WOOD COMPOSITE POWDER PLASTIC RECYCLING TECHNOLOGY USE ALTERNATIVE WASTE WOOD AND PLASTIC INTRODUCTION

WOOD COMPOSITE POWDER PLASTIC RECYCLING TECHNOLOGY USE ALTERNATIVE WASTE WOOD AND PLASTIC 
INTRODUCTION
Due to the unique nature and characteristics, wood is the material most widely used for construction purposes. The ever-increasing demand for wood and forest potential of dwindling demand the use of wood in an efficient and expedient, by utilizing such waste sawdust into useful products. On the other hand, along with the development of technology, the need for plastics continue to increase as a consequence, increased waste plastikpun inevitable. Waste plastic is a material that can not be decomposed by microorganisms decomposing (non-biodegradable), so penumpukkannya in nature feared to cause environmental problems.

Technological developments, particularly in the field of composite board, has produced a composite product which is a combination of sawdust with recycled plastic. The technology was developed in the early 1990s in Japan and the United States. With this technology it is possible utilization of sawdust and recycled plastic to the maximum, thus will reduce the amount of waste generated. In Indonesia, research on these products is limited, whereas raw material waste potential is enormous.

This paper will present a brief overview of the potential and utilization of wood waste, particularly sawdust, and plastic waste as a product of wood-plastic composite powder recycling.

POTENTIAL AND UTILIZATION OF WASTE WOOD POWDER 

Human need for wood as building material for the purposes of construction, decoration, and furniture continues to increase along with the increase in population. Timber demand for the timber industry in Indonesia is estimated at 70 million m3 per year with an average of 14.2% per year while roundwood production estimated at 25 million m3 per year, so there was a deficit of 45 million m3 (Priyono, 2001). This suggests that the actual carrying capacity of the forest has been unable to meet the demand for wood. This situation is exacerbated by the presence komversi natural forests into agricultural land, shifting cultivation, forest fires, harvesting practices are not efisen and infrastructure development, followed by forest encroachment. These conditions require the use of wood in an efficient and prudent, among others, through the concept of the whole tree utilization, while increasing the use of non-wood berlignoselulosa, and the development of innovative products as a substitute for wood building materials.

Regrettably, to date harvesting and processing of timber in Indonesia still produces large amounts of waste. Purwanto et al, (1994) stated the composition of waste in harvesting and wood processing industry are as follows:

1. On timber harvesting, waste generally shaped logs, reaching 66.16%

2. In industrial sawmill wood waste sawdust covering 10.6 &. Sebetan 25.9% and 14.3% cuts, a total waste 50.8% of the total raw material digubakan

3. Industrial waste at the waste pieces of plywood covering 5.6%, 0.7% sawdust, 24.8% wet veneer waste, dry waste veneer peeling the remaining 12.6% 11.0% and a piece of plywood edges 6.3% . Total waste plywood for 61.0% of total raw materials used.

Data from the Ministry of Forestry and Plantations in 1999/2000 showed that Indonesia’s plywood production reached 4.61 million m3 of sawn timber while achieving 2.06 million m3. Assuming the waste generated is estimated to reach 61% of the wood waste generated reached more than 5 million m3 (CBS, 2000).

Wood waste in the form of pieces of logs and sebetan been used as the core block board and particle board material. The waste floured kergaji utilization is still not optimal. For large, integrated industrial, waste sawdust sawn been utilized as a form of charcoal briquettes and activated charcoal are sold commercially. But for the sawmilling industry small-scale industries, which accounted for thousands of units and the countryside, the waste has not been used optimally. An example is the industrial mills in Jambi, amounting to 150 pieces of which are located on the edge of the river Batang, sawn wood waste generated is dumped into the river, causing siltation and reduction process stream segment (Pari, 2002). In most of the wood processing industry waste sawdust are commonly used as furnace fuel, or burned away without meaningful use, which can cause environmental pollution (Febrianto, 1999). In order to efficient use of wood are needed to use sawdust into a more useful product.

FROM PLASTIC TO PLASTIC WASTE RECYCLING 

Plastic name representing thousands of different physical properties of materials, mechanical, and chemical. Broadly speaking, the plastic can be classified into two major categories, namely plastics are thermoplastic and thermoset that is. Thermoplastic can be reshaped easily and processed into other forms, whereas when it has hardened types of thermosets can not be softened again. The most common plastic used in everyday life in the form of thermoplastic.

Along with the development of technology, the need for plastic continues to increase. BPS data in 1999 showed that the volume of trade of Indonesia’s imports of plastic, especially polypropylene (PP) in 1995 amounted to 136,122.7 tons, while in 1999 amounted to 182,523.6 tons, so that in this period there was an increase of 34.15%. The number is expected to continue to increase in subsequent years. As a consequence, an increase in waste plastikpun inevitable. According to Hartono (1998) the composition of the waste or plastic waste dumped by each household was 9.3% of total household waste. In Jabotabek average each plant produces one ton of plastic waste every week. That number will continue to grow, due to the properties owned plastics, among others, can not rot, do not decompose naturally, it can not absorb water, and can not rust, and eventually ended up being a problem for the environment. (YBP, 1986).

Utilization of waste plastics is an effort to suppress plastic waste to a minimum and within certain limits save resources and reduce dependence on imported raw materials. Utilization of waste plastics can be done with reuse (reuse) and recycling (recycle). In Indonesia, the use of plastic waste in the scale of general household usage is back with different purposes, for example, place a plastic paint used for pot or bucket. Reuse ugly side, particularly in the form of packaging is often used for product counterfeiting as it often happens in the big cities (Syafitrie, 2001).

Utilization of waste plastics for recycling is generally done by the industry. Generally, there are four requirements for a plastic waste can be processed by an industry, among others, certain wastes must be in the form as needed (seed, pellets, powder, pieces), the waste must be homogeneous, uncontaminated, and sought not oxidized. To overcome these problems, before use of plastic waste is processed through a simple step, the separation, cutting, washing, and removal of substances such as iron, and so on (Sasse et al., 1995).

There are things that benefit in the use of plastic waste in Indonesia compared to developed countries. This is possible because manual separation is considered not possible in developed countries, can be done in Indonesia, which has abundant labor so that the separation does not need to be done with advanced equipment that require high costs. These conditions allow the development of plastics recycling industry in Indonesia (Syafitrie, 2001).

Use of recycled plastic in the manufacture of plastic goods back has been growing rapidly. Almost all types of plastic waste (80%) can be processed back into the original item must be done despite mixing with new raw materials and additives to improve the quality (Syafitrie, 2001). According to Hartono (1998) four types of plastic waste are popular and sell well in the market, namely polyethylene (PE), High Density Polyethylene (HDPE), polypropylene (PP), and asoi.

UTILIZATION OF WASTE WOOD AND POWDER WOOD PLASTIC COMPOSITES AS PLASTIC RECYCLING 

Composite wood is a term used to describe any product that is made from sheets or small pieces of wood glued together (Maloney, 1996). Referring to the definition above, composite wood powder composite plastic is made of plastic as a matrix and wood powder as filler (filler), which has properties of both. The addition of filler into the matrix aims to reduce density, increase stiffness and reduce the cost per unit volume. In terms of wood, with the polymer matrix inside the strength and physical properties will also increase (Febrianto, 1999).

Composite manufacturing using a matrix of plastic that has been recycled, in addition to improving the efficiency of wood utilization, can also reduce the load on plastic waste in addition to producing innovative products as a substitute for wood building materials. The advantages of this product include: cheaper production costs, abundant raw materials, flexible in the manufacturing process, low density, it is biodegradable (rather than plastic), possesses properties better than the original raw material, can be applied for various purposes, as well as can be recycled (recycleable). Some examples of the use of this product are as interior parts of vehicles (cars, trains, airplanes), furniture, or building components (windows, doors, walls, floors and bridges) (Febrianto, 1999: Youngquist, 1995).
Wood powder as Filler

Filler is added to the matrix in order to improve the mechanical properties of plastics through the deployment of effective stress between the fiber and the matrix (Han, 1990). Besides the addition of filler to reduce costs as well as improve some properties of its products.

Inorganic materials such as calcium carbonate, talc, mica, and fiberglass is the material most commonly used as a filler in the plastics industry. The addition of calcium carbonate, mica and talc may increase the strength of the plastic, but the weight of the product is also increased so that the transportation costs would be higher. In addition, calcium carbonate and talc are abrasive to equipment used, thereby shortening the service life. The addition of fiberglass to increase the strength of the product but the price is very expensive. Therefore the use of organic materials, such as wood filler in the plastics industry began to receive attention. In Indonesia, the potential for very large timber as a filler, especially the utilization of waste sawdust is still not optimal.

According Strak and Berger (1997), sawdust has advantages as a filler when compared to filler minerals such as mica, calcium carbonate, and talc are: process temperature is lower (less than 400 º F) thereby reducing energy costs, can be degraded naturally, weight species are much lower, so the cheaper the cost per volume, low geseknya style so not to damage equipment on the manufacturing process, and comes from renewable sources

Some factors to consider in the use of sawdust as a filler in the manufacture of wood plastic composite is a type of wood, the size ratio between powder and sawdust and plastic. Another thing to consider is the nature of wood dust itself. Wood is a material composed mostly of cellulose (40-50%), hemicellulose (20-30%), lignin (20-30%), and small amounts of inorganic materials and extractive. Therefore hydrophilic wood, rigid, and can be biologically degraded. The properties of the wood causes less suitable when combined with plastic, because it is in the manufacture of wood-plastic composites required assistance coupling agent (Febrianto, 1999).
Plastic Recycling In The Matrix

In Indonesia, most of the recycled plastic used again as the original product with lower quality. Use of recycled plastic as a construction material is still very rare. In the 1980s, the UK and Italy have been recycled plastic used to make telephone poles instead of wooden poles or iron. In Sweden recycled plastic used to manufacture the plastic brick multistory buildings, because lighter and more powerful than common brick (YBP, 1986).

Use of recycled plastic in the field of composite wood in Indonesia is still limited at the research stage. There are two strategies in the manufacture of wood composites by using plastic, plastic first used as a binder, while the wood as the main component, the second used wood filler / filler and a plastic matrix. Research on the use of recycled polypropylene plastic as a substitute for thermoset adhesives in the manufacture of particle board made by Febrianto et al (2001). Particle board product produced has dimensional stability and high mechanical strength compared to conventional particle boards. Research recycled plastic as wood plastic composite matrix made Setyawati (2003) and Sulaeman (2003) by using recycled polypropylene plastic. In the manufacture of wood plastic composite recycling, some thermoplastic polymers can be used as a matrix, but is limited by low temperature decomposition beginning and heating wood (approximately 200 ° C).

Making Process

Basically composite manufacturing recycled plastic wood powder not unlike the plastic matrix composites with pure. These composites can be made through the process one stage, two-stage process, and the continuous process. At one stage of the process, all the raw materials mixed first manually and then entered into the tool pengadon (kneader) and processed to produce a composite product. In the two-stage process of modified plastic raw materials first, then filler mixed together in the kneader and formed into a composite. The combination of these stages is known as a continuous process. In this process the raw materials incorporated gradually and sequentially in a kneader and then processed through a composite product (Han and Shiraishi, 1990). Generally a two-stage process produces a better product than the one stage, but the process takes one step shorter.
Diagram of basic manufacturing process is presented in Figure 1.

Preparation of filler 

In principle the preparation of filler intended to get sawdust or wood flour size and uniform moisture content. The more fine powders greater the contact surface between the matriknya filler, so the products become more homogeneous. However, if the terms of decorative composite powder size larger will produce a better appearance because the distribution of the powder timber provides its own value.

Preparation of Recycled Plastic

Waste plastics are grouped according to the type of plastic (polypropylene (PP), polyethylene (PE), and so on). Once cleaned, the waste is chopped to reduce the size, then heated to its melting point, then processed to form a pellet. Before being used as a composite matrix made analysts differential thermal (DTA). In the two-stage process, the pellets diblending first by serving as a coupling agent in the manufacture of composite compatibilizer.
Blending (Pengadonan)

The stages in this pengadonan adapted to the process used, one stage, two-stage, or continuous. According to Han (1990) pengadonan conditions are most influential in the manufacture of composites is the temperature, rotation rate, and time pengadonan.
The formation of composite

After the mixing is complete, the sample is directly incurred to molded into sheets with heat presses. Compression performed for 2.5 – 3 minutes with a pressure of 100 kgf/cm2 for 30 seconds at a temperature of 170 º C – 190 º C. After cold compression at the same pressure for 30 seconds, the sheet is then cooled at room temperature.
Testing of Composites

Composite testing conducted to determine whether the product meets the requirements specified for a particular use. Type adapted to the needs of testing, testing fterhadap generally includes physical properties, mechanical, and thermal composites.

Composite of high quality can only be achieved if the sawdust is well distributed in the matrix. In fact, the affinity of wood with a plastic powder is very low because the wood is hydrophilic, while the plastic is hydrophobic. As a result, the composite is formed has a drainage properties and low moldability and in turn can reduce the strength of materials (Han, 1990).
The results of research

Studies that have been and are being conducted aiming to produce wood plastic composite with the best properties. Han (1990), Stark and Berger (1997), and Oksman and Clemons (1997), examines the factors that play an important role in the manufacture of wood plastic composite powder, the type and form of raw material, wood species, the ratio of filler to the matrix, type and compatibilizer levels, as well as the conditions at the time of pengadonan. The results show that to some extent an increase in strength of the composite with the smaller size of the powder used, as well as the type, ratio of sawdust and plastic, as well as the type of wood moisture content significantly affect the properties of the resulting composites. The addition of compatibilizer to a certain extent affect both the strength of the composite.

Research on wood plastic composite mostly still use plastic purely as a matrix. Research using recycled matrix, performed by Setyawati (2003), Sulaeman (2003) by using recycled polypropylene. The results of the study are summarized as follows:

Setyawati (2003) examined the effect of the size ratio of sawdust to the matrix and compatibilizer content on physical and mechanical properties of polypropylene wood composite recycling. The results showed a similar pattern with a composite that uses pure polypropylene, the properties of the composites increased with increasing particle size and smoothness. Sawdust ratio of 50:50 with a matrix with the addition of 2.5% MAH as compatibilizer is accompanied by the addition of initiator produces optimal composite force, as well as physical properties sufficient.

Sulaeman (2003), examined the deterioration of wood plastic composite recycled polypropylene by weather and termites. The results showed a composite of recycled plastic lumber can be degraded by weather, but resistant to termite attack.

Research The Moderate / Will Do

Research and testing of wood plastic composite so far has been in the form of thin sheets, so the test is still based on testing plastics. Currently Sutrisno (personal communication) is conducting research on the properties of recycled wood plastic composite in the form of small clear specimen so testing is directed to the possible use of composites instead of wood.

Future studies will lead to the determination of the wood plastic composite board manufacturing the best and the quality of composite board with pre-treatment on the filler, the selection of modifier / compatibilizer, the initiator, the determination of process variables, and the use of materials other than wood berlignoselulosa (research plan) .

CLOSING

Manufacture of composite products sawdust and recycled plastic is one alternative to the use of waste wood and plastic, in order to improve the efficiency of wood utilization, reducing the environmental load of the plastic waste and to produce innovative products as a substitute for wood building materials. The development of these products in the future will hopefully have a positive impact, not only limited to industrial development and foreign exchange savings, but also improve the quality of the environment.