Preparation And Characterization Of Wood Ceramics Base On Polyarylacetylene Resin

The work in this paper included:(1) Diethynylbenzene was prepared by reaction of bromination addition– dehydrobromination with divinylbenzene and bromine as raw material. The effects of amount of alkali, kinds of catalyst, reaction temperature and reaction time on the yield of diethynylbenzene were investigated. The diethynylbenzene and polyarylacetylene were analyzed by FT-IR and TGA. The results showed there existed two characteristic absorption peaks of diethynylbenzene at 3300cm-1 and 2100cm-1, and higher yield could be obtained with poly (ethylene glycol)-400 as phaset ransfer catalyst; the yield of diethynylbenzene was 67.6%, the char yield of polyarylacetylene was about 83%.(2) The boron phenolic resin (BPF) with high char yield has been synthesized with phenol, formaldehyde and boracic acid. The influences of the mole ratio of formaldehyde, phenol and amount of boracic acid on the char yield of BPF were studied, and the synthesis technology of BPF was determined. Chemical structure and thermal properties of BPF were analyzed by FT-IR and TGA. The results showed that the BPF contained B-O-C bonds and had less instable ether bonds than popular phenolic resin. The maximum thermal decomposition temperature of BPF was 560℃and the char yield was 67.8%. The BPF is suitable for using as the typical precursors to fabricate ablation resistance materials.(3) A certain size fir powder was treated with 20% NaOH solution. The fir powder was analyzed by FT-IR,XRD,TGA and SEM.The results showed that after treatment,there was no vibration absorption peak of the C=O bonds at 1732cm-1of fir powder , which means that the fattiness kind of small molecule compound of fir powder was removed. Cross-porous network structure of the tracheid and the pit of fir powder were clear. The hydrogen-bonds and the crystal structure of lignocelluloses were broken partly. The char yield of treated fir powder was about 24%. (4) Polyarylacetylene resin/fir powder composite was prepared by impregnating and thermoforming, and then a novel woodceramics was obtained by carbonizing the composite under high temperatures.The phase composition, thermal stability and pore morphology of woodceramics were analyzed by FT-IR,DTG.,XRD,LRS and SEM, respectively. The results showed that the woodceramics had been of uniform and three-dimensional porous structure. The decomposition temperatureand char yield of the composite was also much high compared to the polyarylacetylene resin. The interlayer spacing (d 002) of woodceramics minished gradually, the content of graphite crystallite increased, the crystallite sizes (Lc and La) increased in different degree, with increasing of carbonization temperature. The mass ratio of polyarylacetylene resin to fir powder had a great of effects on the sizes and shapes of micropore of woodceramics obviously, but a slight effect on the graphite crystallite sizes of the woodceramics.Boracic acid could effectively enhance the graphitization degree of woodceramics. The linear shrinkage, the volume shrinkage and the thermal weight loss of the composite were 13.7%, 36.8% and 35% when the carbonization temperature was 900℃.The bulk density and compressive strength of the composite increased, the open porosity of woodceramics minished when temperature was above 600℃.