Crystallization Behavior of Virgin TR-55 Silicone Rubber Measured Using Dynamic Mechanical Thermal Analysis with Liquid Nitrogen Cooling

Small IV, W ; Wilson, T S

Lawrence Livermore National Laboratory

关键词: Heating;    Storage;    Geometry;    36 Materials Science;    Thermal Expansion;   

DOI  :  10.2172/975213
RP-ID  :  LLNL-TR-426277
RP-ID  :  W-7405-ENG-48
RP-ID  :  975213

美国|英语

来源: UNT Digital Library

【 摘 要 】

Dynamic mechanical thermal analysis (DMTA) of virgin TR-55 silicone rubber specimens was conducted. Two dynamic temperature sweep tests, 25 to -100 C and 25 to -70 to 0 C (ramp rate = 1 C/min), were conducted at a frequency of 6.28 rad/s (1 Hz) using a torsion rectangular test geometry. A strain of 0.1% was used, which was near the upper limit of the linear viscoelastic region of the material based on an initial dynamic strain sweep test. Storage (G{prime}) and loss (G{double_prime}) moduli, the ratio G{double_prime}/G{prime} (tan {delta}), and the coefficient of linear thermal expansion ({alpha}) were determined as a function of temperature. Crystallization occurred between -40 and -60 C, with G{prime} increasing from {approx}6 x 10{sup 6} to {approx}4 x 10{sup 8} Pa. The value of {alpha} was fairly constant before ({approx}4 x 10{sup -4} mm/mm- C) and after ({approx}3 x 10{sup -4} mm/mm- C) the transition, and peaked during the transition ({approx}3 x 10{sup -3} mm/mm- C). Melting occurred around -30 C upon heating.