The purpose of the study was to manufacture water-resistance plywood with using UF resin modified by emulsifiable polyisocyanate. The emulsifiable polyisocyanate which contains plenty of hydrophilic segments and teminal isocyanate groups were synthesized by reaction between various kinds of polyether polyols and polymeric methane dipthenyl diisocyanate (pMDI). A type of composite adhesive was obtained from the mixture of emulsifiable polyisocyanate and urea formaldehyde resin. The process parameters, such as the molar ratio of –NCO and –OH, mass fraction of emulsifiable polyisocyanate in UF resin and accessory ingredient have a great influence on the composite adhesive. X-ray photoelectron spectroscopy (XPS) had been used to analyze the chemical structure of bonding interface. The results showed that the composite adhesive consisting of UF resin and emulsifiable polyisocyanate content of 7.5% and kaolin content of 1.5% was used in plywood with high physical and mechanical properties, water resistance and low formaldehyde emission.

The purpose of the study was to manufacture plywood using starch adhesives modified by isocyanate, the influence factors on the bonding strength and water resistance of starch adhesive were studied by different solid content, adding additives and adding isocyanate. X-ray photoelectron spectroscopy (XPS) analysis was used to characterize the chemical structure of bonding interface. The results show that the bonding strength of starch adhesive was increased significantly when solid content increased to 50%. Bonding strength and water resistance were improved significantly by adding additives and isocyanates to starch adhesive. The analysis of XPS indicated that the chemical bonding derived from the reactions of isocyanate was the key factor to increase bonding strength and water resistance.

Three different nondestructive testing (NDT) methods were used on the wood-plastic composites (WPC), which were made of either recycled or virgin high-density polyethylene (HDPE) with poplar fibers as filler. The values of dynamic Young’s modulus of WPC based on recycled or virgin HDPE were measured by the different NDT methods, and the values of static bending modulus of elasticity (MOE) were also determined by three point bending test according to ASTM D790-03. The paper analyzed the variability of the dynamic young’s modulus of WPC based on recycled or virgin HDPE obtained with different NDT methods, and the correlativity was also estimated between the dynamic Young’s modulus and the static MOE of WPC based on recycled HDPE. These results suggest that WPC can be made of recycled HDPE, and the NDT methods can be appropriate to estimate the dynamic Young’s modulus of WPC based on recycled HDPE.

Polyvinyl acetate（PVAc）hybrid emulsions with nanoparticles SiO2 were prepared by the semi-continuous seeding emulsion polymerization. The micro-morphologies of the hybrid emulsions, the diameters and distributions of the latex particles were characterized with the aid of scanning electron microscope (SEM) and diameter analyzer. Adhesive properties of hybrid emulsions and the properties of the emulsion films were determined by mechanical properties tester and dynamic mechanics analyzer (DMA). And the rheological behaviors of hybrid emulsions were measured via rheometer. SEM and diameter analysis showed that the process of the nanoparticles SiO2 by ultrasonic made a good dispersibility of latex particles in emulsions, diameters of the latex particles were 0.68~0.89μm with the content of SiO2 from 0 to 1.0% (% in relation to the total mass VAc), and indexes of distributions of particle size were increased with the increasing of the content of SiO2 from 0 to 1.0%. Adhesion strengths of PVAc emulsions modified with nanoparticles SiO2 were improved. DMA results indicated that the films of PVAc/SiO2 hybrid emulsions had the higher storage modulus than the film of PVAc, the temperatures of glass transition of the films of PVAc/SiO2 hybrid emulsions were not changed obviously, and the water absorptions of films were decreased. Rheological results revealed that flow consistency indexes were increased then decreased with the increasing of the content of SiO2 from 0 to 1.0%, and PVAc/SiO2 hybrid emulsions were typical pseudoplastic fluid.

The purpose of the study was to use a cheap wheat straw to manufacture particleboard. Wheat straws offer great promise and new challenges as replacement for wood in processed wood products. The particleboard was produced using composite adhesive which the urea-formaldehyde (UF) adhesives modified by emulsifiable polymeric methylene diphenyl diisocyanate (EPU). The properties of the particleboard was evaluated by measuring internal bonding strength(IB), thickness swelling, modulus of rupture(MOR), modulus of elasticity (MOE) and formaldehyde emission. The optimal condition was chosen at density of 0.75g/cm3, UF/EPU ratio of 70/30, adhesive amounts of 10% based on the dry amounts of wheat straw. The test results showed that maximum dry internal bonding strength, wetting internal bonding strength, modulus of rupture, modulus of elasticity was 0.45MPa, 0.072MPa, 31.50MPa and 4564MPa, respectively. The thickness swelling (TS2h) and thickness swelling (TS24h) was 3.51% and 11.1%, respectively. The free formaldehyde of wheat straw particleboard reached E0-type national standards.