Study On Carbonization And Composites Of Water Soluable Phenol-formaldehyde Resin

In this paper, the water soluable PF with low free phenol was prepared from formaldehyde and phenol, with barium hydroxide octahydrate as catalyst. The structure and pyrolytic mechanism of the water soluable PF and phosphoric acid modified water soluable PF was studied, and the effect of quantity of phosphoric acid,molar of phenol to formaldehyde and reaction time on char yield was also studied. The results indicate that the char yield of phosphoric acid modified water soluable PF(66.7%at 850℃) is higher than water soluable PF(55%at 850℃), which is due to an increase in aromaticity by addition of phosphoric acid, resulting in low amount of decomposition at elevated temperature.Three kinds of water soluable PF modified by phosphoric acid with highest char yield were chosen, the structure of residual carbon of them at high temperatures were studied. The structure of residual carbon was characterized by scanning electron microscopy and X-ray diffraction, the results show that the residual carbon of water soluable PF without phosphoric acid at high temperatures have smooth and glassy surface, X-ray diffraction demonstrated that the residual carbon was a typical crystalline carbon,the arrangement of carbon was well-ordered;The residual carbon of water soluable PF with phosphoric acid at high temperatures have the features of typical amorphous carbon,there are lots of pits and cracks in the surface.Composite laminate reinforeced with water soluable PF impregnated glass fiber was made in this paper,The influence of E-glass fiber and C-glass fiber on the flexural strength of Composite laminate was studied.The effect of PVA on the impact strength of sheet impregnated with water soluable PF was also studied. The results show that there is relatively great effect of PVA on the water soluable PF when the molar of phenol to formaldehyde was 1:3,and the toughness of composite laminated was improved greatly.