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1. MECHANICAL CHARACTERIZATION OF PLA/NEEM WOOD POLYMER COMPOSITE Gnanamani college of technology, pachal,namakkal Guid name: S achin s raj Student name: Sakthi R (620816114166), Sakthivel B (620816114167), SandeeshkumarK (620816114169), SaranRaj S (620816114175)

2. ABSTRACT Poly Lactic Acid(PLA) reinforced with neem wood fiber was analyzed in this research.PLA and Neem Wood Sawdust(NWS) were processed by stir casting method to obtain 4 samples of varying fiber to matrix proportion by weight fraction. The four samples were considered in the following ratio of PLA/NWS, 90/10, 85/15, 80/20 and 75/25 wt% respectively. Fabrication was carried out by stir casting at 200 o C. The samples were tested individually for tensile, flexural and impact tests. Mechanical properties of PLA improved with addition of Neem Sawdust. The sample containing 20% of fiber loading had the highest tensile, flexural and impact strengths. Hence the biodegradable PLA/NWS composite may be successfully recommended as a substitute for automobile interior components and in the construction field.

3. keywords Poly Lactic Acid, Neem sawdust, Stir Casting, Mechanical characterization, Bio-composite material.

4. INTRODUCTION Poly Lactic Acid is a biopolymer thermoplastic derived from the starch vegetables hence being biodegradable in nature . The most suitable method for fabricating PLA based natural fiber composites with improved mechanical properties is injection moulding technique. The thermal degradation of PLA is 340oC and the commonly used processing temperature is between 160 – 190oC. Neem wood sawdust which is obtained from its dried wood bark is an economically available cheap source of natural fiber which is abundantly available in tropical regions. Stir casting method is generally used for metal matrix composites but in this research this attempt is made to study the pros and cons of processing a polymer composite material using stir casting method.

5. EXPERIMENTATION Materials PLA Poly Lactic Acid was obtained from Nature teck , Chennai in the form of granules. It had a density of 1.24 g/cm3 and a melting point of 170-180oC. It had a crystallization temperature of 110oC approximately. The glass transition temperature of the PLA was around 55oC.

6. Neem Wood Saw dust Neem sawdust was obtained free of cost from the waste yard of Namakkal district, Tamilnadu . The wood barks were then sun dried for 10 days. The fibers were then pulverized using a grinding machine to obtain the sawdust. NaOH alkali treatment was done on the fibers for 24 hours to help good adhesion with the matrix material during processing. The fibers were then dried in an air oven for 24 hours at 90oC to remove all the moisture.

7. Processing methodology Mixture of weight fraction The PLA and Areca fiber were measured separately by weight fraction using a digital weighing scale to obtain six samples with the respective ratios of PLA/Areca fiber as shown in table. The weighed samples were then individually mixed well together by manually needing and to equally distribute the dry forms of the fiber and the polymer evenly between themselves. Stir casting technique Plain PLA pellets was taken in the specially designed crucible and placed into the furnace such that majority portion of the crucible is exposed to the heat from its bottom and surroundings but the top portion remains above the surface of the furnace to facilitate stirring process as shown in figure and also to avoid PLA to be directly in contact with the heat form the coils which may burn the polymer. Finally the processing temperature was figured out to be 200oC at which the plain polymer turned into complete molten state with good flow ability in a processing time of 5 minutes.

8. EXTRUTION MACHINE

9. Neem Wood Sawdust SAMPLE PLA/NWS wt% PLA in gms per 100 gms sample weight NWS in gms per 100 gms sample weight 1 90/10 90 10 2 85/15 85 15 3 80/20 80 20 4 75/25 75 25

10. Mechanical Testing Tensile test Tensile Test was carried out on a Navin brand, Universal Testing Machine which had a maximum load capacity of 40 kN and a maximum head travel of 500 mm. The gripper width could house upto 25 mm thick work piece. The specimens were tested with a load of 10 kN and cross head speed of 5mm/min.

11. Flexural test Flexural testwas also carried out on the same Universal testing machine at Nandha Engineering College, Perundurai , Erode. The specimens were tested with a flexural load of 5 mm/min considering three point bending method and a load of 10 kN. The flexural strength and the flexural modulus were the parameters analyzed.

12. Impact test Izod impact test was carried out on all the four unnotched samples individually to determine the impact resistance of the composite materials at ASTM standards. The equipment had a hammer head weight of 15 kg that produced a maximum force of 150 N. Impact strength was measured for each of the tested specimens with respect to the impact energy absorbed by them. Figure 2 shows the equipments that were used for the tensile, flexural and impact tests.

13. RESULTSAND DISCUSSIONS Tensile strength Tensile strength of PLA increased with addition of Neem sawdust. PLA had a tensile strength of 58 MPa . Tensile strength of the 20 wt% reinforced composite had the highest tensile strength. The 25 wt% reinforced composite had reduced tensile strength due to the dominating fiber content and insufficient matrix material that had led to improper wetting of the fiber. Tensile modulus and elongation also increased with increasing fiber conten .

14. TENSILE TEST COMPONENT

15. Flexural strength Flexural strength of PLA increased with addition of Neem sawdust. PLA had a flexural strength of 103 MPa . Flexural strength of the 20 wt% reinforced composite had the highest flexural strength as shown in figure . The 25 wt% reinforced composite had reduced flexural strength when compared to the 20 wt% reinforced composite due to the same reason of the reduction in the tensile strength. Flexural modulus also had increased with increasing fiber content.

16. Impact strength Impact strength increased with addition of Neem sawdust. PLA had an impact strength of 35 J/mm2. Impact strength of the 20 wt% reinforced composite had the highest impact strength as shown in figure . The 25 wt% reinforced composite had a reduced impact strength when compared to the 20 wt% reinforced composite due to the improper transfer of impact energy between the polymer and the fiber. The dominating fiber content turned the composite into brittle form which led to the fracture of the tested specimen showing lower impact strength.

17. IMPACT AND FLEXURAL TEST SPECIMAN

18. CONCLUSION Addition of neem sawdust improved the mechanical properties of PLA. Increment in fiber content upto 20 wt% had showed improvement in the mechanical properties. At very high fiber content ie 25 wt%, the mechanical properties dropped down to values lower than that of the 20 wt% reinforced composites. Stir casting method had proven to result in positive manner for the processing of PLA based composites. Stir casting has also shown that it is an economic and cost efficient method of fabrication that requires less processing energy. Further research on this area can be carried out to determine standard specifications for the stir casting of PLA composites.

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