Thermal expansion adjustable polymer matrix composites with giant negative thermal expansion filler

Polymer matrix composites filled with giant negative thermal expansion (NTE) materials were formed by injection moulding. Antiperovskite manganese nitrides, thermal expansion compensating filler of the composites, exhibit NTE greater than −30 ppm K−1 in α (coefficient of linear thermal expansion). This gigantic NTE, several to ten times as large as that of conventional NTE materials, can compensate large thermal expansion of polyamide-imide polymer and thermal expansion of the composites is adjustable in a wide range of α value from positive to even negative. Quantitative analyses reveal that thermal expansion of the composites is less than the estimate based on the volume-weighted sum, which is ascribed to much larger elastic modulus of the nitride filler.