JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS Vol. 9, No. 4, April 2007, p. 923 - 930 Two dimensional infrared correlation spectroscopy studies of wood-plastic composites with a copolyamide as matrix M-C. POPESCU * , M. ZANOAGA, Y. MAMUNYA a , V. MYSHAK a , C. VASILE Romanian Academy, “Petru Poni” Institute of Macromolecular Chemistry, 41 A Grigore Ghica Vodă Alley, Iaşi, Romania a Institute of Macromolecular Chemistry, 48 Kharkivske Shausse,02160 Kiev, Ukraine The natural polymer/synthetic polymer combination offers an attractive solution to create environmentally friendly degradable materials, which should not have negative effects on the environment. A modern solution to create such of materials consists in using natural fibres as reinforcement agent in composites applicable in various fields as automotive industry, building, etc. Their performance strongly depends on solid reinforcement-polymer matrix adhesion that determines stress transfer between the phases. Fourier-transform infrared (FT-IR) spectra and generalised two-dimensional (2D) correlation spectroscopy have been applied to analyse the composition-dependent spectral variations in wood thermoplastic composites, emphasising on components’ interactions. In the present work the wood-plastic composites with a copolyamide as matrix and different contents, varying from 30% to 70% of wood chips have been studied. Significant modifications are evidenced in 2800-3600 cm -1 and 800-1800 cm -1 regions. Detailed analysis of the spectra in respect with those of the components and calculated ones indicated that the interaction between wood and copolyamide is relatively strong. The 2D synchronous correlation analysis allows the separation of the bands of wood from those of copolyamide and clearly evidenced new spectral features in composite materials. Moreover, the 2D asynchronous correlation analysis produces cross-peaks those are indicative of the specific interaction or the conformational changes in the blends. (Received November 2, 2006; accepted February 28, 2007) Keywords: FTIR and 2D-correlation spectroscopy, Copolyamide, Wood chips 1. Introduction Generalised two-dimensional (2D) correlation spectroscopy, [ 1] which is an extension of the original 2D correlation spectroscopy proposed by Noda in 1986 [2-4] has received great attention in the last decades. This novel 2D-correlation method can be applied to analyse the spectral signals that change as functions of not only time but also any other kinds of reasonable physical variables, such as temperature, pressure, concentration, and composition. Generalised 2D correlation spectra emphasise spectral features not readily observable in conventional one-dimensional spectra. It can also probe the specific order of certain spectral events taking place with the development of a controlling physical variable. The type of spectral signals analysed by the newly proposed 2D-correlation method becomes virtually limitless, ranging from IR and Raman spectroscopy to X- ray and fluorescence spectroscopy. Many applications of generalised 2D correlation spectroscopy have been reported, including temperature-dependent spectral variations, [5-10] concentration-dependent spectral changes [11,12] and 2D IR and Raman heterospectral correlation analysis, [13] as well as 2D near-infrared (NIR) and mid-infrared heterospectral correlation analysis [14]. Following the pioneering work of Noda [1-4], many research groups have adopted 2D correlation analysis to study e.g. self-associated molecules [15], polymers [16-18], liquid crystals [19-21], Langmuir–Brogett films [22] and biological molecules, such as peptides [9] proteins [23-25], cellulose and wood [26-31], etc. The birth of the wood polymer composite (WPC) industry involved the interfacing of two industries that have historically known little about each other and have very different knowledge, expertise, and perspectives. The industry was reluctant to use wood fillers, because these fillers are inexpensive, renewable, biodegradable, have lower density than mineral fibres, and are less abrasive to processing equipment than conventional fillers. Most plastic processors ignored wood fillers because of their low bulk density, low thermal stability, and tendency to absorb moisture. Today, there is a considerable commercial interest in thermoplastic composites filled with wood waste, due to potential opportunities of combining the attractive characteristics and properties of both components. The product developed has the aesthetic appearance of wood and the processing capability of thermoplastics. The material can be considered as an easily attainable (natural) option, is competitive as far as price is concerned and convenient for a wide range of applications. Raw material costs outstanding product properties and new design possibilities are the drivers of these new composites. In many cases either the fibres (such as wood, flax, hemp, jute, kenaf) or the polymers (such as polyethylene, polypropylene, polyamide, polyvinyl chloride, polystyrene), can come from residues and vegetable materials, respectively. The total market for WPCs in North America is forecast to grow at an average annual rate of 14% through the remainder of the decade. In Western Europe the market for WPCs is still in its infancy. The current European WPC producers come from a variety of backgrounds, with