AbstractTransitions in polymers have been studied with the use of a differential expansion apparatus modified from a design described by K. L. Floyd. Materials ranging from uncured, soft rubbers to hard, waxy solids have been studied from above room temperature down to liquid air temperatures. Both the first‐order transition temperature,Tmand the second‐order transition temperature,Tg, can be identified. Multiple changes in slope of the expansion curves indicate the possibility of additional second‐order transitions. Expansion curves for several diene rubbers are presented, illustrating typical transition phenomena. Expansion curves for several polyolefin materials are presented which illustrate changes inTgand in the low temperature expansion coefficient with changes in the structure of the po
展开▼
