Abstract
The conditions have been studied for propagation of single discontinuities (cracks and crazes) in poly(methyl methacrylate) under the combined influence of stress and solvents. A series of aliphatic alcohols, water-alcohol mixtures and carbon tetrachloride were employed and temperature effects were investigated over the range 273K to 323K. Using a fracture mechanics approach, the minimum surface work J 0 required to propagate the discontinuity was estimated as a function of temperature for each solvent. J 0 varies with temperature in a consistent manner, decreasing rapidly as the temperature rises up to a characteristic temperature T c and then remaining constant at some value J ∗ 0 for T > T c . The value of J ∗ 0 is a smooth function of the difference ( δ s − δ p ) between the solubility parameters of the solvent and the polymer, both for pure solvents and water mixtures, reaching a minimum at ( δ s − δ p ) = 0. The critical temperature for pure solvents (but not solvent-water mixtures) decreases with increasing ( δ s − δ p ), probably extrapolating to T g for the plastic at ( δ s − δ p ) = 0. The behaviour of J 0 can be explained in terms of a cavitation criterion for craze formation and the necessary theory is developed. It attributes the temperature-independent value of J ∗ 0 to a polymer/solvent interfacial energy effect, and the variation of J 0 at T < T c to a yield stress effect.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
