取代芳酰胺型β成核剂TMB5的形态演变规律及其对iPP的β晶诱导行为的影响

采用示差扫描量热、偏光显微镜、X-射线衍射、热重分析及红外光谱分析等手段,研究了以TMB5为代表的取代芳酰胺型β成核剂在不同加工条件下的形态演变规律及其对i PP的β诱导结晶行为的影响.结果表明,TMB5虽然没有明确的熔点,但其原始晶体可以在升温中逐渐熔融并在降温时形成较细的棒状形态;而TMB5对i PP结晶的诱导作用主要和其在i PP熔融体中产生的二次形态密切相关:在保证TMB5分解不明显的温度条件下,混炼温度的提高有利于TMB5在冷却过程中形成更为细小的棒状形态,使PP中β晶的相对含量提高;在混炼之后的二次加工成型过程中,较低的熔融温度和较慢的降温速度有利于β晶含量提高.     

聚丙烯β-晶型成核剂研究进展

β-晶型成核剂应用于聚丙烯(PP)中,可赋予PP制品优异的抗冲击性、耐热变形性和高气孔率。本文综述了近年来聚丙烯β-晶型成核剂的研究发展状况。重点介绍了β-晶型成核剂的作用、种类和优缺点,并提出了今后开发β-晶型成核剂时需要解决的问题。     

β成核剂修饰多壁碳纳米管增强聚丙烯纳米复合材料的分散及结晶行为

利用非共价键改性方法,用芳香二羧酸酰胺类的β成核剂(β-NA)改性多壁碳纳米管(MWCNTs),采用溶液法制备了聚丙烯(PP)/β-NA-MWCNTs复合材料.通过广角X射线衍射(WAXD)分析了复合材料的结晶形态,结果表明β-NA-MWCNTs诱导聚丙烯生成大量β晶,同时提高了复合材料的结晶度.含5.0 wt％β-N...     

Deformation and stress-induced transformation of polybutene-1

The deformation at room temperature of thick (ca. 2 mm) and thin (ca. 1000 Å) films of polybutene was characterized by electron microscopy and electron x-ray diffraction. The thin films, as studied, draw by micronecking whereas the thick films draw uniformly. In both types of samples the details of the deformation process varied with the orientation of the lamellae in the original spherulitic structure; in all cases, however, the lamellae broke up into “mosaic” blocks prior to uniform fibril formation. The tetragonal-hexagonal phase transformation accompanying the deformation of fresh polybutene films generally appeared to occur within the blocks except in those situations in which the lamellae are being drawn perpendicular to the molecular axes, that is, parallel to the lamella surface; in the latter case the tetragonal form can be at least partially retained until unfolding and fibril formation occurs.     

PET结晶行为研究进展

从二甘醇含量、催化剂、物理老化,增强纤维等方面综述了影响PET结晶行为的研究进展,并介绍了提高PET结晶速率的方法。     

纳米SiO_2对高抗冲聚丙烯树脂相结构与性能的影响

提出一种使高抗冲聚丙烯树脂的韧性和刚性同时得到提高的新方法.以亲油性纳米SiO_2改性高抗冲聚丙烯树脂,发现少量纳米SiO_2可显著降低高抗冲聚丙烯树脂中乙丙橡胶相的粒径和聚丙烯相的球晶尺寸,进而使高抗冲聚丙烯的常温韧性、低温韧性、刚性和耐热性同时得到提高.研究还发现,结晶成核剂和纳米SiO_2有协同效应,可使高抗冲聚丙烯的综合性能进一步得到提高.     

Crystallization behavior of poly(lactic acid) with a self-assembly aryl amide nucleating agent probed by real-time infrared spectroscopy and X-ray diffraction

The effect of a self-assembly nucleating agent, N,N′,N″-tricyclohexyl-1,3,5-benzenetricarboxylamide (BTCA), on the crystallization behavior of poly(lactic acid) (PLA) was probed by time-resolved Fourier transform infrared spectroscopy (FTIR) and wide angle X-ray diffraction (WAXD). The vibrational changes associated with inter- and intra-chain interactions during crystallization were monitored. In the initial period of crystallization, the order of intensity changes is as follows: 1458 cm⁻¹ > 1210 cm⁻¹ » 921 cm⁻¹, 1458 cm⁻¹ ∼ 1210 cm⁻¹ > 921 cm⁻¹, and 1458 cm⁻¹ ∼ 1210 cm⁻¹ ∼ 921 cm⁻¹ for neat PLA, PLAs containing 0.1 wt% and 0.3 wt% BTCA, respectively. This indicates that BTCA can accelerate both the formation of skeletal conformational-ordered structure and, especially, the 10₃ helix one. The incorporation of BTCA changes the crystallization mechanism but has no impact on the crystal form of PLA.     

成核剂对PHBV等温结晶行为的影响

用DSC方法测定了氮化硼及滑石粉成核剂对(β-羟基丁酸酯-与-β-羟基戊酸酯) 共聚物(简称PHBV)等温结晶行为的影响. 结果表明,Avrami方程指数n、成核机理、晶体生长方式基本上不受成核剂的影响.少量的成核剂可使结晶成核自由能降低,结晶速率加大,其中氮化硼的效果最为显著.     

聚醚酯/蒙脱土复合材料的结晶动力学和结晶形态

有机－无机复合材料是近来材料科学发展的热点,无机物对基体的结晶行为有很大的影响［１,２］．聚醚酯嵌段共聚物的高弹性依靠硬段结晶形成的物理交联点［３,４］,因而任何影响结晶的因素必然导致其性能的变化．通过聚醚酯与蒙脱土的复合,研究聚醚酯的结晶行为的变化...     

Nucleating Efficiency of Organic Phosphates in Polypropylene

Organic phosphates used as nucleating agents can remarkably promote the stiffness and crystallization rate of polypropylene homopolymer and ethylene–propylene copolymer. In this article, the nucleating activity of 2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphoric acid and its derivatives for isotactic polypropylene (iPP) were investigated with a differential scanning calorimeter (DSC) and polarized light microscope (PLM), and their influence on mechanical properties of polypropylene was also studied. The results showed that the sodium salt (NA7) and the glyceride ester (NA8) of the organic phosphoric acid were of high nucleating efficiency. If 0.4 wt% of NA7 or NA8 was added to PP, the crystallization peak temperature of PP was raised 15°C or 11°C, respectively, the amount of crystallinity was increased by 3 to 6%, and the crystallization rate was enhanced significantly. The nucleating activity is thermally stable when the mixture of iPP and a nucleating agent was melted and crystallized repeatedly in the DSC. The nucleating agents mentioned above could increase the modulus of the polymer by 20 to about 30% and could increase the flexural strength by 10 to about 20%. However, a number of other organic phosphates tested have little nucleating effect.