No abstract

This study examines the effect of poly(butylene adipate- co-terephthalate) (PBAT) content on the physical, morphological, and mechanical properties of poly(butylene succinate) (PBS)/PBAT foam. A compression molding technique was used to prepare the PBS/PBAT foam using the chemical blowing agent azodicarbonamide and the cross-linking agent dicumyl peroxide. The chemical structure and morphological properties of PBS/PBAT foam were examined via Fourier transform infrared and scanning electron microscopy techniques, respectively, whereas tensile and flexural properties were investigated using a universal testing machine. The results reveal that the incorporation of PBAT barely enhances the viscosity of the PBS/PBAT blend, producing only minor changes in the average cell size of PBS/PBAT foam. However, increasing the PBAT content contributes to a relatively significant improvement in the flexibility and toughness of PBS/PBAT foam, where a decrease in Young’s modulus and tensile strength of the PBS/PBAT foam is observed compared with those of the PBS foam. Similar behavior to the tensile results is noticed for the flexural properties of the neat and PBS/PBAT foams.

Oxygen-plasma treated graphene nanoplatelet (OGNP), multiwalled carbon nanotube (MWCNT) and polycarbonate (PC) hybrid nanocomposites were prepared via a melting process using a twin-screw extruder. The contents of the OGNPs were in the range of 0.0 to 5.0 parts per hundred resin (phr), whilst the dosage of MWCNTs was kept at a constant of 2.0 wt%. Nanocomposites containing 2.0 wt% of MWCNTs and mixtures of 2.0 wt% of MWCNTs at 1.5 to 5.0 phr of OGNPs had tribocharged voltages, surface resistivities, and decay times, all within the electrostatic discharge (ESD) specification. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) results revealed that the OGNPs slightly intercalated and distributed also within the PC matrix. The glass transition temperatureTgand heat capacity jump, at the glass transition stages of nanocomposite, slightly changed, as the contents of the OGNPs increased. The melt flow index (MFI) of nanocomposites significantly decreased when MWCNTs were added to the PC resin and slightly changed as the dosage of OGNPs was increased. Tensile Young’s modulus of nanocomposites tended to increase, as the elongation at break and impact strength decreased, when OGNP concentrations were increased. This research work exhibited that OGNP/MWCNT/PC hybrid nanocomposites do indeed have the potential to be used in ESD applications.

To enhance a viscosity of poly(butylene succinate) (PBS), a crosslinking agent (i.e. dicumyl peroxide, DCP) or branching agent (i.e. Desmodur®N3300, N3300) was incorporated with various amount ranging from 0 to 4 phr via an internal mixer. The thermal transition, rheological properties (e.g. storage modulus, loss modulus, and complex viscosity) and gel content of the compound were determined via differential scanning calorimeter, rheometer, and gel content measurement, respectively. The results revealed that less degree of crystallinity, higher viscosity and more crosslinked structure were detected as increasing amount of DCP and N3300. Subsequently, a compression moulding technique was used to prepare PBS foam with a chemical blowing agent, i.e. azodicarbonamide (ADC). Scanning Electron Microscopy was acquired to examine cell size, cell size distribution, cell structure, and cell density. Besides, physical properties, e.g. foam density and physical appearance, were investigated. The results indicate that the degree of crystallinity, viscosity, and crosslinked structure affect the morphological and physical properties of PBS foams, i.e. greater viscosity and crosslinked structure causing obstacle for cell growth, and less degree of crystallinity allowing easier cell nucleation and cell growth.

Poly(butylene succinate) (PBS) biocomposites incorporated with rubberwood powder (RWP) were fabricated with various RWP weight fractions (i.e., 0 to 40% wt) by injection moulding process. The soil burial test was employed to examine the biodegradability of such biocomposites under outdoor environment for 60 days. The physical appearance, percentage weight loss, chemical structure, and mechanical properties before and after the soil burial test were determined. Apparent changes in physical appearance of the biocomposites from optical micrographs were detected in terms of surface morphology and colour. The percentage of crystallinity of PBS/RWP biocomposites was studied by the X-ray diffraction (XRD) technique, and the XRD pattern revealed a decrease in percentage of crystallinity due to enhancing RWP weight fractions. This may be attributed to a presence of rubberwood powders providing more disordered molecular chain arrangement of PBS matrix and also an agglomeration of the rubberwood powder content at greater concentration as seen in SEM micrographs. With increasing RWP weight fractions and burial time, the results exhibited a considerable change in chemical structure (essentially ester linkage due to biodegradation mechanism of PBS), relatively greater percentage weight loss, and a substantial decrease in flexural properties. Consequently, the results indicate that incorporating RWP enhances biodegradability of PBS/RWP biocomposites; that is, the biodegradation rate of biocomposites increases with increasing RWP weight fractions and burial time.