Recently, there has been an increasing interest in the development of 3-Dimensional (3D) printing technologies. Among those, material development play an important role in helping the growth of 3D printing technique, which led to more supporting of wide range of applications and user requirements. In that regards, advanced materials are continually developed, i.e. filament filled reinforcing fiber and plastic containing metal granulate or wood powder. Special material supporting 3D printer normally showed an expensive cost. On the other hand, it is well known that the processes involving natural rubber from Para rubber trees produced a large amount of wood a year, which resulted in releasing of an abundant waste from wood processing. Therefore, this work focused on the utilization of parawood powder derived from the furniture industry. The processability of polylactic acid (PLA) filament containing wood powder was investigated. Twin and single-screw extrusion machines were used to produce the composite filaments. Coupling agent and treated method were also studied. The results of this work showed that the maleic anhydride (MAH) and sodium hydroxide (NaOH) did not have significantly effects in improving the compatibility and processability. In addition, wood contents were found to influence the quality of filament and mechanical properties. Moreover, it was also found that parawood powder can be filled into PLA with approximately 10 wt%.

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The presence of weldlines in rubber products is regarded as a one of the most undesirable phenomena, since it results in poor mechanical properties. Compression molding of large or complicated products are prepared by multiple charges, which produces weldlines once the melt fronts are joined by the impingement flow. In this work, the effects of curing systems, processing parameters, filler types, and contents on weldline strength of compression molded natural rubber (NR) were investigated. Furthermore, the effects of curing systems on the aging properties of NR vulcanizates were studied in details. The results show that an increased amount of calcium carbonate does not affect the weldline strength. However, the difference in tensile strength between weldline and nonweldline specimens becomes larger with the high loading of silica and carbon black. In addition, for the factors selected in the experiments, clamping pressure, and curing system were found to be the principal factors affecting the weldline property of vulcanizates. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

Additive manufacturing namely 3-Dimensional (3D) printing and it’s feeding materials are increasingly used for producing customized products. Fused Deposition Modelling (FDM) in conventional 3D printers is a cost-effective solution. This is due to the low cost of the machine and various size selections. Although the machine cost is reasonable, the filament material is a higher cost. In general, the current filament is priced about 4 times more than granulated plastic. Moreover, the special filament containing wood powder shows a high cost of approximately 20 times that of pellets. This work proposes a comparative study of the components obtained from different processes. Compression molding and no-mold techniques were used. A previous design, nozzle from extrusion concept, was also used for fabricating the specimens. PLA and wood-based PLA were carried out to produce the testing samples. The results showed that parts obtained from the compressive mold showed low tensile strength. It was indicated that the residue voids were significantly affected by its strength. Taking into account the 3D printed parts, the articles from the designed extruder present a higher strength than the results derived from the conventional 3D printer and compression machine. On the other side, it was found that the moving direction of the nozzle (raster angle) affected directly the maximum tensile strength. Furthermore, the neat PLA had higher stress than the wood-composite materials used for all fabrication methods. However, in the case of using an extrusion device, it represented the enhancing of mechanical strength, which was caused by the homogeneous texture of polymers melting in a hot barrel. In terms of fabrication cost, the molding technique showed the highest cost even though the feeding material has the lowest cost. A similar cost was found for providing parts from the conventional printer and our design nozzle. However, a pellet-based extruder would be printed the sample filled 15%wt, conventional but the 3D printer is unavailable. Furthermore, recycled materials or waste of 3D printed parts can be utilized by using a conceptual extruder.

This work aimed to make use of a rate-controlled capillary rheometer for investigating the effects of vulcanizing system using various fillers on the apparent viscosity and extrudate swelling of natural rubber (NR) compounds. The results suggested that the rubber compounds exhibited a pseudoplastic non-Newtonian behavior. At any given shear rates, the viscosities of rubber compound utilizing conventional (CV) and efficient vulcanizing (EV) systems were lower than that of non-sulfur (NS) system. This was due to the occurrence of premature crosslinking at the skin layer and subsequently led to the wall slip of rubber compound during the flow in capillary die. The irregular surface and the onset of smooth surface of rubber extrudate were evidently seen, especially for CV and EV systems. This could be associated with the amount of required energy to obtain the steady state flow in the die. The results also suggested that the swelling ratio of rubber extrudate ranged from 1.2 to 2.2 and the effect of filler type was more pronounced at high shear rates above 400 s-1. In the case of silica filler (SiO 2) system, the severe irregularity of rubber extrudate was observed. The lower shear rate employed to obtain the smooth surface for rubber extrudate containing 30 phr of SiO 2 was possibly caused by high amount of PEG acting as an external lubricant which promoted the uniform slippage during the flow in capillary die.