Study On The Synthesis And Properties Of Phenolic Resin Modified With Boric Acid And Cardanol

As the world's first industrialization synthetic polymer resin of low price and convenient synthesization, phenolic resin has been widely used in electronics, paint, transportation, aerospace and other fields. However, the phenolic hydroxyl and methylene are easily oxidized resulting in poor heat resistance and oxidation resistance. The cured phenolic resin is brittle because of methylene linkage between benzene rings. Therefore, the research about modified phenolic resin in order to improve its heat resistance and toughness becomes the focus of attention.In this paper different synthesis methods were adopted to prepare phenolic resin of better properties modified with boric acid and cardanol in view of toughness and heat resistance. Influences of the amount of catalyst, the molar ratio of formaldehyde to phenol, the amount of boric acid, and the amount of cardanol on the comprehensive properties of phenolic resin were studied by single factor sxperiments. FTIR results indicated that the modified phenolic resin synthesized by the method of hydroxybenzyl alcohol showed higher ortho-ortho ratio. Apart from boron-oxygen bond, the coordination bond of boron-oxygen also existed in structure of phenolic resin which further improved its heat resistance.TG results showed that the modified phenolic resin synthesized by the method of hydroxybenzyl alcohol had better heat resistance. With the increase of the amount of boric acid, the thermal decomposition temperatures of modified phenolic resin synthesized by the method of phenol-borate were 401.8?,423.0?,429.6?, 457.2?,463.7? and the char yield increased and then became flat. In comparison, with the increase of the amount of boric acid, the thermal stability of modified phenolic resin synthesized by the method of hydroxybenzyl alcohol increased and then decreased, the thermal decomposition temperatures were 436.6 ??453.7 ??475.1??479.5??541.1 ?. The XRD pattern of modified )henolic resin showed that boric acid almost completely reacted by the method of hydroxybenzyl alcohol, and incompletely reacted by the method of phenol-borate when the amount of boric acid was 0.2(mol/mol).The DSC analysis showed that the approximate gelling point of the modified phenolic resin synthesized by the method of hydroxybenzyl alcohol was 90?, suing temperature was 189? and post-processing temperature was 259?. By the Kissinger, Ozawa and Crane equation, the cuing reaction system's average apparent activation energies were 67.75 kJ/mol and 75.88 kJ/mol, pre-exponential factors were 96550.57 s-1 and 209644381.52 s-1, reaction order was 0.95, which illustrated ;he curing reaction of the modified phenolic resin was a complex reaction. The curing kinetics model of phenolic resin was as follows:...