Epoxy resin (ER) is one of the most widely used synthetic resins, and the improvement of its toughness is an important issue. In this study, Epon 828 is used as ER resin, polytetramethylene ether ...glycol (PTMG) and liquefied wood (LW) are used as polyol, and IPDI, H12‐MDI, Desmodur N, and Desmodur L are used as isocyanate. The influence of polyurethane resin (PU) composition on the reactivity of ER/polyol/isocyanate blended resin and the properties of ER/PU composite are investigated. The results show that the mixture of ER/PTMG/IPDI has greater reactivity, followed by ER/PTMG/Desmodur N, while ER/PTMG/Desmodur L has lower reactivity. In the structure of ER/PU blended resin composites, ER and PU resins not only form a physical interpenetrating structure, but also undergo a copolymerization crosslinking reaction. The modulus of elasticity of ER/PU composites prepared with trifunctional Desmodur L and Desmodur N is greater than that of bifunctional IPDI and H12‐MDI, while those with LW as polyol is greater than that of PTMG as the raw material.
Different polyols (PTMG and LW) and isocyanate (IPDI, H12‐MDI, Desmodur N, and Desmodur L) are added directly to epoxy resin, the reactivity of epoxy/polyol/isocyanate blended resins and the properties of ER/PU composites are investigated. The results show that the ER resin and the PU not only form a physical interpenetrating structure, but also undergo a copolymerization crosslinking reaction.
Waterborne polyurethane (WPU) is one of the most important resins. The properties of WPU can be modified by introducing inorganic components. Tetraethoxysilane (TEOS) is a precursor for preparing ...inorganic polymers and can be used to prepare WPU/silica hybrids. In this study, WPU dispersion was synthesized by reacting polytetramethylene ether glycol and dimethylolpropionic acid with isophorone diisocyanate, followed by chain extension with ethylenediamine. After mixing WPU with TEOS, the mixture was sealed and stored at room temperature for different lengths of times. The influence of time on the characteristics of the WPU/TEOS mixture and the properties of films were investigated. The results showed that the viscosity, surface tension and average particle size of the mixture increased with prolonged storage time. 29Si‐NMR analysis indicated that the structure of silica exists in the WPU film. DSC, DMA and TGA results showed that WPU/silica films made from the mixture have less thermal activity, higher storage modulus, lower damping peak heights and better heat resistance after relatively long storage times.
Epoxy resin (ER) is one of the most important synthetic resins, but it has the disadvantage of lacking impact resistance. However, it can be improved by mixing with polyurethane resin (PU). In this ...study, Epon 828, triethylenetetramine (TETA), polytetramethylene ether glycol (PTMG), isophorone diisocyanate (IPDI), and dibutyltin dilaurate (DBTDL) were used as raw materials to prepare ER/PU interpenetrating polymer network structures (IPNs) by three different blending processes. The results showed the reactivity between TETA and IPDI were greater than that between TETA and ER. When ER/TETA/PTMG/IPDI/DBTDL were mixed at the same time, or ER and PU resins were prepared separately and then mixed, the ER/PU composites produced had a phase separation inside the structure. The most appropriate blending method was to mix ER with PTMG, IPDI, DBTDL first, and then add TETA after 10 min. The composite formed had a uniform appearance, and had better physical, mechanical, and thermal properties than the others did.
Phenol‐formaldehyde resin (PF) is the oldest synthetic resin. Through the design of synthesis conditions, PF resins with different characteristics can be provided, which are widely used in molding ...materials, adhesives and impregnation. Spherical PF beads are a hardened resin prepared by a special synthesis method. In this study, a mixture of phenol and formaldehyde was added with triethylamine, polyvinyl alcohol (PVA), and hexamethylenetetramine as a catalyst, granulating agent, and hardening agent, respectively. Spherical PF beads were prepared by a three‐stage suspension polymerization in a large‐scale water system, and the effects of PVA addition conditions on the reaction behavior and particle characteristics were discussed. The results show that formalin with a concentration of 14 % can be used as a formaldehyde raw material to prepare spherical PF beads by suspension polymerization. The largest spherical PF beads can be obtained with a reactant‐liquid ratio of 2/1, a stirring speed of 300 rpm, and an addition amount of BF‐04 of 2 %. The particle size of 14–20 mesh accounts for 83.9 % and has the average particle size of 1016 μm.
Spherical PF beads were prepared by reacting phenol with formaldehyde by a three‐stage suspension polymerization. TEA, PVA and hexamine were used as catalyst, granulating agent and hardening agent, respectively. Formalin with 14 % concentration can be used as the raw material. The largest PF beads obtained with a reactant‐liquid ratio of 2/1, stirring speed of 300 rpm, and BF‐04 addition amount of 2 %. The particle size of 14–20 mesh accounts for 83.9 % and has the average particle size of 1016 μm.
CeO
2 nanocrystals with cube and rod shapes synthesized under hydrothermal conditions have been used to prepare Rh/CeO
2 catalyst (5% mass) on Al
2O
3 support to test their catalytic activity for ...ethanol reforming. The catalysts as prepared show H
2 selectivity superior to a catalyst with irregular CeO
2 nanoparticles. Although the shape of CeO
2 particles gradually altered and the activity decreased during the reforming, the {1
0
0}/{1
1
0}-dominant surface structures play a crucial role to enhance the ethanol reforming, which is important for fuel-cell applications.
CeO
2 nanocrystals of cubic and rod shape have been synthesized under hydrothermal conditions on controlling the pH, temperature and duration of reaction. High-resolution transmission electron microscopy indicates that exposed crystal planes are {1
1
0} and {1
0
0} for rods but {1
0
0} for cubes. These nanocrystals have been used in the preparation of a Rh/CeO
2 catalyst on an Al
2O
3 support to test the catalytic activity for ethanol reforming. These catalysts as prepared show good H
2 selectivity compared to catalysts with irregular CeO
2 nanoparticles. The {1
0
0}/{1
1
0}-dominant surface structures play a crucial role in enhancing ethanol reforming; this reaction is important for fuel-cell applications.
PDF