Poly(vinyl alcohol) hydrogels: Reinforcement of radiation‐crosslinked networks by crystallization

Wiley - Tập 14 Số 2 - Trang 441-457 - 1976
Nikolaos A. Peppas1, Edward W. Merrill1
1Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139

Tóm tắt

AbstractAqueous poly(vinyl alcohol) solutions were crosslinked via electron‐beam irradiation to form transparent hydrogels of varying crosslinking densities. Typical crosslinked hydrogels with Mc between 3500 and 8000 were weak, easily shattered, nonextensible materials with very low tensile moduli (up to 70 psi) and tensile strengths at break (less than 10 psi). Reinforcement by induction of partial crystallization was accomplished by a two‐stage drying process, consisting of a slow dehydration stage at room temperature and an annealing stage at elevated temperatures, which was mainly responsible for the introduction of the crystallites. The swollen hydrogels after the annealing process had crystallinities widely varying between 30 and 65% and polymer volume fractions between 30 and 60%, depending on the temperature‐time history of the specimen. These materials showed greatly improved mechanical properties (modulus, ultimate tensile strength, tear strength), as compared to the uncrystallized hydrogels.

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Tài liệu tham khảo

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Thông tin
Thông tin xuất bản

Wiley

Tập 14 Số 2

441-457

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