1990 Fiscal Year Final Research Report Summary
Formation Mechanism of Extended-Chain Crystal of Polyethylene
| Project/Area Number |
63550027
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Applied materials
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| Research Institution | Fukuoka University |
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Principal Investigator |
YASUNIWA Munehisa Fukuoka Univ., Assistant Prof., 理学部, 助教授 (90044289)
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| Co-Investigator(Kenkyū-buntansha) |
TSUBAKIHAR Shinsuke Fukuoka Univ., Assistant, 理学部, 助手 (70188613)
TSUBAKIHAR Shinsuke Fukuoka Univ.., Assistant (70188613)
TSUBAKIHAR Shinsuke Fukuoka Univ., Assistant (70188613)
TSUBAKIHAR Shinsuke Fukuoka Univ., Assistant (70188613)
TSUBAKIHAR Shinsuke Fukuoka Univ., Assistant (70188613)
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| Project Period (FY) |
1988 – 1989
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| Keywords | Polyethylene / High Pressure / Thermal Analysis / Small Angle X-ray / Melting / Crystallization / Lamella / Single Crystal |
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| Research Abstract |
Following results were obtained in our research project "Formation Mechanism of Extended-Chain Crystal of Polyethylene"
1. A solution crystallized sample of ultra-high molecular weight polyethylene (PE) was made. Melting process of it under high pressure was studied by high pressure DTA, and a phase diagram of it was obtained from peak melting temperature of DTA curves.
In the high pressure region such as 600 MPa, thick lamellae similar to extended-chain crystal (ECC) are formed very rapidly in the heating process. The rapid lamellae thickening is suggested to be due to the decrease of entanglements.
2. A single-crystal mat sample of PE crystallized from dilute solution was made. The melting and crystallization processes were studied by high pressure DTA. Lamellar thickening and change of orientation of molecular chain in the melting process were studied by small and wide angle X-ray analysis.
(1) In the pressure region lower than 300 MPa, lamellar thickening proceeds up to the peak melting temperature in the DTA curve. Above it, melting of the crystal starts, therefore ECC does not form.
(2) In the pressure region higher than 300 MPa, the lamellar thickening proceeds even in the hexagonal phase, therefore very thick lamellae like as ECC is formed in the melting process.
(3) In the high pressure region, original orientation of the molecular chain does not change after the melt, then this persistence of the molecular orientation have an effect on the growth of ECC.
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