AbstractThis research work deals with the manufacture, properties and characterisation of layered silicate (LS) reinforced novel spent polymer nanocomposites. Three different materials used for nanocomposites preparation were polyamide 12 (PA-12), DuraForm polyamide 11 (EX) and Glass Filled polyamide 12 (GF-12).
Various concentrations (1, 3, 5 and 7 wt. %) of the layered silicates were dispersed in three different types of spent polyamide matrix by the melt compounding method, in order to investigate the effect of LS reinforcement on mechanical and thermal properties of spent polymer. The interlayer d-spacing, interlamellar structure and surface morphologies were investigated by wide angle x-ray diffraction (WXRD), transmission electron microscope (TEM) and scanning electron microscope (SEM), respectively.
The tensile strength and modulus of the un-reinforced spent PA-12 samples were found to increase with the incorporation of LS. This improvement in the tensile strength and modulus appear to be directly related to the LS loading. Similarly, the flexural strength and modulus were found to increase significantly with incorporation of the LS reinforcement.
Nanoindentation test results were used to evaluate the nanomechanical properties (i.e. hardness and modulus) of spent PA-12/nanocomposites. The results show that the hardness and modulus of LS reinforced spent PA-12 nanocomposites were higher compared to the un-reinforced spent PA-12 sample.
Crystallisation temperature measured using DSC showed a gradual decrease as the LS loading increased. For spent PA-12 nanocomposites samples the melting temperature slightly increased with 1 and 3 wt. % of LS loading when compared with the un-reinforced spent PA-12 sample. However, samples with 5 and 7 wt. % of LS have approximately the same melting temperature of the un-reinforced spent PA-12 sample. Glass transition temperature (Tg) of the spent PA-12 nanocomposites slightly decreased in comparison to the un-reinforced spent PA-12 sample.
It was found that the incorporation of LS does not affect or improve the tensile strength and modulus of the spent EX nanocomposites. However, flexural strength and modulus for the spent EX nanocomposites are improved when compared with the un-reinforced spent EX sample. The nanoindentation results show that as the LS concentration increased up to 3 wt.%, the hardness and modulus were improved. Different levels of layered silicates dispersion as characterised by XRD, TEM and SEM correlated strongly with improvements in mechanical and thermal performances.
The crystallisation temperature of spent EX and GF-12 nanocomposites samples shows gradual increases with increasing LS loading. The measured crystallisation temperature was approximately 6˚C higher for the spent EX nanocomposites samples than for the un-reinforced spent EX sample. Secondary heating of the un-reinforced spent EX sample and the nanocomposites samples resulted in an increase in melting temperature which corresponded to increasing LS loading. However, the melting temperature for all the spent GF-12 nanocomposites samples was similar to the one for the un-reinforced spent GF-12 sample. It was found that Tg values decreased with increased in LS loading for spent GF-12 samples. The presence of layered silicate did not contribute in improving tensile and flexural strength of spent GF-12 matrix. However, the hardness and elastic modulus were found to increase with increased layered silicates loading up to 7 wt.%.
|Date of Award||2011|
|Supervisor||Hom Dhakal (Supervisor), Zhong Yi Zhang (Supervisor), Nick Bennett (Supervisor) & Zhong Yi Zhang (Supervisor)|