α成核剂和β成核剂对高流动性聚丙烯结晶行为的影响

研究了α成核剂和β成核剂对高流动性聚丙烯(PP)结晶行为的影响,采用偏光显微镜、差示扫描量热法和广角X衍射对其微观结构和结晶形态进行了表征。结果表明:α成核剂的加入细化球晶而不改变结晶形态;β成核剂的加入改变球晶的形态,使部分α晶型向β晶型转变;两种成核剂的加入使高流动性PP的结晶速率加快结、晶过程的成核方式和生长机理发生改变,结晶活化能降低。     

不同成核剂成核聚丙烯的结晶行为与力学性能

制备了６种成核剂成核聚丙烯（ＰＰ）母料研究了成核母料和成核母料／ＰＰ的结晶,熔融行为,力学性能和透明性等物理性能,不同成核在成核母材料和成核母料／ＰＰ中对ＰＰ的结晶与熔融行为以及性能有不同的作用,观察到成核型Ａ成核ＰＰ具有较高的结晶温度与综合性能,而成核剂Ｂ成核ＰＰ的透明性较好。     

浅析成核剂在聚丙烯中的作用

添加成核剂是一种有效的聚丙烯改性方法。聚丙烯成核剂可使聚丙烯结晶度增加、结晶细微化,提高其机械性能等。本文通过介绍聚丙烯成核剂的种类,特性,浅析了成核剂在聚丙烯中作用及其发展。     

高相对分子质量聚丙烯的成核行为

在反应器内合成了不合成核剂及含有成核剂的高相对分子质量聚丙烯(HMWPP)，将其与均聚聚丙烯(F401)混合制备了成核改性的PP。用差示扫描量热计和偏光显微镜分析了混合体系的结晶行为和形态。结果表明，HMWPP可以诱导β晶形成，细化PP球晶，使材料冲击强度增加50％。而成核剂与HMWPP共同作用使PP的结晶温度和结晶速率显著升高，球晶尺寸细化，弯曲模量增加32％，热变形温度提高18℃。     

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。     

聚丙烯成核剂研究进展

介绍了聚丙烯成核剂的种类及其对聚丙烯结晶性能的影响；对国内外聚丙烯成核剂的研究进展和应用前景进行丁综述。     

高相对分子质量成核剂对聚丙烯结晶行为的影响

采用差示扫描量热仪和偏光显微镜研究了高相对分子质量成核剂（PNA）改性聚丙烯（PP）的结晶行为和结晶形态。结果表明,添加PNA后,PP的起始结晶温度（Tc）和结晶峰温（Tp）明显升高,降温速率为5 ℃/min,加入0.7份PNA时,Tc和Tp分别提高到131.90 ℃和128.32 ℃,结晶度由未添加PNA时的56.32 %提高到61.63 %;加入PNA后,球晶数量明显增多球晶尺寸更加细小且均匀,促进了PP的结晶,提高了PP制品的定型温度,能够缩短制品的生产周期。     

成核剂在聚丙烯中的应用

介绍成核剂在聚丙烯中开发,应用概况,成核剂的作用机理,选择及其对聚丙烯性能的影响。     

成核剂技术在聚丙烯改性中的应用研究

介绍了聚丙烯成核剂的种类及其在聚丙烯改性中的应用研究。通过聚丙烯产品的开发应用,分析了α、β两种晶型成核剂对聚丙烯力学性能、光学性能和加工性能的影响。     

成核剂改性聚丙烯技术

分析了添加成核剂的改性效果,介绍成核剂的种类,分析了添加成核剂后聚丙烯性能的改变,还简单介绍了目前研究热点β成核剂。     

有机磷酸盐类成核剂改性聚丙烯

具有蝶形结构的有机磷酸盐类成核剂HBP能显著改善PP的结晶行为和综合性能。当添加成核剂HBP的质量分数为0．2％时,PP的结晶度从46．4％提高到52．2％,弯曲强度和弯曲模量分别提高了23％和21％,热变形温度和结晶温度分别提高23．9℃和22．7℃,而制品的雾度则降低60％。     

Photodegradation of polypropylene containing a nucleating agent

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     

低收缩率成核剂在抗冲共聚聚丙烯EP5010C中的应用

通过对抗冲共聚聚丙烯EP5010C与国内外同类产品的力学性能和收缩率的比较与分析,研究了EP5010C收缩率较大和翘曲变形的原因.结果表明:将EP5010C配方中的苯甲酸钠成核剂替换为低收缩率成核剂B,对EP5010C力学性能影响较小,明显降低了EP5010C的横向和纵向收缩率,解决了EP5010C收缩率大和易翘曲变形...     

Polystyrene as a versatile nucleating agent for polypropylene

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 (iPS_amorphous) or semicrystalline (iPS_crystalline). 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 iPS_crystalline was found to selectively nucleate the β phase while iPS_amorphous nucleated the α phase of iPP. Compared to the control sample (iPP_control), 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.     

成核剂对提高聚丙烯刚性的影响

研究了8种成核剂对聚丙烯(PP)刚性的改性效果。结果表明:成核剂TMA-3,NAA-325,M1128使PP的弯曲模量明显提高;成核剂的最佳用量为0.10%～0.15%(w);成核剂可以显著提高PP的刚性、拉伸屈服应力,但断裂拉伸应变下降;两种成核剂复配使用不利于提高PP的弯曲模量;加入成核剂会细化PP的球晶,显著降低球晶的尺寸,加快结晶速率。     

Enhancement of drawdown force in polypropylene containing nucleating agent

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.     

Toughening effects of nucleating agent on impact polypropylene copolymer

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.     

Effect of nucleating agent addition on crystallization of isotactic polypropylene

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, σ_e, was examined by the Hoffman and Lauritzen nucleation theory. It showed that σ_e 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     

成核剂对聚丙烯性能的影响

研究了各种α晶型成核剂和β晶型成核剂对聚丙烯性能的影响,发现用α晶型成核剂NA-11和用N催化剂生产的高等规指数聚丙烯组合,可制成透明型高强度、高耐热聚丙烯。这种高性能聚丙烯在家电、汽车等方面具有极为广泛的应用前景。     

β成核剂对聚丙烯力学性能的影响

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,在升高聚丙烯耐热温度的同时有效提高聚丙烯树脂EPS30R的冲击强度,研究酰胺型β成核剂PA-01、TMB-5和FB-1添加量对聚丙烯树脂EPS30R力学性能的影响,通过微观形态分析增韧的内在原因,并考察成核剂对聚丙烯树脂EPS30R的成核效果。结果表明,添加β成核剂后,聚丙烯的力学性能明显改善,且β成核剂诱导聚丙烯的成核效果较好。