在观察水在管内的流动特性试验中，用聚丙烯颗粒作为示踪粒子，其密度与水非常相近。
Particles of polypropene, with densities approaching that of water were used as tracer in the water system for the investigation of the flow characteristics.
预聚除能够提高催化剂的活性外，对提高聚丙烯粉料的表观密度和等规指数、减少聚丙烯颗粒的破碎有显著影响。
Besides increasing the catalyst activity, the pre-polymerization can not only raise the bulk density and isotacticity of the PP product, but also significantly diminish the cracking of the PP powders.
用动态光散射方法研究了以聚丙烯酸丁脂（ PBA）为核、 聚甲基丙烯酸甲脂（ PMMA）为壳的核壳双层纳米颗粒的粒径和粒径分布。
The size and size distribution of core-shell particles, PBA as core and PMMA as shell, are studied by dynamic light scattering.
应用推荐