On-Demand Tailoring between Brittle and Ductile of Poly(methyl methacrylate) (PMMA) via High Temperature Stretching.

Dog-bone shaped poly(methyl methacrylate) (PMMA) samples were pre-stretched at different temperatures (within the glass transition range and slightly above) to different strains. Subsequently, these pre-stretched samples were aged at 40 °C for up to three months, and finally, all samples were uniaxially stretched to fracture. The Young's modulus, ultimate stress and toughness of the samples were obtained and plotted as a function of the temperature, and strain in pre-stretching in the contour format. The influence of aging was revealed when the contours of different aging times were compared. One of the most interesting findings was that the toughness of this PMMA can be tailored via controlling the temperature and strain in pre-stretching. The toughness of the pre-stretched samples ranged from 1.317 MJ/m 3 to 23.281 MJ/m 3 (without aging) and from 1.476 MJ/m 3 to 27.532 MJ/m 3 (after three months of aging). Based on the results of a series of additional experiments, a mechanism was proposed to reveal the fundaments behind the influence of the temperature and strain in pre-stretching and aging.