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Interfacial evaluation and the durability of alkaline and silane treated Jute fibers/polypropylene (PP) composites were investigated by micromechanical test combined with the wettability and nondestructive acoustic emission (AE). After boiling water test, tensile strength and interfacial shear strength (IFSS) between Jute fibers and PP matrix decreased due to the deterioration of swelled fibrils by water infiltration and microfailure. The IFSS decrement of the untreated and treated Jute fibers/PP composites was different from each other, respectively. IFSS between silane treated Jute fiber and PP matrix was higher than the untreated or even alkaline treated cases. From the dynamic contact angle results, micromechanical IFSS was not always consistent with thermodynamic work of adhesion, Wa in the interface. Since hemicellulose and lignin could be removed from Jute fiber after boiling water test, Jute fiber surface became more hydrophilic and surface roughness increased. With water present, the work of adhesion did not only decrease but they were negative, which indicates the instability of the interfacial system. Microfailure pattern of boiled Jute fiber was obviously different from the untreated case based on monitored AE parameters. AE energy increased for the alkaline and silane treated Jute fibers/PP composites, whereas AE energy for all three cases decreased distinctly after boiling water test. |
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