Dependence of the glass transition temperature of poly(methyl methacrylate) on tacticity and molecular weight

Abstract

The preparation of five samples of poly(methyl methacrylate) covering a wide range of tacticity and their electron irradiation to produce series of varying molecular weight are described. The glass transition temperature Tg of each polymer was determined by DTA techniques. Plots of Tg and the reciprocal of the molecular weight are well fitted in every case by a straight line. The data are also fitted to the Gibbs‐DiMarzio theory and the values of the energy and free‐volume parameters obtained are discussed. A method of estimating Tg of pure syndiotactic poly(methyl methacrylate) by extrapolation is presented, the value obtained being 160°C.

Synthetic Uniform Polymers and Their Use for Understanding Fundamental Problems in Polymer Chemistry

“…The reported [85] K value of highly isotactic PMMA (1.06 Â 10 5 ) is also more than twice as large as the present result (Equation (1)). One possible reason for the overestimation is that the authors [85,89] determined (M n of their PMMA samples on the basis of the intrinsic viscosity; the Mark-Houwink equation may not be useful for the correct measurement of M n . The data plotted in Figure 10 are exactly correct values in terms of the values of M n since all the samples except two are uniform polymers.…”

“…[85] The T g1 in Equation (3) agrees approximately with that determined for an st-PMMA of similar tacticity (128 8C). [88] Moreover, the T g data of the nonuniform it-and st-PMMAs having an M n larger than 5 Â 10 4 fit the linear relationship defined by Equation 2 and 3 (see Figure 10).…”

“…DSC curves recorded at a heating rate of 10 8C min À1 of uniform and nonuniform stereoregular PMMAs: [83] Synthetic Uniform Polymers and Their Use for Understanding Fundamental Problems in Polymer Chemistry and White obtained K ¼ 2.1 Â 10 5 for at-PMMA prepared by radical polymerization, [89] and Thompson found K ¼ 2.95 Â 10 5 for similar PMMA samples (rr ¼ 64%). [85] These K values are larger than that found for highly syndiotactic PMMA (Equation (3)). The reported [85] K value of highly isotactic PMMA (1.06 Â 10 5 ) is also more than twice as large as the present result (Equation (1)).…”

“…[85] These K values are larger than that found for highly syndiotactic PMMA (Equation (3)). The reported [85] K value of highly isotactic PMMA (1.06 Â 10 5 ) is also more than twice as large as the present result (Equation (1)). One possible reason for the overestimation is that the authors [85,89] determined (M n of their PMMA samples on the basis of the intrinsic viscosity; the Mark-Houwink equation may not be useful for the correct measurement of M n .…”

Structural Reasons for Restricted Backbone Motion in Poly(n‐alkyl methacrylates): Degree of Polymerization, Tacticity and Side‐Chain Length

“…65 K found for PEMA here was observed when comparing i-and a-PMMA (rr % 0.80). [42] Structural Reasons for the Isotropization III:…”