Papers by Author: Shi Feng Zhang

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Authors: Xiao Ying Liu, Ji Zhi Zhang, Yong Lin Yang, Shi Feng Zhang, Jian Zhang Li
Abstract: The effect of melamine content in melamine modified urea formaldehyde (MUF) resin on durable properties of plywood was investigated using ammonium chloride (NH4Cl) with different melamine/urea (M/U) ratios. The plywood specimens were exposed to laboratory accelerated aging and/or cyclic soak-dry (SD). The experiment results indicated that the melamine contents in MUF resin showed an unobservable effect on the durable properties of MUF resin bonded plywood. The mechanical properties of plywood decreased more severely after accelerated aging test in acidic condition. However, the influence of different curing catalyst contents on mechanical properties and formaldehyde emission of UF resin can be minimized by adding melamine to the resin.
3160
Authors: Shi Feng Zhang, Jian Zhang Li, Xiao Ying Liu, Yan An Ou, Qiang Gao
Abstract: For increasing the curing rate and decreasing the curing temperature, modified phenol-formaldehyde (PF) resins were synthesized under a complex catalyst. The bonding strength and formaldehyde emission of the plywood bonded by them were measured according to Chinese National Standards methods. The curing behavior was conducted by differential scanning calorimetry (DSC) measurement. The results indicate that PF resins catalyzed by the complex catalyst show more moderate pH values, lower curing temperature and shorter gel time comparing with control ones. Plywood bonded with modified PF resins shows good bonding strength and low formaldehyde emission even at low hot press temperature (110 °C), which is closed to the plywood bonded with normal control PF resin at high hot press temperature (130 °C).
2124
Authors: Qiang Gao, Yao Hui Dong, Shi Feng Zhang, Jian Zhang Li
Abstract: For manufacturing high mechanical properties and environmental-friendly particleboard, a formaldehyde-free soybean meal (SM)-based adhesive was developed and applied in the mechanical manufacture of particleboard. The thermal behavior of the adhesive was investigated and the properties of the particleboard were tested according to Chinese Standards methods. The results show that the optimum technical parameters were: hot-pressing temperature was 180 °C, hot-pressing time was 65 s/mm, moisture content was 12 %, and glue content was 15 %. The MOR and IB of particleboard were 20.6 MPa and 0.59 MPa respectively. It fully fits the Chinese National Standards GBT 4897.5-2003. Therefore, it is a practical way for manufacturing environmental friendly particleboard by SM-based adhesive.
2085
Authors: Qiang Gao, Rui Dang, Zi Tao Sang, Shi Feng Zhang, Jian Zhang Li
Abstract: For developing high bonding strength and environmental-friendly wood composites, a soybean/PF resin based (SP) adhesive was investigated and applied in the manufacture of plywood. Formula of the adhesive, the thermal behavior of the adhesive, and the optimum technical parameters of the plywood manufacture were investigated. The bonding strength and formaldehyde emission of plywood bonding by the adhesive were tested according to Chinese Standards methods. The result shows: the optimum formula of SP adhesive was: soy-based adhesive was 70%, PF resin was 30%; the optimum technical parameters of the plywood manufacture were: hot-pressing temperature was 160 °C, hot-pressing time was 80 s/mm, pressure intensity was 1.2 MPa, and glue content was 160 g /m2; Properties of plywood made under the optimum technical parameters were: the bonding strength was 1.30 MPa, the formaldehyde emission was 0.32 mg/L. It completely meets the type Ⅰ plywood requirement and level E0 of formaldehyde emission.
2007
Authors: Zi Tao Sang, Shi Feng Zhang, Qiang Gao, Jian Zhang Li
Abstract: In this study, a sodium hydroxide modified soybean protein adhesive (NSP adhesive) was prepared and mixed with phenol-formaldehyde (PF) resin in a ratio of 7:3 to form a compound adhesive (NSPF adhesive), and three-layer plywoods were prepared using the NSP adhesive and the NSPF adhesive. In order to understand the reactions between SP and PF resin during the curing process of NSPF adhesive, the SEM and FTIR spectra were employed to character the adhesives and the bonding strength of the plywoods was measured. The results showed that the bonding strength of the poplar plywood prepared with NSPF reached 1.00 MPa, and met type I plywood requirement in GB/T 17657-1999. There was new absorption peak appear at 1390 cm-1 in the FTIR spectra of NSPF adhesive, indicating that there were -NHCH2- structures generate in NSPF during the curing process in this research.
706
Authors: Shi Feng Zhang, Lu Lu Zhou, Qiang Gao, Xu Xia Guo, Li Ou Chen, Chun Rui Han, Jian Zhang Li
Abstract: For improving the performance of acorn starch (AS) based bio-adhesive, AS graft glycidyl methacrylate (AS-g-GMA) adhesive was prepared in this paper. The properties of the AS-g-GMA adhesive were studied by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) measurement. The bonding strength of the plywood bonded by AS-g-GMA adhesive was measured according to Chinese National Standards methods to evaluate its water resistant. FTIR results indicated that GMA was grafted on the AS successfully. The bonding strength of the plywood bonded by AS-g-GMA adhesive showed lower curing temperature, better bonding strength, and water resistance comparing with that of control. The water resistant could reach type II grade (63°C water bath 3h) plywood requirement when the glycidyl methacrylate adding amount was 6% based on AS.
293
Authors: Lu Lu Zhou, Chun Rui Han, Shi Feng Zhang, Qiang Gao, Hong Yan Li, Jian Zhang Li
Abstract: A friendly environmental wood adhesive was prepared using wild acorn starch as a raw material. The physical properties of wild acorn starch were investigated by scanning electron microscope (SEM) and brookfield viscometer. The polyvinyl acetate emulsion and isocyanate were employed to prepared modified wild acorn starch adhesives. The plywoods were prepared using the adhesives and their bonding strength was measured. The experimental results showed that 1) the wild corn starch was adaptive for preparing adhesive; 2)the optimum preparing conditions of the modified wild acorn starch adhesive were as follows: the mass ratio of acorn starch/water/modifing agent was 8/9/3, the addition amount of viscosity reducer was 0.6%, the mass proportion of polyvinyl acetate emulsion/starch adhesive was 1/1, the addition amount of isocyanate was 15% weight of starch adhesive. The plywood using the adhesive prepared at the optimum condition was 0.9 MPa, could meet the type ⅡChinese Strandard plywood requirement.
2834
Authors: Shi Feng Zhang, Fei Song, Qiang Gao, Jian Zhang Li
Abstract: In order to improve the flame resistance and reduce the formaldehyde emission of plywood, a multifunctional formaldehyde scavenger with flame resistance (FSFR) was prepared and used to treat plywoods bonded with high molar ratio urea-formaldehyde (UF) resin. The weight percent gain (WPG), formaldehyde emission, oxygen index (OI), and bonding strength of plywoods after FSFR treated were measured to evaluated properties of FSFR. The results showed that the formaldehyde emission of the treated plywood was 0.1-0.32 mg/L, which could meet the E0 grade requirement (<0.5 mg/L ). The flame resistance of treated plywood increased significantly and the bonding strength changed little. The formaldehyde emission decreased 96.8 % and OI increased 47.2 % and the bonding strength kept unchanged when FSFR reached 8.87 % compared with that of untreated plywood.
649
Authors: Ji Zhi Zhang, Jian Zhang Li, Shi Feng Zhang
Abstract: This study modified urea-formaldehyde (UF) resin with a modifier, and focused on properties of particleboard manufactured with the modified UF resin. The orthogonal design was used to analyze the effects of different levels of hot-pressing temperature, hot-pressing time, glue content, and waterproof agent content on the modulus of rupture (MOR), internal bonding strength (IB), and formaldehyde emission (FE) of the particleboard, and thus determined the optimum technical parameters of hot-pressing. The conclusions were as follows: (1) the modifier used in this study could significantly reduce the free formaldehyde content of UF resin and the formaldehyde emission of particleboard; (2) the optimum hot-pressing technical parameters of particleboard manufactured with the modified UF resin were hot-pressing temperature 180°C, hot-pressing time 50s/mm, glue content 12%, and waterproof agent content 0.6%. The MOR and IB under the optimum technical parameters could reach 20.7 and 0.47 MPa, and the FE was 0.85 mg/L.
1135
Authors: Ya Kai Feng, Shi Feng Zhang, Li Zhang, Jin Tang Guo, Yong Shen Xu
Abstract: In this paper, the release of model drug aspirin (ASP) from biodegradable polyesterurethane networks was studied. Poly(D,L-lactide-co-glycolide)urethane (PULG) networks were prepared from hydroxyl telechelic star-shaped oligo(D,L-lactide-co-glycolide) coupled with 1,6-diisocyanate-2,2,4-trimethylhexane and 1,6-diisocyanate-2,4,4-trimethylhexane or isophorone diisocyanate. PULG networks turned from transparent to opaque after ASP loading. PULG networks with lower crosslinking density always resulted in higher drug loaded content. The results of differential scanning calorimetry (DSC) and scanning electron microscope (SEM) measurements demonstrated that ASP was uniformly distributed in the networks. The drug release courses of ASP from PULG networks in phosphate buffered saline pH = 7.0 at 37 °C could be divided into three stages. Firstly, ASP release was at approximately uniform rate from PULG networks; Secondly, the release rate obviously increased for the degradation of the PULG networks; Thirdly, the release rate decreased gradually because most of the ASP had diffused out of the PULG networks. The crosslinking density of polyesterurethane networks also affected drug release rate. The in vitro release test revealed that ASP accelerated the degradation process of PULG, which exhibited a typical erosion-controlled release mechanism.
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