Chemical imaging of wood-polypropylene composites.
Recent investigations of wood plastic composites have revealed a detrimental effect of using lubricant systems in production. This includes nullifying part or all of the mechanical benefit of using a polar compatibilizer, maleic anhydride polypropylene (MAPP), in the composite formulation. This investigation utilizes lubricants labeled with deuterium in conjunction with Fourier transform infrared (FT-IR) spectroscopy to allow for the separation of individual lubricants from all other material constituents. All of the deuterium labeled lubricants, used without MAPP, revealed their expulsion from the wood interface during crystallization. MAPP coupling agent was found to exist near the wood, but it is unclear if any covalent bonding with the hydroxyl functionality on the wood surface occurred. The addition of zinc stearate lubricants appears to nullify the activity of the anhydride functionality near the wood surface as evidenced by a shift in the FT-IR spectra to the hydrolyzed form of the coupling agent. Most of the additives collect at the edges of the spherulites in mostly amorphous regions of the material. The consequence of this morphology may be a weak interface between crystallites.
Harper
David P
DP
Tennessee Forest Products Center, The University of Tennessee, Knoxville, Tennessee 37996-4570, USA. dharper4@utk.edu
Wolcott
Michael P
MP
D003903:Deuterium; D005583:Fourier Analysis; D008153:Lubrication; D008299:Maleic Anhydrides / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D011126:Polypropylenes / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D013228:Stearates / Q000737:chemistry; D014934:Wood / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry
D008299:Maleic Anhydrides; D011108:Polymers; D011126:Polypropylenes; D013228:Stearates; D003903:Deuterium; D015032:Zinc