Studies of surface-modified wood flour/polypropylene composites
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Wood flour (WF)/polypropylene (PP) composites have been made by extrusion and hot press compression molding. The composite water uptake and flexural properties were investigated. The composite fracture surfaces were studied by SEM. WF esterified with octanoyl chloride was used in WF/PP composites to improve the composites’ water resistance. Maleated polypropylene (MAPP) was also studied and compared with esterification by acid chlorides. Esterification by octanoyl chloride reduced the composite water uptake. However, the C8 chain is still not long enough to form effective entanglements with the PP matrix. So, despite enhancements in hydrophobic interactions, flexural strengths and flexural moduli decreased. MAPP (MW = 47000) polymer chains can entangle with the matrix polypropylene molecules. Therefore, when MAPP’s maleic anhydride functions esterify WF surface hydroxyls, improved water resistance and composite flexural properties were achieved. The modifier chain length is of critical importance and more important than the surface density of hydrophobic groups for improving WF–PP interfacial adhesion and composite mechanical performance.
KeywordsFlexural Strength Water Immersion Wood Flour Flexural Modulus Octanoyl
This work was funded by Center for Advanced Vehicular Systems of Mississippi State University (“Hybrid composites for a hybrid car” project). This work was also partly supported by the Forest Products Laboratory at Mississippi State University. The SEM characterization was supported by MCL Follow-up Funding from Mississippi State University. The authors thank Mr. Dustin Black for performing water absorption and third-point bending measurements. The authors also thank Ms. Amanda M. Lawrence for her help in SEM characterization.
- 1.Clemons CM (2000) Proceedings of the 3rd international wood and natural fibre composites symposium, Kassel, GermanyGoogle Scholar
- 13.Zhang Y, Pittman CU Jr, Toghiani H, Zhang J, Xue Y (2009) Compos Interfaces (accepted)Google Scholar
- 14.ASTM D 790-92Google Scholar
- 15.ASTM D 570-98Google Scholar