Influence of Type of Vulcanization on Rheological and Thermal Properties of PP/NR Blends

Summary Rheological and thermal behavior of isotactic polypropylene (PP) and natural rubber (NR) blends were studied, with special reference to the type of vulcanization (dynamic and static). It was found that dynamic crosslinking of the NR phase increases the viscosity of the system, while it decreases crystallinity degree. Statically vulcanized blends show similar properties regardless curing time while dynamically vulcanized blends show enhanced properties if compared to the corresponding uncured blends.     

PP/Rosin Blends: Mechanical and Rheological Properties

Abstract

Melting mixtures of polypropylene (PP) and glycerol ester of hydrogenated rosin (ester gum) were prepared under select conditions using up to 50% of rosin. The addition of modified rosin on PP increased the elastic modulus which maximum value was observed in the 70/30 PP/ROSIN blend. The stress dropped monotonically with rosin content. Above 10% rosin, the elongation at yield diminished and reached a constant value. The elongation at break dropped abruptly above 10% of rosin. The density and hardness of blends increased with amount of rosin. The melt flow index of blends increased exponentially with the rosin content while the torque decreased monotonically with the composition and the processability was improved.     

PP/PEG共混体系熔体流变性能研究

以聚乙二醇(PEG)为抗静电剂,在不同共混比例下与聚丙烯(PP)熔融挤出,用流变仪分析了PP/PEG二元共混体系的流变性能,并深入研究了剪切速率、温度、PEG含量等因素对共混体系熔体流变性能的影响。结果表明:PP/PEG共混体系为典型的假塑性流体;随着PEG含量的增加,非牛顿指数n先增大后减小;黏流活化能随PEG含量的增加而增加;结构黏度指数Δη则随PEG含量的增加先减小后增大,且在PEG含量为6%时达到极小值,此时共混体系的可纺性相对较好。     

聚丙烯／无规共聚聚丙烯共混物的流变行为与力学性能研究

以毛细管流变仪研究了聚丙烯(PP)／无规共聚聚丙烯(PP-R)共混物熔体的流变行为。讨论了共混物的组成、剪切应力和剪切速率以及温度对熔体流变行为、熔体粘度的影响。测定了不同配比共混物熔体的非牛顿指数和膨胀比。结果表明：PP／PP-R共混物熔体属假塑性流体，其熔体粘度随PP-R含量的增加而迅速增大。力学性能测试结果表明，PP-R对PP有很好的增韧改性作用。另外，也用偏光显微镜研究了PP-R对共混物结晶形态的影响。     

NR/NBR共混物动态力学性能研究

对ＮＲ／ＮＢＲ共混物的动态力学性能进行了研究。结果表明,加入改性剂Ａ后,共混物在两个玻璃化温度（（Ｔｇ１,Ｔｇ２））下有两个动态力学损耗因子（ｔａｎδ）峰。随着体系中改性剂Ａ用量的增大（５～２０份）,Ｔｇ１基本不变,其对应的ｔａｎδ峰值下降;Ｔｇ２则向高温方向移动,其对应的ｔａｎδ峰值增大。因此,ｔａｎδ的大小和位置（Ｔｇ２）可以通过控制共混物各组分的用量来调节,从而获得抗湿滑性能好、滚动阻力低的材料。     

HDPE／NBR共混物流变性能研究

通过熔融共混法制备了HDPE／NBR共混物,用毛细管流变仪研究了其流变特性,此共混物属于假塑性流体,表观粘度随剪切速率和温度的升高而降低,随NBR和增容剂含量的降低而降低。     

PP/HDPE共混体系毛细管流变性能研究

用毛细管流变仪对以马来酸酐接枝聚丙烯(PP-g-MAH)为相容剂的聚丙烯/高密度聚乙烯(PP/HDPE)共混体系的流变性能进行研究。研究发现,PP/HDPE共混体系属于假塑性流体;随着剪切速率的增加,表观黏度下降;PP-g-MAH的加入降低了共混体系的表观黏度;HDPE与PP的非牛顿指数在低剪切速率区与适宜温度下适用于幂律方程的经验公式;HDPE与PP共混后,HDPE含量越低,体系出现壁面滑移的临界剪切速率越高,可加工性能越好。     

mPE弹性体/PP共混物的流变行为与力学性能

用茂金属聚乙烯弹性体（mPE)代替传统的弹性体,对聚丙烯（PP）进行增韧改性,绘制了不同配比mPE/PP共混物熔体的流变曲线,讨论了共混物的组成,切应力和剪切速率以及温度对熔体流变行为,熔体粘度的影响。测定了共混物熔全的非牛顿指数,熔体质量流动速率及力学性能,为mPE共混改性PP提供了理论依据。结果表明,mPE适用于PP的增韧改性,增韧效果取决于共混物中mPE的用量,当mPE质量分数达到25%-40%时,共混材料既有较高的拉伸强度和韧性,又有较好的加工性能,mPE/PP共混物熔体的假塑性流动随mPE用量的增加向更高切应力或更高剪切速率方向移动。     

PLA/PBS共混物的动态流变性能

研究聚丁二酸丁二酯(PBS)对聚乳酸(PLA)流变性能的影响。通过熔融挤出的方法在双螺杆挤出机上制备PLA/PBS共混物,采用旋转流变仪研究PLA/PBS共混物的动态流变性能。结果表明,当应变为6%时,PLA/PBS共混物的储能模量和损耗模量随着角频率的增加而增大,而PLA/PBS共混物的损耗因子和复数黏度随着角频率的增加而降低,共混物熔体表现出剪切变稀现象。用Han方法分析表明,共混物没有发生明显的相分离现象。动态时间扫描表明,时间对于纯PLA的储能模量没有影响,但是对于PLA/PBS共混物的储能模量有较大的影响。     

Rheological Studies of Dynamic Vulcanization of Butyl Rubber and Polypropylene Blends

Butyl rubber (BR) is blended with polypropylene (PP) in ratios of 92: 8, 84: 16, 68: 32, 50: 50, 32: 68, 16: 84, and 8 : 92 (w/w) for the study of dynamic vulcanization. It is observed that the cure torque increases with the decrease in BR content up to the ratio of 50: 50. No cure torque is observed in the ratios of 16: 84 and 8: 92 of BR: PP blends as the PP content becomes very high. On comparison of cure rate of the blends, the BR (100%) shows the highest cure rate because of the fast saturation of double bonds present in BR, whereas maximum cure torque, work energy, and totalized torque are observed in the 32: 68 BR: PP blend. It is the result of the formation of an interpenetrating network.     

NBR/聚丙烯酸酯橡胶共混物动态硫化的研究

ＮＢＲ的溴化酚醛树脂硫化体系和聚丙烯酸酯橡胶（ＡＣＭ）的硫化剂ＡＢＳ会相互干扰，产生硫化不相容性，导致ＮＢＲ，ＡＣＭ和ＮＢＲ／ＡＣＭ共混物性能下降。通过在ＮＢＲ／ＡＣＭ共混物中加入溴化酚醛树脂对ＮＢＲ进行动态硫化，然后加入ＡＢＳ对ＡＣＭ进行静态硫化的方法，能够较好地解决这两种不相容硫化体系的相容性问题，所得到的共混物表现出良好的物理性能，且优于相应的静态硫化共混物。同时考察了ＮＢＲ／ＡＣＭ的共混比对共混物性能的影响。     

动态固化聚丙烯／环氧树脂共混物流变性能与热性能研究

研究了马来酸酐接枝聚丙烯（MAH-g-PP）增容的动态固化PP饼氧树脂（EP）共混物的流变性能和热性能。实验结果表明，动态固化PP／EP／MAH—g—PP共混物属于假塑性流体，与PP／EP共混物相比，动态固化共混物表观黏度明显增加，随EP用量的增加，动态固化PP／EP／MAH-g-PP共混物的表观黏度逐渐增大。动态固化PP／EP／MAH-g—PP共混物维卡软化点明显高于PP，当EP的用量超过10质量％，共混物的维卡软化点反而有所下降。动态固化PP／EP／MAH-g-PP共混物具有较好的热稳定性，随EP用量的增加，共混物的热稳定性有所提高。     

Effects of Dynamic Vulcanization and Acrylic Acid on Properties of Recycled Poly(vinyl chloride)/Acrylonitrile Butadiene Rubber (PVCr/NBR) Blends

Effects of dynamic vulcanization and acrylic acid (AAc) on processability, mechanical properties, swelling behavior, morphology, and thermal stability of recycled poly(vinyl chloride)/acrylonitrile butadiene rubber (PVCr/NBR) blends were investigated. Blends were prepared in a Haake Rheomix at a temperature of 150°C and a rotor speed of 50 rpm. Recycled poly(vinyl chloride)/acrylonitrile butadiene rubber (PVCr/NBR) blends were also prepared as comparison. It was found that the dynamic vulcanization and the addition of acrylic acid improved the stabilization torque, mechanical energy, stress at peak, stress at 100% elongation (M₁₀₀), swelling resistance, and thermal stability but decreased the elongation at break of the blends. The introduction of a cross-link into the elastomer phase and better compatibility between PVCr and NBR are responsible for the enhancement of thermal stability and mechanical properties of dynamically vulcanized PVCr/NBR + AAc as evidence from the scanning electron microscopy (SEM) of the tensile fracture surfaces and infrared spectroscopy study of the dynamically vulcanized of PVCr/NBR + AAc shows.     

丁腈橡胶/聚甲醛共混物动态硫化的研究

采用２４０２树脂硫化体系以动态硫化方法制备了了腈橡胶（ＮＢＲ）／聚甲醛（ＰＯＭ）热塑性弹性体。研究了丙烯睛含量、硫化体系、橡塑比等对共混物性能的影响。实验结果表明：ＮＢＲ中丙烯睛含量增加，共混物的拉伸强度显著提高；随着ＰＯＭ用量增加，共混物的强度略有提高，表观粘度降低，加工性能改善，电性能、老化性能和耐油性能均得到明显提高。ＤＳＣ分析表明，共混物中ＰＯＭ的结晶度明显比纯ＰＯＭ低，熔点也有所下降。     

Melt Rheological and Impact Properties of Thermally Stable PP/mLLDPE Blends

Effect of the heat stabilizer on the melt rheological properties of the blends of polypropylene (PP) with mLLDPE (mettalocene linear low density polyethylene), after thermal degradation in an air oven, was studied. Study carried out is presented to describe the effect of blending ratio and presence of stabilizer on shear stress, shear rate, melt viscosity and melt elasticity parameters. In general, blending of PP with mLLDPE results in an increased viscosity. The viscosity of PP abruptly decreases after the thermal degradation. Interestingly the melt viscosity PP/mLLDPE blend does not show such a marked decrease. This shows that mLLDPE not only acts as an impact modifier but also acts as a thermal stabilizer. The presence of stabilizer in both materials has not shown much difference in melt viscosity thereby suggesting adequate stabilization of the blend system.     

氯醚橡胶/丁腈橡胶橡胶共混物性能的研究

研究了共聚型氯醚橡胶／丁腈橡胶共混比、促进剂ＮＡ－２２用量、补强剂及软化剂对共混物性能的影响。结果表明：随着氯醚橡胶用量的增加，共混物的耐低温性、耐热氧老化性、耐油性及耐ＣＣｌ＿４和ＣＨＣｌ＿３性能提高，但拉伸强度降低；当促进剂ＮＡ－２２和半补强炭黑的用量分别为１．５和６０份时，氯醚橡胶／丁腈橡胶（６０／４０）共混物的拉伸强度及撕裂强度出现峰值；使用液体丁腈橡胶作软化剂．使共混物的耐低温性、回弹值、撕裂强度、扯断伸长率及耐油性提高，但耐热氧老化性及耐ＣＣｌ＿４和ＣＨＣｌ＿３性能降低。     

酚醛交联PP/EPDM/SEBS的动态硫化性能

系统研究了酚醛树脂交联剂对聚丙烯/三元乙丙橡胶/苯乙烯一乙烯一丁二烯一苯乙烯共聚物(PP/EPDM/SEBS）动态硫化弹性体性能的影响:随着交联剂用量增加,材料的硬度和拉伸强度先增加然后趋于稳定,断裂伸长率、撕裂强度和熔体流动速率随之降低,压缩永久形变呈现先减小然后增大的趋势。在交联剂用量为10份(质量份,下同)时,制备出了高温下弹性优异的TPV材料,70 0C,125℃条件下的压缩永久形变分别为23. 9%和28. 30%,比未添加SEBS时分别降低了9. 8%和20. 7%,加人SEBS有效改善了材料的回弹性。随着剪切速率增加,材料的表观黏度降低,呈现剪切变稀现象。随着交联剂用量的增加,表观薪度呈现先增加后减小的规律,用量为10份时黏度最大。     

无机填料对CM/NBR共混胶性能的影响

研究了陶土、碳酸钙、高岭土及蒙脱土对CM/NBR共混胶性能的影响。结果表明,加入陶土可导致共混胶焦烧时间缩短,正硫化时间延长,拉伸强度、拉断伸长率和撕裂强度均增大;当陶土用量超过10份时,填料与橡胶结合形成填料网络,共混胶耐油性能提高。RPA分析结果表明,碳酸钙、高岭土和蒙脱土分别填充的CM/NBR共混胶Payne效应依次增强。随着碳酸钙、高岭土及蒙脱土用量的增大,共混胶硬度、门尼粘度、磨耗体积和定伸应力均增大,拉伸强度和撕裂强度却下降。高岭土填充的CM/NBR共混胶物理机械性能下降最小。     

氯醚橡胶/丁腈橡胶共混物的研究

采用过氧化二异丙苯(DCP)／2，4，6-三巯基均三嗪(TMT)作为氯醚橡胶(CO)／丁腈橡胶(NBR)共混胶料的硫化体系，研究了胶料配比对其拉伸性能、压缩变形及耐油性能的影响。     

PP/POE共混物的流变行为分析

采用双螺杆挤出机对聚丙烯(PP)和乙烯-辛烯共聚物(POE)进行共混,并对其共混物的流变行为进行了研究。毛细管流变分析结果表明,PP/POE共混物的表观黏度呈现出正偏差行为,表明PP与POE具有良好的相容性。随着POE含量的增加,PP/POE共混物的非牛顿指数增大,非牛顿性减弱。旋转流变分析结果表明,在低频区域内,PP基本上符合线性黏弹理论,POE则反之。根据Steinmann的相反转流变学标准,PP/POE共混物在POE含量为30%时开始发生相转变。