Research Article
Feasibility of Reprocessing Natural Fiber Filled Poly(lactic acid) Composites: An In-Depth Investigation
Table 3
Physical and mechanical properties of WF-PLA composites after six reprocessing cycles.
| (a) Composite with 30% wood flour |
| | Properties | WF 30 PLA | | Cycle 0 | Cycle 1 | Cycle 2 | Cycle 3 | Cycle 4 | Cycle 5 | Cycle 6 |
| | Tensile strength (MPa) | 55.46 (2.96) | 55.89 | 56.55 (0.68) | 53.73 (1.53) | 52.54 (1.49) | 50.58 (1.52) | 29.21 (3.23) | | Flexural strength (MPa) | 90.96 (2.54) | 89.23 (2.21) | 87.06 (2.72) | 86.70 (2.70) | 87.40 (2.08) | 81.07 (2.94) | 26.81 (3.93) | | Impact resistance (J/m) | 47.18 (5.48) | 45.56 (9.62) | 35.36 (6.09) | 34.90 (6.05) | 34.51 (4.45) | 28.91 (7.17) | 13.13 (3.73) | | Tensile modulus (MPa) | 6949.95 (332) | 6361.13 (267.86) | 6484.70 (490.03) | 6185.56 (792.19) | 6533.57 (594.27) | 5978.74 (541.50) | 6303.36 (759.82) | | Flexural modulus (MPa) | 5811.89 (273.48) | 5424.19 (138.78) | 5368.78 (81.01) | 5288.02 (205.17) | 5347.51 (144.87) | 5256.00 (94.96) | 4163.17 (74.57) | | Storage modulus (MPa) | 6405.88 (303.48) | 6179.75 (88.9) | 6237.50 (144.73) | 6365.25 (101.37) | 5927.38 (302.9) | 5844.25 (274.45) | 5721.88 (271.06) | | Heat deflection temperature (°C) | 56.78 (0.39) | 56.58 (0.27) | 56.73 (0.21) | 56.52 (0.10) | 56.65 (0.24) | 56.15 (0.63) | 54.83 (0.26) | | Failure strain (%) | 1.59 (0.27) | 2.05 (0.10) | 2.32 (0.05) | 2.19 (0.25) | 2.20 (0.18) | 2.21 (0.22) | 0.46 (0.05) | | Coefficient of thermal expansion (mm/mm/°C) 10−5 | 0.68 (0.31) | 1.22 (0.23) | 1.31 (0.22) | 1.19 (0.25) | 1.63 (0.46) | 1.69 (0.24) | 1.90 (0.33) | | Melt flow index (g/10 min) | 2.85 (0.26) | 6.45 (0.20) | 7.84 (0.59) | 12.00 (0.36) | 14.26 (0.92) | 14.62 (0.50) | 21.09 (0.13) |
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| (b) Composite with 50% wood flour |
| | Properties | WF 50 PLA | | Cycle 0 | Cycle 1 | Cycle 2 | Cycle 3 | Cycle 4 | Cycle 5 | Cycle 6 |
| | Tensile strength (MPa) | 53.98 (3.61) | 53.20 (2.90) | 32.78 (5.17) | 36.84 (6.19) | 27.86 (6.08) | 34.34 (8.15) | 31.38 (9.56) | | Flexural strength (MPa) | 91.24 (5.81) | 92.16 (2.71) | 28.57 (1.45) | 36.63 (8.83) | 31.74 (3.73) | 30.74 (1.87) | 27.26 (2.16) | | Impact resistance (J/m) | 31.32 (6.13) | 31.33 (3.65) | 22.06 (5.46) | 20.48 (6.19) | 18.93 (4.90) | 15.71 (5.45) | 18.76 (4.15) | | Tensile modulus (MPa) | 8487.95 (698.60) | 8847.76 (894.24) | 6925.42 (1428.47) | 5251.07 (1326) | 6156.28 (2333.36) | 4660.82 (1572.32) | 3907.93 (725.54) | | Flexural modulus (MPa) | 6685.00 (480.84) | 5936.28 (547.61) | 6582.87 (440.04) | 6850.69 (243.49) | 6713.83 (104.07) | 6428.03 (293.98) | 6284.67 (135.05) | | Storage modulus (MPa) | 7347.88 (498.78) | 7286.13 (476.55) | 7060.13 (825.99) | 7391 (199.80) | 7106.13 (653.38) | 6622.25 (589.05) | 6317.00 (288.40) | | Heat deflection temperature (°C) | 56.07 (0.33) | 55.71 (0.59) | 54.49 (0.43) | 54.58 (0.33) | 54.71 (0.33) | 55.18 (0.28) | 54.62 (0.20) | | Failure strain (%) | 1.41 (0.15) | 1.26 (0.18) | 1.31 (0.52) | 1.84 (0.43) | 1.41 (0.24) | 1.93 (0.45) | 1.83 (0.55) | | Coefficient of thermal expansion (mm/mm/°C) 10−5 | 1.29 (0.48) | 0.91 (0.54) | 0.49 (0.15) | 0.57 (0.23) | 0.54 (0.17) | 0.64 (0.21) | 0.76 (0.19) | | Melt flow index (g/10 min) | 2.50 (0.21) | 3.15 (0.12) | 15.34 (0.99) | 25.09 (0.55) | 28.85 (0.59) | 32.73 (0.56) | 36.67 (0.58) |
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Values are shown as the mean with standard deviation in parenthesis. Means with different letters are significantly different ().
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