Physical properties of vinyl polymers. Part 2.—The glass-transition temperature of block and random acrylonitrile + methyl methacrylate copolymers

Abstract

The glass-transition temperature of methyl methacrylate and acrylonitrile block and random copolymers is shown to be sensitive to the structural arrangement in the copolymer. Block copolymers have glass temperatures which are intermediate between those of polyacrylonitrile and polymethylmethacrylate whereas the random copolymers have glass temperatures which fall below that of either homopolymer. Results show that the acrylonitrile block, to a large extent, governs the properties of the block copolymer.

Physical Constants of Linear Homopolymers

“…For large x (17) Substituting Equations (15) and (17) in Equation (14) and rearranging, we obtain (18) The experimental melting points of a series of mixtures can be plotted as (l/Ts -1/Tm)/01 against °1, whence the intercept equals RVu/Li Hu VI and the slope equals this quantity multiplied by x. Heats of fuSion determined in this manner are generally consistent with the calorimetric values and both are listed in the table.…”

The effect of surfactant and copolymer polarity on the film‐formation temperatures of some vinylidene chloride copolymers

“…The glass transition temperatures of copolymers of vinylidene chloridemethyl acrylate and vinylidene chloride-ethyl acrylate, which form clear, transparent films, were measured by the refractive-index method described by Beevers et al 13 The copolymers were precipitated from the emulsion by adding solid COz and purified by repeated precipitation from tetrahydrofuran by the addition of methanol. Films were cast on glass from tetrahydrofuran solution and dried at 100°C.…”

X‐ray scattering by acrylonitrile + styrene copolymers

“…Observation of t h e x-ray scattering by acrylonitrile + methylmethacrylate (AN + MMA) block and random copolymers h a s been of value in confirming differences in the glass-transition behavior of t h e s e copolymers a s arising from structural differences (1). Glass-transition measurements (2) on acrylonitrile + styrene (AN + s) copolymers have shown a very different behavior to the AN + MMA and MMA + S random copolymers previously examined (3,4). In particular, over the composition range 80 to 100% AN two types of behavior were observed, one case showing a very sharp minimum at 89% AN.…”