DCPMS作为外给电子体生产低熔融指数聚丙烯

二环戊基二甲氧基硅烷(DCPMS)作为外给电子体,在12 m3反应釜中采用间歇式液相本体法聚丙烯生产工艺,通过控制氢气钢瓶压降为0.1 MPa或绝氢及主催化剂用量为53 g生产熔融指数在0.2-0.3 g/10 min之间的低熔指聚丙烯。与甲基环已基二甲氧基硅烷(CMMS)生产低熔指聚丙烯相比,单釜主催化剂用量由78 g降至53g,并在绝氢状况下熔融指数更易控制在0.2-0.3 g/10 min之间。     

CMMS和DCPMS在丙烯聚合中的应用

将CMMS(环己基甲基二甲氧基硅烷)和DCPMS（二环戊基二甲氧基硅烷）外给电子体分别与CS-1型和CS-2型聚丙烯主催化剂进行丙烯聚合评价，结果表明CMMS和DCPMS是高效催化剂的有效助催化剂，它们能够提高聚丙烯的真实等规度。它们提高聚丙烯真实等规度的能力为DCPMS>CMMS>DDS。     

聚丙烯结晶度的实验测定

用密度法和Ｘ射线衍射法测定了加入成核剂的聚丙烯材料的结晶度。结果表明，２种方法测定结果虽然存在较大差异，但所测得的结晶度随成核剂加入量的变化具有相同的变化规律。     

聚丙烯结晶度对锂电池隔膜硬弹性的影响

通过对某锂电池隔膜生产企业所用不同批次聚丙烯(PP)原料进行检测,结合该企业的使用情况,对PP高结晶度有利于锂电池隔膜硬弹性提高的结论进行验证。实验结果表明,相同工艺条件下,高结晶度PP原料对于膜坯硬弹性性能没有明显提高,PP结晶度提高与膜坯硬弹性性能提高没有明显关联。在一定的条件下,膜坯硬弹性随原料结晶度提高有降低的趋势。     

熔性流动性对聚丙烯材料结晶度和力学性能的影响

用Ｘ射线法测定了不同熔体流上聚丙烯材料的结晶度。结果表明，材料熔体流动性的变化将会影响其结晶行为，随熔体流动速率降低，结晶度越低，拉伸强度下降，断裂伸长率增大。熔体流 性对冲击强度的影响较为复杂，发现存在一极大值，该极值的出现预示可能与分子量和分子量分布的变化有关。     

X射线衍射法测定聚丙烯树脂结晶度及影响因素探讨

采用X射线衍射法测定了聚丙烯树脂的结晶度,考察了制样方法、测试条件以及计算方法等因素对测试结果的影响.通过精密度试验考察了方法的精密度.结果表明,95％置信水平时,在重复性试验条件下,两次测定结果绝对差不大于3.5％;在再现性试验条件下,两次测定结果绝对差不大于5.0％.方法具有较好的重复性和再现性,可以满足聚丙烯树脂...     

熔体流动性对聚丙烯材料结晶度和力学性能的影响

用X射线法测定了不同熔体流动速率下聚丙烯材料的结晶度。结果表明 ,材料熔体流动性的变化将会影响其结晶行为 ,随熔体流动速率降低 ,结晶度越低 ,拉伸强度下降 ,断裂伸长率增大。熔体流动性对冲击强度的影响较为复杂 ,发现存在一极大值 ,该极值的出现预示可能与分子量和分子量分布的变化有关。     

外给电子体Donor-D在聚丙烯装置上的应用

将新型高效外给电子体Donor-D在三井油化聚丙烯(PP)装置上进行应用考核,考察了该催化剂的适应性及产品质量情况。实验表明,Donor-D催化剂与DDS相比有其独特性,可以在聚丙烯工艺上进行推广。     

复配外给电子体技术及CHMMS、DCPMS性能比较

介绍了利用复配外给电子体技术在洛阳石化HYPOL工艺聚丙烯装置开发高性能PPH（均聚聚丙烯）管材专用树脂的实施方案,同时阐述了在Ziegler-Natta催化剂体系中外给电子体的作用及原理,并且对环己基甲基二甲氧基硅烷（CHMMS,C-Donor）和二环戊基二甲氧基硅烷（DCPMS,D-Donor）对主催化剂催化活性、立体定向性及氢调敏感性的影响及原理进行了比较分析。通过外给电子体的非对称加入和两反应器的加氢调整,以实现产品宽相对分子质量分布及小分子部分高等规度、大分子部分低等规度,使材料具有良好的机械加工性能和力学性能。     

异丁基三乙氧基硅烷作为外给电子体生产高熔融指数聚丙烯

利用异丁基三乙氧基硅烷作为外给电子体与N-Ⅲ催化剂组成高活性及高氢调敏感性催化体系,在间歇式液相本体法聚丙烯生产工艺中,通过控制每釜氢气加入量为氢气钢瓶压降23~25 MPa,单釜主催化剂加入量65 g,生产熔融指数在30~35 g/10 min之间的高熔指聚丙烯,产品等规度97.0%,灰分1.3×10-4。实验证明,异丁基三乙氧基硅烷作为外给电子体的N-Ⅲ催化体系反应初期活性适中,活性衰减慢,无明显放热高峰。     

Orientation and crystallinity in film casting of polypropylene

In the cast film process a polymer melt is extruded through a slit die, stretched in air, and cooled on a chill roll. During the path in air the melt cools while being stretched. Film casting experiments were carried out with an isotactic polypropylene resin. The temperature and width distributions were measured along the draw direction. Further, the crystallinity and Hermans orientation factor were measured on the final film. The process was described by a simple thermomechanical model derived elsewhere. The evolution of the molecular orientation parameters was calculated on the basis of a dumbbell model coupled with velocity and temperature distributions provided by the thermomechanical model. The experimental crystalline orientations of the final films collapsed into a single step‐shaped curve (from low to high orientation) if plotted versus the stress calculated by the model at the frozen line. The experimental values of the crystallinity and Hermans orientation factors are discussed on the basis of predictions of the dumbbell model for melt orientation at the frozen line and the crystallinity data obtained in quiescent conditions under the same cooling rate. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1981–1992, 2002; DOI 10.1002/app.10422     

Quantification of the Young's modulus for polypropylene: Influence of initial crystallinity and service temperature

In this study, the mechanical properties of isotactic polypropylene (iPP) materials with different crystallinities at room and elevated temperatures were investigated. In order to obtain samples with a certain range of crystallinity, and to ensure a uniform microstructure of these samples, the iPP samples obtained by injection molding required melt compression molding and controlled annealing. In the macromechanical studies, the experimental results showed that the storage modulus and Young's modulus of polypropylene were sensitive to the service temperature. The crystallinity also had a great influence on this relationship. A function was proposed to evaluate the dependence of the Young's modulus of polypropylene on initial crystallinity and service temperature, and tested based on experimental data. The Young's modulus of iPP is reduced by about 90% when the service temperature rises from 25 to 125 °C. Moreover, the reduced value in Young's modulus between polypropylene having the highest and lowest crystallinity was reduced from 214.55 to 56.75 MPa. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48581.     

The microstructure of polypropylene welds as a guide to processing history

The well known occurrence of different crystalline forms in polypropylene and their easy recognition in the polarising microscope has provided a method of analysing the behaviour of this material during the production of hot plate welds. The different thermal behaviour of the α- and the β-forms of crystalline polypropylene allows estimation of the thermal history of the polymer in the region of the weld. In particular it is possible to estimate the amount of material actually melted by contact with the hot plate. The effect of the original crystalline microstructure of the components being welded on the microstructure of the recrystallised material forming the weld bond has also been explored. It is possible to characterise the general crystalline texture in the weld bead in terms of the shear and thermal history of the material. The influence of pre- and post-welding annealing of the polypropylene has been investigated and a difficulty is encountered in explaining an apparent ‘memory’ of β-form crystallisation which conflicts with established x-ray diffraction results.     

高熔体强度PP的制备研究

用辐照法制备出了高熔体强度聚丙烯（PP）：对其物理机械性能、熔体强度、熔体拉伸粘度、粘垂等进行了测试，研究了辐照剂量、交联剂种类和浓度，辐照后PP的热处理条件等对制备高熔体强度PP的影响；并在此基础上，还制备出了发泡倍率为15倍以上的发泡PP。     

丙纶纤维自增强聚丙烯树脂的研究

以丙纶纤维为增强体,聚丙烯树脂为基体,采用热压成型的方法制备丙纶纤维/PP复合材料板材.研究了不同热压温度、不同纤度的丙纶纤维用量对复合材料力学性能的影响.结果表明:本实验最佳热压温度为195℃,在此温度下,随着纤维用量的增加,复合材料的拉伸强度呈先升后降的趋势,在用量为15%时达到最高点,纤度为240D的丙纶纤维/P...     

发泡用高熔体强度聚丙烯的研究

以过氧化苯甲酰(BPO)为引发剂,在同向双螺杆挤出机上对聚丙烯(PP)进行硅烷交联,制备了高熔体强度聚丙烯(HMSPP),然后制得高发泡倍率的PP制品.实验对改性PP的熔体强度、力学性能、热性能和发泡性能进行了表征.结果表明:自制HMSPP的熔体强度是纯PP的5.01倍,力学性能和耐热性与纯PP相比均有较大提高,可用于成型高发泡倍率制品.     

聚丙烯催化合金组成与性能研究

利用国产齐格勒-纳塔催化剂在反应器中合成出了聚丙烯（PP）催化合金,并系统地研究了不同气相聚合压力以及气相单体组成比所合成的聚合物合金组成与性能的关系,结果表明,在反应器中直接合成出的PP催化合金具有非常高的常温冲击强度和低温冲击强度,且随着合金中乙丙共聚物含量的增加而增加,但其模量却随之下降;若控制合金中乙丙共聚物的含量不超过10%,则可使PP合金材料既具有较高的冲击强度又具朋较高的模量。     

Natural weathering of polypropylene in a tropical zone

Natural weathering of isotactic polypropylene (PP) plates (2 mm in thickness) was conducted for 15 months in the Philippines. Optical microscopy, scanning electron microscopy, and atomic force microscopy revealed that the surface layer (200–300 nm in thickness) was affected in the first month, and cracks are formed toward the deeper layer. On the basis of the microscopic observations along with FTIR, DSC, GPC, and tensile strength measurements, the following degradation mechanism of PP was proposed. At first, through oxygen introduced into the PP, only the surface layer seems to be affected. Gradually, the surface layer may be removed, exposing the inner layer. Then, molecular chains of the inner layer start to be degraded, accompanying a significant loss of tensile properties. Part of the degraded materials seems to be eroded, leading to the formation of cracks on the surface of the uncovered inner layer. Finally, the original surface layer may be totally eroded, making the structure of the inner layer (which should reflect the spherulitic texture) evident. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 931–938, 2003