炭/石墨材料的成型工艺综述

由于炭/石墨材料在冶金、太阳能、核能、原子能、半导体、航空航天等领域的广泛应用,本文针对当前国内炭/石墨材料的成型方式,主要探讨挤压成型、模压成型和等静压成型,以及它们的技术特点.     

贝壳粉对饰面型防火涂料阻燃性能的影响分析

将贝壳粉与膨胀型防火涂料按一定比例混合,采用隧道燃烧法探测贝壳粉的加入对防火涂料防火阻燃性能的影响。并寻找出最佳配比浓度范围,使废弃贝壳粉能够投入到室内装修材料中形成一种绿色环保的产品。     

Novolen 工艺聚丙烯细粉产生原因及改进措施

介绍了聚丙烯（ PP）细粉过多对循环气系统、载气系统、粉料输送系统的影响,主要从催化剂、生产负荷、开停车、切换产品牌号、丙烯质量等方面分析产生过多细粉的原因,提出相应改进措施,并对过滤器和主密封气进行技改。生产实践表明,通过以上措施降低了细粉产生量,使装置长周期稳定运行。     

反应降解聚丙烯的高速挤出流动稳定性

采用双毛细管流变仪研究了反应降解聚丙烯试样的挤出稳定性。结果表明:基础树脂聚丙烯PP-2401的挤出压力随剪切速率增高呈阶梯状稳定增高,而降解聚丙烯的挤出压力随剪切速率增高出现不规则波动;低相对分子质量降解聚丙烯的压力波动主要发生在口模入口区;发生波动的原因与聚丙烯分子链结构特征有关,同时与熔体在口模区的Weissenberg准数和Reynolds准数较大有关。     

涡流空气分级机的发展与应用

随着羰基铁粉市场的细化,市场需要粒度更小、分布区间更窄的羰基铁粉,为满足这一需求,我们做了大量市场调研,根据羰基铁粉特性与流能粉体设备有限公司合作研发成功了国内首台用于羰基铁粉的氮气保护涡流分级机。本文在兴化涡流分级机研发的基础上,介绍了涡流空气分级机的工作原理和发展过程,对不同类型的涡流空气分级机进行了分析对比。简要介绍了兴化在选型与研发、改造涡流分级机的过程中取得的经验和效果。     

粉末涂料的质量控制及优劣判断方法探讨

对目前粉末涂料的市场状况做了简单的分析,从原料、设备、配方、工艺4个方面介绍了粉末涂料生产质量控制方法,以及作为涂装企业快速简单判断粉末涂料优劣的几种简易方法。     

Structure and properties of polypropylene/high‐density polyethylene blends by solid equal channel angular extrusion

The solid equal channel angular extrusion (ECAE) process on polypropylene (PP)/high‐density polyethylene (HDPE) blends was carried out. Scanning electron microscopy (SEM) was used to observe the sample structures. Results showed that ECAE process could make PP/HDPE blends to produce orientation structure. Impact performance of ECAE‐PP/HDPE samples after ECAE process improved remarkably, especially for ECAE‐PP/HDPE (90/10)‐O whose impact strength reached 91.91 kJ/m², 18.1 times higher than that of pure PP and 11.2 times higher than that of PP/HDPE (90/10). The mechanism of enhancing between HDPE and PP was discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39759.     

Effects of rare earth samarium oxide on the properties of polypropylene‐graft‐cardanol grafted by reactive extrusion

Rare earth elements can improve the performance of polymers because of their special 4f orbitals. The nucleation and stabilization of radical groups of rare earth particles can affect the structure of polypropylene (PP) and its properties. In this study, samarium oxide (Sm₂O₃) particles were used as a cocatalyst and nucleating agent in polypropylene‐graft‐cardanol (CAPP) grafted by reactive extrusion. The properties of polypropylene‐graft‐cardanol containing modified Sm₂O₃ with a titanate coupling agent (CAPPMS) were investigated by ultraviolet–visible spectrometry, polarizing microscopy, differential scanning calorimetry, scanning electron microscopy, universal testing, and capillary rheometry with the reference of CAPP containing unmodified Sm₂O₃ particles. The results show that the titanate coupling agent (TCA‐401) coated on the surface of the Sm₂O₃ particles improved the dispersion of the Sm₂O₃ particles and the adhesion between the Sm₂O₃ particles and CAPP matrix. The Sm₂O₃ particles promoted more cardanol to graft onto PP. Acting as nucleator for CAPP, the Sm₂O₃ particles increased the crystallization rate, increased the melting temperature, and decreased the spherulite size of CAPP. The modified Sm₂O₃ particles showed a greater effect on the mechanical and rheological properties than the unmodified Sm₂O₃ particles did. The tensile strength, impact strength and flexural strength of CAPPMS increased by 10 MPa, 0.64 kJ/m², and 6.5 MPa, respectively, compared to those of CAPP when we used 4.5 mol % modified Sm₂O₃ particles. The viscosity of CAPPMS increased to a certain extent in the presence of the modified Sm₂O₃. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41012.     

Perfluorosulfonated ionomers membranes: Melt‐processing and characterization for ion exchange applications

Perflurosulfonated ionomers membranes with different ionic‐exchange capacity were successfully fabricated via melt‐extruding and casting of their –SO₂F precursors. A systematical investigation of the thermal stability, crystallinity, and rheological properties of the precursors was performed to secure their optimized processing conditions. The tensile properties of acid‐form membranes are found to increase with base‐hydrolysis time, where a tensile strength of 38.2 MPa is readily obtained after 24 h's base‐hydrolysis. The content of –SO₂F or –SO₃H containing side‐chains plays an important role in the thermal stability, rheological, and mechanical properties of the precursor or the acid‐form membranes. The strong ionic interactions, attributed to the –SO₃H groups, lead to decreased crystallinity and tensile strength for different IEC membranes. The acid‐form membranes exhibit good proton conductivity and low methanol crossover in comparison with reference Nafion membrane. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39944.     

Preparation and reaction kinetics of polypropylene‐graft‐cardanol by reactive extrusion and its compatibilization on polypropylene/polystyrene

Polypropylene‐graft‐cardanol (CAPP) was prepared by reactive extrusion with polypropylene (PP) and natural renewable cardanol, which improved the inherent defects of PP such as its chemical inertness and hydrophobicity. Moreover, the cardanol grafted onto PP resolved the degradation of PP during reactive extrusion and use. The effects of reactive extrusion on the change of the molecular structure of PP, the change in the free‐radical concentration during processing, and the compatibilization of CAPP on the PP/polystyrene (PS) composite materials were examined in this study. The constants of the grafting reaction rate at the beginning of reactive extrusion were also deduced. The results show that cardanol was grafted onto PP, and the p–π conjugate system in cardanol was observed to stabilize free radicals. The grafting reaction rate (R_g) at the initial stage of the grafting reaction process was calculated through the equation R_g = k_g[M·][Cardanol], where k_g is the constant of the apparent grafting reaction rate and [M·] is the concentration of free radicals in the reaction system. k_g first increased with the growth of temperature and then began to decrease when the temperature exceeded the critical temperature of 200°C. The mechanical properties showed almost no change after the samples were aged for 72 h. This was due to CAPP, which changed PP/PS to a ductile material from a brittle one. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39911.