Simultaneous SAXS/WAXS experiments on shear induced iPP crystallization near nominal melting temperature
Simultaneous SAXS/WAXS experiments on shear induced iPP crystallization near nominal melting temperature
复制标题
DOI：
10.1016/j.polymer.2012.05.062
复制
发表时间：
2012-07
期刊：
影响因子：
4.6
通讯作者：
I. Polec;T. Fujiwara;T. Kanaya;C. Deng
中科院分区：
文献类型：
--
作者：
I. Polec;T. Fujiwara;T. Kanaya;C. Deng
同时进行小角度和广角同步加速器辐射 X 射线散射，以监测施加脉冲剪切期间和之后 iPP 熔体内晶体结构的演变。 iPP 熔体在低于和高于标称熔化温度 Tm 150 至 170 °C 的温度下经受 240 s−1 的强脉冲剪切 6 秒。结果发现，施加的剪切仅在最低温度下影响熔体。在高于 150 °C 的流动过程中产生的结构太稀，无法检测到。为了提取隐藏的结构，在剪切后立即或在剪切温度下退火长达 30 分钟后，将熔体冷却至 150 °C 的结晶温度。这种处理在淬火后几分钟内就表现出各向异性结构，当剪切温度和退火温度呈现相同值时无法检测到。获得的数据还揭示了退火时间、剪切温度和孵育时间之间的密切相关性。
Simultaneous small- and wide-angle synchrotron radiation X-ray scattering was performed to monitor the evolution of crystalline structure within the iPP melt during and after applying pulse shear. The iPP melt was subjected to a strong pulse shear of 240 s−1for 6 s at temperatures between 150 and 170 °C below and above the nominal melting temperature Tm. It was found that the imposed shear affected the melt only at lowest temperature. Structures generated during flow above 150 °C were too dilute to be detected. To extract the hidden structure, the melt was cooled to crystallization temperature of 150 °C either immediately after shearing or after annealing at shear temperature for up to 30 min. This treatment manifested with an anisotropic structure in a few minutes after quenching, undetectable when both shear and annealing temperatures presented the same value. The data obtained revealed also close correlations between annealing time, shear temperature and incubation time.