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Conducting thermal analysis of fibers in the swollen state possesses certain characteristics and advantages. The thermograms including both TMA and DSC of 12 acrylic fiber samples of different composition and mode of formation are given in this part of the paper. The lowering of the transition temperature as a depression of the melting points according to the theory of Flory is tested. The DSC thermograms of a commercial acrylic fiber sample are separated into its constituent peaks and the bond energy of the four regions is calculated. Finally the relation of the magnitudes of the different peak of a PACAbbreviation of polyacrylonitrile copolymer.) fiber sample is sought and the effects of annealing and hot stretching of acrylic fibers on its texture are demonstrated.

The construction of an improved model of TMA for fibers is briefly described. Two special features are: use of an electronic balance for measuring force and use of a precision screw driven by a servo-step motor for measuring length. Besides the usual thermomechanical measurements, the use of the instrument as a research tool for a number of purposes like fiber texture, orientation, heat treatment, and so on has been amply illustrated.