Study on Urea-Formaldehyde Prepolymer and Hot-Press Treatment of Italian Poplar Wood

The purpose of this study was to modify Italian poplar (Populus euramevicana cv. 'I-214') wood with urea-formaldehyde prepolymer followed by hot pressing. The timbers were impregnated with urea-formaldehyde prepolymer using a pulsed-dipping machine and cured in a hot press. The results showed that the timbers could be easily compressed and cured at temperatures between 90 degrees C and 120 degrees C. The characteristics and quality of the modified wood were up to A grade according to Chinese Standard GB/T 6491-1999. The air-dried density of modified wood was improved by 58 percent, and the hardness in the transverse, tangential, and radial directions was increased by 67, 210, and 160 percent, respectively. The bending strength was improved by 78 percent; the bend elastic modulus was improved by 66 percent. The water absorption of treated wood decreased relative to that of the untreated timbers. Fourier transform infrared spectroscopy of the modified wood showed a significant reduction in the C=O absorbance at 1,750 cm(-1). The peak at 1,645 cm(-1) was found to increase as a result of treatment with the prepolymer.