No abstract

This research attempted to prepare composite foams of PLA/bagasse fiber with various fiber content at 0, 5, 10, 15, 20 wt% and a fixed foaming agent with extra added 2 wt% for all composites. The mechanical properties and morphology of neat PLA and PLA/bagasse fiber composite foams were investigated. The tensile strength showed that the highest fiber content of 7 wt% was 45.27 MPa, while neat PLA was 25.63 MPa. Impact strength showed a decreasing trend with increasing fiber content. SEM analysis was important to reveal the phase of fiber and matrix for support to discuss the results trend of PLA and composite properties.

Composite foams from PLA, natural rubber and modified coconut fibers was prepared employing a compression molding method, which is suitable for the fabrication of composites containing high fiber content. The results revealed that the incorporation of natural rubber into composite foams increases the compressive stress to 101.17 kN/m2. Further, a 10% wt increase of modified coconut fiber added into composite foams resulted in an increase of compressive stress to 105.24 kN/m2. The addition of modified coconut fibers in composite foams showed a slight decrease of the crystallization state, obtained by DSC results by about 1-3 oC. Thus, modified coconut fibers played a role as a nucleating agent. Moreover, the combination of modified coconut fibers in composite foams could lead to improved adhesion between the surface area of PLA matrix and the natural rubber phase.

A blend of natural rubber (NR) and styrene butadiene rubber (SBR) was tested against conventional rubber products sold in department stores and markets, using nuclear magnetic resonance (NMR) spectroscopy to measure the amount of natural or synthetic rubber in the product. 1H-NMR spectroscopy was employed for the rubber blend and 13C-NMR spectroscopy for conventional products. The chemical shift of all the samples from the structure of natural rubber (cis-1,4 polyisoprene) was observed.

The investigation focused on the properties of composite foam obtained by a compression molding method. The results could clarify the interaction among PLA, silica nanoparticles and coconut fiber. The compressive properties, including the compressive force and modulus of composites, contained in coconut fiber were improved. The incorporation of silica nanoparticles was able to modify the compressive properties slightly, whereas the thermal properties were decreased explicitly. Hydrogen bonding between the carboxylic group of PLA and the silica bonded group affected the increment in mechanical properties of composites. However, the incorporation of coconut fibers in composites exhibited a rougher surface. In addition, beneficial distribution of silica nanoparticles and porosity in the nanocomposite foam, equivalent to neat PLA foam, could be obtained.