Papers by Keyword: Phenolic Resin

Abstract: The pyrolysis of phenolic-formaldehyde (PF) resin was studied by TG-MS technique. The structure changes of pyrolysis of PF resin heated to different temperatures were investigated by Fourier-transform infrared rays (FTIR). The experimental results shows that the pyrolysis of PF can be divided into three stages. Ether bonds and unreacted terminal hydroxymethyl groups of the cured resin degradate in the first stage. In the second stage, crosslinks are broken, involving formation of a thermally crosslinked intermediate structure and the breaking of methylene bridges into methyl groups. Cyclodehydration and forming char of phenolic hydroxyl occurs in the third stage. The thermal stability and char yield of resin are depended on the pyrolysis of methylene bridges.

Abstract: A new route for improving the thermal property of phenolic resin was described. Firstly, a soluble preceramic polymer was synthesized by condensation polymerization of zirconium oxychloride, salicyl alcohol and acetylacetone in the presence of triethylamine at room temperature. A modified phenolic resin was then obtained via blending the preceramic polymer and phenolic resin in solution. The preceramic polymer was characterized by FTIR, NMR and GPC. The thermal property of the modified phenolic resin was also investigated by TGA. It was found that the preceramic polymer was composed of Zr-O-Zr as the main chain and the ligands (salicyl alcohol and acetylacetone) as the side chain. It pyrolyzed completely at 600°C and formed ZrO2 in nitrogen atmosphere. The results of TGA indicated that 5 wt% preceramic polymer could increase the thermal decomposition temperature and the char yield of the modified phenolic resin by 18°C and 25%, respectively. Moreover, the preceramic polymer allowed the char formation from phenolic resin at relatively low temperature.

Abstract: This paper introduced the preparation method of PF-CaCO3/fast-growing poplar composite. Adopting AFM, DSC and SEM samples characterization methods was to explore the intersolubility of this PF and nano-CaCO3. And WPG and contact angles of treated veneers were measured. The results showed that this treatment method improved greatly density and hydrophilic of poplar veneers.

Abstract: This paper introduced common special effects of nano-CaCO3 with nanometer materials and prepared nano-CaCO3 using the raw material, CaCl2 and (NH4)2CO3 and surfactant, appropriate organic matter. The intermiscibility of Phenolic resin and CaCO3 was preliminarily researched and the distribution, morphology and size and of nano-CaCO3 were characterized and analysed by sample characterization methods.

Abstract: In this research, two buildings were constructed using phenolic insulation along with considerations of various experimental elements and condition. These environmental factors include natural ventilation, forced ventilation, the mist system, and shading. The results show that when the building is well insulated, the heat transported across the well is effectively prevented indicating that the phenolic resin is effective in insulating the building. Under full sunshine, the room temperature is 10 °C lower than the ambient temperature under full sunshine with the best insulation effect observed at 10:00 am. Shading will provide additional insulation effect to lower the room temperature by 3 °Cmore; the insulation efficiency can also be improved by ventilating the room. Results at 12:00 noon show that shading can effectively reduce solar radiation on the wall whereas force ventilation will carry away heat to reduce the room temperature. Shading will always be effective in reducing the room temperature by about 4 °C, and at 14:00, forced ventilation is the most effective in lowering the room temperature.

Abstract: Millimeter size Hollow carbon spheres (HCSs) with high specific surface area were successfully prepared from resole-type phenolic resin by suspension polymerization method at ordinary pressure. During the polymerization process, large sums of small molecule gathered at the center and formed the hollow part, bigger spheres with a broad size distribution were then formed under stirring force and surface tension, the maximum external diameter of the obtained HCSs was 1.2mm and the hollow diameter was about 0.35mm. After activating at 800°C under a stream of steam, the specific surface area and total pore volume of the HCSs were reached as 1117m²/g and 0.61cm³/g.

Abstract: LiMn_1-xMg_xPO₄/C(x=0, 0.01, 0.04, 0.05, 0.1) were synthesized by using wet-ballmilling and solid-state calcining with phenolic resin as the carbon source. All samples are single phase with a similar morphology, but the cation substitution results in a crystal lattice shrink because of the smaller ionic radii of Mg²⁺, the particles are small and homogeneous. CV, EIS and charge/discharge measurement shows that the Mg substitution leads to a significantly increased reversible capacity due to the enhanced electrochemical kinetics. LiMn_0.96Mg_0.04PO₄/C calcined at 600°C has a discharge capacity of 144mAh/g at 0.05C. When charging-discharging by CC-CV-CC mode at high rates, LiMn_0.96Mg_0.04PO₄/C composite exhibits a good cycle and rate performance.

Abstract: SiC powder can be produced generally through the Acheson process and it is required long carbothermic reaction time of SiO2 with carbon powder around 2200 °C ~ 2400 °C. Due to the high reaction temperature and long reaction time of the process, the powders produced have a large particle size and consist of mostly alpha phase SiC. Synthetic temperature of beta phase SiC powder is known to produce at 1700 °C ~ 1900 °C which is lower temperature than that of alpha phase SiC powder. We prepared β-SiC powder by heating precursor derived from the mixture of phenolic resin and tetraethyl orthosilicate. The precursor was heated at 1800 °C for 4 h in an Ar atmosphere. In order to examine the pyrolysis residue after the heat treatment, the SiC powder was analyzed with XRD and SEM. The X-ray diffraction result of the SiC powder shows the diffraction peaks around 35°, 60°, and 73° corresponded to the beta SiC phase. β-SiC powder prepared in this study contains lower metallic impurities compare than that of α-SiC powder prepared from Acheson method and is able to use as a good starting material for SiC single crystal growing.

Abstract: A phenolic resin-bonded cubic boron nitride (CBN) wheel was designed and manufactured for precision grinding ferrous materials. The resin was determined to be a linear phenolic resin pre-polymer added with hexamethylenetetramine by infrared spectrum and the curing reaction, which characterized by an exothermic peak at about 180°C with release of NH₃, was analyzed by differential scanning calorimeter and thermogravimetry. Based on thermal analysis, a hot press forming process and a post thermal treatment were employed for fabricating the resin-bonded CBN wheel. Grinding experiment results showed that normal grinding forces vary from 7 to 11 N and fluctuate slightly with 1~2 N. The grinding ratio of 585 and the surface roughness of 0.18 μm were obtained under an appropriate grinding condition.

Abstract: With increasing concern about the protection of the environment and the shortage of petroleum resources, the synthesis of polymer materials from renewable biomass resources has attracted a lot of attention. Starch based phenolic resin was prepared via hydrolyzation and condensation of starch at different temperatures from 120 °C to 200 °C. Gel time, apparent activation energies for curing reaction, impact strength, crystal structure and thermal resistance were studied. The results showed that: (1) the apparent activation energy for curing reaction was 19.8 kJ/mol; (2) crystal structure changed as a function of starch hydrolysis; (3) electron microscopy showed the disappearance of starch during the hydrolyzation; (4) the impact strength of starch based phenolic resin was 741 J/m² and residual mass at 600 °C was 40%. These results were compared with those of formaldehyde based phenolic resin, and it was detected that starch could be used to prepare phenolic resin in replacement of formaldehyde