INTERACTIONS OF SOLVENTS WITH POLY(METHYL METHACRYLATE)

A slightly crosslinked sample of atactic poly(methyl methacrylate) was used to determine the solubility parameters from gravimetric sorption tests made at 40 degrees C with about 30 solvents of solubility param eter ranging from 17.2 to 47.4 MPa1/2. It was shown that solubility sp ectra of this sample and a linear homopolymer do not differ significan tly. Classical methods of unidimensional or bidimensional mapping fail ed to determine precisely and unambiguously the solubility parameters of the polymer. The best approach consisted of distinguishing between three solvent families, respectively, poorly, moderately and strongly hydrogen bonded, as proposed by Burrell. The maximum capacity of solve nt absorption varies in the order poorly > moderately > strongly hydro gen bonded solvent, which was tentatively explained by the importance of the plasticizing efficiency of the solvents. This provides an expla nation of the difference between the solubility parameter value determ ined from solvent sorption tests (19-21.5 MPa1/2) and from ultrasonic measurement of the bulk modulus (23 MPa1/2). (C) 1997 Elsevier Science Ltd.