Hai Yan Tan

Preparation of Plywood Using Starch Adhesives Modified with Isocyanate

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.

Study on Film of Polyvinyl Acetate Emulsion Modified by Starch

The use of starch on polyvinyl acetate emulsion blend modified in order to achieve improved film toughness, which aims to improve water resistance and film-forming emulsion adhesive performance. Dynamic mechanical properties (DMA), scanning electron microscopy (SEM) method was used to analyze the dynamics of film emulsion blend composite mechanics, the distribution of latex particles and glass transition temperature. The results show that: with pure polyvinyl acetate (PVAc) compared to starch-modified film-forming emulsion film distribution, glass transition temperature of the homopolymer emulsion up to 30°C.

Preparation of the Plywood Using UF Resin Modified with Blocked Isocyanates

The plywood was prepared using the UF resin modified with isocyanate blocked by sodium bisulfate in this paper. And the effects of the ratio of UF resin and blocked isocyanate, hybrid method and the additive on the properties of the plywood were also studied. The results showed that under the condition of BPI / UF =5%, the order of urea-formaldehyde resin mixed mode curing agent, additive and finally joined the BPI , the bonding strength of the plywood was improved obviously and the formaldehyde release of the plywood could achieve the demand for the national standard.

The Impact of Different Dosage of Additives on the UF Resin Used in Plywood

Through the study of the effects of different dosage of additives on the properties of urea formaldehyde resin adhesive prepared at low mole ratio of formaldehyde/urea, optimize the synthetic process of the UF resin which is used at the E0 grade plywood. The results showed that the product synthesized under the following condition: the mole ratio of formaldehyde/urea is 0.99:1, the dosage of the specific additive is 1.0% and that of melamine is 3-4%, had a good comprehensive performance and the formaldehyde emission of the plywood meets the E0 grade which is environmental-friendly.

Mechanical Properties of Wheat Straw Particleboard Using Composite Adhesives

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.

Preparation of Particleboard Made from Wheat Straw with Low-Formaldehyde-Emission Composite Adhesive

This research attempted to prepare the E0 type wheat straw particleboards with low emission formaldehyde composite adhesive. The composite adhesive combined UF resin and blocked polyisocyanate with low deblocked temperature was synthesized with sodium bisulphate as blocking agent. The effects of different blocking agents, mol ratio, reaction temperature and time on block reaction were studied. The influence of mixed ratio of composite adhesive on the performance of wheat straw particleboard was investigated.

Mechanical Properties of a Sandwich Construction Material with Paper Honeycomb Core

In this paper, sandwich construction was made up of wood surface sheet and paper honeycomb core. Some cores were impregnated with phenolic resin. Compared to untreated honeycomb materials, impregnated honeycomb core greatly improved the mechanical properties of sandwich construction composites. The results of the study showed that, sandwich construction with phenolic resin treated honeycomb core had higher bonding strength than those bonded with isocianate resin. With the increasing of honeycomb core thickness, sandwich composite material decreased in flat pressure strength, side pressure strength, and flexural properties. The results we got in this research would provide a very good reference to the application of sandwich construction with honeycomb core.

Carbon Sequestration Analysis of Wood Construction Architecture

Carbon in wood accounted for 50% of oven dry weight, and wood construction architecture consumes less energy than any other material architecture. Through using drying of wood, fire-retardant, wood preservative and other protective treatment for the materials of wood construction architecture can extend service life of wood construction architecture and increase carbon storage. This article based on the processing characteristics of wood, estimated carbon storage and carbon emissions of the wood construction architecture, conclude that wood construction architecture has significant influence on the greenhouse effect and the recycling of carbon sequestration.

Preparation of Water-Resistance Plywood with UF Resin Modified by Emulsifiable Polyisocyanate

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.

Study on Characteristic of Aqueous Polymer Isocyanate Curing Reaction

In this study the effect of isocyanate at room temperature on the curing behavior of PVAc was investigated. Crosslinking reactions are one of the most commonly used techniques to improve physical properties of PVAc. Commonly used crosslinkers for these reactions have high reaction activity such as isocyanate. Quantitative analysis of isocyanate with PVAc will be described in this report. A XPS technique has been established to analyze structure of crosslinking in PVAc. And physical property analysis will also be described.