成核聚丙烯的研究进展

综述了近几年聚丙烯（ＰＰ）成核剂及其成核ＰＰ的结晶与熔融行为、形态、断裂韧性、降解行为、成核作用对温度的依赖性和成核机理的研究进展,讨论了成核剂对ＰＰ物理与力学性能的影响。     

等规聚丙烯的结晶成核剂

本文介绍了等规聚丙烯α型、β型结晶和成核剂及应用,成核剂与制品透明性、成型收缩、光泽、耐热性能的关系。指出等规聚丙烯的结晶行为对其加工和制品质量及性能关系重大,通过结晶成核剂进行结晶行为改性,可开发高透明、高光泽、耐热、低收缩和后变形小等新品种聚丙烯塑料。     

聚丙烯β成核剂增韧母料的研制

屏蔽粉状β成核剂,使其首次熔融冷却过程不产生结晶,用分散剂使粉状成核剂均匀分散在载体树脂中, 经双螺杆挤出得到聚丙烯β成核剂增韧母料,并用DSC与偏光显微镜分析该母料在与聚丙烯基础树脂二次熔融挤出过程产生的结晶类型。结果表明,该母料在与聚丙烯基础树脂二次熔融挤出过程产生大量β晶型,使基础树脂在保持其它性能不变的前提下提高韧性,并增加了流动性。     

复合成核剂对PBT结晶行为的影响

采用熔融共混法制备了聚对苯二甲酸丁二醇酯(PBT)和成核剂二苄山梨醇(DBS)或苯甲酸钠(SB)的共混物,通过差示扫描量热仪(DSC)、X射线衍射仪(XRD)、偏光显微镜(PLM)分析了各成核剂对PBT的结晶行为的影响,结果表明:添加任何一种成核剂均能明显改善PBT的结晶行为,即加快结晶速度、提高结晶度、细化晶体及完善晶体形态;其中复合成核剂要明显优于单一成核剂,复合成核剂中SB的影响程度要大于DBS。还采用热重分析(TGA)仪对体系的热性能进行了研究,发现成核剂的加入并未降低体系的热性能。     

成核剂对增韧聚丙烯力学性能和结晶行为的影响

研究了成核剂对ＰＰ／ＰＯＥ共混物的力学性能和结晶行为的影响。加入成核剂提高了共混物的冲击强度和弯曲模量,使ＰＰ／ＰＯＥ共混物的刚性韧性得到了很好的平衡,同时,成核剂提高了ＰＰ／ＰＯＥ共混物的结晶速率和结晶温度,减小了球晶的尺寸,有利于力学性能的提高和缩短加工时间。     

成核剂对聚乳酸结晶改善的研究进展

聚乳酸作为一种有良好应用前景的绿色生物材料,结晶速率缓慢制约着聚乳酸更广泛的应用。添加成核剂是改善高聚物结晶性能的有效手段。文章综述了不同种类聚乳酸成核剂近年来的研究进展,对各类成核剂的特点和成核机理进行总结,并展望了今后聚乳酸成核剂的研究方向。     

复合成核剂对聚丙烯性能的影响

研究了新型分子结构成核剂NX8000和有机磷酸盐成核剂NA-11复合使用对PP性能的影响。通过力学性能分析、雾度测试、DSC、XRD等手段研究了复合成核剂对PP力学性能、透明性、热性能和结晶行为的影响。研究结果表明:复合成核剂提高了PP的结晶温度和结晶度,加快PP的结晶速率。XRD结果显示:NX8000和NA-11都是ɑ成核剂,复合后成核PP结晶形态不改变。复合成核剂综合了NX8000、NA-11两者的优点,制备出了透明性和刚性兼顾的成核PP。     

尼龙成核剂的研究与进展

尼龙材料在工程塑料、纤维材料中占有重要的地位,且随着近年来合成长链尼龙单体生产的实现,其应用更受关注。尼龙材料的性能与材料的聚集态结构中结晶结构密切相关。成核剂是一种用于改变结晶型聚合物的结晶度和结晶形态,加快结晶速率并改善聚合物性能的加工助剂。常用的尼龙成核剂可以分为无机成核剂、有机成核剂、复合成核剂三类。该文以聚合物结晶理论和成核剂作用机理为基础,介绍不同种类成核剂的加入对尼龙的晶型、结晶速率、结晶度、拉伸强度、弯曲性能、冲击强度以及透明度等结构与性能上的影响。     

成核剂对BP结晶行为及力学性能影响的研究

选择适宜的成核剂，对ＰＰ／成核剂共混物结晶动力学，结晶形态及力学性能进行综合研究，得出所选用的酰胺类成核剂对ＰＰ的结晶参数，结晶形态，宏观物性的影响结果。     

成核剂对PP结晶行为及力学性能影响的研究

选择适宜的成核剂，对ＰＰ／成核剂共混物结晶动力学、结晶形态及力学性能进行综合研究，得出所选用的酸胺类成核剂对ＰＰ的结晶参数、结晶形态、宏观物性的影响结果。     

Detecting crystallization structure evolution of polypropylene injection‐molded bar induced by nucleating agent

The crystallization structures of Polypropylene (PP) injection‐molded bars nucleated by nucleating agent were detected from the skin layer to the core zone, layer by layer. α‐phase nucleating agent 1,3:2,4‐bis (3,4‐dimethylbenzylidene) sorbitol (DMDBS, Millad 3988), β‐phase nucleating agent aryl amides compounds (TMB‐5), and their compounds were introduced into PP matrix, respectively. The relative content of β‐phase PP in the different zones of an injection‐molded bar was characterized and calculated by Wide angle X‐ray diffraction (WAXD) and Differential scanning calorimetry (DSC). The results show that, whether in pure PP or in nucleated PP, both β‐phase PP and α‐phase PP grow in the skin layer of the injection‐molded bar. However, in the intermediate layers and the core zone, the crystallization structures of PP are dependent on the used nucleating agent. β‐phase is the main crystallization structure of TMB‐5 (0.1 and 0.2 wt%) nucleated PP, and α‐phase in DMDBS (0.1 and 0.2 wt%) nucleated PP. Compounding nucleating agents with 0.1 wt% DMDBS and 0.1 wt% TMB‐5 induces PP crystallization almost in β‐phase; however, PP nucleated by 0.2 wt% DMDBS and 0.2 wt% TMB‐5 crystallizes exclusively in α‐phase. The crystallization mechanism of PP nucleated by compounding nucleating agents was further studied in this work. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Glass fiber reinforced and β‐nucleating agents regulated polypropylene: A complementary approach and a case study

A two‐step process for preparing glass fibers (GFs) reinforced β‐nucleated PP composites was designed and developed. The complementary approach combined GFs reinforcement and β‐nucleating agents regulation using N,N′‐dicyclohexyl‐2,6‐napthalene‐dicarboxamide (TMB‐5) in the presence of maleic anhydride grafted polypropylene (PP‐g‐MA) through extrusion blending. The influence of TMB‐5 and GFs on the mechanical properties and crystallization behavior of PP was studied by mechanical test, wide‐angle X‐ray diffraction, differential scanning calorimetry, and scanning electron microscopy. A distinct complementary effect of GFs and β‐nucleating agent TMB‐5 on mechanical properties and crystallization behavior of PP was observed. Results showed that addition of 20 wt % GFs and 0.1 wt % TMB‐5 into PP matrix with the two‐step process could lead to significant increase to its mechanical properties: specifically 64.8% improvement in tensile strength, 107.1% enhancement in flexural modulus, and 167.7% increasement in notched impact strength compared to that of neat PP. Furthermore, with the combination of TMB‐5 and GFs, not only led to promoted interfacial adhesion, but also significantly improved overall comprehensive mechanical properties. The complementary process provided an alternative approach for the development of PP with balanced toughnesss and stiffness. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45768.     

Effect of continuous oscillatory shear on isothermal crystallization of non‐nucleated and nucleating‐agent‐treated isotactic polypropylene assessed by dynamic mechanical analysis

Using dynamic mechanical analysis (DMA), we investigated the in situ crystallization kinetics of non‐nucleated and nucleating‐agent‐treated isotactic polypropylene (iPP) under continuous oscillatory shear during the entire crystallization process, and then compared the DMA results with those measured using differential scanning calorimetry under conventional quiescent crystallization. Our analyses, based on the Avrami equation, show that continuous oscillatory shear accelerated crystallization of non‐nucleated iPP, but interfered with crystallization for nucleating‐agent‐treated iPP. Our results indicate that, for the present nucleating agent, its accelerating effect on crystallization cannot coexist with the accelerating effect of shear on crystallization. We attributed this difference to the disruptive effect of shear on growth and the different nucleation models of non‐nucleated and nucleating‐agent‐treated iPP. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41685.     

聚丙烯的高性能化研究

在小型反应器内合成了不含及含有成核剂的聚丙烯(PP)、双峰聚丙烯(BMPP)和聚丙烯共聚物(PPc)，并用纳米CaCO3改性PPc。研究结果表明：釜内成核的PP和BMPP的弯曲模量和热变形温度显著增加，结晶温度和结晶速率明显提高，BMPP的拉伸强度也较PP大幅增加；但成核剂对PPc的性能影响不大，而加入纳米CaCO3后则使PPc的力学性能和结晶温度同步显著增加。     

Melting characteristic and β‐crystal content of β‐nucleated polypropylene/polyamide 6 alloys prepared using different compounding methods

BACKGROUND: The distribution of nucleating agents in different phases is still an open question in general, and how to control conditions to prepare alloys rich in β‐crystals of polypropylene (PP) is hardly reported. The main goal of this study was to find out the factors influencing the β‐crystal content in β‐nucleated PP/polyamide 6 (PA6) alloys and determine the best preparation conditions to obtain β‐nucleated PP/PA6 alloys rich in β‐crystals. RESULTS: The compounding methods had little influence on the crystallization temperature of both PP and PA6. However, the melting characteristic and β‐crystal content in β‐nucleated PP/PA6 alloys not only depended upon the compounding methods, but also on the temperature at which the nucleating agent was added. A higher β‐crystal content can be obtained by adding the nucleating agent at a temperature below 190 °C, which is also dependent on the mixing time. CONCLUSION: It is proved by etching the alloys with sulfuric acid that the nucleating agent mainly disperses in the PA6 phase and/or the interface between PP and PA6 when blended at high temperature. Copyright © 2009 Society of Chemical Industry     

有机磷酸盐与硅溶胶复配成核剂对PP性能的影响

利用偏光显微镜(PLM)、光电雾度仪、差热分析(DSC)及力学性能测试考察有机磷酸盐(NA-21)与硅溶胶复配成核荆对均聚聚丙烯(PP)透明性、结晶行为及力学性能的影响.研究结果表明:有机磷酸盐与硅溶胶有良好的协同异相成核作用;复配体系中,纳米微粒的分散性明显好于添加单一纳米成核剂的分散性;硅溶胶的添加量为0.15%,有机磷酸盐的添加量为0.35%时,成核PP的雾度降低到36.3%,结晶温度升高到132℃;与单-NA-21增透PP相比,复配成核荆增透PP的冲击强度与拉伸强度都有明显提高.     

Effects of nucleating agents on crystallization behavior and mechanical properties of high-fluid polypropylene

The effects of organic aluminum phosphate (NA-21) and rare earth organic coordination compounds (WBG), serving as ??, ?? nucleating agents, on crystallization and mechanical properties of high-fluid polypropylene (PP) have been investigated. As determined by differential scanning calorimetry, the isothermal crystallization temperature of PP increased from 126.5 to 137.7?°C and 133.6?°C with NA-21 and WBG, respectively. The two endothermal melting peaks of PP blending with WBG indicated the transformation of ??-crystal. The wide-angle X-ray diffraction pattern and melting behavior of PP blending with WBG testified that a high proportion of ??-crystal, which was more than 70%, was induced, while the crystal-phase of PP modified with NA-21 had little change. The mechanical properties of nucleated PP were tested by tensile testing machine and izod pendulum impact tester. A dramatic increment of impact strength, as high as 191%, was obtained for PP with the introduction of WBG, comparing to 132% by NA-21 addition. The impact fracture surfaces were observed by scanning electron microscope; the resistance of crack growth of nucleated PP was better than that of pure PP. Although flexural strength of PP improved in both scenarios, the influence of nucleators on yield strength of PP differed. Yield strength of PP increased by 8.5% when using 0.2?wt% NA-21, but decreased by 6% when using WBG at the same content. Therefore, WBG, a novel ??-nucleator, played an essential role in enhancing impact strength of PP.     

Isothermal crystallization behavior and melting characteristics of injection sample of nucleated polypropylene

The isothermal crystallization behavior and melting characteristics of pure polypropylene (PP) and PPs nucleated with a phosphate nucleating agent (A) and a sorbitol derivative (D) have been studied by differential scanning calorimetry (DSC). Compared with pure PP, nucleated PPs show a shorter half‐times of crystallization. Dependence of crystallization rate of nucleated PP on the crystallization temperature is stronger than that of pure PP at the higher crystallization temperature, whereas the opposite results are obtained at the lower crystallization temperature. Addition of nucleating agent shifts the temperature at the deviation from the baseline of DSC melting curve, T, and the temperature at the completion of melting, T, to higher temperatures, indicating that nucleated PPs exhibit a higher perfection of PP crystals. A shoulder peak in the high temperature range of melting peak of nucleated PP and a wider low temperature region in the melting peak of pure PP are observed. Obviously, PP and nucleated PPs form different distribution of crystal perfection in the isothermal crystallization process. According to the half‐time of crystallization, nucleating agent A is more effective than D. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2547–2553, 2000     

Effects of rosin‐type cocrystal nucleating agents on the crystallization process and the properties of polypropylene

A new kind of rosin‐type nucleating agent for polypropylene (PP), the cocrystal of dehydroabietic acid, potassium dehydroabietate, and sodium dehydroabietate, was prepared, and the effects of the nucleating agents on the mechanical and crystallization properties of PP were also studied. The results of differential scanning calorimetry and X‐ray diffraction proved that the cocrystal of dehydroabietic acid and compound alkali dehydroabietate was formed rather than a simple blend of dehydroabietic acid and single alkali dehydroabietate. When it was added to PP, the size of the PP spherulite decreased; the mechanical properties, crystallization temperature, and transparency of PP were substantially improved. Thus, the cocrystal of dehydroabietic acid, potassium dehydroabietate, and sodium dehydroabietate acted as a more effective nucleating agent for PP. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2137–2141, 2003