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Abstract

Thermomechanical and shape memory behavior on thermo plastic segmented polyurethane (SPU) copolymers based on polytetramethylene glycol (number average molecular weight, M_n = 2900 g mol ₁), 1,4-butane diol, 4,4′-diphenylmethane diisocyanate (MDI), and with/without polyethylene glycol (PEG) (number average molecular weight, M_n = 3400 g mol_-1) were studied. SPU with 5 wt% of PEG 3400 showed the highest tensile storage modulus at all temperatures due to the increased interaction between the polymer chains. On the other hand, SPU containing 15 wt% of PEG has a broad loss modulus (E″) due to increasing chain flexibility. The recovery process in shape memory behavior has been noticed to be the orientation of disoriented chains due to the thermodynamic entropy effect. Experimental studies revealed that the shape recovery properties are improved by increasing the percent crystallinity and/or physical cross-linking between the polymer chains. However, all SPU samples show excellent shape fixity.

Keywords

segmented polyurethane shape recovery thermomechanical property,crystallinity

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Studies of Shape Memory Property on Thermoplastic Segmented Polyurethanes: Influence of PEG 3400

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