Creep deformation of amorphous polymer (polyurethanes)

Chua, Ngeah Boon (2008) Creep deformation of amorphous polymer (polyurethanes). Masters thesis, University of Malaya.

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Chua Ngeah Boon_MSC_Dissertation 2008.pdf

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Polyurethanes (PU) based on two different molecular weight, poly(tetramethylene oxide) polyol, PTMO-1000 and PTMO-2000 and three different diisoscyanates, TDI (toluene diisocyanate), IPDI (isophorone diisocyanate), HDI (hexamethylene diisocyanate) with chain extender BDO (butanediol) have been synthesised by a two-step polymerization. The effect of soft segment chain length and the effect of hard segment structures on creep behaviour of four different type polyurethanes; PU1-TDI, PU2-TDI, PU1-IPDI and PU1-HDI have been investigated. The PUs obtained were characterized by Dynamic Mechanical Analysis (DMA), Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The creep studies mainly involve variable load constant-temperature creep measurement. Outstanding creep resistance was observed at the long-term creep test at room temperature for PU1-TDI, PU2-TDI and PU1-HDI. No failure occurred for all these three PUs until the end of the creep test. The mechanical studied reveals that PU1-TDI has the highest tensile strength whereas PU1-HDI showed the highest modulus properties. The increase of molecular weight of polyol causes an observed decrease in tensile strength and elastic modulus and leads to increase in strain at maximum. From the DMA and DSC results, PU1-HDI show the lowest Tg value indicated that the degree of microphase separation of PU1-HDI is the highest which will lead to the better mechanical properties. PU1-HDI exhibits multiphase morphologies whereas the morphologies of the PU1-TDI and PU2-TDI are relatively homogenous. The XRD results indicate that crystallinity decreased from aliphatic to aromatic based diisocyanates of PUs.

Item Type: Thesis (Masters)
Subjects: Q Science > Q Science (General)
Date Deposited: 31 Jul 2013 03:14
Last Modified: 31 Jul 2013 03:14

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