Presently WPCs are developed through either of a non reactive or reactive process. A non reactive process is based on extrusion of wood flour with thermoplastic or thermosetting polymers. Non reactive process delivers highly finished panels of WPCs for immediate applications [3-4]. A reactive process involves infusion of monomers along with co monomers, coupling agents, initiators into properly shaped wood panels swollen in organic media followed by thermal or radiation polymerization [5]. Reactive method delivers WPCs with improved mechanical, thermal dimensional stability and microbial resistance. Many of low grade wood varieties viz; Akamatsu pinus and Cryptomeria japonica, Birch, Poplar-alder, Eucalyptus, Cedar, spruce and beech has been modified using vinyl monomers with acrylate, methacrylate functionalities and styrene [5-8].In this context, a few efforts on development of WPCs using AN has been documented [9-2].Development of wide variety of WPCs from different wood varieties has made difficult to discuss their relative performance and stability. The properties and applications of WPCs are best defined on the basis of their method of processing, product design, service environment, physical and biological durability of wood substrates, reinforced polymer and their mutual compatibilities [3-4].
Socio-economic benefits associated with cultivation of MW for production of nutritious fruit and use of hardwood as construction materials [5-8] and pharmaceutical applications [9] has been realized by many ancient civilizations. Vegetating mango trees suffer from invasion of microorganisms [20], that on harvesting delivers deteriorated wood. Harvested MW exposed under humid environments suffers from dimensional instability, breaking or cracking [2], wherein the wood texture is protected through application of coating finish, that often discolors the texture and native color of MW. [22-23]. For such reasons, MW has been the subject of modification through reinforcing polymer materials. A combined documentation of existing reports interestingly reveals that AN as a monomer has been used for modification of limited number of wood varieties [9-2], no reports are available on modi
fication of MW 2,2-azobisisobutyronitrile (AIBN) assisted through reactive reinforcement of PAN. In the present work, a simplified and straight forward method of synthesis of WPCs has been developed through reactive reinforcement of PAN into MW (Mangifera Indica, family Anacardiaceae). Wood and respective WPCs were collectively defined as specimens and were investigated for their mechanical, thermo-oxidative stability, fungal degradation and solubility behavior. AN and AIBN were procured from Ms Sigma Aldrich. AN and purified through multiple number of extractions with aqueous sodium hydroxide solution (0%), followed by washing with distilled water. Fraction of AN collected at 780C was used for development of WPCs. Rest of the chemicals and solvents involved in the study were locally purchased with purity > 98% and were used without further purifications. Planks of MW were fabricated into dimensions as per guidelines of S 708 66, WPCs were prepared through modifications in the early protocol of wood treatment. [9, -2]. A representative protocol demonstrates steps of soxlet extraction of properly finished MW planks in required dimensions (moisture content:2.5%) with toluene: ethanol mixture (2:,v/v) over 0h , followed by thermal aging at 95±0C and subsequent leaching with water over additional 0 h. The conditioned MW planks were then swollen in methanolic solution of acrylonitrile (20-60%,v/v) supplemented with 2,2-azobisisobutyronitrile (.0% w/v) at 30 ± 0C 48h. The treated MW planks were subjected to heat curing at 80 ± 0C over subsequent 3h to derive the WPCs. PAN loading (%) into MW was calculated on the basis of dry weights of unextracted MW and corresponding treated specimens [9]. Electron micrographs of gold coated specimen were scanned at 50x magnifications over LEO-435. Compression and static bending strength of specimen were evaluated over ENKAY-UT-40 Universal testing machine with capacity of 40 tons and least count of 80 kg. Impact testing was carried out over indigenous swinging pendulum machine. Moisture content (ASTM D037 72a 79), solubility of WPCs in hot water, NaOH (%), organic media (ASTM D 09 56 72) lignin content (ASTM D 06-56) were investigated.