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在均聚聚丙烯(PPH)、无规共聚聚丙烯(PPR)和嵌段共聚聚丙烯(PPB)中分别加入刚性成核剂,研究其对聚丙烯(PP)结构与性能的影响。利用电子万能试验机、差示扫描量热仪(DSC)、傅立叶红外光谱仪(FT-IR)和偏光显微镜(POM)等表征手段对改性PP的力学性能、微观结构和结晶性能进行了研究。结果表明,刚性成核剂有细化球晶和加快结晶速率的作用;同时能有效提高PP的弯曲模量、冲击强度、热变形温度;添加0.2份刚性成核剂的PPH和PPB以及添加0.3份刚性成核剂PPR的综合性能最佳。 相似文献
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成核剂对增韧聚丙烯力学性能的影响 总被引:11,自引:0,他引:11
主要研究成核剂种类及用量对乙烯-辛烯共聚物(POE)增韧聚丙烯(PP)力学性能的影响。研究表明:随着成核剂NA1的加入,PP/POE共混物的透明性、冲击强度、弯曲强度、拉伸屈服强度均明显提高,研制的改性PP的透明性、韧性和刚性得到了平衡。 相似文献
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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。 相似文献
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成核剂在改善聚丙烯冲击强度中的作用 总被引:4,自引:1,他引:3
探讨一种既经济又能规模化生产的提高聚丙烯(PP)冲击强度的新方法;简述生产控制过程;成核剂在聚丙烯冲击改性中的机理和效果;在保持基础树脂的熔体流动速率、屈脂拉伸强度不变(降幅不大)的情况下,提高PP的冲击强度。 相似文献
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The isothermal and nonisothermal crystallization kinetics of nonnucleated and nucleated isotactic polypropylene (iPP) were investigated by DSC and a polarized light microscope with a hot stage. Dibenzylidene sorbitol (DBS) was used as a nucleating agent. It was found that the crystallization rate increased with the addition of DBS. The influence of DBS on fold surface energy, σe, was examined by the Hoffman and Lauritzen nucleation theory. It showed that σe decreased with the addition of DBS, suggesting that DBS is an effective nucleating agent for iPP. Ozawa's theory was used to study the nonisothermal crystallization. It was found that the crystallization temperature for the nucleated iPP was higher than that for nonnucleated iPP. The addition of DBS reduced the Ozawa exponent, suggesting a change in spherulite morphology. The cooling crystallization function has a negative exponent on the crystallization temperature. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2089–2095, 1998 相似文献
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The effect of including 0.5 wt % talc on the photodegradation behavior of polypropylene (PP) was investigated in injection-molded samples exposed to ultraviolet radiation (UV) in the laboratory for periods of up to 24 weeks. The structure of the talc-nucleated samples was characterized by X-ray diffraction and light microscopy and compared with that of nonnucleated PP, and the information was used to explain the differences in their photodegradation behavior. Measurements of the extent of chemical degradation were made by Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC), and they showed that there is no significant effect of a nucleating agent on the kinetics of photooxidation. PP bars containing a nucleating agent showed a larger reduction in mechanical properties with UV exposure and a partial recovery in properties after prolonged exposure was observed with both types of samples. An increase in crystallinity during UV exposure (chemicrystallization) was detected by X-ray diffraction and differential scanning calorimetry (DSC) and the dependence with exposure time was similar in nucleated and nonnucleated samples. DSC was also used to determine the melting behavior and transition temperatures of the specimens during exposure and after recrystallization from the melt. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2505–2517, 1997 相似文献
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Miaomiao Sun Dali Gao Hongbo Zhang Hao Zou Meng Xu Shijun Zhang Jie Li Jianye Liu 《应用聚合物科学杂志》2014,131(17)
In this study, the impact polypropylene copolymer (IPC) blended with the sorbitol‐based nucleating agent (NA) NX8000 was prepared and then characterized using a wide range of instrumentations. The results showed that the NA formed a fibril network which resulted in the increased viscosity of system and the decreased size of ethylene–propylene random copolymer (EPR) phase. The results of mechanical tests revealed “the brittle–ductile transition (BDT)” occurred while the ethylene content was between 3.5 wt % and 6 wt % and indicated that the impact strength of IPC was greatly improved by the addition of NX8000 when the EPR content was right over the critical value of BDT. The investigations provided valuable information for the further development of IPC materials and boarded its potential industrial applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40705. 相似文献
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The morphology of isotactic polystyrene (iPS) particles which had been compounded into an isotactic polypropylene (iPP) matrix was varied in-situ by selective heat treatment to be either amorphous (iPSamorphous) or semicrystalline (iPScrystalline). The influence of iPS morphology on the quiescent and shear-induced isothermal crystallisation of iPP was then studied using differential scanning calorimetry (DSC), in-situ simultaneous small and wide angle X-ray scattering (SAXS/WAXS) and polarised optical microscopy (POM). In the quiescent condition iPScrystalline was found to selectively nucleate the β phase while iPSamorphous nucleated the α phase of iPP. Compared to the control sample (iPPcontrol), the presence of both morphologies of iPS increased the number of shear-induced oriented crystal precursors that form as a result of the step shear. During isothermal crystallisation the shear-induced nuclei promote oriented α form crystal growth, accelerate the crystallisation kinetics and ultimately swamp the effect of the nucleating particles present. 相似文献
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Panitha Phulkerd Takehiro Nakabayashi Shohei Iwasaki Masayuki Yamaguchi 《应用聚合物科学杂志》2019,136(7):47295
The effect of the nucleation efficiency of three commercial nucleating agents, such as 1,3:2,4-bis(3,4-dimethylbenzylidene)sorbitol (DMDBS), sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl)phosphate (SMBP), and magnesium silicate (talc), on the melt-stretching performance of isotactic polypropylene (PP) is studied. It is found that the addition of 0.5 wt % of a nucleating agent enhances the crystallization temperature and that effect is pronounced for DMDBS and SMBP. Furthermore, DMDBS is more efficient than the other tested nucleating agents in enhancing the drawdown force, defined as a force required for stretching a molten strand. Nanofibers of DMDBS, which show significant alignment in the flow direction, are responsible for the rapid crystallization of PP in the flow field leading to an increase of drawdown force. The stretched strand shows a highly oriented structure in which the α-form crystals orient to the flow direction. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47295. 相似文献
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In this investigation the effects of a rosin‐type nucleating agent, which was prepared from cocrystallizing of dehydroabietic acid and Na‐dehydroabietate, on polypropylene (PP) crystallization were studied. The results of differential scanning calorimetry and X‐ray diffraction proved that a cocrystal of dehydroabietic acid and Na‐dehydroabietate was formed. The lower melting point of the cocrystal caused it to be uniformly dispersed in PP. When cocrystals were added as nucleating agent, the mechanical properties, heat distortion temperature, and crystallization temperatures of PP were obviously improved, and the size of spherulites was also decreased. This proved that the cocrystals of dehydroabietic acid and Na‐dehydroabietate could act as an effective nucleating agent for PP. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1069–1073, 2002 相似文献
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通过在抗冲聚丙烯基础树脂中添加自主研制的酰胺型高效β成核剂FB-1,在提高聚丙烯耐热温度的同时有效提高聚丙烯的冲击强度,介绍β成核剂的复配及超细化,研究β成核剂含量对共聚聚丙烯EPS30R冲击强度的影响,考察β成核剂改性聚丙烯的加工稳定性及β成核剂改性共聚聚丙烯的结晶行为。结果表明,加入成核剂后,聚丙烯冲击性能显著提高,β晶型聚丙烯的热稳定性及反复加工性能良好, FB-1成核剂能有效促进聚丙烯中β晶型的形成,而且β成核剂只改变β晶型含量,不改变其微观结构,β成核剂对聚丙烯中的α晶型没有影响。 相似文献