GAS-PERMEABILITY OF CROSS-LINKED HTPB-H(12)MDI-BASED POLYURETHANE MEMBRANE

Crosslinked membranes were prepared by the addition of a crosslinking agent of benzoyl peroxide (BPO) to the hydroxyl-terminated polybutadie ne (HTPB) and 4,4'-dicyclohexylmethane diisocyanate (H(12)MDI)-based p olyurethane (PU) solutions. The stress-strain properties of segmented HTP-B based PUs were changed by the crosslinking between soft-soft seg ments. The gas permeabilities of HTPB-based PU membranes with a suitab le amount of crosslinking agent were higher than those of uncrosslinke d membranes, which is due to the stretched and extended soft-segment m olecular chains. The reproducibility of gas permeability was improved by the crosslinked membranes. Thermal stability conducted by TGA was i ncreased with increasing crosslinking agent content. FTIR was utilized to identify the segregation between hard and soft segments and struct ure change, which affects the gas-transport properties. The change of glass transition temperature was detected by DSC, which can be used to manifest the degree of crosslinking of these membranes. The results o f TGA, FTIR, and DSC measurements explain the crosslinking degree with different BPO content and, hence, the gas permeabilities as well. (C) 1995 John Wiley & Sons, Inc.