Natural plant fibers, including flax, kenaf, jute, bamboo, ramie and much more are renewable and sustainable resources and are considered good candidates for cost-effective alternatives to glass and carbon fibers. In this research, cross ply biodegradable composites were fabricated by press-forming method. The biodegradable composites consist of Manila hemp textile as a reinforcement and starch-based biodegradable plastics as a matrix was fabricated and investigated about mechanical properties. The tensile strength increased with the fiber content until fiber content of about 50% and leveled off thereafter. This dependence on the fiber content is due to the decrease in fiber strength of loading direction caused by fiber damages introduced during hot-pressing. In order to decrease the damage of fibers aligned in loading direction, Manila hemp textile was produced by using Manila hemp fibers for warp and biodegradable resin thread for weft. As a result, the tensile strength of cross ply composites increased from 153 MPa to 202 MPa.
These past few years have witnessed the speedy development of scientific techniques and an addition in the standard of living of human. However, these developments have their disadvantages. Fossil fuels were running out and there is insufficient space for our garbage. In order to reduce the environmental load generated from the disposal of used plastic products, significant attention has been placed on biodegradable resin. This resin can be completely resolved into water and carbon dioxide by the action of the microorganism, when it is disposed of in the soil. Moreover, there are no emissions of toxic gases during incineration. The application of biodegradable resin has been restricted due to their relatively lower strength compared to conventional plastics such as POM (polyacetal) and nylon. Resent years, because of their extensive use in many diverse fields, plastics, including FRP (fiber reinforced plastics) products have become indispensable to our life. However, the primary raw material used in plastic production is petroleum and there are strong social and economic pressures to conserve petroleum resources. Furthermore, because FRP wastes are non-flammable, they must be disposed of in landfills after use, and this contributes to high environmental loads. The use of natural plant fibers as a reinforcement in FRP to replace synthetic fibers such as glass and carbon fibers is presently receiving attention because of advantages such as renewable resources, low density and high specific strength. Furthermore, in recent years, development of biodegradable composites using natural plant fibers such as flax [
In former paper [
As a matrix, emulsion-type biodegradable polymer (Miyoshi Oil & Fat Co., LTD.,CP-300) was used. Plastic particles of approximately 5 μm in diameter are suspended in water-based solution with a mass content of about 40%. The properties of this biodegradable plastics are shown in
Firstly, Manila hemp textiles of 100mm square were produced using Manila hemp fibers with textile machine. Next, emulsion-type biodegradable polymer was put on the surface of Manila hemp fibers. The preliminary molded sheets were produced by drying at 105˚C for 120 min in an oven. The photograph of Manila hemp textile produced is shown in
As shown in
Specimens were produced by the hot-pressing with a metallic mold and a press machine. Firstly, laminated preliminary molded sheets were put into the metallic mold, and then they were heated to 130˚C with the flexible heater rolled around the metallic mold. Next it held at 130˚C for 5 min, and specimens were produced by pressing at 10 MPa for 10 min.
Density (g/cm3) | 1.18 |
---|---|
Melting point (˚C) | 58 |
Water absorption (%) | 2 |
Tensile strength (MPa) | 11.7 |
Young’s modulus (MPa) | 415 |
Fiber bundle | Single fiber | ||
---|---|---|---|
Length (m) | Diameter (mm) | Length (mm) | Diameter (μm) |
2 - 3 | 0.1 - 0.3 | 2 - 12 | 10 - 50 |
Tensile test was carried out by using 5567 type Instron testing machine. The width, thickness and length of the tensile specimen are 10 mm, 0.8 - 1.5 mm and 100 mm, respectively. Tensile test was performed at a strain rate of 0.03 per min and the gauge length of 30 mm.
The top view and transverse section of fabricated cross ply biodegradable composites is shown in
σ = σ p ⋅ a / ( a + b ) (1)
Since the cross ply was laminated as a = b in this research, fracture stress is given by Equation (2).
σ = ( σ p + σ v ) / 2 (2)
The dotted line in
The experimental values of cross ply laminates are slightly higher than calculated values from Equation (2) in
σ = ( σ p + σ v ) / 2 (3)
The solid line in
This research was performed to examine the tensile properties of cross ply biodegradable composites that were made using an emulsion-type biodegradable resin as the matrix and Manila hemp textile as the reinforcement. The results obtained are as follows:
1) Using an emulation type biodegradable polymer and Manila hemp textile, cross ply biodegradable composites that their fibers are arranged straightly and fiber content is high were fabricated.
2) Tensile strength increased with the fiber content until 50% and remained constant thereafter. This fiber content dependence is due to the decrease in fiber strength caused by fiber damage introduced during hot-pressing.
3) Tensile strength of cross ply composites using biodegradable resin thread for weft increased lineally with the fiber content until fiber content of 70%. And at fiber content of 70%, the composites possessed extremely high tensile strength of 202 MPa.
Ochi, S. (2018) Fabrication of Manila Hemp Fiber Reinforced Cross Ply Biodegradable Composites and Their Tensile Properties. Open Journal of Composite Materials, 8, 75-83. https://doi.org/10.4236/ojcm.2018.83007