A HIGH SPEED STRETCHING APPARATUS FOR OPTICAL STUDIES ON POLYMER FILMS.
MASSACHUSETTS UNIV AMHERST POLYMER RESEARCH INST
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The report describes the design, calibration and operation of a pneumo-hydraulic high speed stretching apparatus in which a polymer film sample can be rapidly stretched from both ends. Provision is made for the concurrent measurement of stress and strain. The rise time of the piston velocity is approximately 4 msec. and the linear range covers 85-90 of the piston travel. At the maximum operating pressure of 1500 psi., stretching rates in excess of 4000 inmin are obtainable. The apparatus is equipped to take low angle light scattering photographs during rapid extension of the sample and subsequent relaxation. A continuous wave gas laser is used as source and a high speed motion picture camera as the detector. With appropriate polarization of the light beam the system is readily adapted to investigate birefringence changes on stretching, using a photomultiplier as the intensity detector. Instructions for operating the high speed apparatus are appended. Author