Fracture surface morphology of some crystalline block copolymers—propylene/ethylene and tetramethyl‐p‐silphenylenesiloxane dimethylsiloxane
作者:
M. Kojima,
J. H. Magill,
期刊:
Journal of Applied Physics
(AIP Available online 1974)
卷期:
Volume 45,
issue 10
页码: 4159-4166
ISSN:0021-8979
年代: 1974
DOI:10.1063/1.1663031
出版商: AIP
数据来源: AIP
摘要:
The fracture surface morphology of block copolymers of (i) tetramethyl‐p‐silphenylenesiloxane/dimethylsiloxane (TMPS/DMS) and (ii) propylene/ethylene (P/E) has been studied. The TMPS/DMS samples had compositions ranging from 90/10 to 30/70 wt% ratios. The ethylene content in the P/E samples ranged from 8 to 13%. A few polyolefin blends were also examined. Materials were fractured at liquid‐nitrogen temperatures and studied under ambient conditions by scanning and transmission electron microscopy. X‐ray methods and differential scanning calorimetry (DSC) techniques were also used. Copolymers with higher TMPS compositions exhibited a lamellar texture, but at high DMS contents fracture appeared ``glassy''. All TMPS/DMS samples exhibited spherulitic structures. Spherulites were mainly banded and were negatively birefringent. In samples with higher TMPS content, fracture occurred predominately between lamellar bands. The DMS component rejected by the crystalline TMPS hard segments is largely responsible for the observed fracture behavior and for the tensile properties of these copolymers particularly where this phase predominates. In the P/E copolymers both large and small globular particles are observed. Ethylene and propylene form separate crystalline phases. The interfacial characteristics between the large aggregates and the polypropylene matrix are believed to be responsible for impeding fracture porpagation in these materials, as assessed by impact tests. The influence of annealing conditions on the observed morphology has been investigated.
点击下载:
PDF
(902KB)
返 回