Study on direct-chain diacid modified phenolic resin for Al-alloy casting

摘要

Resin coated sand (RCS) with phenolic resin matrix can hardly be collapsed when it is used in Al-alloycasting. Adding collapsing agent and reducing the concentration of resin are solutions adopted by workers, but thesemethods tend to reduce the initial strength of RCS. Synthesis of modified phenolic resin with direct-chain diacid DAnwherenmeans carbon amount) was studied here. The effects of the addition of modifying agent on molecularweight, gel time and softening point were investigated. Optimal addition of DAn (10% phenol) was obtained by testing theinitial and retained flexural strengths of the modified resin. FT-IR spectra showed that carbonyl shifts to higher wavenumber. With the use of TG, SEM and strength loss curves, the relation between initial and retained strengths wasanalysed. Tests on the heated deformation curve, before and after resin modification, show that PF-DA10 has thecharacteristic of higher initial and retained strengths together