Dynamic thermomechanical investigation of polymeric systems supported on inert substrates

The use of inert supports for the study of mechanically weak polymer systems is becoming more widespread, particularly since Gillham established its acceptability in the torsional braid technique. A description and review of work using glass braid, glass filter mat and cellulose mat supports is presented. This consists of coverage of the dynamic mechanical response of a series of mono and di‐alkyl esters of polyitaconic acid ranging in ester chain length from C 1 to C 18 . The major features, e.g., glass and sub‐glass transitions, are identified and evidence of a double glass transition was found, when the ester chain length exceeds C 6 . The relaxations of ring systems in the glass phase are also examined. Controversy over the precise value of T g for amorphous polyethylene has continued for some time and our attempt to resolve the problem has centered on a study of hydrogenated polybutadienes. The data obtained support the proposition that the polyethylene T g is about 195K and that its γ‐relaxation, suggested by some workers to be the T g , arises from crankshaft motion involving methylene sequences of 6 to 10 units. Other topics discussed include the damping characteristics of low molecular weight polymers such as poly(dimethylsiloxane), polystyrene, and poly(propylene oxide) with special reference to the existence of T n transitions.