Role of Maleated Coupling Agents on the Interface Adhesion of Polypropylene—Wood Composites

Abstract

The main accomplishment of compounding wood-flour with thermoplastics is an increase in rigidity and specific strength. Filler-matrix interactions play a key role in the composite performance and the strength of the interface is determined by the nature of the coupling agents employed. The coupling efficiency of maleated polypropylene (PP-MAH) with varying MAH content and melt flow index in polypropylene-wood composites has been investigated. A method based on a simplified single rule of mixtures aiming to compare differences in interface adhesion in the presence of PP-MAH is proposed in terms of relaxation spectra of polypropylene-wood composites obtained by dynamic-mechanical thermal analysis (DMTA). The criterion is an attempt to determine an adhesion factor as derived from the relative mechanical damping (tan ) of the composite as a function of the filler content and temperature. Experimental results deviate from model predictions possibly owing to assumptions of wood-flour as a rigid filler as well as neglect of an interphase volume fraction and its damping characteristics. However, good correlations of coupling efficiency and yield properties have been found for wood composites with homopolymer and copolymer matrices within a range of varying wood-flour content and type of coupling agent. Further evidences of improved matrix-filler interactions, wettability, and filler dispersion in the presence of the PP-MAH are observed by scanning electron microscopy.

Mechanical, dynamic mechanical and morphological properties of composites based on recycled polystyrene filled with wood flour wastes

“…At high levels of interface adhesion, the molecular mobility surrounding the filler is reduced, and this reduces the tan δ c values and consequently the A values. Thus, a low value for the adhesion factor A suggests improved interactions at the matrix-filler interface (Kubát et al 1990, Correa et al 2007). …”

Thermoplastic Matrix Reinforced with Natural Fibers: A Study on Interfacial Behavior

“…This parameter is obtained from DMTA data. Effect of PP-g-MA as coupling agent on the interface adhesion of WPC investigated by Correa et al, (2007). They mentioned a method based on a simplified single rule of mixtures aiming to compare differences in interface adhesion in the presence of PP-g-MA is proposed in terms of relaxation spectra of polypropylene-wood composites obtained by DMTA.…”

“…For determination of adhesion factor as interfacial intraction criterion, Correa et al, (2007) has been used equation originated from Kubat et al, (1990) work, about high density polyethylene filled with 20 Vol. % glass fibers.…”

Processing and structure–property relationships of natural rubber/wheat bran biocomposites

“…Presented calculations explain the differences in static mechanical properties between studied biocomposites. Negative values of adhesion factor in case of samples containing wood flour and microcellulose can be associated with the simplification of model and neglecting of the filler anisotropy and with development of the interphase region, which obviously have slight influence on the macromolecular mobility at the filler surroundings (Correa et al 2007). …”