in this study, the particleboard was made with rice husk and urea formaldehyde resin of 7, 8, 9 and 10 percent (based on dry weight of rice husk). to improve mechanism of bondability a definite amount of isocyanate resin is introduced to replace the same amount of urea formaldehyde resin. the effect of urea formaldehyde resin and diisocyanate content on bondability was evaluated by studying the...

this paper reports on formaldehyde exposure and its health hazards in a melamine manufacturing industry. the mean of workers' exposure was measured according to 3500 njosh and was found to be 1.44±o.2l, and 2. 17±o.24 ppm in morning and evening shifts, respectively. for stationary ones it was 1.37±o.20, and 2.06±o.25ppm, respectively. the results show that formaldehyde concentration at the...

This study reports the results of a study aimed at reducing the free formaldehyde content of Phenolformaldehyde resin by using Urea as means for forming a reversible adduct with formaldehyde. The highly volatile formaldehyde has an unpleasant odour and irritates the eyes and nasal passages. The free formaldehyde content (FFC) of the modified resol resin was determined by titration method. With ...

Three formaldehyde-based resins were prepared: urea-formaldehyde (UF) resin without melamine modifier (named UF0 resin) and melamineurea-formaldehyde (MUF) resins with melamine modifier added at two different synthesis stages (named MUF1 resin and MUF2 resin). The effects of the melamine addition stage on the performance and curing behavior of MUF resin were studied. Three-ply plywood bonded by...

We report the cases of three subjects who developed asthma after being exposed to formaldehyde dust or gas. For two subjects, specific bronchial provocation tests with formaldehyde gas did not cause significant bronchoconstriction, whereas exposure to formaldehyde resin dust did. One subject experienced asthmatic reaction after being exposed to formaldehyde resin dust and gas. These findings su...

Three types of adhesives, urea-formaldehyde (UF) resin, phenol-formaldehyde (PF) resin, and polymeric methylene bis(phenyl isocyanate) (pMDI), were used for investigating the effect of pressing variables on volatile organic compound (VOC) emissions. The variables examined included press temperature and time, mat moisture content and resin content, and board density. The VOCs emitted during part...

the acrylated epoxidized soy oil (aeso) was synthesized from epoxidized soy oil and its properties were investigated.  wheat straw particle boards were produced by the synthesized resin with 8% and 13% contents based on straws weight at three pressing times: 8,10 and 12 min. boards’ modulus of rapture, modulus of elasticity, internal bonding, minimum degree of thickness change and water absorpt...