用SPEX冷冻研磨机研究研磨等规聚丙烯在低温研磨下之不可

Abstract


The influence of cryogenic
mechanical mil领 on the structure
and the thermal behavior of isotactic
polypropylene was investigated by
means of wide-angle X-ray scattering,
differential scanning calorimetry
and transmission electron microscopy.
The results presented show
that structural changes caused by
mechanical mil领 at cryogenic
temperatures are only partly reversible.
The decrease in the degree of
crystallinity as determined by differential
scanning calorimetry with
increasing mil领 time is attributed
to a reversible transformation of the
initial morphology into a nanostructured
morphology, consisting
of small fragments of the original
isotactic polypropylene lamellae.
During recrystallization from the
molten state, there still exists an
influence of the previous mil领
treatment, leading to significantly
changed crystallization behavior.
The reason for this behavior might
be a decrease in the molecular
weight or a change in the molecular
weight distribution or the formation
of long-chain branched polypropylene
molecules induced by cryogenic
mechanical mil领.
Keywords Cryogenic mechanical
mil领 Æ Polypropylene Æ Transmission
electron microscopy Æ Nanostructure
Æ Differential scanning
calorimetry SPEX6770 全自动冷冻研磨机 SPEX6870 全自动冷冻研磨机 SPEX6970EFM 冷冻研磨机