PP-g-(MAH/St)和PP-g-MAH对聚丙烯/木粉复合材料性能的影响

在转矩流变仪中用熔融接枝法制备马来酸酐(MAH)和苯乙烯(St)接枝聚丙烯（PP）-PP-g-(MAH/St)和PP-g-MAH,将其作为聚丙烯/木粉复合材料的相容剂。 FTIR证实MAH和St单体与PP发生接枝反应。 用SEM和DSC等手段考察两种相容剂对PP/木粉复合材料微观形貌和结晶性能的影响,探索了各种PP/木粉复合材料加工和力学性能不同的内在原因。 SEM显示,PP-g-(MAH/St)改性木粉比PP-g-MAH改性木粉在PP基体中分散性更佳,木粉与PP的界面更加模糊,相容性进一步改善。 DSC结果表明,PP-g-(MAH/St)改性体系可增强木粉对PP的异相成核作用,提高结晶温度和结晶度。 复合材料的加工和力学性能测试结果表明,PP-g-(MAH/St)改性效果明显优于PP-g-MAH。 复合材料的熔体质量流动速率随相容剂用量的增加而逐步下降,PP-g-(MAH/St)改性体系拉伸强度和弯曲强度却逐步上升,并在相容剂用量为4.8 g/100 g PP时达到极值。 此时其拉伸强度达40.62 MPa,分别是未改性体系和PP-g-MAH改性体系的1.29和1.17倍;其弯曲强度达45.72 MPa,分别是未改性体系和PP-g-MAH改性体系的1.23和1.59倍;而无缺口冲击强度却在相容剂用量为3.6 g/100 g PP时达到极值13.35 kJ/m2,分别是未改性体系和PP-g-MAH改性体系的1.62倍和1.42倍。     

界面改性剂在聚丙烯／高岭土二相复合体系中的作用

从高岭土（Ｋａｏｌｉｎ）填充聚丙烯（ＰＰ）体系的界面分子设计入手，研究了界面改性剂对填料的分散性，聚丙烯基体的结晶行为，填充熔体流变性质以及材料力学性能的影响．结果表明，界面改性剂降低了填料的高表面能，改善了填料分散状况．界面改性剂的加入，填充熔体粘度接近纯聚丙烯数值．经界面改性剂处理后，填充材料缺口悬臂梁冲击强度随填料量的增加而急剧升高，在填料量为３０Ｗｔ％时，冲击强度达到４８０Ｊ／Ｍ，是未处理材料的十二倍，添加至填料量为５０ｗｔ％时，冲击强度没有明显降低．     

通过熔体自由基反应调控聚丙烯体系的链结构和相结构

熔融反应加工是聚合物改性和制备聚合物纳米复合材料的重要途径之一.在此过程中,多数加成聚合物由于受到热、剪切或引发剂作用,通常可原位形成大分子自由基反应中间体.我们系统地研究了如何利用这类大分子自由基调控聚合物分子链的拓扑结构和聚合物纳米复合体系的相结构与界面.然而,某些聚合物大分子自由基,如聚丙烯(PP),受其分子链化学结构决定,在熔融反应条件下非常易于发生降解.研究发现,将可控自由基聚合中调控自由基反应活性的方法应用在熔融反应过程中可以显著抑制PP的降解,促进主反应的发生,在制备长链支化聚合物、调控聚合物纳米复合材料的相结构方面发挥了重要作用.本文介绍了本研究组近几年来通过熔体自由基反应调控PP体系的链结构和相结构的相关研究工作,如实现PP的长链支化,制备高熔体强度PP;在制备PP/C60 、PP/碳纳米管(CNTs)纳米复合材料过程中,利用熔体界面区域所发生的自由基反应,提高了纳米粒子与PP的界面相互作用,改善了纳米粒子在PP中的分散状态等.     

无机粉体对微发泡聚丙烯复合材料力学行为的影响

通过改性的不同形状（针状MgSO4晶须、片状云母粉、球形状SiO2）无机粉体材料,以5％含量加入到聚丙烯中,在二次开模条件下制备微发泡PP复合材料;测定PP／无机粉体材料复合体系接触角,联合粘接理论计算液-固界面的黏附功;以异相成核理论和填充增强机理为基础,分析了不同形状的无机粉体材料对微发泡PP材料力学行为的影响规律...     

复合成核剂对聚丙烯结晶行为的影响

以超细橡胶粒子与有机磷酸盐成核剂复配的方法制备了一种新型复合成核剂,通过示差扫描量热法(DSC)比较了复合成核剂改性PP以及有机磷酸盐成核剂改性PP的结晶温度、等温结晶行为及等温结晶动力学;利用扫描电子显微镜(SEM)的能谱附件和透射电子显微镜(TEM)研究了复合成核剂的微观形态及其在PP中的分散情况.研究结果表明,复合成核剂中超细橡胶粒子作为载体使有机磷酸盐成核剂附着在其表面,提高了成核剂在聚丙烯中的分散性,因而提高了成核剂的成核效率,当成核剂用量较小时,即可明显提高PP的结晶速率和力学性能.     

CaCO_3表面包覆改性及其对填充PP力学性能的影响

先用丙烯酸(AA)处理CaCO3,在其表面引入活性双键基团后,再通过固相包覆反应将聚丙烯蜡(PPW)固定在CaCO3表面.实验发现改性CaCO3可经受甲苯、稀盐酸处理而不发生溶解,结合红外及热重分析结果,证明PPW已经通过化学键合而成功地包覆在CaCO3表面.将该改性CaCO3填充聚丙烯(PP)后,发现PP的冲击性能及拉伸性能均有不同程度的提高,当改性CaCO3的填充量为15份时,体系的缺口冲击强度达到最大值,为基体树脂的1.68倍;当改性CaCO3的填充量10份时拉伸强度达到峰值,为同等添加量的未改性CaCO3的1.22倍.     

聚丙烯“催化合金”组成对结晶行为的影响

用示差扫描量热仪(DSC)和偏光显微镜(POM)研究了聚丙烯“催化合金”(PP-cats)组成对等温结晶行为与动力学的影响,并与等规聚丙烯(iPP)进行比较.结果表明,与纯PP相比较,PP-cats的平衡熔融温度明显下降,表明PP-cats中作为主要组分的丙烯均聚物和乙丙无规共聚物之间存在较强的相互作用.PP-cats的结晶初期动力学可用Avrami模型很好地描述,结晶过程均为预先成核和三维生长方式.PP-cats的结晶速率随体系中乙丙共聚物含量的增加而增大,而PP-cats的晶体生长速率随体系中乙丙共聚物含量的增加而减小.由于PP-cats熔体的粘度远高于纯PP,使得PP-cats中PP分子链运动能力降低,导致了PP-cats较低的晶体生长速率.此外,与纯PP相比,PP-cats的成核密度大幅度提高,被认为是PP-cats具有快的结晶速率的主要原因.     

2,2-亚甲基-二(4,6-二正丁基苯酚)磷酸钠/凹凸棒土/二氧化硅复合成核剂改性聚丙烯的研究

通过喷雾干燥技术制备了一系列无机纳米粒子(凹凸棒土和/或二氧化硅)与有机磷酸盐类成核剂(NA11)复配的复合成核剂.研究了复合成核剂对聚丙烯力学性能与结晶行为的影响.采用透射电镜(TEM)、扫描电镜(SEM)、偏光显微镜(POM)、广角X射线衍射仪(WAXD)等对复合成核剂在聚丙烯中的分散和对结晶行为的影响进行了表征和分析,并且对复合成核剂改性聚丙烯的机理进行了探讨.结果表明,这种复合成核剂对聚丙烯力学性能的改善明显,聚丙烯的刚性迅速增加,其中三元成核剂对聚丙烯刚性的提高更显著,该成核剂在0.2%用量下对聚丙烯力学性能的改善效果,相当于同等添加量下纯NA11的改性效果.微观形态研究表明三元复合成核剂体系中,三组分形成了相互隔离的分散状态,使有机成核剂和无机纳米粒子可以在聚丙烯基体中实现良好分散.     

丁醛等离子体处理填料对填充聚烯烃熔体流变性的影响

用毛细管流变仪研究了经丁醛等离子体处理的云母粉填充高密度聚乙烯熔体(160℃)和聚丙烯熔体(180℃)的流变性。数据表明,处理削弱填充聚烯烃熔体流动的非牛顿性,熔体流动非牛顿指数随等离子体处理时间的延长而增大;处理降低填充聚烯烃熔体在低切变速率下的表观粘度,提高其在高切变速率下的表观粘度,发生转变的临界切变速率对填充聚乙烯和聚丙烯分别为150S~(-1)和50S~(-1)。扫描电镜观察熔体形态证实,处理对熔体粘度的复杂影响,是处理改善填料在熔体中的分散性和提高填料与基体界面结合力两者综合作用的结果。     

改性高岭土对PP/高岭土纳米复合材料结晶性能的影响

通过将不同改性的高岭土与聚丙烯共混, 制备了聚丙烯插层的PP/高岭土纳米复合材料. 并通过X射线衍射分析(XRD)、透射电子显微镜(TEM)研究了复合材料的微观结构, 同时通过差示扫描(DSC)非等温结晶方法和偏光显微镜(PLM)照片, 研究了改性高岭土母粒对聚丙烯的结晶性能的影响. 采用Avrami方程式及Jeziorny修正过的Avrami的方程式对PP/高岭土的非等温结晶动力学进行了研究. 结果表明, 有机改性过的高岭土可被聚丙烯完全剥离, 在XRD谱图中, 高岭土的001峰不可见, 在TEM中可见剥离的片层. 同时随着改性高岭土的加入, 使得聚丙烯异相成核结晶增长, 且填充聚丙烯的最快结晶温度在395K. 结果也表明, 有机改性的高岭土能有效促进PP的异相成核, 提高PP的结晶速率和结晶温度, 但对结晶速率常数影响不是很大.     

热塑性聚氨酯及其复合材料的界面形态与流变特性

以聚酯型热塑性聚氨酯(thermoplastic polyurethane,TPU)、玻璃纤维(glass fiber,GF)和玻璃微珠(glass bead,GB)为主要原料制备了TPU/GF、TPU/GB共混物,考察了复合体系的热性能、微观结构、动态流变特性.研究发现,TPU是温敏型聚合物,其温敏性与材料的硬段含量有关,在加工过程中,除考虑剪切速率的影响外,需重点考虑温度对其加工性能的影响;GF,GB填充TPU体系具有良好的分散形态和界面结合牢度,GF和GB的加入能够增加体系的黏度,降低TPU的温敏性,加宽TPU的加工温度窗口,从而改善其成型加工性,并能一定程度地提高其耐热性.研究还发现,复合体系黏度的增加程度不仅和填料的含量有关,而且与填料的形状有关,可用等效直径表征.另外,从比表面积的角度比较了玻璃纤维和玻璃微珠对体系热稳定性的影响.     

Effect of the interfacial interaction on the phase structure and rheological behavior of polypropylene/ethylene– octene copolymer/BaSO4 ternary composites

In polypropylene (PP)/ethylene–octene copolymer (POE)/BaSO₄ ternary composites, two different kinds of phase structures are assumed:(1) POE and BaSO₄ filler are separately dispersed in the PP matrix and (2) POE‐encapsulated filler particles (core–shell structure) are dispersed in the matrix. This depends on the interfacial interaction of the composites. For the design of composites with different interfacial interactions, three routes for the preparation of BaSO₄ master batches were developed. First, a mixture of BaSO₄, POE, and maleic anhydride (MAH) in a certain ratio was extruded in the presence of dicumyl peroxide and then pelletized. In extrusion, MAH‐functionalized POE was in situ formed to enhance the interfacial interaction between POE and BaSO₄. Second, a mixture of POE and BaSO₄ was directly extruded and then pelletized. Third, after BaSO₄ was treated with an organic titanate coupling agent, the treated BaSO₄ and POE were blended in extrusion and then pelletized. Scanning electron microscopy observations showed that the core–shell structure in which POE encapsulates BaSO₄ particles is formed through route 1, whereas POE and BaSO₄ are separately dispersed into the PP matrix through routes 2 and 3. The rheological behavior of PP/POE/BaSO₄ ternary composites was studied with a controlled stress rheometer. The results showed that the interfacial interaction in composites with core–shell morphology is the strongest. Interparticle interactions give rise to the formation of interparticle networks; the stronger the network is, the larger the shear yield stress is and the smaller the thixotropic loop area is. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1804–1812, 2002     

纳米CaCO_3/相容剂/PP中的界面相互作用研究

采用不同相容剂(PP-g-MAH、POE-g-MAH和EVA-g-MAH)制备了不同界面相互作用的纳米CaCO3(CC)/相容剂/PP体系,研究了相容剂/PP和相容剂/CC界面相互作用对PP/CC的结晶形态、结晶行为、熔融特性和力学性能的影响.观察到PP/CC界面相互作用提高PP结晶温度和PP/CC的模量和冲击强度,但降低了屈服强度.相容剂/CC界面相互作用进一步提高了PP/CC的结晶温度.PP/相容剂界面相互作用取决于PP与相容剂相容性.PP/PP-g-MAH相容性高有利于提高PP/CC的异相成核作用和PP/CC屈服强度和模量,但降低冲击强度.PP/POE-g-MAH部分相容对相容剂/CC界面的异相成核作用、PP/CC屈服强度和模量影响不大,可明显提高冲击强度.但PP/EVA-g-MAH不相容导致PP/CC冲击强度明显降低.     

马来酸酐-苯乙烯熔融接枝聚丙烯的影响因素及其性能研究

用单螺杆挤出机制备了马来酸酐 (MAH) 苯乙烯 (St)对聚丙烯 (PP)的多组分单体自由基熔融接枝体系 .研究证实了当两种单体物质的量比约为 1∶1时 ,接枝物的接枝率最高 ,而熔体流动速率 (MFR)最大 .对反应体系影响因素的研究表明单体用量和引发剂用量对不同单体用量比的系列接枝物的接枝率会产生不同的影响 ;另外 ,单体用量增加 ,接枝物的MFR减小 ,过氧化二异丙苯 (DCP)用量增加 ,接枝物的MFR增加 .对多单体熔融接枝聚丙烯PP g (MAH co St)的力学性能研究发现 ,选用合适的单体用量比、单体用量和DCP用量时 ,所制备的接枝物可具有与纯PP相当或更佳的力学性能     

An Electroconductive Filler for Shielding Plastics

A well characterised grade of mica was used to prepare nickel-coated mica fillers by an electroless coating technique. These fillers were incorporated into polypropylene (PP) and acrylonitrile-butadiene-styrene (ABS) using a Haake Internal mixer and a two-roll mill to produce conducting composites suitable for EMI shielding applications. Compounded polymers were fabricated into sheets of different thickness by compression moulding. The dependence of conductivity on sample thickness was studied and samples were tested for electrical resistivity, shielding efficiency, and thermal and mechanical properties. Reduced sample thickness during compression moulding decreased the electrical resistance of the polymer composites due to orientation and the formation of a good conducting network. Volume resistivity of PP composites was lower than for ABS composites with 50% Ni coating and equivalent filler weight fracions, showing that better conductivity could be achieved in a semi crystalline polymer than in an amorphous polymer. 0.6 weight fraction of 50 wt.% nickel coated mica in ABS showed a shielding efficiency of 16dB compared with 27.8dB in PP.     

Dispersion evaluation of microcrystalline cellulose/cellulose nanofibril-filled polypropylene composites using thermogravimetric analysis

Microcrystalline cellulose-filled polypropylene (PP) composites and cellulose nanofiber-filled composites were prepared by melt blending. The compounded material was used to evaluate dispersion of cellulose fillers in the polypropylene matrix. Thermogravimetric analysis (TG) and mechanical testing were conducted on composites blended multiple times and the results were compared with single batch melt blended composites. The residual mass, tensile strength, and coefficient of variance values were used to evaluate dispersion of the microcrystalline cellulose fillers in the PP matrix. The potential of using TG to evaluate cellulose nanofiber-filled thermoplastic polymers was also investigated and it was found that the value and variability of residual mass after TG measurements can be a criterion for describing filler dispersion. A probabilistic approach is presented to evaluate the residual mass and tensile strength distribution, and the correlation between those two properties. Both the multiple melt blending and single batch composites manufactured with increased blending times showed improved filler dispersion in terms of variation and reliability of mechanical properties. The relationship between cellulose nanofiber loading and residual mass was in good agreement with the rule of mixtures. In this article, the authors propose to use a novel method for dispersion evaluation of natural fillers in a polymer matrix using TG residual mass analysis. This method can be used along with other techniques such as scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray diffraction (XRD) for filler dispersion evaluation in thermoplastic composites.     

原位固相接枝改性碳酸钙/聚丙烯复合材料的制备

用马来酸酐（MAH）在碳酸钙（CaCO3）表面引入双键,通过原位固相接枝法将聚丙烯蜡（PPW）化学键合在CaCO3表面,制得3种接枝率的CaCO3-MAH-PPW。 将这3种改性CaCO3填充聚丙烯（PP）制备复合材料,研究了PP/CaCO3界面作用对复合材料强度的影响。 结果表明,CaCO3表面经PPW接枝改性后在PP中的分散性提高,与PP相容性变好;随着改性CaCO3表面PPW接枝率的提高,CaCO3与PP之间界面作用逐渐增强。 当PPW接枝率为4.48 mg PPW/g CaCO3时,CaCO3与PP之间的界面作用最强,复合材料拉伸强度下降最小,杨氏模量提升最大,当m(PP)∶m(CaCO3)=100∶50时,杨氏模量达0.86 GPa,是纯PP的1.63倍;而PPW化学接枝率为2.49 mg PPW/g CaCO3时,CaCO3与PP之间的界面作用适中,复合材料缺口冲击强度提升最大,且当m(PP)∶m(CaCO3)=100∶10时,缺口冲击强度达3.91 kJ/m2,是纯PP的1.35倍。     

PPO/SEBS-g-MAH共混体系的形态结构与冲击性能

从亚微相态和冲击性能出发 ,对比了采用熔融挤出法制备的PPO/SEBS和PPO/SEBS g MAH两种共混物 .结果表明 ,在本文所研究的弹性体用量范围内 ,PPO/SEBS为“海 岛”型结构 ,而PPO/SEBS g MAH呈现网状结构 ;PPO/SEBS体系无脆韧转变现象 ,PPO/SEBS g MAH体系则在弹性体用量为 10 %～ 15 %时出现明显的脆韧转变 ,缺口冲击强度达到 95 0J/m ,这种超韧现象源于其网状结构的形成 .文中进一步用DSC和毛细管流变仪对共混体系的热性能和流变性能进行了测试 ,探讨了PPO/SEBS g MAH共混物网状结构的形成原因     

The interfacial enhancement of LLDPE/whisker composites via interfacial crystallization

Interfacial interaction plays a key role in the preparation of high performance polymer composites. In this work, in order to explore the possibility to enhance the interfacial interaction via interfacial crystallization of polymer matrix onto the filler surface, interfacial crystallization structure and mechanical properties of linear low density polyethylene (LLDPE)/whisker composites were investigated. The composites were firstly prepared by melt compounding, followed by processing in both traditional and dynamic injection molding. DSC, WAXD, SEM were used to characterize the interfacial crystallization structure. And the mechanical properties were measured by tensile testing. An imperfect shish‐calabash structure, with whisker served as shish, and irregular LLDPE spherulite as imperfect calabash, was formed during common injection molding processing. Such a structure was considered as the main reason for the strong interfacial adhesion and the obviously improved tensile strength and modulus. Furthermore, introducing shear could cause the formation of relatively perfect shish‐calabash structure, leading to the stronger interfacial adhesion. Copyright © 2011 John Wiley & Sons, Ltd.