Curing behavior of urea-formaldehyde resin modified with cooking waste oil-based pMDI prepolymer and its influence on particleboard properties

摘要

This research attempted to study the curing behavior of polymeric diphenylmethane-4, 4'-diisocyanate (pMDI) modified with cooking waste oil (CWO) that could replace expensive polyol in the preparation of isocyanate prepolymer. The adhesion propertiesof the isocyanate prepolymer mixed with urea-formaldehyde (UF) resin are also investigated. For this purpose, CWO/pMDI prepolymers with different ratios of CWO to pMDI were prepared, and their chemical structure and adhesive performance were examined byFourier transform Infrared (FT-IR) spectrum and bond strength measurement. The CWO/pMDI ratio with the highest bond strength was selected and mixed with UF resin at four different concentrations. The chemical structures and curing behaviors of CWO/pMDI prepolymers were examined using FT-IR spectrometers and differential scanning calorimetry (DSC). Particleboard (PB) was also produced to evaluate the adhesion strength of CWO/pMDI prepolymers. When the CWO and pMDI were mixed, the -NCO group's peak was detected at 2,008 to 2,543 cm~(-1), and the bond strength was highest when the CWO/pMDI ratio was 1.0. When the UF resin and CWO/pMDI prepolymers were mixed at designated ratios, the -NCO group's peak appeared at 2,270 cm~(-1) and increased as the CWO/pMDIprepolymer content increased. Fastest gel time and lowest on-set and peak temperatures occurred at the CWO/pMDI prepolymer content of 10 %wt, at which both heat of reaction (AH) and activation energy (Ed) also reached their lowest points. PBs manufactured with UF resin-CWO/pMDI prepolymer at different ratios showed an increase in bending and internal bonding properties and a decrease in thickness swelling as the ratio of the CWO/pMDI prepolymer to the UF resin increased. The formaldehyde emission of PBprepared with CWO/ pMDI prepolymers was generally greater than that of the UF resin. In conclusion, the mixing ratio of CWO to pMDI was optimal at 1.0, and the addition of 10 %wt UF resin to the CWO/pMDI prepolymer yielded the best properties of PB.