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The thermal expansion of reinforced nylon‐6 composites through the matrix glass transition temperature
Author(s) -
Segal Leon
Publication year - 1979
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760190508
Subject(s) - materials science , composite material , thermal expansion , glass transition , glass fiber , composite number , nylon 6 , fiber , volume fraction , reinforcement , modulus , nylon 66 , polymer , polyamide
Abstract The coefficient of thermal expansion (CTE) of nylon‐6 reinforced with particulate filler, short glass fibers, and long‐to‐continuous glass fibers was measured between −30 and 170°C. As the reinforcement level, the reinforcement aspect ratio, or degree of orientation increases, the linear CTE decreases. The T g range for the composite system is equal to the T g for the pure nylon‐6 matrix. An unexpected result is observed when the nylon‐6 is reinforced with long or continuous glass fibers in random planar orientation and the weight fraction of reinforcement exceeds 10 percent. In this case, the longitudinal linear CTE (parallel to the plane of the fibers) above the T g is lower than the longitudinal linear CTE below the T g . Analysis of the mathematical descriptions of composite thermal behavior indicates that an extremely low composite modulus in the transverse direction above the T g may be a cause for this low CTE. The differences in CTE between short fiber and long fiber reinforced compositions indicate that the critical fiber length for thermal stress transfer may be higher than the critical fiber length for mechanical stress transfer.