Dimensional effects in the thermal expansion of carbon fiber reinforced plastic at low temperatures

Thermal expansion behavior of carbon fiber-reinforced composite plastics (matrix: commercial carbon fiber TS36S, binder: EDT-10P) and composite plastics with a braided base was studied in the temperature range of 160–293 K using high-sensitivity capacitive dilatometry. Over the entire temperature range, the thermal expansion of the composite materials is anisotropic, with thermal expansion coefficients measured along and perpendicular to the fiber direction differing by two orders of magnitude in absolute value and showing opposite signs. The negative thermal expansion along the fiber direction is likely due to the transverse thermal vibrations of the two-dimensional carbon planes that form the fiber structure.