Effect of phytic acid–modified layered double hydroxide on flammability and mechanical properties of intumescent flame retardant polypropylene system

Phytic acid–modified layered double hydroxide (Ph‐LDH) was synthesized via coprecipitation method and subsequently was used in polypropylene (PP) by combining with an ammonium polyphosphate (APP) via melt compounding method. The synergistic effect between APP and Ph‐LDH on the thermal stability, flammability, and mechanical properties of the resultant PP composites was investigated by thermogravimetric analysis, limiting oxygen index, vertical burning test (UL‐94), cone calorimeter tests, tensile test, and impact test. Morphologies of the chars obtained from the samples after the cone calorimeter tests were studied by scanning electron microscopy. The combination of APP and Ph‐LDH slightly influenced the impact and tensile properties of PP. Also, the synergistic effect between APP and Ph‐LDH occurred in the cone calorimeter test. Moreover, the combination of APP and Ph‐LDH produced better quality char that effectively suppressed the spread of the flame and volatile and finally extinguished the fire.     

专用聚丙烯树脂PPH-Y35生产及应用研究

针对无纺布的应用特性,对专用聚丙烯树脂PPH-Y35生产工艺、性能进行了优化。利用专用生产聚丙烯树脂PPH-Y35装置,用高效催化剂氢调法、选取复合抗氧化剂生产出高质量的产品。将用PPH-Y35生产的无纺布与同类产品的性能对比,其性能优异,在医疗卫生领域中的应用更有优势。     

A facile one‐step method for spherical support preparation of Ziegler‐Natta catalyst

This study reports a novel one‐step method to synthesize a new spherical support for Ziegler‐Natta catalyst under moderate condition. The support is obtained from a dispersion system where the particle stabilizer polyvinylpyrrolidone plays a main role to stabilize the spherical particles. The new chemical of the support is CH₃CH₂OMgOCH(CH₂Cl)₂, which is first reported here, has been approved by newly filed patents and also confirmed by solution NMR, solid state NMR, pyrolysis‐gas chromatography‐mass spectrometry (Py‐GC‐MS), and ICP‐MS. The support and catalyst particles have uniform distributions. The catalyst prepared from this support has been evaluated with high activity. The polypropylene obtained has high isotacticity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41014.     

Atom transfer radical polymerization (ATRP): A versatile and forceful tool for functional membranes

The progress in atom transfer radical polymerization (ATRP) provides an effective means for the design and preparation of functional membranes. Polymeric membranes with different macromolecular architectures applied in fuel cells, including block and graft copolymers are conveniently prepared via ATRP. Moreover, ATRP has also been widely used to introduce functionality onto the membrane surface to enhance its use in specific applications, such as antifouling, stimuli-responsive, adsorption function and pervaporation. In this review, the recent design and synthesis of advanced functional membranes via the ATRP technique are discussed in detail and their especial advantages are highlighted by selected examples extract the principles for preparation or modification of membranes using the ATRP methodology.     

DBDPE–Sb2O3复合阻燃LGFPP的热氧老化研究

采用十溴二苯乙烷(DBDPE)协同三氧化二锑(Sb2O3)组成复合阻燃剂DBDPE–Sb2O3(D–S)阻燃长玻纤增强聚丙烯(LGFPP),并采用热烘箱老化法研究了140℃条件下不同热氧老化时间对复合材料热氧老化性能的影响。结果表明,随着热氧老化时间的延长,LGFPP/D–S阻燃体系的氧指数值呈现出先升高后下降的趋势,垂直燃烧等级始终保持FV–0级的阻燃级别,复合材料的结晶度减小,力学性能逐渐下降。PP基体分子链的断裂以及玻纤与PP基体间发生界面脱粘是导致LGFPP/D–S复合材料宏观力学性能下降的主要原因。红外光谱表明,随着热氧老化时间的延长,试样表面会产生更多的生色基团使材料发生黄变,说明PP基体分子链的断裂加剧。     

CaCO_3对EPDM/PP热塑性弹性体性能的影响

在双螺杆挤出机上采用动态硫化的方法制备CaCO3改性三元乙丙橡胶/聚丙烯(EPDM/PP)共混型热塑性弹性体(TPV),研究了CaCO3添加量对热塑性弹性体拉伸性能、流动性能和邵氏A硬度的影响,并对材料进行热失重分析、差示扫描量热分析以及X射线衍射分析。结果表明:CaCO3对TPV有增强的作用,随着CaCO3含量的增加,热塑性弹性体的拉伸强度和断裂伸长率有很大提高,当CaCO3质量分数为9%时,拉伸强度、断裂伸长率、100%定伸应力与邵氏A硬度达到最大值,随后逐渐降低;CaCO3的加入增加了TPV的流动性,使其热稳定性提高,结晶温度降低,使PP的β(300)晶面消失。     

不同化学结构的PP对热塑性弹性体复合材料性能的影响

研究了不同化学结构的聚丙烯(PP)对苯乙烯-乙烯/丁烯-苯乙烯共聚物(SEBS)/白油/PP热塑性弹性体复合材料力学性能和流动性能的影响。结果表明,复合材料的力学性能与所添加PP的力学性能保持一致,按照均聚PP、无规共聚PP、共聚PP的化学结构特性,复合材料的拉伸性能、弯曲性能和硬度都依次变小;但是复合材料的流动性能不仅和PP的熔体质量流动速率(MFR)有关系,而且还与PP和SEBS的相互作用有关。在PP的MFR相同的情况下,复合材料的MFR按照均聚PP、无规共聚PP、共聚PP的不同依次降低。     

PP-R给水管材检测方法探讨

PP R给水管材属新产品 ,有关其产品标准及检测方法的国家标准尚未出台 ,本文就如何规范PP R给水管材检测作一些探讨     

新型绿色环保给水管材PP—R管安装技术

通过对京珠铁粤北附属工程的施工监理 ,阐述了PP R管材的性质、特点及应用范围 ,并对其施工工艺、安装方法进行了详细说明 ,指出PP R管道系统严密不渗漏     

PP纤维水稳碎石抗弯韧性及疲劳性能试验研究

通过四点弯曲试验和疲劳试验,对聚丙烯(PP)纤维水泥稳定碎石和普通水泥稳定碎石半刚性基层材料的弯曲韧性及疲劳性能进行了研究。试验得到两种材料的荷载-挠度曲线,按照JCI和ASTMC1018-97标准方法,计算得到两种材料的韧性指数;试验还得到材料在不同应力水平下的疲劳寿命,并回归出疲劳方程。研究结果表明,与普通水泥稳定碎石相比,体积掺量仅为0.077%的PP纤维水泥稳定碎石的抗折强度提高约10%,极限变形提高150%,JCI韧性指数提高67.7%,ASTM C1018-97韧性指数提高36.1%~79.8%,疲劳寿命提高126%~352%,增强效果十分显著。同时,基于断裂力学原理,揭示了纤维的阻裂增韧和抗疲劳机理。