Relaxation behavior of polymer blends with complex morphologies: Palierne emulsion model for uncompatibilized and compatibilized PP/PA6 blends

This paper deals with the dynamic rheological behavior of polypropylene/polyamide6 (PP/PA6) uncompatibilized blends and those compatibilized with a maleic anhydride grafted PP (PP/PP-g-MAH/PA6). The terminal relaxation times of the blends predicted by the Palierne emulsion model were compared with those obtained from experimental relaxation time spectra. The Palierne model succeeded well in describing PP/PA6 uncompatibilized blends with relatively low dispersed phase contents (10 wt%) and failed doing so for those of which the dispersed contents were high (30 wt%). It also failed for the compatibilized ones, irrespective of the dispersed phase content (10 or 30 wt%) and whether or not interface relaxation was taken into consideration. In the case of the uncompatibilized blend with high dispersed-phase content, interconnections among inclusions of the dispersed phase were responsible for the failure of the Palierne model. As for the compatiblized blends, in addition to particle interconnections, the existence of emulsion-in-emulsion (EE) structures was another factor responsible for the failure of Palieme model.

Compatibilization of PP/EPDM blends by grafting acrylic acid to polypropylene and epoxidizing the diene in EPDM

In this article, ethylene-propylene-diene-rubber (EPDM) was epoxidized with an in situ formed performic acid to prepare epoxided EPDM (eEPDM). The eEPDM together with the introduction of PP-g-AA was used to compatibilize PP/EPDM blends in a Haake mixer. FTIR results showed that the EPDM had been epoxidized. The reaction between epoxy groups in the eEPDM and carboxylic acid groups in PP-g-AA had taken place, and PP-g-EPDM copolymers were formed in situ. Torque test results showed that the actual temperature and torque values for the compatibilized blends were higher than that of the uncompatibilized blends. Scanning electron microscopy (SEM) observation showed that the dispersed phase domain size of compatibilized blends and the uncompatibilized blends were 0.5 and 1.5 mu m, respectively. The eEPDM together with the introduction of PP-g-AA could compatibilize PP/EPDM blends effectively. Notched Izod impact tests showed that the formation of PP-g-EPDM copolymer improved the impact strength and yielded a tougher PP blend.

Brittle-ductile transition in PP/EPDM blends: effect of notch radius

The toughness of polypropylene (PP)/ethylene-propylene-diene monomer (EPDM) blends was studied over wide ranges of EPDM content and temperature. In order to study the effect of notch radius (R), the toughness of the samples with different notch radii was determined from Izod impact test. The results showed that both toughness and brittle-ductile transition (BDT) of the blends were a function of R, respectively. At test temperatures, the toughness tended to decrease with increasing 1/R for various PP/EPDM blends. Moreover, the brittle-ductile transition temperature (T-BT) increased with increasing 1/R, whereas the critical interparticle distance (IDc) reduced with increasing 1/R. Finally, it was found that the different curves of IDc versus test temperature (T) for different notches reduced down to a master curve if plotting IDc versus T-BT(m)-T, where T-BT(m) was the T-BT of PP itself for a given notch, indicating that T-BT(m)-T was a more universal parameter that determined the BDT of polymers. This conclusion was well in agreement with the theoretical prediction.

新型CNBR/PP全交联型热塑性弹性体的制备与形态、结构及性能研究

将具有纳米尺度的全交联型羧基丁腈粉末橡胶 ( CNBR)与聚丙烯 ( PP)及用甲基丙烯酸环氧丙酯( GMA)官能化的聚丙烯 ( PP-g-GMA)进行反应共混 ,制备了一种新型 CNBR/PP热塑性弹性体 .用原子力显微镜 ( AFM)和透射电子显微镜 ( TEM)研究了 CNBR/PP热塑性弹性体的形态 ,加入 PP-g-GMA增容剂后 ,CNBR分散相的粒子尺寸显著降低 ,分布也趋于均一 .与未增容体系相比 ,增容体系的拉伸强度和断裂伸长率均有大幅度的改善 ,如 CNBR含量为 75 %时 ,拉伸强度提高了 94% ,断裂伸长率增加了 1 3 6% .用差示扫描量热法 ( DSC)研究了热塑性弹性体中聚丙烯的结晶行为 ,在增容体系中 ,共混前后聚丙烯的结晶温度提高了 1 0℃ ,表明橡胶粒子或两相界面处形成的反应产物起到了类似成核剂的作用.

采用新萃取方法的PP-b-PE的研究

采用独特的二次溶解和沉淀的萃取方法,将PP b PE中的不可溶物与可溶物分离,并通过1 3C NMR,DSC,FT IR进行结构与性能的研究

Rheology and morphology of reactively compatibilized PP/PA6 blends

This work aims to use the Palierne emulsion type model to describe the relationship between the rheological response to small amplitude oscillatory deformation and morphology of polypropylene/polyamide 6 (PP/PA6) blends compatibilized with maleic anhydride grafted polypropylene (PP-g-MAH). It was found that the Palierne emulsion type model could describe very well the linear viscoelastic responses of binary uncompatibilized PP/PA6 blends and failed to describe the ternary compatibilized PP/PP-g-MAH/PA6 blends. These features could be attributed to the fact that the morphology of the ternary blends was not of the emulsion type with the PA6 particles dispersed in the PP matrix but of an emulsion-in-emulsion type, i.e., PA6 particles dispersed in the PP matrix themselves contained PP or PP-g-MAH inclusions. By consideration of PP-in-PA6 particles as pure PA6 particles, where the volume fraction of the PA6 phase was increased accordingly, the Palierne emulsion type model could work very well for a ternary blending system. Preshear at low frequencies modified the morphology of both binary and ternary blends. The particles of the dispersed phase (PA6) became more uniform. These results suggested that the Palierne emulsion type model could be used to extract information on rheological properties and interfacial tension of polymer blends from known morphology and vice versa.

Compatibilization by main-chain thermotropic liquid crystalline ionomer of blends of PBT/PP

The miscibility and mechanical properties of the blends of polybutylene terephthalate (PBT) and polypropylene (PP) with a liquid crystalline ionomer (LCI) containing a sulfonate group on the terminal unit as a compatibilizer were assessed. SEM and optical microscopy (POM) were used to examine the morphology of blends of PBT/PP compatibilized by LCI. DSC and TGA were used to discuss the thermal properties of PBT/PP blends with LCI and without LCI. The experimental results revealed that the LCI component affect, to a great extent, the miscibility and crystallization process and mechanical property of PBT/PP blends, The fact is that increasing LCI did improve miscibility of PBT/PP blends and the addition of 1% LCI to the PBT/PP blends increased the ultimate tensile strength and the ultimate elongation.

Brittle-tough transition in PP/EPDM blends: effects of interparticle distance and tensile deformation speed

The toughness of polypropylene (PP)/ethylene-propylene-diene monomer rubber (EPDM) blends containing various EPDM contents as a function of the tensile speed was studied. The toughness of the blends was determined from the tensile fracture energy of the side-edge notched samples. A sharp brittle-tough transition was observed in the fracture energy versus interparticle distance (ID) curves when the crosshead speed < 102.4 mm/min. It was observed that the brittle-ductile transition of PP/EPDM blend occurred either by reducing ID or by decreasing the tensile speed. The correlation between the critical interparticle distance and tensile deformation rate was compared with that between the critical interparticle distance and temperature for PP/EPDM blends. (C) 2000 Elsevier Science Ltd. All rights reserved.

Influence of the size of ultrafine CaCO3 powder on PP crystallization

The effects of CaCO3 on the crystallization behavior of polypropylene (PP) were studied by means of DSC and WAXD. The average sizes of the CaCO3 powders used were 0.1 mum (UC) and 0.5 mum (GC), respectively. The PP/CaCO3 composites at compositions of 1 phr and 10 phr were investigated. The results showed that the addition of CaCO3 reduced the supercooling, the rate of nucleation and the overall rate of crystallization (except for the 10 phr UC/PP sample). The crystallinity of PP was increased and the size distribution of the crystallites of alpha -PP; was: broadened. On the other hand,the crystallization rate of 10 phr UC/PP is 1.5 times higher than that of neat PP. It has an overall rate of crystallization 2 times as much as that of the neat PP and has the maximum crystallinity. The sizes of crystallites and the unit cell parameters of alpha -PP were varied by the addition of CaCO3. beta -PP was formed by addition of Ge and was not detected by addition of UC. The differences of crystallization behaviors of PP might be attributed to the combined effects of the content and size of CaCO3 filled.

反应挤出条件对PP-g-GMA接枝率、接枝效率和熔体流动速率的影响

用反应挤出法在聚丙烯 (PP)分子链上接枝甲基丙烯酸环氧丙酯 (GMA) ,制备功能化聚丙烯 .重点讨论了单体浓度、引发剂浓度、反应温度及物料在螺杆中的停留时间等对接枝产物 PP-g-GMA的接枝率、接枝效率和熔体流动速率的影响 .结果表明 ,PP-g-GMA接枝率与加入的单体浓度成正比 ,与引发剂浓度无关 ,反应挤出的适宜温度窗口在 1 95～ 2 3 0℃之间 ,停留时间超过 1 min后接枝率与停留时间无关 ;PP-g-GMA的熔体流动速率与单体浓度成反比 ,与引发剂的用量成正比 ,在反应温度窗口内与反应挤出温度和物料停留时间关系不大 ;单体和引发剂的浓度、反应挤出温度及物料停留时间对 PP-g-GMA的接枝效率无显著影响 .

PA46/PP-g-GMA合金的研制和表征

用反应挤出方法制备了PA46/PP-g-GMA合金。研究了合金的力学性能,吸水性与形态结构的关系。与PA46/PP相比,PA46/PP-g- GMA的力学性能如拉伸强度,杨氏模量,弯曲强度,弯曲模量以及冲击强度都有不同程度的提高。PA46/PP-g-GMA的吸水率比PS46/PP大幅度降低。用扫描电镜(SEM)研究了PA46/PP-g-GMA和PA46/PP样品的冲击断面。PA46/PP-g-GMA中的PP-g-GMA分散相粒子半径远比PA46/PP中的PP相粒子半径小和均匀。这表明改性后的PP-g-GMA与PA46的相容性有很大的改观。DMA研究结果表明,PA46 /PP-g-GMA样品的储能模量比相同组分的PP/PA46高。在组成为50/50时PA46/PP-g-GMA的软化点温度比PA46/PP高 120℃。

HIPS/PP反应共混物的热性能研究

研究了高抗冲聚苯乙烯(HIPS)/聚丙烯(PP)在过氧化二异丙苯(DCP)存在下熔融反应共混物的热学性能。HIPS在DCP存在下以PS的降解为主，PS的Tg明显下降，PP在DCP存在下也以降解为主，PP的结晶完善性受到破坏，HIPS/PP共混物在DCP存在下以PP同HIPS的反应接枝为主，分子运动的特征及热性能较前两者发生明显变化，PS的Tg略有下降，PP分子链的规整性降低，结晶熔点降低，完善性变差。

Effects of the compatibilizer PP-g-GMA on morphology and mechanical properties of PP/PC blends

Effects of the compatibilizer polypropylene grafted with glycidyl methacrylate(PP-g-GMA) on the morphology, thermal, rheological and mechanical properties of polypropylene and polycarbonate blends (PP/PC) were studied. It was found that the addition of PP-g-GMA significantly changed their morphology. The mean size of domains reduced from 20 mu m to less than 5 mu m. The dispersed domain size is also strongly dependent upon the content of PP-g-GMA. The interfacial tension of PP/PC/PP-g-GMA (50/30/20) is only about one-tenth of PP/PC (70/30). The crystallization temperature of PP in PP/PC/PP-g-GMA is 5-8 degrees C higher than that of PP in PP/PC blends. Characterization studies based on mechanical properties, differential scanning calorimetry, rheology and morphological evidence obtained by using scanning electron microscopy support the hypothesis that an in-situ copolymer PP-g-PC was formed during the blending process. (C) 1997 Elsevier Science Ltd.

PP-EPR-PP增容PP/EPT的研究

采用δ－ＴｉＣｌ３－Ｅｔ２ＡｌＣｌ催化合成了三元乙丙嵌段共聚物ＰＰ－ＥＰＲ－ＰＰ，作为乙丙橡胶（ＥＰＴ）增韧聚丙烯（ＰＰ）的增容剂，以改善ＰＰ的低温冲击性能。实验发现，ＰＰ－ＥＰＲ－ＰＰ中ＥＰＲ段较长，有利于提高其增容效果，ＰＰ－ＥＰＲ－ＰＰ的加入量仅为４％，就可以显著的改善ＰＰ和ＥＰＴ相容性，使ＰＰ／ＥＰＴ／ＰＰ－ＥＰＲ－ＰＰ共混物的无缺口冲击强度比相应的ＰＰ／ＥＰＴ在－２０℃时提高４０％，在－４０℃时提高了１２０％，达到较高的耐冲击等级。形态观察表明，ＰＰ－ＥＰＲ－ＰＰ同时又起到了“乳化剂”的作用，使ＥＰＴ在ＰＰ中均匀分散。还提出了ＰＰ－ＥＰＲ－ＰＰ的增容模型，完满地解释了实验结果。