MAN), and styrene-co-acrylonitrile ( 3 : 2; STAN), were prepared by in situ polymerization using gamma radiation or the catalyst-heat treatment. The FTIR spectra of the three types of WPC, with polymer loadings ranging from 10 to 70%, were compared with that of the wood itself and the respective polymers. Characteristic peaks due to C=O vibration of MMA, CEN stretching of acrylonitrile, and ring stretching and bending of styrene monomers, were prominent in the samples that had higher polymer loadings. For the copolymeric systems, quantitation of the FTIR spectra of these characteristic peaks enabled calculations of incorporated acrylonitrile and styrene monomers in the composites to be made, The FTIR spectra of the residues remaining, after exhaustive extraction to remove homopolymer, showed that graft copolymerization of wood components with acrylonitrile and styrene monomers was possible, but not with MMA. Composites prepared by the two methods, gamma radiation and the catalyst-heat treatment, were shown to be chemically very similar. I NTRO DU CTlO NThe impregnation of wood with vinyl monomers followed by in situ polymerization by either gamma radiation or the catalyst-heat treatment, results in composite materials known generally as wood-polymer composites ( WPC ) . WPC exhibited improved strength properties, dimensional stability, and resistance to bi~deterioration.'-~ The extent of improvement in property was directly related to the polymer content, which, in turn, was dependent on the type of wood, the nature of the polymer, and the processing applied.Infrared spectroscopy is widely used to elucidate chemical structures, enabling functional groups and linkages to be identified. Greatly improved spectra of wood and wood products have been reported using Fourier transformed infrared (FTIR) spectropho-* To whom correspondence should be addressed. tometers compared to the conventional dispersive IR instruments. FTIR was used by Faix' as a rapid method for determining lignin in woody materials and in pulps, and Michel17 studied the chemical changes in wood during pulping by FTIR. This study on the characterization of WPC using FTIR complements other investigations on the behavior and properties of WPC prepared from a wide range of Malaysian tropical hardwoods and various vinyl monomers.8-12 In this study, three types of Geronggang-polymer composites, with polymer loadings ranging from 10 to 70%, were prepared and their FTIR spectra compared with that of wood and the bulk polymer. FTIR spectra of residues remaining, after exhaustive extraction of the composites to remove homopolymer, were also determined. The purpose was to obtain information, which would indicate the nature of wood-polymer interactions, i.e., specifically, to determine if chemical linkages between wood cell wall components and the impregnated monomers existed, indicating graft copolymerization. 2083

SYNOPSISWood-polymer composites ( WPC) of Geronggang ( GE; Crutoxylon arborescens) , a light tropical hardwood, impregnated with methyl methacrylate (MMA ) , styrene-co-acrylonitrile ( 3 : 2; STAN), methyl methacrylate-co-bis( 2-chloroethy1)vinyl phosphonate ( 3 : 1; MVP) and methyl methacrylate-co-bis (chloropropyl) -2-propene phosphonate ( 3 : 1; MPP) , were prepared by in situ polymerization using y-radiation or catalyst-heat treatment. Thermal characterization of these WPC by limiting oxygen index measurements (LOI) , thermogravimetry (TG) , and differential scanning calorimetry (DSC) showed that the impregnants greatly modified the wood properties. The LO1 values of the GE-MVP and GE-MPP composites were much higher than that for GE and the other composites, indicating the effectiveness of the phosphonates as flame retardants. Concomitantly, the flaming characteristics also compared favorably against that for GE and the other composites. The decomposition temperature and maximum rate of weight loss determined by TG for GE-MVP and GE-MPP were substantially reduced, whereas the char yields were greatly higher. These observations again indicate that phosphonates imparted flame-retarding properties to their composites. The thermal properties of GE-MMA and GE-STAN composites were not vastly different from that of untreated GE. Flame retardancy in the phosphonatecontaining composites was effected through both the condensed-and gaseous-phase mechanisms due to the presence of phosphorus and chlorine, respectively. Indication of grafting of polymer to wood was found for GE-STAN, GE-MVP, and GE-MPP composites, but not for GE-MMA. Composites prepared by y-radiation or by the catalyst-heat treatment had similar thermal characteristics.

Polybenzoxazine (PBa) composites based on phosphorous-containing bio-based furfurylamine type benzoxazines (D-fu) and bisphenol-A type benzoxazines (Ba) were developed for flame retardation. The structure of D-fu was analyzed by Fourier transform infrared (FTIR) spectroscopy and 1H-NMR spectroscopy. The curing temperature of Ba/D-fu mixtures was systematically studied by differential scanning calorimetry (DSC). Thermogravimetric analysis (TGA) demonstrated the excellent char formation ability of the PBa composites with the addition of phosphorous-containing D-fu. The flame retardancy of the PBa composite materials was tested by the limited oxygen index (LOI), vertical burning test (UL-94) and cone calorimeter (CONE). The LOI and UL-94 level of PBa/PD-fu-5% reached 34 and V0 rate, respectively. Notably, the incorporation of 5% D-fu into PBa led to a decrease of 21.9% at the peak of the heat-release rate and a mass-loss reduction of 8.0%. Moreover, the fire performance index increased, which demonstrated that the introduction of D-fu can diminish fire occurrence. The role of D-fu in the condensed and gas phases for the fire-resistant mechanism of the PBa matrix was supported by SEM-EDS and TGA/infrared spectrometry (TG-FTIR), respectively. Dynamic mechanical analysis (DMA) revealed that the Tg of PBa flame-retardant composites was around 230 °C. Therefore, PBa composites are promising fire-retardant polymers that can be applied as high-performance functional materials.

Phosphated cellulose (PCF) was synthesized based on urea, phosphated acid and cellulose. The structure of the PCF was confirmed by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy coupled with the Energy Dispersive Spectrometer (SEM-EDS). Benzoxazine (Ba)/PCF hybrid materials were fabricated and thermally cured to prepare polybenzoxazine composites (PBa/PCF). The effects of PCF on the curing temperature of Ba were analyzed through differential scanning calorimetry (DSC). The thermogravimetric (TGA) results demonstrated an increased char residue of 50% for the PBa composites incorporating PCF-5% compared with the pure PBa. The peak heat release rate (PHRR) and total heat release (THR) values of the PBa/PCF-5% composites clearly decreased by 58.1% and 16.5% compared to those of the pristine PBa. The smoke released from the PBa/PCF system significantly reduced with the loading of PCF. Moreover, the limited oxygen index (LOI) and vertical burning test level (UL-94) of PBa/PCF-5% reached up to 31 and V0. The flame retardant mechanism of the PCF in the PBa matrix was investigated TG-FTIR and char residues analysis. Finally, the dynamical mechanical analysis (DMA) results demonstrated that the Tg of the PBa/PCF composites was approximately 230 °C, which does not affect further applications of PBa composites.

A silicon-containing benzoxazine (PDpsp-a) was synthesized from bis( p-hydroxyphenyl)diphenylsilane, aniline, and paraformaldehyde. The structure of the monomer was supported by 1H-NMR and FTIR spectra. The curing behavior of benzoxazine was evaluated by differential scanning calorimetry and in-situ FTIR spectra. The thermal properties were studied by MDSC, TGA, and Py-GC/MS. The results indicated that the characteristic peak of oxazine ring began to disappear when the temperature was heated to 180°C and completely disappeared at 260°C. The polybenzoxazine (PDpsp-a) possessed a high glass transition temperatures (174°C) and had good thermal stability (T10 = 420°C). In the pyrolysates of polybenzoxazine (PDpsp-a), no silicon-containing compounds, no phenol species, and more benzene were detected, we speculated that the Ar-Si bond would fracture with the increase of temperature. The benzene was volatilized from the system as a pyrolysis product and the silicon could react with oxygen to form siloxanes remained in the carbon residue in the form of siloxane compounds. The formed silica layer could endow the silicon-containing polybenzoxazine high thermal degradation stability and high char yield.