Chemical Structure and Curing Characteristics of Phenol Formaldehyde Resins Catalyzed with Calcium Oxide

Abstract

Phenol formaldehyde resin catalysed by calcium oxide was synthesised under controlled temperature, material mixture ratios. The effects of catalysts on chemical structure of phenol formaldehyde resin was investigated by high performance liquid chromatography, fourier transform infrared and differential scanning calorimetry. The results indicated that synthesis parameters, including formaldehyde to phenol molar ratio and catalyst to phenol ratio, influence the rate of cure. Phenol formaldehyde resin catalysed by calcium oxide showed higher addition of formaldehyde onto ortho positions of phenolic rings, whereas in the presence of sodium hydroxyde addition onto para sites was favoured. The result of DSC was applied to investigate that Phenol formaldehyde resin catalysed by calcium oxide could cure at a low temperature. INTRODUCTIONPhenol formaldehyde (PF) resins were the first commercial synthetic polymeric materials. This type of resin have been widely used as industrial impregnating resins and adhesives in various applications for more than 50 years [1,2] . One of the drawbacks of PF resin is its slow cure which requires longer hot-pressing time and higher hot-pressing temperature for the manufacture of composite products.There have been many attempts to cure PF resins faster, including mixed with various resins [3] , adding accelerators and different catalysts such as ester [4,5] , copolymerized urea [6][7][8] , carbonate [9,10] and amides [11,12] .Faster curing PF resins may also be prepared by metallic ion catalysis, which increases the proportion of the free higher reactive para positions available for the reaction during curing of the resin. It was investigated that the valence and ionic radius of hydrated cations of basic catalyst on the mechanisms and kinetics of phenol formaldehyde

Three-Dimensional Coating Layer Modified Polyolefin Ceramic-Coated Separators to Enhance the Safety Performance of Lithium-Ion Batteries

“…19 PFR is chosen as the modification material based on the following consideration: 1) PFR has been widely used in electrical equipment and fire prevention materials because of its good insulating property, dimensional stability and heat resistance. 20,21 2) Low molecular weight PFR oligomer is small enough to permeate into the dozens nanometers pores of separators, and then, after a simple thermal curing process at a relatively low temperature, it will form a cross-linked macromolecule three-dimension coating layer throughout entire separators, which can further improve the thermal stability and mechanical strength of the whole separator. 3) The abundant source and low cost of PFR provide the solid foundation of practical application, and the preparation process is environment friendly.…”