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Methanol‐Induced crack healing in poly(methyl methacrylate)
Author(s) -
Lin C. B.,
Lee Sanboh,
Liu K. S.
Publication year - 1990
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760302109
Subject(s) - materials science , composite material , fractography , ultimate tensile strength , fracture (geology) , wetting , methyl methacrylate , methacrylate , crack closure , bone healing , fracture mechanics , glass transition , polymer , polymerization , surgery , medicine
Crack healing in poly(methyl methacrylate) (PMMA) by methanol treatment at 40°C–60°C has been investigated. It is found that the methanol treatment reduces the glass transition temperature in PMMA. Crack healing only occurs at an operating temperature higher than the effective glass transition temperature. There are two distinctive stages for crack healing based on the recovery of mechanical strength. The first stage corresponds to the progressive healing due to wetting, which has a constant crack closure rate at a given temperature. Immediately following the first stage, the second stage corresponding to diffusion enhances the quality of healing behavior. The surface morphologies obtained during healing and after fracture tests confirm these two stages. By comparing the fracture stress with the fractography, the fracture surface for stage I of crack healing is coplanar to the original crack surface. On the other hand, the original crack surface is destroyed in stage II of crack healing. It occurs in the region incorporating the original healed surface and appears to be like the Virgin fracture surface. It is also found that the tensile fracture stress of PMMA treated by methanol can recover to that of the virgin material. In addition, it is interesting to find that after sustained methanol treatment, the “snake bone” phenomenon on the fracture surface emerges.