POE的异相成核作用提高了共混物中PP的结晶温度和结晶速率,有效地诱导β晶型PP的形成,增大了共混物中α晶型和β晶型PP的晶面表观厚度。另一方面,由于POE与PP之间存在较强的相互作用,POE大分子链使PP分子链的扩散和堆积受阻,从而导致PP/POE共混物总结晶度的降低。     

PP／s-1，2PB共混物的非等温结晶动力学

用DSC方法研究了聚丙烯(PP)、PP与间同1,2-聚丁二烯(s-1,2 PB)共混物的非等温结晶行为,结果表明:Mo法处理PP及PP/s-1,2 PB(90/10)共混物是非常适宜的,而用Ozawa法处理则存在缺陷.用Jeziorny法处理共混物也是适宜的,但对PP处理存在缺陷;s-1,2 PB对PP有加速结晶的作用; s-1,2 PB使PP的结晶活化能降低,s-1,2 PB在PP结晶过程中起到异相成核的作用.     

大分子相容剂改性纳米CaCO3 / PP复合材料的非等温结晶行为

熔融混炼制备了4 种大分子相容剂改性的纳米CaCO₃ / PP 复合材料, 用DSC 和WXRD 研究了复合材料中PP 的结晶与熔融行为。结果表明, 纳米CaCO₃对PP 结晶存在异相成核作用, 并诱导PP 形成β晶。相容剂丙烯酸接枝聚丙烯( PP-g-AA) 和马来酸酐接枝聚丙烯( PP-g-MA) 也存在异相成核作用, 提高PP 结晶温度。PP-g-AA、PP-g-MA 和马来酸酐接枝乙烯2辛烯共聚物(POE-g-MA) 与纳米CaCO₃存在异相成核协同作用, 进一步提高PP 的结晶和熔融温度, PP-g-MA 和POE-g-MA 还促使纳米CaCO₃诱导PP 生成β晶。但马来酸酐接枝乙烯2醋酸乙烯酯共聚物( EVA-g-MA) 则阻碍纳米CaCO₃对PP 的异相成核作用。实验结果表明纳米CaCO₃ / PP 复合材料中PP 结晶的异相成核作用与纳米CaCO₃ / PP 界面的相互作用有关, 而纳米CaCO₃ / PP 界面的相互作用与相容剂的结构有关。      

聚丙烯/聚苯乙烯共混体系模量的细观力学研究

应用复合材料细观力学理论和相应分析模型,预测了聚丙烯/聚苯乙烯(PP/PS)共混体系的弹性模量并进行相应的试验研究。系统研究了非相容PP/PS共混物的体积含量和共混时间对共混物形态和弹性模量的影响,分析了细观形态与宏观力学性能间的关系。对PP/PS共混物的拉伸实验结果表明:微观力学模型在模量预报上是可行的,其中Mori-Tanaka法更有效,因为与半经验模型(如Halpin-Tsai法和改进的混合模型)相比,它没有试验参数,在材料设计时具有更大的优越性。     

功能化石墨烯/埃洛石纳米管对聚丙烯的协同强韧化改性研究

以功能化氧化石墨烯(GO)-埃洛石纳米管(HNTs)杂化材料(GO@HNTs)为纳米填料,以聚丙烯(PP)为基体,通过熔融共混法制备了不同GO@HNTs 含量的GO@HNTs/PP纳米复合材材料,并对所得杂化填料和PP纳米复合材料的结构与性能进行系统研究。研究结果表明,功能化GO与HNTs之间存在化学相互作用,二者之间形成的“屏障效应”抑制了彼此在PP基体中的团聚。仅添加0.5%GO@HNTs杂化纳米填料后,PP复合材料的拉伸强度和冲击强度分别较纯PP提高了17.5%和80.4%,与单独添加相同含量的GO或HNTs所得复合材料的力学性能相比,GO@HNTs杂化纳米填料对PP基体具有明显的协同增强增韧改性作用。与纯PP相比,GO@HNTs/PP试样表现出更高的储能模量、损耗模量和玻璃化转变峰值。由于GO@HNTs的“异相成核效应”和“物理热阻效应”,有效提高了PP纳米复合材料的结晶温度、熔融温度、结晶度和耐热分解温度。     

PP／PS共混体系相容性及共混纤维性能研究

研究了以聚丙烯（PP）为基质,聚苯乙烯（PS）为改性组分的PP／PS共混体系,其为热力学不相容体系,但通过选择合适的原料,共混体系可以获得较好的工艺相容性,纺丝和牵伸实验表明,共混改性树脂的可纺性良好,改性纤维的物理力学性能,挺刮性有明显提高。     

液晶聚合物对尼龙1010/聚丙烯共混合金的结晶行为和力学性能的影响

用DSC研究了液晶聚合物（LCP）的含量对PA1010／聚丙烯（PP）共混合金结晶和熔融行为的影响：用TGA研究了共混合金的热稳定性：用拉伸试验检测共混材料的力学性能。结果表明：PA1010／PP共混合金中加入0．6％－0．8％（质量）LCP时能起微纤增强和异相成核剂作用,提高合金结晶温度和结晶度,使结晶完善程度略有增加,结晶速率略受影响,并且共混材料的拉伸强度明显增强,但对其热稳定性影响不大。当LCP含量增加到5％时,将作为独立组分在共混合金中起作用,使PA1010和PP的结晶峰均出现明显分峰现象,共混材料的力学性能和热稳定性显著下降。     

Effect of blend composition on the rheology property of polypropylene/poly (ethylene-1-octene) blends

In the present study, the dynamic viscoelastic properties for binary blends consisting of polypropylene (PP) and poly (ethylene-1-octene) (POE) were investigated using a Stresstech Rheometer in molten states at 210 °C. The results show that the blends with different content of POE present diversified rheological behaviors. Meanwhile, the blends with 10 wt% and 20 wt% POE show especial rheological behaviors. The dynamic complex viscosity of the blends with 10 wt% and 20 wt% POE are higher than that of others. The storage modulus and loss modulus of the blends with 10–40 wt% POE are different from other blends, and the blends with 10 wt% POE present the largest relaxation time. This behavior is probably related to the miscibility and long chain branch of POE in the PP/POE blends.     

Effect of nanoclay and SEBS-g-MA on the morphology and properties of immiscible poly(methyl methacrylate)/polystyrene blend

In recent years, nanoclays are being used as compatibilizer for various immiscible polymer blends. However, little work has been done on the morphology of immiscible polymer blends in presence of both the nanoclay and a reactive compatibilizer. Here, we report the synergistic effect of nanoclay and SEBS-g-MA on the morphology and properties of (70/30 w/w) PMMA/PS blend. Scanning electron microscopy study of the blend with various amount of nanoclay and SEBS-g-MA indicated a reduction in the average domain sizes (D) of dispersed PS phase in PMMA matrix compared to that in the pure blend. Addition of both SEBS-g-MA and nanoclay significantly lowered the D of PS in the blend compared to that with only SEBS-g-MA or clay. X-ray diffraction study and transmission electron microscopy revealed the presence of intercalated clay platelets in PMMA matrix, as well as, at the interface of the (70/30 w/w) PMMA/PS blend-clay nanocomposites. Addition of SEBS-g-MA in the blend-clay nanocomposites promoted the exfoliation of clays in PMMA matrix. Thus, exfoliated clay platelets in PMMA matrix effectively restricted the coalescence of dispersed PS domains while SEBS-g-MA improved the adhesion between the phases at the interface. At certain loading (phr), storage modulus, elongation at break and thermal stability of the blend were greatly improved when both the nanoclay and SEBS-g-MA were present in the blend. The use of reactive compatibilizer and nanoclay in polymer blends may lead to a high performance material which combines the advantages of compatibilized polymer blends and the merits of polymer nanocomposites.     

Mechanical properties of injection moulded blends of polypropylene with thermotropic liquid crystalline polymer

Blends of a thermotropic liquid crystalline polymer (LCP) with polypropylene (PP) were injection moulded. The LCP exhibited a higher viscosity than that of PP. Static and dynamic mechanical measurements, Izod impact tests, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) were performed on these blends. The static tensile tests show that the tensile modulus and strength of PP are improved with the addition of LCP. The improvement in mechanical properties is associated with the formation of LCP fibrils as evidenced by SEM observations. Dynamic studies on these blends show an increase in the storage modulus but a decrease in loss factor with the addition of LCP. Furthermore, TGA measurements show that the thermal stability of PP is improved substantially with the addition of LCP.