PET/PP合金流变性能的研究

利用XLY-Ⅱ流变仪研究了PET/PP(1:3)合金以及含有增容剂PP-g-MA(马来酸酐接枝PP)的PET/PP(1:3)合金的流变性能,分析了增容剂对PET/PP合金流变性能的影响。结果表明,含增容剂的PET/PP合金流变性能好。     

叔丁基酚醛树脂在PP／EPDM合金中的作用研究

采用熔融分段共混法制备含有叔丁基酚醛树脂的PP/EPDM合金,通过SEM、DMA、拉伸和结晶速度试验,研究了PP合金的结构形态、相分离、结构行为和力学性能。结果表明过氧化物能改进PP/EPDM/PE合金的动态交联密度。PP/EPDM/PF/过氧化物合金的力学性能和结晶速度优于PP/EPDM和PP/EPDM/PF系统。     

PP/PET/POE-g-MAH共混合金的等温结晶动力学特性

应用差示扫描量热法(DSC),研究了加入不同份数增容剂POE-g-MAH的PP/PET共混合金及纯PP的等温结晶行为,采用Avrami方程处理等温结晶过程,计算结晶动力学参数。结果表明,随着结晶温度的升高各体系的结晶速率下降,结晶速率常数K、n降低,半结晶时间t1/2延长。同一温度下PET有明显的异相成核作用,提高了基体的结晶速率;POE-g-MAH的加入降低了基体的结晶速率,并且随着增容剂含量的增加,基体的结晶速率逐渐下降。纯PP的等温结晶过程具有异相成核与均相成核的机理,共混合金的等温结晶过程属于异相成核机理。     

PP／PET合金纤维的形态和热性能研究

用聚丙烯接枝丙烯酸(PP-g-AA)作增容剂,制备了PP／PET共混合金纤维。对合金纤维碱处理后的表面以及拉伸断裂后的断面形态进行SEM观察,结果表明分散相PET原位形成微纤。DSC研究结果显示,PET在复合体系中起到了异相成核的作用,使PP的结晶速率加快,同时发现加有增容剂PP-g-AA的结晶性能稍有下降,说明增容剂起到了良好的增容效果。     

PTW反应性增容PP/PET热致形状记忆共混合金的性能研究

以乙烯-丙烯酸丁酯-甲基丙烯酸缩水甘油酯三元共聚物(PTW)作为反应性增容剂,采用熔融共混法制备了聚丙烯/聚对苯二甲酸乙二醇酯/PTW(PP/PET/PTW)共混合金。借助扫描电子显微镜(SEM)、差示扫描量热仪(DSC)、万能试验机考察了PTW对PP/PET共混合金相容性、力学性能和热致形状记忆性能的影响。结果表明:少量PTW即可明显改善PP与PET之间的相容性,提高PP/PET共混合金的力学性能和热致形状记忆性能。     

不同相容剂对PP/PET合金性能的影响

以乙烯-丙烯酸甲酯共聚物接枝甲基丙烯酸缩水甘油酯(EMA-g-GMA),聚烯烃弹性体接枝GMA(POE-g-GMA)和聚丙烯接枝GMA (PP-g-GMA)为相容剂,采用熔融共混法制备了PP/聚对苯二甲酸乙二醇酯(PET)合金,并对PP/PET合金的性能进行了分析;研究了不同相容剂对PP/PET合金的加工性能、力学性能和微观形貌的影响。结果表明:在添加质量分数5%相容剂的情况下,PP/PET合金加工性能都得到了明显改善,POE-g-GMA可以显著地提高合金的韧性,而PP-g-GMA则可以有效地提高合金的刚性。     

β晶型PP/纳米CaCO3/短切PET纤维复合材料的制备

通过熔融挤出共混制备β晶型聚丙烯(PP)/纳米CaCO3/对苯二甲酸乙二酯(PET)纤维复合材料,并用马来酸酐(MAH)接枝PP(PP-g-MAH)改善材料的相容性。研究了PET纤维、β成核剂和相容剂对材料力学性能、相容性和结晶熔融行为的影响。结果表明:CaCO3和PET纤维对PP的结晶具有异相成核作用,能协同诱导形成β晶型PP。加入PET纤维可提高材料的刚性和韧性,但会损坏拉伸性能。PP-g-MAH能改善PP和PET纤维之间的相容性,并能促进成核剂在材料中的分散,形成更多的β晶。     

PP/PET共混体系及其合金纤维的研究

用增容剂PP-g-AA增容PP/PET共混体系。研究了增容剂含量、共混物组成、共混时间、共混温度以及螺杆转速对PP/PET相形态的影响。结果表明:增容剂的加入大大改善了PP/PET两相间的相容性,并且增容剂的添加量有一最佳值,为PET质量的50%。随着PET含量的增加,分散相的尺寸有所增加。共混温度和共混时间均有一最佳值。随着螺杆转速的提高,分散相的尺寸减小,分布趋于均一,相容性也得到改善。另外,还制备了PP/PET合金纤维,对其表面处理后以及断面SEM观察均表明分散相PET原位成纤,这些微纤提高了合金纤维的力学性能。测试了合金纤维的力学性能,发现组分比为90/10/5时,合金纤维具有最好的力学性能。     

PET/PP共混体系的熔融及非等温结晶行为

用熔融共混法制备了聚对苯二甲酸乙二醇酯(PET)/聚丙烯(PP)复合材料。对复合体系的形态结构、熔融及非等温结晶行为进行了研究。结果表明:两相界面或PP相对PET结晶无明显的异相成核效应;当PP为连续相时,已结晶的极性PET粒子对PP的异相成核作用较为明显;而当PP为分散相时,固态的PET在一定程度上阻碍了PP分子链的运动,促使PP结晶均相成核趋势增加。与纯PET或PP相比,共混体系中两组分结晶的完善程度都有所下降。     

PE/PP/PS反应性共混研究

研究了无水AlCl₃在PE/PP/PS共混过程中的反应性作用,考察了无水AlCl₃用量对PE/PP/PS合金力学性能和PP结晶行为的影响。结果表明:在PE/PP/PS共混过程中加入适量的无水AlCl₃,可以起到有效的增容作用,提高了合金的力学性能。     

Melting behavior and isothermal crystallization kinetics of PP/mLLDPE blends

The melting/crystallization behavior and isothermal crystallization kinetics of polypropylene (PP)/metallocene-catalyzed linear low density polyethylene (mLLDPE) blends were studied with differential scanning calorimetry (DSC). The results showed that PP and mLLDPE are partially miscible and interactions mainly exist between the mLLDPE chains and the PE segments in PP molecules. The isothermal crystallization kinetics of the blends was described with the Avrami equation. Values of the Avrami exponent indicated that crystallization nucleation of the blends is heterogeneous, the growth of spherulites is almost three-dimensional, and the crystallization mechanism of PP is not affected much by mLLDPE. The Avrami exponents of the blends are higher than that of pure PP, showing that the mLLDPE helps PP to form perfect spherulites. The crystallization rates of PP are decreased by mLLDPE because the crystallization temperature of PP was decreased by addition of mLLDPE and consequently the supercooling of the PP was correspondingly lower. The crystallization activation energy was estimated by the Friedman equation, and the result showed that the activation energy increased by a small degree by addition of mLLDPE, but changed little with increasing content of mLLDPE in the blends. The nucleation constant (K _g) was determined by the Hoffman–Lauritzen theory. Supported by the Science Foundation of Hebei University (2006Q13).     

动态硫化EPDM/PP热塑性弹性体等温结晶行为研究

采用差示扫描量热仪（DSC）对比研究了聚丙烯（PP）和动态硫化三元乙丙橡胶/聚丙烯热塑性弹性体（EPDM/PPTPV）的等温结晶行为,并用Avrami方程对其进行等温结晶动力学分析。结果表明,在相同的结晶温度下,EPDM/PPTPV比PP结晶更快。2种试样的等温结晶行为符合Avrami方程,在相同的结晶温度下,TPV的Avrami指数n比PP的低,半结晶时间t_1/2比PP的低,结晶速率常数k比PP的高。     

PET/粘土纳米复合材料加工条件下结晶行为的研究

采用DSC手段测试了PET、PET／粘土纳米复合材料熔体降温时的结晶行为。结果表明，在PET中引入纳米粘土可提高PET基体的降温结晶峰峰温，并使结晶速率提高1倍以上。PET及PET／粘土纳米复合材料的结晶峰峰温随降温速率的增大而移向低温，半结晶时间及结晶度随降温速率的增大而减小。基于Avrami方程的动力学分析表明，PET／粘土纳米复合材料的非等温结晶过程是带有异相成核的三维增长过程。     

Nonisothermal crystallization kinetics of polypropylene/polypropylene‐g‐polystyrene/polystyrene blends

The nonisothermal crystallization kinetics of polypropylene (PP), PP/polystyrene (PS), and PP/PP‐g‐PS/PS blends were investigated with differential scanning calorimetry at different cooling rates. The Jeziorny modified Avrami equation, Ozawa method, and Mo method were used to describe the crystallization kinetics for all of the samples. The kinetics parameters, including the half‐time of crystallization, the peak crystallization temperature, the Avrami exponent, the kinetic crystallization rate constant, the crystallization activation energy, and the F(T) and a parameters were determined. All of the results clearly indicate that the PP‐g‐PS copolymer accelerated the crystallization rate of the PP component in the PP/PP‐g‐PS/PS blends. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Nonisothermal melt crystallization kinetics of poly(ethylene terephthalate)/Barite nanocomposites

Poly(ethylene terephthalate) (PET)/Barite nanocomposites were prepared by direct melt compounding. The nonisothermal melt crystallization kinetics of pure PET and PET/Barite nanocomposites, containing unmodified Barite and surface‐modified Barite (SABarite), was investigated by differential scanning calorimetry (DSC) under different cooling rates. With the addition of barite nanoparticles, the crystallization peak became wider and shifted to higher temperature and the crystallization rate increased. Several analysis methods were used to describe the nonisothermal crystallization behavior of pure PET and its nanocomposites. The Jeziorny modification of the Avrami analysis was only valid for describing the early stage of crystallization but was not able to describe the later stage of PET crystallization. Also, the Ozawa method failed to describe the nonisothermal crystallization behavior of PET. A combined Avrami and Ozawa equation, developed by Liu, was used to more accurately model the nonisothermal crystallization kinetics of PET. The crystallization activation energies calculated by Kissinger, Takhor, and Augis‐Bennett models were comparable. The results reveal that the different interfacial interactions between matrix and nanoparticles are responsible for the disparate effect on the crystallization ability of PET. POLYM. COMPOS., 31:1504–1514, 2010. © 2009 Society of Plastics Engineers     

Crystallization of poly(ethylene terephthalate)/polycarbonate blends. I. Unreinforced systems

The crystallization and transition temperatures of poly(ethylene terephthalate) (PET) in blends with polycarbonate (PC) is considered using thermal analysis. Additives typically used in commercial polyester blends, transesterification inhibitor and antioxidant, are found to enhance the crystallization rate of PET. Differential scanning calorimetry (DSC) reveals two glass transition temperatures in PET/PC blends, consistent with an immiscible blend. Optical microscopy observations are also consistent with an immiscible blend. Small shifts observed in the T_g of each component may be due to interactions between the phases. The degree of crystallinity of PET in PET/PC blends is significantly depressed for high PC contents. Also, in blends with PC content greater than 60 wt %, two distinct crystallization exotherms are observed in dynamic crystallization from the melt. The isothermal crystallization kinetics of PET, PET modified with blend additives, and PET in PET/PC blends have been evaluated using DSC and the data analyzed using the Avrami model. The crystallization of PET in these systems is found to deviate from the Avrami prediction in the later stages of crystallization. Isothermal crystallization data are found to superimpose when plotted as a function of time divided by crystallization half-time. A weighted series Avrami model is found to describe the crystallization of PET and PET/PC blends during all stages of crystallization. © 1996 John Wiley & Sons, Inc.     

Nonisothermal crystallization kinetics of AB2 hyperbranched polymer‐filled polypropylene

In this article, nonisothermal crystallization kinetics of polypropylene (PP) and AB₂ hyperbranched polymer (HBP)‐filled PP have been investigated by differential scanning calorimetry. The Avrami analysis modified by Mandelkern and a method combined with Avrami and Ozawa equations were employed to describe successfully the nonisothermal crystallization kinetics of samples. The conclusion showed that HBP can prompt crystallization effectively. Furthermore, in blends of different HBP contents, the value of t_1/2 became smaller with increasing HBP content; however, the crystallization rate of the blend decreased slightly when content of HBP is 5%. An increase in the Avrami exponent showed that addition of HBP influenced the mechanism of nucleation and the growth of PP crystallites. The possible explanation could be attributed to the fractal structure of HBP. The polarized micrographs showed that HBP acts as a heterogeneous nucleation agent, and the nucleation efficiency has increased remarkably in HBP/PP blends. POLYM. ENG. SCI., 53:2535–2540, 2013. © 2013 Society of Plastics Engineers     

Preparation and nonisothermal crystallization behavior of polypropylene/layered double hydroxide nanocomposites

Polypropylene (PP)/layered double hydroxide (LDH) nanocomposites were prepared via melt intercalation using dodecyl sulfate anion modified LDH and maleated PP as compatibilizing agent. Evidently the interlayer anions in LDH galleries react with maleic anhydride groups of PP-g-MA and lead to a finer dispersion of individual LDH layers in the PP matrix. The nanostructure was characterized by XRD and TEM; the examinations confirmed the nanocomposite formation with exfoliated/intercalated layered double hydroxides well distributed in the PP matrix. The nonisothermal crystallization behavior of resulting nanocomposites was extensively studied using differential scanning calorimetry (DSC) technique at various cooling rates. In nonisothermal crystallization kinetics, the Ozawa approach failed to describe the crystallization behavior of nanocomposites, whereas the Avrami analysis and Jeziorny method well define the crystallization behavior of PP/LDH nanocomposite. Combined Avrami and Ozawa analysis (Liu model) also found useful. The results revealed that very small amounts of LDH (1%) could accelerate the crystallization process relative to the pure PP and increase in the crystallization rates was attributed to the nucleating effect of the nanoparticles. Polarized optical microscopy (POM) observations also support the DSC results. The effective crystallization activation energy was estimated as a function of the relative degree of crystallinity using the isoconversional analysis. Overall, results indicated that the LDH particles in nanometer size might act as nucleating agent and distinctly change the type of nucleation, growth and geometry of PP crystals.