Preparation and properties of poly (lactic acid) halloysite nanotube nanocomposites
| dc.contributor.author | Tham Wei Ling | |
| dc.date.accessioned | 2021-05-04T03:19:02Z | |
| dc.date.available | 2021-05-04T03:19:02Z | |
| dc.date.issued | 2015-09-01 | |
| dc.description.abstract | In this research, halloysite nanotube (HNT) was used to improve the properties of poly(lactic acid) (PLA). The PLA/HNT nanocomposites were prepared using melt compounding followed by compression molding. Three types of impact modifiers i.e., maleic anhydride grafted styrene-ethylene/butylene-styrene copolymer (SEBS-g- MA), N,N’-ethylenebis(stearamide) (EBS), and epoxidized natural rubber (ENR), were used to toughen the PLA nanocomposites. The properties of PLA/HNT nanocomposites were characterized by mechanical tests (i.e., tensile, flexural, and impact tests), thermal analysis (i.e., differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)), morphological analysis (i.e., field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM)), and Fourier transform infrared spectroscopy (FTIR). The impact strength of PLA/HNT nanocomposites was increased significantly to approximately 300% by the addition of 15 wt% ENR. A finely dispersed HNT could eventually increase its nucleation effect and assist in the crystallization process of PLA whilst in the presence of EBS and ENR. Nevertheless, the presence of SEBS-g-MA and HNT retard the formation of large crystallites of PLA. The kinetics of water absorption of PLA/HNT nanocomposite fitted Fickian diffusion behaviour at immersion temperatures of 30oC and 40oC. For the samples exposed to 50oC, the water uptake followed Fick's law during the initial stages, but at longer time periods, deviations and weight loss were observed. This may have been due to the hydrolysis of PLA at higher immersion temperatures, which was confirmed by the pH change, reduction of molecular weight, increase in carbonyl index (CI) values, and thermal property changes. From the TGA results, it was found that single decomposition took place in the nitrogen atmosphere, while a double-stage decomposition process occurred in the oxygen atmosphere. The incorporation of EBS and ENR could improve the thermal stability of PLA/HNT under oxygen atmosphere. The PLA/HNT6/ENR5 nanocomposites exhibited high thermo-oxidative stability under oxygen atmosphere. Furthermore, the addition of 5 wt% of ENR in PLA/HNT6 nanocomposites increased the oxidation onset temperature (OOT) (from 239.5oC to 296.5oC). The PLA/HNT6/ENR5 showed the lowest oxygen permeability coefficient ( O2 P ) value of approximately 1.567x10-4 cm3.m.m-2.day-1.kPa-1. However, the incorporation of SEBS-g-MA could not improve the oxygen gas barrier properties of PLA/HNT nanocomposites. From the UV-Vis spectroscopy analysis, the incorporation of impact modifiers in PLA/HNT nanocomposites decreases light transmittance and nearly no UV light can be transmitted through thin film at 300 nm. Nevertheless, all PLA/HNT nanocomposites remain transparent from visual view. In summary, the addition of ENR in PLA/HNT nanocomposites can effectively improve the properties of polymer nanocomposites in term of impact strength, activation energy of water diffusion (Ea), OOT, and oxygen gas barrier properties among the others impact modifiers. | en_US |
| dc.identifier.uri | http://hdl.handle.net/123456789/13248 | |
| dc.language.iso | en | en_US |
| dc.title | Preparation and properties of poly (lactic acid) halloysite nanotube nanocomposites | en_US |
| dc.type | Thesis | en_US |
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