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Effects of coupling agents on the oxidation and darkening of cellulosic materials used as reinforcements for thermoplastic matrices in composites
Author(s) -
Urreaga J. Martínez,
Matías M. C.,
De La Orden M. U.,
Munguía M. A. Lechuga,
Sánchez C. González
Publication year - 2000
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.11174
Subject(s) - methyltrimethoxysilane , silanes , materials science , composite material , cellulose , cellulosic ethanol , thermoplastic , polypropylene , silane , wax , polymer chemistry , organic chemistry , chemistry , coating
Oxidation and darkening occur during the processing of composites made from thermoplastic matrices and cellulosic reinforcements. We have studied the effects of several coupling agents on both the oxidation and darkening of cellulosic materials at temperatures close to those used in the processing of cellulose‐reinforced thermoplastics. A maleated polypropylene wax (Epolene E‐43 TM ) and two silanes (N‐2‐aminoethyl‐3‐aminopropyltrimethoxy silane and methyltrimethoxysilane) were used as coupling agents. Oxidation was measured by Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy. Standard colorimetry was used to measure darkening. Coupling agent effects depend on the nature and extent of cellulose modification achieved by treatments and the nature of the coupling agent. Epolene wax E‐43 produced scarce effects on both the oxidation and darkening of cellulosic materials at 200°C. Only for longer oxidation times was an increase in oxidation and darkening observed in E‐43‐treated samples. Silane coupling agents inhibited the formation of carbonyl and carboxyl groups for shorter oxidation times. The diaminosilane produced a stronger darkening, probably due to a chemical reaction that generated new chromophores containing CN bonds.