IMPROVED CONSTRUCTION MATERIALS FOR POLAR REGIONS USING MICROCELLULAR THERMOPLASTIC FOAMS

THERMOPLASTICS ARE NOT WIDELY USED IN POLAR REGIONS BECAUSE THEY EMBRITTLE AND MAY LOSE 70 PERCENT OF THEIR FRACTURE TOUGHNESS AT LOW TEMPERATURES. RESEARCHERS HAVE IDENTIFIED A PROMISING MICROCELLULAR FOAM (MCF) STRUCTURE WHICH MAY SIGNIFICANTLY IMPROVE LOW TEMPERATURE THERMOPLASTIC PERFORMANCE. MCF FOAM STRUCTURE IS CREATED BY INDUCED THERMODYNAMIC INSTABILITY IN PLASTICS SUPERSATURATED WITH INERT GAS (NON-CFC). THE RESULTING CELL STRUCTURE INCORPORATES 10(9) TO 10(15) VOID PER CM(3), AT A SIZE OF 0.3 TO 20 MICRONS. MCF THERMOPLASTICS SHOW BETTER FRACTURE TOUGHNESS, IMPACT STRENGTH, AND FATIGUE IN TESTS AT ROOM TEMPERATURE. MORPHOLOGY AND PHYSICAL PROPERTIES ARE BEING QUANTIFIED FOR SEVERAL POLYMERS UNDER VARYING PROCESS PARAMETERS, INCLUDING SUPERSATURATION, NUCLEATION, SKIN THICKNESS, AND CELL SIZE. PROPERTY IMPROVEMENTS ARE BEING EVALUATED UNDER FREEZE/THAW CYCLING. FRACTURE TOUGHNESS IS CHARACTERIZED BY TENSILE AND IMPACT TESTING. MCF THERMOPLASTICS CAN REPLACE METALS AND COMPOSITES IN POLAR REGION CONSTRUCTION WHERE LOW-COST LIGHTWEIGHT, RIGID, STRUCTURAL MATERIALS ARE REQUIRED.