DURABILITY OF IN-PLANT RECYCLED GLASS-FIBER-REINFORCED POLYAMIDE-66

A study of the effect of in-plant recycling on the durability of glass fiber reinforced polyamide 66 is reported. Injection-molded test bars were exposed to thermal aging, coolant aging, and creep testing. It w as shown that thermal aging and coolant aging induced similar effects. The onset of embrittlement was revealed by both a reduction in elonga tion at break and loss of impact resistance. Samples based on 100% in- plant regrind exhibited a more intense embrittlement compared to virgi n samples during both thermal and coolant aging. For samples based on 25% recycled material, the deterioration rate was similar to that of v irgin samples during thermal aging but slightly faster during coolant aging. Creep experiments indicated that in-plant recycled materials ca n display reduced dimensional stability, which may be explained by a r educed degree of reinforcement due to fiber breakage during the recycl ing operation. Knock-down (KD) factors were defined and determined for the in-plant recycled samples. For creep resistance, tensile strength and modulus, the KD factors were strongly affected by fiber length. T he highest ICD factor, as determined for samples based on 25% and 100% recycled material, was 8% and 16% respectively.