利用球形纳米蒙脱土(MMT)负载Ziegler-Natta催化剂制备了聚丙烯(PP)/MMT纳米复合树脂.复合树脂中的PP具有与普通PP相仿的等规度和熔点;可通过改变聚合条件调节复合树脂中PP的相对分子质量和MMT含量.采用SEM,WAXRD,POM,DMA,TG等方法研究了复合树脂的形态结构、结晶形态、流变行为、动态力学行为、力学性能、阻隔性能和热稳定性.表征结果显示,复合树脂颗粒呈球形,流动性良好;MMT片层均匀分散于PP基体中,MMT片层与PP基体的相容性较差,在熔融加工过程中会发生部分聚集.当MMT含量约为1 1％(w)时,复合树脂中可形成MMT的逾渗网络.当MMT含量为1.29％(w)时,复合树脂的综合力学性能较好.少量MMT的存在可提高复合树脂的液体阻隔性能和热稳定性.

目前国内煤炭企业经过兼并重组,大部分都组建了煤炭集团,集团规模不断扩张,集团投资管理部门对投资管理控制力度不够,“三超”现象严重,针对上述现象,本文研究了煤炭工程项目在投资方面所具有的决策特征,并论述了这些决策特征对煤炭工程项目投资活动所产生的影响.

On the basis of development strategy and industry layout of Shenhua Group in the core economic circle of "golden triangle",this paper puts forward relevant suggestions to solve medium and long-term inadequate guarantee of the coal resources in Shenhua Ningxia Coal Industry Group,speed up the development of electric power industry,and promote the development of high-end clustering of coal chemical industry by combining medium and long-term development planning of energy chemical industry in Ningxia Hui Autonomous Region after deeply analyzing coal,electric power,coal to oil chemical industry,coal deep processing and comprehensive utilization of "the Four Pillar Industrial Development " in Shenhua Ningxia Coal Industry Group.