Deterioration of plasticized PVC components in Apollo spacesuits

Spacesuits from the Apollo era are unique in their history, materials and construction. This project involved the first detailed examination of the condition of the spacesuits since their acquisition by the National Air and Space Museum in the 1970s. Plasticized polyvinyl chloride (PVC) tubing in the Life Support System, used to transport air and water to the astronaut, and in the Liquid Cooling Garment, used to cool the wearer of the spacesuit, exhibited high levels of deterioration. Tubing was unacceptably discoloured, tacky to the touch and surfaces were obscured by crystals. Visual examination, Fourier Transform infrared spectroscopy and Low-Vacuum scanning electron microscopy suggested that discolouration was a result of dehydrochlorination of the PVC polymer, tackiness was caused by migration of di (2-ethylhexyl) phthalate (DEHP) plasticizer to surfaces, and phthalic acid crystals formed either by hydrolysis of the ester groups of DEHP or by oxygen attack on alkyl groups.