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NEW TYPE OF WOOD-POLYMER COMPOSITES
Q.N. Khoshimov
S.Q. Sodiqjonov
A.A.Ataxojayev
A.M.Razzoqova
E.A. Egamberdiyev
Tashkent State Technical University named after Islam Karimov
https://doi.org/10.5281/zenodo.15105753
Household waste is generated in residential areas, including workplaces. The
accumulated solid household waste is transported to specially designated locations using
specialized vehicles. When solid household waste remains stationary for an extended period at
permanent storage sites, biological changes occur under external influences, leading to the
decomposition of the organic components of the waste. During the chemical and biochemical
transformation process of decomposition reactions, various by-products are released, which
disperse into the air through the wind and spread across residential areas. At the same time,
soil, water, and the atmosphere become contaminated.
It is well known that the disposal of solid household waste is a major global issue, and
different approaches are taken to solve it in various regions. In Japan, after waste is collected at
designated locations and placed in waste containers, it is sent to waste incineration plants. The
energy generated from incineration is used to heat water until it turns into steam. The steam's
energy is then directed to special units, where its mechanical energy is converted into electrical
energy. This entire process takes place without causing any negative impact on the
environment. Additionally, in developing industrial countries, research is being conducted on
efficiently utilizing such waste to produce composite materials. As a continuation of these
studies, we have also conducted research on obtaining wood-polymer composites using local
wood species.
The use of plastic and wood waste for composite production is a promising solution to
reducing the amount of waste in landfills. It is worth noting that landfills contain various types
of wood waste, such as branches, leaves, and twigs, which, due to their chemical composition
and surface morphology, significantly affect the properties of wood-polymer composites
(WPCs). Thus, this study examines the impact of different types and compositions of wood
waste on the mechanical and physical properties of WPCs processed under natural weathering
conditions. The ultimate goal of this study was to explore the effects of wood waste types and
compositions under natural weather conditions to develop environmentally friendly WPCs
from plastic and wood waste accumulated in landfills. The new findings are beneficial for the
construction and infrastructure sectors, particularly for exterior applications such as decking,
fencing, cladding, roofing, walls, and paneling, which require resistance to natural weathering.
Moreover, the research results are expected to increase interest in utilizing waste materials to
develop WPC products, thereby helping to reduce landfill waste.
For the study, waste materials were selected from a landfill located in the Tashkent region,
including plastic bags, wooden branches, twigs, and leaves. Before processing, the plastic bags
were washed with a liquid detergent solution and rinsed three times with water. Then, they
were shredded into 0.5–1.5 cm pieces using a cutting mill and converted into granules using an
extruder at temperatures ranging from 200 to 225°C. The material was then processed using a
hot press.
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Figure 1. a) Plastic waste, b) Wooden twigs, c) Leaves, and d) Other tree leaf waste.
Processes for Obtaining Wood-Polymer Composites.
The raw materials prepared for
the experiment were mixed together in a co-rotating twin-screw extruder with wood waste
flour and pigment. The extrusion temperature was adjusted to 165-185°C, and the screw
rotation speed was set at 60 rpm until full mixing was achieved. Then, the extruded mass was
prepared for pressing before leaving the extruder. For this, it was preheated in a hydraulic
compression machine at a temperature of 300°C-350°C under a pressure of 3.55 MPa for 5-7
minutes, followed by shaping under a pressure of 6.90 MPa for 15 minutes. The WPC samples
were then cooled under a pressure of 6.90 MPa for 15 minutes. Finally, WPC panels were
prepared as samples for testing mechanical and physical properties.
Natural Weathering Test.
The natural weathering tests were conducted in the Gazalkent
district, near the Chirchiq River, at a field house where the samples were placed around a pond.
The WPC samples were exposed directly to natural weathering conditions in the climate of the
river vicinity. The samples were tested for six months during the rainy season, from July 2024
to December 2024. During the experiment, the average relative humidity was 82.03% RH, the
total precipitation over 117 days amounted to 2366.8 mm, and the temperature ranged from
22.8°C to 34.8°C. The samples were evaluated after 2, 4, and 6 months of exposure.
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Figure 1. Physical and Mechanical Properties of Wood-Polymer Composites
The results of the tests on valence forces, elasticity modulus, and deformation properties
of all composites can be seen in Figure 1. The results indicate that the physical and mechanical
properties mentioned above are higher in samples with a greater amount of walnut wood waste
flour. The maximum tensile strength was observed in sample-1. The addition of 6% MAPPS
improved interfacial adhesion. Moreover, as the MAPPS content increased, the material's
hardness also increased. Consequently, due to the weak boundary between the matrix and
additives, the deformation values decreased. Taking the above into account, it can be seen from
the table that in samples with lower MAPPS content, the valence forces increased, whereas the
elasticity modulus decreased. On the other hand, as the amount of walnut wood waste flour
increased, the elastic modulus also increased. As a result, when the MAPPS content was
increased from 2% to 6%, the elasticity modulus and valence forces of all four types of wood
composites also increased. MAPPS ensured a stronger boundary between the polymer matrix
and the additives.
Conclusion:
This study demonstrated that exposure time, as well as different types and
compositions of wood waste, significantly affected the physical and mechanical properties of
WPC materials. Although all properties of WPCs deteriorated with increased exposure to
natural weather conditions, the hardness of WPCs increased as the amount of wood waste in
all wood types increased. Raising the wood waste content in wood-polymer composites from
30% to 60% increased the percentage loss of MOR, MOE, SWS, and hardness properties due to
microcracks on the WPC surface. Based on the results of this study, wood-polymer composites
based on branches and twigs are recommended for the production of WPC materials for
construction and building products. Additionally, it was concluded that solid household waste
39,85
38,92
37,08
36,96
36,92
36,6
36,9
37,2
37,5
37,8
38,1
38,4
38,7
39
39,3
39,6
39,9
40,2
1
2
3
4
5
Wood-Polymer Composite Samples
Bonding Forces in Composites,
MPa
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could be used as a raw material in WPC production. Recycling waste is a promising solution to
reducing the accumulation of various types of waste in landfills.
Foydalanilgan adabiyotlar/Используемая литература/References:
1.
Klason, C. The efficiency of cellulosic fillers in common termoplastics / C. Klason, Kubat
and H.E.Stromvall // Filling without processing aids or coupling agents. International J. of
Polymeric materials. – Part I. 10: – 1994. – P. 159-187.
2.
Бикбау, М.Я. Производство супернаполненных пластмасс - искусственного дерева,
композиционных материалов и изделий. Технологическая и технико- экономическая
оценка [Электронный ресурс] – Электрон. текст. дан. – Режим доступа:
http://bikbau-
marsel.narod.ru /olderfiles/1/kompozit.pdf
(Дата обращения: 24.08.2015)
3.
Термопластичные древесно-полимерные композиты в интерьере [Электронный
ресурс] – Электрон. текст. дан. – 12.10. 2006. – Режим доступа
обращения: 28.03.2015).
