庚二酸类成核剂对等规聚丙烯β晶结晶行为的影响

研究了结晶温度（100～140℃）对添加庚二酸钠、庚二酸锌、庚二酸钙、庚二酸钡成核剂的等规聚丙烯中β晶结晶行为的影响。发现庚二酸钠、庚二酸锌、庚二酸钙和庚二酸钡是有效的β晶型成核剂，随着结晶温度的提高，成核改性聚丙烯的β晶型含量持续增大，并在130℃时达到最大值，结晶温度在130℃～140℃之间，成核改性的聚丙烯发生明显的β→α晶型转变。β晶型成核效率由大到小的顺序为：庚二酸钙〉庚二酸钡〉庚二酸锌〉庚二酸钠，庚二酸钙是最佳β晶型成核剂。     

庚二酸钙/石墨烯复合成核剂的制备及应用研究

制备了一种新型、高效的聚丙烯用庚二酸钙/石墨烯(CaHA/Gra)复合成核剂。采用傅里叶变换红外光谱仪(FTIR)测试了CaHA/Gra的复合结构,采用差示扫描量热仪(DSC)测试了CaHA/Gra改性聚丙烯(PP)的结晶和熔融行为。结果表明,庚二酸钙与石墨烯之间并不是简单的机械混合,而是通过化学键结合从而改善了CaHA/Gra在PP中的分散性;且在PP中加入成核剂CaHA/Gra可明显提高PP的结晶温度,在复合成核剂的添加量为0.2%(质量分数)时,可使PP的结晶峰温度从空白PP的121℃升高到126℃,同时在成核聚丙烯中出现含量相当的α晶型和β晶型,对平衡PP的刚性和韧性有着良好的作用。     

负载型β-成核剂——β-SiO_2对PP结晶熔融行为的影响

采用纳米二氧化硅为载体,负载庚二酸钙制备具有β-成核作用的β-Si O2,利用DSC和XRD探究β-Si O2用量对PP结晶熔融行为的影响,并用TGA分析β-Si O2中庚二酸钙的含量。研究表明,制备的β-Si O2提高PP的结晶温度并具有高效的β-成核作用,提高添加量即可提高PP中β-晶的含量。质量分数3%的β-Si O2可使PP形成92%的β-晶体,其中庚二酸钙含量为0.0423%,因此负载型β-成核剂β-Si O2比传统的庚二酸钙具有更高的成核效率。     

纳米TiO_2填充聚丙烯复合材料中β-成核及结晶行为研究

基于CaCO_3与庚二酸反应可得到具有高效β-成核作用的庚二酸钙(Ca PA)的原理,采用负载法和直接添加法制备了高β晶含量的聚丙烯(PP)/TiO_2复合材料,并对复合体系的成核及结晶行为进行了研究。结果表明:纳米TiO_2对PP具有显著的异相成核作用,可显著提高PP结晶温度,诱导PP形成α晶。纳米TiO_2经乙酸钙溶液处理及高温处理后,可在粒子表层形成CaCO_3,将其引入PP,能使PP的结晶温度明显提高,但与未经处理的TiO_2相比,其对PP的成核作用有所下降。采用负载法并未能使纳米TiO_2对PP具有显著的β-成核作用,仅在其用量较少时形成少量的β晶。在TiO_2(经乙酸钙溶液处理)填充PP复合体系中直接加入0.1%的Ca PA,可得到高β晶含量的PP/TiO_2复合材料,当乙酸钙溶液浓度在0.5%~5%之间时,复合材料的β晶含量可达50%以上。因此,可通过乙酸钙溶液处理减弱纳米TiO_2的异相成核作用,同时加入高效β-成核剂,从而制得高β晶含量的PP/TiO_2复合材料。     

β晶型成核剂改性小本体法无规共聚聚丙烯研究

研究了β晶型成核剂（庚二酸钙）用量对小本体法无规共聚聚丙烯（PP—R）力学性能和结晶行为的影响。β晶型成核剂使小本体法PP—R的断裂伸长率有所下降，弯曲模量有所提高，拉伸强度变化不大，缺口冲击强度提高，特别是低温（0℃）缺口冲击强度得到较大改善。广角X射线衍射分析表明β成核剂不仅促进了小本体法PP—R中β晶型的生成，而且提高了γ晶型的相对含量。示差扫描量热分析也表明β成核剂改性小本体法PP—R中同时存在α、β和丫三种晶型。偏光显微镜观察发现β成核剂改性小本体法PP—R中出现了β晶型，晶体尺寸明显减小。     

改性玻璃纤维/聚丙烯复合材料结晶熔融行为研究

本研究使用熔融共混挤出法,制备了改性玻璃纤维/聚丙烯复合材料,利用差式扫描量热仪对复合材料的结晶熔融行为进行了探究,同时测试了各材料的冲击强度。结果表明,利用混合稀酸刻蚀后的玻纤,不但具有异相成核作用,提高结晶峰温,而且具有β晶诱导作用,使冲击性能提高。经庚二酸钙表面修饰后,β晶诱导和异相成核效应更强,β晶成主要晶型,进一步改善了复合材料的冲击性能。     

β成核剂对等规聚丙烯结晶性能的影响

研究硬脂酸盐作为β成核荆对聚丙烯结晶性能的影响.WAXD结果表明:硬脂酸盐能诱导聚丙烯生成β晶型,在添加量为0.3%时,β晶的相对含量达到最大为76.64%.DSC曲线表明:硬脂酸盐改性的聚丙烯在152℃出现β晶型的熔融吸热峰,其结晶起始温度和结晶峰温度均向高温移动,表明添加硬脂酸盐可诱导PP中α晶向β晶转变,具有明显的β成核作用.     

改性鸡蛋壳粉作为聚丙烯的β成核剂的性能研究

生活中会产生大量的废弃钙化物,如蛋壳和贝壳。本文提出一种用表面改性鸡蛋壳粉填充聚丙烯的方法,通过熔融挤出得到聚丙烯复合材料。分析表明,经庚二酸钙改性后的蛋壳粉能有效诱导聚丙烯β晶的形成,最高达99%,使复合材料冲击强度增幅达到228%。综合考虑,当PP/蛋壳粉/庚二酸质量比在100∶5∶0.025时,复合材料可以获得最优的力学性能。     

β晶型PP的结构与性能

采用差示扫描量热法、广角X射线衍射等表征了β晶型聚丙烯(β-PP)的结晶性能.β晶与α晶有不同的熔融温度,β晶的熔融峰在155℃附近,而α晶的熔融峰在165℃附近.从冲击试样的断面照片可明显看出:β-PP的冲击断面凹凸不平,说明其韧性较高,而α晶型PP的冲击断面相对平滑得多.     

等规聚丙烯与液晶成核剂的共混改性研究

以单丙烯酸酯液晶单体（RLC）为成核剂,通过共混反应法对等规聚丙烯（iPP）进行改性,制备含β晶型的聚丙烯产品（β-iPP）。首先介绍了β-iPP的制备工艺,然后通过偏光显微镜、广角X射线衍射对纯iPP、iPP/RLC共混物的球晶结构进行了分析;最后通过X射线衍射、差示扫描量热分析等测试方法研究共混物的结晶结构、结晶行为和热性能。结果表明,液晶成核剂RLC能够诱导iPP生成β晶型;制备β-iPP的最佳工艺条件是RLC含量为0.5 %（质量分数,下同）,结晶温度为110 ℃;β晶型相比于α晶型处于热力学亚稳态,在升温过程中,会发生β晶向α晶的转变,但较高的升温速率会抑制这一转变。     

Crystallization behavior and melting characteristics of PP nucleated by a novel supported β-nucleating agent

The β-nucleated PP with high β-PP content was prepared by a novel supported β-nucleating agent, which was prepared with pimelic acid supported on nano-CaCO₃ as support. The influences of the content of the support and supported β-nucleating agent, pre-melting temperature (T_melt) and scan rates on crystallization behavior and melting characteristics, and the β-PP content of β-nucleated PP were determined by Differential Scanning Calorimeter (DSC) and Wide-Angle X-ray Diffraction (WAXD). The results indicated that the addition of supported β-nucleating agent markedly increased the crystallization temperature (T_c) of PP. Increasing the content of supported β-nucleating agent slightly increased the T_c, but had no influence on the melting temperatures (T_m) of β-nucleated PP. The T_c and T_m of β-nucleated PP decreased slightly with increasing the content of the support nano-CaCO₃. The effects of scan rates and multiple scans with different T_melt on the crystallization and melting behavior of PP nucleated by supported β-nucleating agent are similar to that of PP nucleated by calcium pimelate (CaHA). The β-PP content above 90 percent was obtained in PP nucleated by supported β-nucleating agent and was not influenced by the content of nano-CaCO₃. The supported β-nucleating agent prepared by supporting pimelic acid on nano-CaCO₃ is a β-nucleating agent with high efficiency and selectivity, and low cost.     

Pimelic acid-based nucleating agents for hexagonal crystalline polypropylene

Isotactic polypropylene (PP) resin was doped with pimelic acid, sodium pimelate, and calcium pimelate to stimulate the growth of hexagonal crystalline polypropylene (β-PP). The doped resin was crystallized in a differential scanning calorimeter (DSC) and during compression molding and injection molding. The effect of the additives on the formation of β-PP was examined using DSC and wide angle X-ray scattering (WAXS). Pimelic acid alone was found ineffective while the pimelates induced 64% to 90% of β-growth depending on the nucleating agent system and crystallization condition. In particular, the pimelic acid/calcium stearate system produced a more consistent and higher yield of β-PP. This was attributed to finer particle size and better dispersion of the nucleating agent.     

β‐Nucleation of pimelic acid supported on metal oxides in isotactic polypropylene

To investigate the nucleation of metal pimelate for isotactic polypropylene (iPP) crystallization, iPP filled with a series of metal oxides with and without metal pimelate on their surface was prepared. There was a chemical reaction between pimelic acid (PA) and metal oxides MgO, CaO, BaO or ZnO, but not TiO₂. The corresponding metal pimelate formed by the chemical reaction between PA and MgO, CaO, BaO or ZnO had a different influence on the crystallization behavior and melting characteristics of iPP. Addition of metal oxides increased the crystallization temperature of iPP and mainly formed α‐phase due to the heterogeneous α‐nucleation of metal oxides. The α‐nucleation of CaO could be easily changed into β‐nucleation using CaO‐supported PA, and 90.1% β‐phase was obtained. The β‐nucleation of BaO could be markedly enhanced by barium pimelate formed using supported PA. However, no β‐phase was observed for iPP filled with MgO‐ or ZnO‐supported PA. The various metal oxides with supported PA had a different influence on the crystallization behavior and melting characteristics of iPP due to the different structure of metal pimelate formed by chemical reaction between PA and the metal oxides. Copyright © 2012 Society of Chemical Industry     

A novel highly efficient β‐nucleating agent for polypropylene using nano‐CaCO3 as a support

In order to increase the isotactic content of β‐nucleated polypropylene (β‐iPP) and decrease the cost of its production, the investigation and development of novel highly efficient β‐nucleators are important issues. Nano‐CaCO₃ was used as a support to prepare a supported β‐nucleator, nano‐CaCO₃‐supported calcium pimelate. Fourier transform infrared spectral analysis shows that an in situ chemical reaction takes place between nano‐CaCO₃ and pimelic acid. Differential scanning calorimetry results indicate that the crystallization and melting temperatures of β‐phase in supported β‐nucleator‐nucleated iPP are higher than those of calcium pimelate‐nucleated iPP. The β‐nucleating ability of the supported β‐nucleator is little influenced by the cooling rate and crystallization temperature over a wide range. The decreased content of pimelic acid in the supported β‐nucleator slightly decreases the crystallization temperature of iPP but it has no influence on the content of β‐phase in nucleated iPP. A novel supported β‐nucleator has been successfully synthesized via pimelic acid supported on the surface of CaCO₃. The crystallization temperature of iPP and melting temperature of β‐phase in iPP nucleated using the supported β‐nucleator are higher than those of iPP nucleated using calcium pimelate. The concept of a supported nucleator will provide a new way to increase the efficiency of polymer additives and to decrease the amounts of them that need to be used by using nanoparticles as supports. Copyright © 2010 Society of Chemical Industry     

Effect of acrylonitrile–butadiene–styrene copolymer (ABS) on β-nucleation in β-nucleated polypropylene/ABS blends

β-PP/acrylonitrile–butadiene–styrene (ABS) blends were prepared with PP, ABS and a novel supported β-nucleating agent or β-PP and ABS. The effect of ABS on the β-nucleation of PP and crystallization and melting behavior of β-PP/ABS blends were investigated by differential scanning calorimeter, wide angle X-ray diffraction, and polarized light microscopy. Results suggested that addition of low content of ABS has no effect on the β-nucleation of PP and crystallization behavior, and melting characteristic of β-PP/ABS blends. However, the increasing content of ABS decreases the β-nucleation, crystallization temperatures, and spherulite size of PP in the blends. However, the blends with the β-PP content above 80?% were obtained at the content of ABS below 40?%.     

Non-isothermal crystallization kinetics of calcium carbonate-filled β-crystalline phase polypropylene composites

The non-isothermal crystallization behaviour of high purity β-phase and α-phase polypropylene (PP) and their calcium carbonate-filled composites was investigated by means of differential scanning calorimetry. High purity β-PP polymer was prepared by adding an effective β-nucleator consisting of equal amounts of pimelic acid and calcium stearate. The crystallization temperature and crystallization rate coefficient of pure β-PP polymer were considerably higher than those of the α-PP polymer. This was due to the β-PP polymer containing nucleating agents, which act as nuclei for β-spherulites. The calcium carbonate content had little or no effect on the crystallization rate coefficient and Ozawa exponent of the β-phase PP in the composites. On the other hand, the crystallization temperature, crystallization rate coefficient and Ozawa exponent of the α-phase PP composites depended on the calcium carbonate loading. The effect of calcium carbonate additions on the crystallization of α-PP and β-PP is discussed. ©1997 SCI     

降解PP/EPDM共混物的结晶性能研究

采用过氧化二异丙苯(DCP)降解聚丙烯(PP),熔融法制备了降解PP与三元乙丙橡胶(EPDM)共混物,采用差示扫描量热分析(DSC)及广角X射线衍射(WAXD)研究了降解PP/EPDM共混物的结晶行为,结果发现PP降解后β-PP晶型(300)消失 ;降解PP/EPDM共混物的非等温结晶过程是由成核控制的,并伴有明显的快速初级结晶和缓慢的次级结晶过程,降解PP以均相成核的三维球晶方式生长.     

Influence of different β‐nucleating agent on crystallization behavior,morphology, and melting characteristic of multiwalled carbon nanotube‐filled isotactic polypropylene nanocomposites

To obtain isotactic polypropylene (iPP) nanocomposites with high β‐crystal content, TMB5, calcium pimelate and calcium pimelate supported on the surface of nano‐CaCO₃ were used as β‐nucleating agent and MWCNT filled β‐nucleated iPP nanocomposites were prepared. The effect of different β‐nucleating agent and MWCNT on the crystallization behavior and morphology, melting characteristic and β‐crystal content of β‐nucleated iPP nanocomposites were investigated by DSC, XRD and POM. The results indicated that addition of MWCNT increased the crystallization temperature of iPP and MWCNT filled iPP nanocomposites mainly formed α‐crystal. The β‐nucleating agent can induce the formation of β‐crystal in MWCNT filled iPP nanocomposites. The β‐nucleating ability and β‐crystal content in MWCNT filled β‐nucleated iPP nanocomposites decreased with increasing MWCNT content and increased with increasing β‐nucleating agent content due to the nucleation competition between MWCNT and β‐nucleating agents. It is found that the calcium pimelate supported on the surface of inorganic particles as β‐nucleating agent has stronger heterogeneous β‐nucleation than calcium pimelate and TMB5. The MWCNT filled iPP nanocomposites with high β‐crystal content can be obtained by supported β‐nucleating agent. POLYM. COMPOS., 36:635–643, 2015. © 2014 Society of Plastics Engineers     

各种羧酸二盐对嵌段共聚聚丙烯的β成核研究

合成了6种己二酸盐、庚二酸盐作为嵌段共聚聚丙烯(PP-B)的成核剂,研究其对PP-B的β成核影响。结果表明,庚二酸钙、庚二酸钡、庚二酸镁均具有明显β成核PP-B的效果,且成核效应由大到小次序为:庚二酸钙、庚二酸钡、庚二酸镁;庚二酸钠是低活性的β成核剂;己二酸盐类中己二酸钠和己二酸钡对PP-B是高效的β-成核剂,二者的成核效果相当。通过差示扫描量热分析(DSC)和力学性能测试表明,当己二酸钠的用量为0.2%(质量分数)时,经β成核改性产物的缺口冲击性能最佳,且KDSC(β晶型相对含量)最大。     

Compatibility,morphology, and crystallization behavior of compatibilized β-nucleated polypropylene/poly(trimethylene terephthalate) blends

β-Nucleated polypropylene (PP), uncompatibilized β-nucleated PP/poly(trimethylene terephthalate) (PTT), β-nucleated PP/PTT blends compatibilized with maleic anhydride (MA)-grafted PP (PP-g-MA), and styrene–ethylene–propylene copolymer were prepared with a twin-screw extruder. The morphology, compatibility, crystallization characteristic, melting behavior, and crystallization kinetics were investigated. The result shows that β-nucleated PP was incompatible with PTT, and the addition of the two compatibilizers decreased the interfacial tension between β-nucleated PP and PTT; this led to improved dispersion and strengthened interfacial bonding in the blends. PP-g-MA had a better compatibilization effect. All of the researched β-nucleated PP/PTT blends contained β crystals of PP, and the compatibilizers exhibited synergistic effects with the β-nucleating agent to further increase the content of β crystals. Nonisothermal kinetic analysis indicated that Mo's method described the nonisothermal crystallization behavior of the β-nucleated PP/PTT blends satisfactorily, and the Avrami approach could only describe the early stage of the crystallization appropriately, whereas the Ozawa method failed to have the same effect. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012