碳酸钙在塑料中的应用

CaCO_3是塑料加工中使用最广泛,用量最大的一种无机填料。本文介绍了CaCO_3品种及其在国内外的应用动向;较系统地阐明了CaCO_3在塑料应用中的表面处理技术和CaCO_3填充母料的配方设计原则及生产工艺路线。     

改性碳酸钙用于聚氯乙烯的研究

研究了一种改性碳酸钙的性质及其在聚氯乙烯中的应用情况。研究结果表明,这种改性碳酸钙与普通碳酸钙相比,具有吸油值低、堆积密度大、分散性好、热稳定性高等特点。填充于聚氯乙烯中,不仅能改善物料的加工性能及制品的物理力学性能,而且还具有较高的热稳定性能。     

纳米碳酸钙在橡胶中的应用

分别将纳米碳酸钙与白炭黑、半补强炭黑、沉淀碳酸钙和活性硅粉在NR,SBR,EPDM和NBR中的应用进行了对比试验。结果表明,纳米碳酸钙分别对4种橡胶具有较好补强性能,可提高拉伸强度、拉断伸长率、撕裂强度、弹性和热老化性能,降低低温性能;对非补强性橡胶的补强性能特别明显。     

碳酸钙填充PP的断裂韧性研究

用仪器化落重式冲击实验装置研究CaCO_3填充PP复合材料的断裂韧性。测量了CaCO_3含量为10wt%～40wt%复合材料试样的冲击强度、G_(?)(临界应变能释放速率)和K_(?)(临界应力强度因子)。结果表明,在上述CaCO_3含量范围内,CaCO_3填充PP的断裂韧性高于纯PP,当CaCO_3含量为20～30wt%时,断裂韧性达最大值。由此说明,在一定条件下,CaCO_3可改善PP的断裂韧性。此外,还简要地讨论了增韧机理。     

碳酸钙市场前景看好

碳酸钙是重要的无机化工产品。由于价格低、原料广、无毒性，被广泛地用作橡胶、塑料、纸张、涂料、牙膏等的填料。全世界每年在纸张中碳酸钙的用量约1100万t，占填料总量的60％以上，用于塑料的约150万t以上。近来科学家发现，超细碳酸钙具有补强作用，可用作汽车底盘防石击的涂料。日本、美国和英国在超细碳酸钙的研制、生产、应用方面处于国际     

碳酸钙的活化改性

一、前言碳酸钙作为一种无机填料,使用已有一百余年历史,但是在填充各种高聚物时,也存在着明显的缺点;一是碳酸钙是无机化合物,它表面性质是亲水疏油,在高聚物内部,分散性极差,另一是碳酸钙不能与高聚物产生化学结合,不能起补强作用,仅能起增容作用。所以,由于碳酸钙的填充,会造成高聚物的某些性能降低,特别是过量填充,使高聚物性能急剧下降,以致制品无法使用。     

碳酸钙在粉末涂料中的应用

根据多年来从事粉末涂料生产的经验,结合碳酸钙的综合性能,提出了在粉末涂料中用不含重金属的碳酸钙填料代替常用的硫酸钡填料,并列举其应用配方。     

高性能无机填料在PP改性中的应用

讨论了无机填料微细化和表面活化以及无机粒子对聚丙烯增韧增强机理,介绍了无机填料对聚丙烯的改性效果与应用。     

无机纳米填料改性聚丙烯的研究进展

综述了聚丙烯/无机纳米复合材料的制备、填料表面处理、物理力学性能。可用大分子相容剂或官能化聚丙烯,改善PP纳米材料的分散性、界面黏结和力学性能。研究表明:少量无机纳米粒子可增强增韧PP。     

The toughening mechanism of polypropylene/calcium carbonate nanocomposites

The toughening mechanism of polypropylene (PP) filled with calcium carbonate (CaCO₃) nanoparticles is described. In a previous study (Macromolecule 2008;41:9204), we observed that intensive ligament-stretching following debonding of nanoparticles was responsible for the significant improvement in the impact toughness of the annealed PP/CaCO₃ nanocomposites. Furthermore, we hypothesized that strong ligaments, which have high fracture stresses, are needed to stabilize the crack-initiation process and to increase the energy dissipation in the crack-initiation stage. In this study, we used a high-molecular-weight PP to test this hypothesis because strong ligaments could be created from this high-molecular-weight PP. The notched Izod impact strength of the nanocomposites containing the high-molecular-weight PP and 20 wt% CaCO₃ nanoparticles with a monolayer coating of stearic acid was measured to be about 370 J/m, whereas the impact strength of the unfilled PP was 50 J/m. The size of the plastic deformation zone was found to be dependent on the molecular weight of the PP matrix because the strong ligaments of the high-molecular-weight PP enabled the expansion of the plastic deformation zone, leading to a considerable increase in the impact strength. The synergic effect of the high-molecular-weight PP and the monolayer-coated nanoparticles produced nanocomposites with high impact strength, which is much greater than the inherent impact strength of the unfilled polymer. In addition, the effect of the high-molecular-weight PP on the dispersion of the nanoparticles was investigated.     

Crystallization and impact energy of polypropylene/CaCO3 nanocomposites with nonionic modifier

Isotactic polypropylene (PP) and calcium carbonate (CaCO₃) nanocomposites were prepared by melt extrusion in a twin screw extruder. The commercial CaCO₃ nanoparticles had a poor dispersion in PP matrix. The addition of a small amount of a nonionic modifier during melt extrusion greatly improved the dispersion of CaCO₃ nanoparticles. The influence of CaCO₃ nanoparticles on the crystallization of PP was studied by wide angle X-ray diffraction and polarized optical microscopy. The introduction of CaCO₃ particles resulted in small and imperfect PP spherulites, decreased spherulite growth rate and induced formation of β-form PP. The yield strength of PP decreased gradually while its Young's modulus increased slightly with increasing CaCO₃ loading. By adding 1.5 wt% of nonionic modifier to PP/CaCO₃ (85/15) nanocomposite these tensile properties were not changed much but the notched Izod impact energy of the composites was significantly increased.     

Polypropylene/calcium carbonate nanocomposites

Polypropylene (PP) and calcium carbonate nanocomposites were prepared by melt mixing in a Haake mixer. The average primary particle size of the CaCO₃ nanoparticles was measured to be about 44 nm. The dispersion of the CaCO₃ nanoparticles in PP was good for filler content below 9.2 vol%. Differential scanning calorimetry (DSC) results indicated that the CaCO₃ nanoparticles are a very effective nucleating agent for PP. Tensile tests showed that the modulus of the nanocomposites increased by approximately 85%, while the ultimate stress and strain, as well as yield stress and strain were not much affected by the presence of CaCO₃ nanoparticles. The results of the tensile test can be explained by the presence of the two-counter balancing forces—the reinforcing effect of the CaCO₃ nanoparticles and the decrease in spherulite size of the PP. Izod impact tests suggested that the incorporation of CaCO₃ nanoparticles in PP has significantly increased its impact strength by approximately 300%. J-integral tests showed a dramatic 500% increase in the notched fracture toughness. Micrographs of scanning electron microscopy revealed the absence of spherulitic structure for the PP matrix. In addition, DSC results indicated the presence of a small amount of β phase PP after the addition of the calcium carbonate nanoparticles. We believe that the large number of CaCO₃ nanoparticles can act as stress concentration sites, which can promote cavitation at the particle-polymer boundaries during loading. The cavitation can release the plastic constraints and trigger mass plastic deformation of the matrix, leading to much improved fracture toughness.     

Studies on the Effect of Reactive Polypropylene on the Properties of Filled Polyolefin Composites. Part 1. Advantages of Solid-Phase-Grafted Maleated Polypropylene Over Melt-Phase-Modified Polymers

The results summarize the problem associated with grafting of maleic anhydride (MAH) on polypropylene (PP) in the melt phase and also describe a new method for grafting PP with MAH in the solid phase. The effectiveness of the solid phase modified maleated polypropylene (MAH-PP) as interphase modifier has been documented by comparing the properties of calcium carbonate filled polypropylene composites (PP-CaCO₃) treated with solid phase modified MAH-PP with that of the melt phase modified MAH-PP treated composites. The solid-phase modification of PP by MAH is nontoxic and is also free from unreacted MAH. The modifier also improves the tensile strength and impact resistance of unmodified PP-CaCO₃ composites.     

Influences of Ternary Graft Copolymers on the Morphology and Properties of Polypropylene/Calcium Carbonate Composites

The ternary graft copolymers were synthesized by solid-phase grafting maleic anhydride (MAH), methyl methacrylate (MMA), and butyl acrylate (BA) onto polypropylene (PP), and applied in the interfacial modification of the PP/Calcium carbonate (CaCO₃) composites. Fourier transform infrared (FTIR) spectroscopy was used to analyze the structure of the ternary graft copolymers. Scanning electron microscopy (SEM), thermogravimetry (TG), differential scanning calorimetry (DSC), and dynamic rheological testing were used to investigate the morphology and the properties of the composites. FTIR results confirmed the occurrence of the solid-phase graft copolymerization, and SEM exhibited the improvement of the compatibility between PP and CaCO₃ by PPTM. The properties testing showed that PPTM significantly contributed to the reinforcement of the composites in terms of mechanical properties, thermal properties, and rheological properties by acting as interfacial modifiers and plasticizers. The preferable loadings of PPTM for the properties improvement of the PP/CaCO₃ composites were between 7 and 9 phr.     

聚丙烯复合材料应用的研究进展

在很多领域中单纯聚丙烯材料因其易被氧化、不易接合等缺点无法被应用,因此对聚丙烯的改性并研究其复合材料有着重大意义,从而扩大聚丙烯的应用范围,进而为社会带来收益。以不同的填充或增强材料来对聚丙烯复合材料进行综述,主要对玻纤维增强聚丙烯复合材料、天然纤维增强聚丙烯复合材料和无机填料/聚丙烯复合材料进行描述。     

多种无机填充材料在聚丙烯共混体系中的不同作用

着重讨论了轻质碳酸钙、重质碳酸钙、滑石粉、硅灰石、钛酸钾、硫酸钡和云母对聚丙烯和聚丙烯共混体系的影响。实验表明：对聚丙烯强度提高较大的是云母粉,对含有交联物的聚丙烯共混体系强度提高较大的是滑石粉,对冲击强度影响最小的是钛酸钾ＴＫ１,对光泽度影响最小的是硫酸钡,对耐热性提高较大的是轻质碳酸钙。     

A Review on Biodegradable Plastics

The interaction between synthetic polymers and the natural environment in terms of the effects of oxygen, radiant energy, and living organisms has been extensively studied over the past two decades [1]. However, the recent trends in the preservation of the environment have created much public interest. This is due to the heavy usage of plastics as packaging materials in consumer industry. Materials used as packaging films and the like are not expected to have a long service life. Among several such materials, polyolefins have received special criticism because of their longevity and stability under soil burial conditions. The most likely degradative processes acting on buried polyolefins are simple oxidation and microbial attack, in addition to photodegmdation under the influence of UV sunlight. The disposal of plastics as refuse or litter is thus a volume problem rather than a weight problem. The relative proportion of plastics in refuse increases every day on account of their low degradability. The widespread concern of the public regarding waste plastic products prompted us to undertake an overview of the biodegradation of plastic products.     

PP/弹性体/无机粒子三元复合材料的研究

以新型聚烯烃弹性体(POE)为增韧剂,以玻璃微珠、nano-CaCO3为增强剂,将传统的弹性体增韧方法和新型的纳米粒子增韧增强手段相结合,利用双螺杆挤出机,通过熔融共混工艺制备了聚丙烯(PP)/聚烯烃热塑性弹性体(POE)/无机粒子复合材料。测试了复合材料的力学性能并利用扫描电子显微镜(SEM)对三元复合材料的的断面形态进行了研究。