【摘要】 采用逐步降温和控制沉淀剂用量的方法对HDPE进行溶液分级 ,以期制备具有特定结晶度的PE标准物质。在特定的分级工艺下 ,级分 2结晶度的均值和扩展不确定度分别为 79 3 4%和 0 45 %。同时采用GPC、FTIR和DSC对级分的摩尔质量、支化度和结晶性能进行了测定和分析 ,结果表明溶液分级能够将HDPE分成窄摩尔质量分布且具有特定结晶度的级分。在本研究范围内 ,在同样热历史和降温速率条件下 ,摩尔质量从高到低、支化度由大到小的级分非等温结晶能力依次增强 ,形成晶体的有序度逐渐增大。较低摩尔质量且支化度小的窄摩尔质量分布级分具有较完善、分布更加均匀的薄片晶结构。更多还原

【Abstract】 A novel solution fractionation technique was used to fractionate a commercial HDPE via controlling the system temperature and the amount of ethylene glycol mono etyl ether (EGME), in order to prepare the reference material of PE. By given conditions the average crystallinity of fraction Ⅱ was to be 79.34% with the expanded uncertainty of 0.45%. The molecular weight, the content of short chain branching and crystallinity for each fraction were characterized by GPC, FTIR and DSC, respectively. The results confirmed that HDPE could be effectively fractionated into three different fractions with relatively narrow molecular weight distribution and defined crystallinity. Under the same thermal history and the rate of cooling, these fractions exhibited gradually enhanced crystallization ability with good perfection of crystals in accordance with the order, which was from larger to smaller molecular weight, and from higher to lower content of short chain branching. The fraction with smaller molecular weight, molecular weight distribution and lower content of short chain branching could form thinner and more uniform laminar crystals.更多还原