多单体接枝聚丙烯对PP/PA6共混物形态及力学性能的影响

用同向双螺杆挤出机制备了马来酸酐(MAH)、苯乙烯(St)多单体熔融接枝聚丙烯[PP-g-(St-MAH)],将其作为增容剂在Haake转矩流变仪上与PP/PA6共混得到PP/PA6/PP-g-(St-MAH)共混物,并对共混物的性能及结构进行了表征。结果表明,该增容剂明显改善了共混物的力学性能,当增容剂含量为15~20份时,共混物的冲击强度和拉伸屈服强度达最大值。采用扫描电子显微镜观察共混物试样断面的形态,发现分散相的粒径明显减小,且分散均匀。     

混沌螺杆混沌混合性能模拟与实验

针对混沌螺杆的混沌单元,对其加工高分子材料的混合性能进行模拟并与螺杆单元比较,采用PP/ABS共混物进行力学性能与微观形态实验。结果表明:混沌单元的停留时间概率密度曲线峰宽,拉伸长度对数曲线斜率增大,对物料拉伸折叠作用强,有利于提高共混物的混合性能;随着混沌螺杆转速的增加,PP/ABS共混物的冲击强度和拉伸强度先下降后上升;混沌单元的周期性间断多副螺棱具有很好的混沌混合特征,物料开始进入混沌单元时分散相被迅速分离,分散相粒径减小有一个相对缓慢期,随后分散相又被迅速分离,使得分散相粒径不断减小,提高了PP/ABS共混物的混合效果。     

高分子共混物的相结构对力学性能的影响

本文以聚丙烯 尼龙1010(PP PA1010)共混体系为模型研究了高分子共混物的微观相结构对宏观力学性能的影响,并通过微观力学模型来预测共混物的拉伸强度。通过光散射试验和扫描电镜结果讨论了两相平均弦长比(L1 L2)以及分散相的质心相关距(D)与拉伸性能的关系。结果表明,当分散相一定时,拉伸强度随两相相对尺寸的增大和分散相颗粒相关性的减弱而减小。理论计算的分散相最小体积分数与相形貌观察的结果非常接近,添加增容剂的体系,由于改善了界面粘合,使理论预测值与试验结果很好的吻合。     

纳米蒙脱土对PA66/PP共混物结构与性能的影响!

通过融挤出制备了PA66/PP/纳米蒙脱土(OMMT)共混物,采用广角X射线衍射(WAXD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等研究了OMMT在PA66/PP共混物中的分散及其对PA66/PP共混物力学性能、结构的影响。结果表明,OMMT主要为剥离状态分布于PA66/PP中。随OMMT含量增加,PP分散相尺寸逐渐减小,且5 phr OMMT时,PP分散相尺寸达到最小。PA66/PP/OMMT共混物的拉伸强度和模量呈上升趋势,缺口冲击强度下降。     

粘度比对PP/HDPE共混物材料形态结构与性能的影响

研究了粘度比对聚丙烯(PP)/高密度聚乙烯(HDPE)共混物的拉伸性能、弯曲性能、冲击性能以及热变形温度的影响。结果表明,随着粘度比由大到小的变化,共混物的拉伸强度、热变形温度由小到大再到小的变化;粘度比越大,冲击强度相对较高;粘度比接近1时,分散相的颗粒最小。     

PTT/PP共混物的性能研究

通过熔融共混制备了聚对苯二甲酸丙二酯/聚丙烯(PTT/PP=75/25)及其马来酸酐接枝PP(PP-g-MAH)增容共混物,研究了PTT/PP及其增容共混物的结晶性能、力学性能、流变性能和结晶形态。研究结果表明,PTT与PP共混能提高PP、PTT组分的结晶温度;对于增容共混物,随PP-g-MAH用量的增加,PP和PTT的结晶温度基本不变。加入PP使PTT拉伸强度降低,冲击强度提高;PP-g-MAH增容使共混物的拉伸和冲击强度都提高。增容共混物的熔体粘度明显降低,存在明显的剪切变稀现象,但熔体粘度与PP-g-MAH用量无关。在一定用量范围内,随PP-g-MAH用量的增加,PP分散相的尺寸变小。     

化学交联PP/LDPE共混材料的熔体强度及发泡性能

通过化学交联提高聚丙烯/低密度聚乙烯(PP/LDPE)共混物的熔体强度,并对交联PP/LDPE共混物的发泡性能进行了研究.结果表明:交联PP/LDPE共混物熔体在拉伸过程中出现明显的应变硬化现象,熔体强度明显提高;采用交联PP/LDPE共混物可制得泡孔均匀、性能良好的闭孔泡沫材料;随着LDPE含量的增加,交联PP/LDPE共混物的凝胶含量逐渐增加,熔体流动速率(MFR)减小;随着发泡剂用量的增加,交联PP/LDPE共混物泡沫的密度逐渐减小,泡孔孔径略有增大;随着泡沫密度的减小,泡沫材料的拉伸强度、压缩强度及压缩永久变形逐渐减小,拉伸断裂伸长率基本不变.     

HYBRAR与α成核剂对PP性能的影响

将高性能热塑性弹性体苯乙烯、乙烯支化异戊二烯三嵌段共聚物（HYBRAR）及α成核剂与PP进行共混,并参照各测试标准制备试样。对共混物的力学性能及热稳定性进行了表征。研究结果表明,HYBRAR的加入使共混物的冲击强度和断裂伸长率显著提高,而拉伸强度降低,α成核剂的加入使得PP及PP／HYBRAR共混物的冲击强度和拉伸强度升高;α成核剂提高了共混物的热稳定性,而HYBRAR降低其热稳定性。     

云母粉对注塑发泡PP/EPDM共混物泡孔结构和力学性能的改善

采用注塑发泡方法制备了质量比为75/25的聚丙烯/三元乙丙橡胶(PP/EPDM)共混物和质量比为75/25/7.5的PP/EPDM/云母粉复合材料制品,分析了两种制品泡孔结构和结晶性能的差异及其对制品力学性能的影响。结果表明:与共混物发泡制品相比,复合材料发泡制品的拉伸屈服强度、拉伸断裂强度、断裂伸长率和无缺口冲击强度分别提高约5%、48%、206%和22%,并呈现应变硬化现象。复合材料发泡制品的泡孔直径明显较小且分布较均匀,泡孔密度明显较大,结晶度较高,这些是使复合材料发泡制品具有较高力学性能的主要原因。     

EVA对PP/EVA共混物力学性能的影响

将不同配比的聚丙烯(PP)和乙烯-乙酸乙烯共聚物(EVA)进行共混,测试了共混物的拉伸强度和冲击强度;用差示扫描量热法研究了共混物的结晶性能;用扫描电镜(SEM)二次电子成像系统分析了试样的断口形貌,研究了EVA含量对共混物力学性能的影响。结果表明:EVA的加入提高了EVA/PP共混体系的韧性,同时降低了PP的结晶度。     

PP/HDPE/SBS三元共混物的研究——基体韧性和弹性体分散相对PP三元共混物脆—韧转变的影响

研究了固定PP/HDPE/SBS三元共混物配比,采用不同共混工艺条件下的脆-韧转变规律。研究表明:PP三元共混物的冲击强度与SBS分散相粒径有密切关系。当SBS分散相粒间距T等于临界值T_c时,PP三元共混物将发生脆-韧转变。研究还表明基体韧性与T_c有密切关系,当基体韧性增高时,T_c值将增大。     

The Use of Ethylene/Propylene Copolymers as Compatibilizers for Recycled Polyolefin Blends

Compatibilizing effects of ethylene/propylene (EPR) diblock copolymers on the morphology and mechanical properties of immiscible blends produced from recycled low‐density polyethylene (PE‐LD) and high‐density polyethylene (PE‐HD) with 20 wt.‐% of recycled poly(propylene) (PP) were investigated. Two different EPR block copolymers which differ in ethylene monomer unit content were applied to act as interfacial agents. The morphology of the studied blends was observed by scanning‐ (SEM) and transmission electron microscopy (TEM). It was found that both EPR copolymers were efficient in reducing the size of the dispersed phase and improving adhesion between PE and PP phases. Addition of 10 wt.‐% of EPR caused the formation of the interfacial layer surrounding dispersed PP particles with the occurrence of PE‐LD lamellae interpenetration into the layer. Tensile properties (elongation at yield, yield stress, elongation at break, Young's modulus) and notched impact strength were measured as a function of blend composition and chemical structure of EPR. It was found that the EPR with a higher content of ethylene monomer units was a more efficient compatibilizer, especially for the modification of PE‐LD/PP 80/20 blend. Notched impact strength and ductility were greatly improved due to the morphological changes and increased interfacial adhesion as a result of the EPR localization between the phases. No significant improvements of mechanical properties for recycled PE‐HD/PP 80/20 blend were observed by the addition of selected block copolymers.     

SBS and SEBS block copolymers as impact modifiers for polypropylene compounds

Blends of polypropylene (PP) and thermoplastic elastomers (TPE), namely SBS (styrene‐butadiene‐styrene) and SEBS (styrene‐ethylene/1‐butene‐styrene) block copolymers, were prepared to evaluate the effectiveness of the TPE type as an impact modifier for PP and influence of the concentration of elastomer on the polymer properties. Polypropylene homopolymer (PP‐H) and ethylene–propylene random copolymer (PP‐R) were evaluated as the PP matrix. Results showed that TPEs had a nucleating effect that caused the PP crystallization temperature to increase, with SBS being more effective than SEBS. Microstructure characterization tests showed that in most cases PP/SEBS blends showed the smallest rubber droplets regardless of the matrix used. It was seen that SEBS is a more effective toughening agent for PP than SBS. At 0°C the Izod impact strength of the PP‐H/SEBS 30% b/w blend was twofold higher than the SBS strength, with the PP‐R/SEBS 30% b/w blend showing no break. A similar behavior on tensile properties and flexural modulus were observed in both PP/TPE blends. Yield stress and tensile strength decreased and elongation at break increased by expanding the dispersed elastomeric phase in the PP matrix. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 254–263, 2005     

Electroconductive polyblend fibers of polyamide‐6/polypropylene/polyaniline: Electrical,morphological, and mechanical characteristics

Melt spun drawn fibers were prepared using a ternary blend of PP/PA6/PANI‐complex (polypropylene/polyamide‐6/polyaniline‐complex). Their electrical and mechanical properties were compared to those of binary blend fibers of PP/PANI‐complex. The results of the morphological studies on 55:25:20 PP/PA6/PANI‐complex ternary fibers were found to be in accordance with the predicted morphology for the observed conductivity vs. fiber draw ratio. The scanning electron microscopy (SEM) micrographs of the ternary blend illustrated at least a three‐phase morphology of a matrix/core‐shell dispersed phase style, with widely varying sizes of droplets. This resulted in a dispersed morphology that, in some parts of the blend, approached a bicontinuous/dispersed phase morphology due to coalescence of the small droplets. The matrix was PP and the core‐shell dispersed phase was PA6 and PANI‐complex, in which a part of the PANI‐complex had encapsulated the PA6 phase and the remaining was solved/dispersed in the PA6 core, as later confirmed by X‐ray mapping. When the ternary blend fibers were compared to the binary fibers, the formers were able to combine better conductivity (of an order of 10^?3 S cm^?1) with a greater tensile strength only at a draw ratio of 5. This indicated that the draw ratio is more critical for the ternary blend fibers, because both conductivity and tensile strength depended on the formation of fibrils from the core‐shell dispersed phase of the PA6/PANI‐complex. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Studies on binary and ternary blends of polypropylene with ABS and LDPE. II. Impact and tensile properties

Studies on impact and tensile properties of binary blend of PP and ABS and ternary blend of PP, ABS, and LDPE are presented. Variation of impact strength and the fracture surface morphology with blend composition is examined and interpreted. Tensile behavior in the yield region is studied and the trends of variation of work of yield and impact strength are compared to ascertain the predominent mechanism of impact toughening in these binary and ternary blends. An analysis of yield–stress data in terms of theoretical models is presented to reveal the differences in these binary and ternary blends, attributable to the role of LDPE component in the ternary blend.     

增韧增强阻燃聚丙烯的研制

采用溴／锑复合阻燃剂、三元乙丙橡胶(EPDM)和无碱玻璃纤维对聚丙烯(PP)进行了复合改性研究，考察了复合阻燃剂、EPDM和无碱玻璃纤维含量对PP性能的影响。研究结果表明，溴／锑复合阻燃剂对PP有良好的阻燃作用；EPDM对PP有很好的增韧作用，并且可以提高阻燃剂的阻燃效率；无碱玻璃纤维的加入在有效提高复合材料拉伸强度、弯曲强度及弯曲模量的同时，还可以提高其冲击强度。     

PA／PP—g—MAH／PP共混物的界面和形态研究

用小角X光衍射和偏光显微镜等方法研究了具有相容区的PA101／PP-g-MAH/PP熔融共混物的界面和结晶开态，PA101和PP－g-MAH在熔融共混过程中生成新的基团，在相间存有界面，体系中两相的结晶形态均匀，共混物的拉伸屈服强度随着界面层厚度的增大而提高。     

Effect of organoclay on the morphology, phase stability and mechanical properties of polypropylene/polystyrene blends

The effect of organically modified clay on the morphology, phase stability and mechanical properties of polypropylene (PP) and polystyrene (PS) blends was studied using three molecular weight grades of PP. Maleated polypropylene was used, at a PP-g-MA/organoclay ratio of 1, to preferentially promote dispersion of the organoclay in the PP matrix. The MMT content was fixed at 3 wt% based on the PP/PP-g-MA/MMT phase and the PS content was varied from 0-100 wt% in the blend. All blends were processed using a twin screw extruder. The organoclay resides in the PP phase and at the PP/PS interface. The dispersed PS particle size is significantly reduced by the presence of MMT, with maximum decrease observed for the low viscosity PP compared to its blend without MMT. The blends with MMT did not show any change in onset of co-continuity, though MMT shifts the phase inversion composition toward lower PS contents. The phase stability of the blend was significantly improved by the presence of MMT; for blends annealed at 210 °C for 2 h the dispersed phase particle size increased by as much as 10x without MMT with little change was noted with MMT present in the blend. The tensile modulus of blends improved with the addition of MMT at low PS contents. Blends based on the highest molecular weight grade PP showed increase in the tensile yield stress up to 40 wt% PS in the absence of MMT. The tensile strength at break for blend increased slightly with MMT while elongation at break and impact strength decreased in the presence of MMT. Surface energy analysis model was used to predict the orientation and equilibrium position of the clay platelet at the interface based on the surface energies.     

i-PB/PP共混物和SP179型PP性能比较

比较了高全同聚丁烯-1/聚丙烯(i-PB/PP)共混物和SP179型PP的力学性能和微观结构。共混物的拉伸强度、屈服强度、断裂伸长率、弯曲模量等力学性能都要优于SP179,而韧性却大大低于SP179。SP179中乙烯嵌段对PP结晶影响较大,而共混物中i-PB对PP结晶影响较小;SP179可溶物中含有较多的抗氧剂,并且含有聚乙烯长嵌段;SP179的热稳定性优于共混物。     

动态硫化EPDM／PP热塑性弹性体相态结构及其力学行为

研究动态硫化ＥＰＤＭ／ＰＰ热塑性弹性体相态结构及其力学行为。结果表明：动态硫化ＥＰＤＭ／ＰＰ共混物相态是ＥＰＤＭ橡胶以颗粒状分布在ＰＰ连续相中,这种相态结构一般不随橡塑比的变化而改变,但ＥＰＤＭ橡胶颗粒的形态变化显著。动态硫化ＥＰＤＭ／ＰＰ共混物,在橡塑比小于２５／７５,共混物具有类似橡胶应力－应变特征。