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Abstract-
Plastic nowadays has been a common need in day to day life. From using a toothbrush to installing pipelines plastic has a vital role to play. One side it is a boon to the mankind but when the coin is turned it is causing a serious hazard to the living beings. It was observed that the strength and hardness of the polymeric materials have been increased with the addition of wood powder available as a carpentry waste. Specimens were prepared with different plastics like LDPE, HDPE, PVC etc, and waste wood. Different compositions were tried as to know the amount of wood can be combined with plastic. Composite with PVC couldn’t be produced as it started to burn upon heating. Compression and tensile tests were carried out using Universal Testing Machinefor the prepared specimens and results were compared. The microstructure of the surface of the specimen were studied using Scanning Electron Microscopy. Hence, composite materials made from waste wood powder and waste plastic would result in better utilization of solid waste.
Keywords- LDPE, HDPE, Compression and Tensile Testing
I. INTRODUCTION
Plastic pollution is a major global phenomenon that has crept up on us over decades and it really requires a global and comprehensive solution that includes systematic rethink about usage and production. About 300 million tons of plastic is produced globally each year, only about 10 % of that is recycled. Of the plastic that is thrashed and estimated, several million tons end up in the sea each year. So production of wood plastic composite can be a better solution to recycling of plastic.Wood plastic composite, known as green composite, combines natural wood fibers and plastic and thus acquires the plastic of both. Composites containing recycled plastics and wood fiber offer an interesting combination of properties, as well as lower cost than competitive materials, especially those based on synthetic fibers.Plastic products used for packaging are often discarded after a single use resulting in an inexhaustible supply of waste polymeric materials. The stiffness and strength of polymeric materials have been known to improve with addition of lignocellulosic fibres available in abundance in nature. Hence, composite materials containing natural fibres and waste plastics would result in the reduction of solid wastes and the use of cheap, renewable resources (Jayaram et al., 2004) .Composite specimens, consisting of waste plastics and wood fibres have been produced. The effects of fibre content, matrix type and interfacial bonding on the tensile and flexural properties of these composite materials have been determined through extensive testing at various conditions. The mechanical properties of these composites at room temperature and humidity depend on the amount of wood fibres, the mechanical properties of waste plastics used.
Jayaraman et al. (2004)[I] experimentally prepared the composite specimens consisting of waste plastics obtained from a Kerbside collection (high density polyethylene (HDPE) waste, Janitorial waste, Kerbside waste I and Kerbside waste II) and Pinus radiata wood fibers (medium density fibers (MDF)), through melt blending and injection moulding. The effects of fiber content, matrix type and interfacial bonding on the tensile and flexural properties of these composite materials were determined through extensive testing at various conditions. It was observed that tensile strengths of MDF/waste plastic composites do not generally change with fiber content except for 40% MDF/HDPE waste and 40% MDF/Kerbside waste II (plus1%EpoleneTM) composites where the tensile strengths increase by about 25% compared to those of the corresponding waste plastics. Flexural strengths of MDF/waste plastic composites increased with the addition of medium density fibers with the exception of MDF/Kerbside waste I composites. The tensile and flexural moduli of MDF/waste plastic composites mostly increased with increasing fiber content. From the experiments it was incurred that plastics from the post-consumer waste stream can be successfully utilized to make composite materials with useful mechanical properties.
Higher fiber content generally improves the mechanical properties of all the waste plastics composites reinforced by medium density fibers. Results showed that mechanical properties of MDF/HDPE wastecomposites are generally the greatest, closely followed by MDF/Janitorial waste composites and MDF/Kerbside waste I composites. In most cases MDF/Kerbside waste I composites have inferior mechanical properties of all the MDF/waste plastic composites tested along with a substantial amount of voids and unmelted inclusions. The properties of 40% MDF/Kerbside waste II composites are only slightly lower than those of the MDF/HDPE waste composites due to the addition of 1% Epolene which may have improved interfacial bonding. The MDF/Kerbside waste II composites also have the advantage of lower cost because the waste plastics used would require the least amount sorting after collection.
. In a study,Wechsler et al. (2007) [II] determined some of the important properties of experimentally manufactured wood-plastic composites. Specimen having 60% and 80% particle and fiber of radiate pine were mixed with polypropylene and four different additives, namely Structor TE 016 which is coupling agent, CIBA blue pigment (Irgalite), and their combinations. Based on the initial finding of this work static bending properties of the samples enhanced as above chemicals were added into both particle and fiber-based specimens. Thickness swelling of the samples were also improved with having additives in the panels. Micrographs taken on scanning electron microscope (SEM) revealed that coupling agent and pigment resulted in more homogeneous mixture of wood and plastic together. In the light of the preliminary results of this study both physical and chemical properties of the samples were improved with addition of four types of chemicals into the panels. It seems that using less than 1.2% anti-microbial agent as fungicide would yield better properties of the samples.
Wood-plastic composites undergo cyclic dimensional changes due to periodic absorption and desorption of moisture, and the resulting loss of mechanical integrity can be ameliorated using a coupling agent. Injection-molded, polypropylene (PP)-based wood-plastic composites was examined and investigated why the rate of moisture absorption can be reduced by changing extruder operating extruder operating conditions. At a given wood content, the mechanical properties were found to be similar, but the use of high screw rotating speeds, whether in the co-rotation or counter-rotation modes, and long residues of times gave lower rates of moisture absorption even in the absence of a coupling agent.
As the results were incurred it was observed that reduction in moisture absorption rate ranges from 10% to 40% and this happens without a change in the mechanical properties of the WPC. It is found that density of the WPCs is decreased under severe compounding conditions. It is speculated that moisture absorption rate decreases when severe compounding conditions are employed because these because the loss of hydrophilic volatile organic compounds contained in the WPCs. (Shu-Kai Yeh et al. (2008)) [III].
. The feasibility of using recycled plastic and wood particles from chromated copper arsenate (CCA)-treated wood removed from service was investigated in this study. CCA pressure-treated red pine lumber removed from service after 21 years utilization was Wiley milled to wood flour and blended with virgin or recycled high-density polyethylene at 50:50 wood flour-to-plastic weight ratios. The blended materials were compression molded into panels and the physical and mechanical properties characterized. Samples containing particles from recycled CCA-treated pine exhibited flexural bending properties higher than those made with either particles from virgin pine or recycled urea formaldehyde bonded particleboard. The higher modulus of elasticity and modulus of rupture from CCA-treated material were attributed to the increased thermal coefficient of the solid deposits rich in copper chromium and arsenic present in the cell wall of the recycled CCA-treated wood. The biological durability and the photo-protection properties were improved for samples containing recycled CCA-treated wood. (Kamdem et al. (2004)) [IV].
Composites containing recycled plastics and wood fiber offer an interesting combination of properties, as well as lower cost than competitive materials, especially those based on synthetic fibers. By permitting use of moderately contaminated recycled plastics rather than requiring the use of virgin resin, these materials provide an additional market for recycled plastics, thereby helping to reduce waste disposal burdens. Composites can also be fabricated using recycled wood fiber, such as recovered paper fiber, providing an additional market outlet for recovered paper and thus further waste diversion benefits. Wood fiber/polyolefin composites are often unable to take full advantage of the potential of the fiber reinforcement, due to poor adhesion between the polymer matrix and the fiber. Use of additives to improve adhesion between the fibers and matrix can significantly improve performance. (Susan et al. (2004)) [V]
Tieqi Li et al. (2007)[VI] studied the structure and mechanical properties of wood flour composites with HDPE/ionomer blends as matrices at a fixed wood loading of 60% by weight. It was found that toughness and strength properties of the composites can be improved significantly by adding ionomers of different types and contents. It was observed that there was enhancement in the interfacial interaction through short creep analysis. The interfacial interaction and the structure of the matrix phase were characterized through the melting behavior using differential scanning calorimetry (DSC) and with small strain oscillatory tests on the melts using a Dynamic Mechanical Analyzer. Both the sodium and zinc ionomers were found to be immiscible with the HDPE in matrix. The immiscible characteristics was correlated with the interfacial load transfer efficiency was revealed by creep tests.
When the results were obtained it was observed that the sodium ionomers result in decrease in Modulus of Elasticity (MOE) but an increase in booth strain at break and ‘izod impact strength. The more rigid zinc ionomers at low contents are less effective in toughening the HDPE/wood composites but are proved to be useful in achieving significantly higher Modulus of rupture (MOR). Upon characterization of the composite using creep DSC and DMA experiments, it was shown that the ionomers modified the wood-polymer interface and formed immiscible matrix morphology.
Rocha. N et al. (2009) [VII] described an approach to study of the influence of the nature and the composition on the performance of wood flour/PVC composites. The raw materials were mixed on a two-roll mill. The final composites were obtained by controlled press moulding. The results indicate that properties such as surface tension and flexibility do not change significantly with the composition in the chosen range. A thermal and morphological study has been performed on the raw materials and on the composites to assess the effect of wood flour into PVC leads to poorer tensile properties. It was observed that how color of the composite was controlled by the type and amount of the wood flour. The wood four content of the composites has little influence on the composite properties such as wettability and the flexural properties of the composites. However, there is a trend for a decrease in the wettability and in the flexural strength at high wood flour contents. It was seen that increase in the wood flour content lead to a lower elongation at break.
II. PRODUCTION OF SPECIMEN
Following steps were involved in the preparation
• Drying of wood powder obtained as carpentry waste.
Wood was first dried in the sunlight for one whole day and further in a hot air oven to remove any moisture
III. TESTING
The tensile and Compression properties of the waste wood particle and plastic composites at room temperature were determined by following the ASTM standards (ASTM A 370-12a) in a computer controlled Universal Testing Machine.In addition to this microstructure images of each composition were obtained using Scanning Electron Microscopy. The microstructures study explained how the different compositions varied. The images are shown under results and discussion.
V. CONCLUDING REMARKS
The study made on the WPCs has shown that plastics that are discarded after the use can be successfully utilized to make composite materials with useful mechanical properties. The composite specimens were prepared without using any binding agent or coupling agent as it important to know the behavior of WPC in absence of agents.
It is observed that, more the wood content more will be the strength and the point to be considered the most is that it is difficult to prepare specimen having more than 30% wood due to lack of interfacial bonding. The mechanical properties of LDPE waste composites are generally greatest, closely followed by HDPE waste composites. The problems associated with PVC is that the release of toxic gases and very low bonding property. The WPCs of combined plastic wastes (HDPE+ LDPE+ wood) also proved to be beneficial with better mechanical properties. The rate of water absorption (moisture absorption) is significantly less for WPCs. It is found that more the plastic content lesser will be the moisture absorption.