| This thesis investigated modify process of melamine and formaldehyde after referring to a great deal of domestic and foreign documents. The derivative of polyethylene glycol and melamine (M-PEG) and di-ethylene glycol (DG) were used to modify melamine formaldehyde resin (MF resin). A series of semi-interpenetrating polymer network (semi-IPN) were prepared by incorporating polyvinyl alcohol (PVA) into cross-linked modified melamine formaldehyde resin. The modified mechanism of modifier for MF resin was also discussed.The micro-structure of semi-IPN was studied by FTIR, Raman, TG and DSC. The results showed that M-PEG and DG were successful chemical grafted with melamine, PVA as linear chain has physical crosslinked with modified melamine-formaldehyde resin to build two semi-interpenetrating network structures. The adjunction of PEG has decreased the thermal decomposition temperature of Semi-IPN 50℃, and the adjunction of DG has no effect on the thermal decomposition temperature of Semi-IPN. The effect of M-PEG addition, DG addition, the molar ration of formaldehyde and melamine n(F)/n(M) and reaction time on viscosity, storage stability, solid content of Semi-IPN dope were also studied by orthogonal test. The viscosity can reach at 21350 mpa.s with M-PEG addition at 40%, n(F)/n(M) at 2.0, the reaction time at 180 min, and which can reach at 94000 mpa.s with DG addition at 9 mL, n(F)/n(M) at 2.5, the reaction time at 6 h. The storage stability can reach at 44 h with M-PEG addition at 10%, n(F)/n(M) at 2.5, the reaction time at 270 min, and which can reach at 194 h with DG addition at 15 mL, n(F)/n(M) at 2.0, the reaction time at 6 h. The solid content can reach at 51.2% with M-PEG addition at 40%, n(F)/n(M) at 3.0, the reaction time at 270 min, and which can reach at 62.4% with DG addition at 15 mL, n(F)/n(M) at 2.5, the reaction time at 4h.The thesis forces on the factors for toughness and free formaldehyde content of Semi-IPN. The toughness of Semi-IPN can reach at 20.340 kJ/m2 with the M-PEG addition at 40%, n(F)/n(M) at 2.0, the reaction time at 180 min, and which can reach at 31.200 kJ/m2 with DG addition at 9 mL, n(F)/n(M) at 2.5, the reaction time at 8 h. Free formaldehyde content can be as low as 0.00% with the addition of M-PEG at 40%, n(F)/n(M) at 2.0, reaction time at 270 min, which can reach at 0.15% with DG addition at 3 mL, n(F)/n(M) at 2.0, the reaction time at 6 h. The above-mentioned results has provided a useful reference for the structural evolution and the means of improving toughness and controlling free formaldehyde content. |
