Synthesis of foaming resol resin modified with oxidatively degraded lignosulfonate.

摘要

A new method of introducing lignosulfonate into foaming resol resin was explored in the present work. Lignosulfonate was oxidatively degraded to phenolic compounds in water medium (pH=10), lignosulfonate concentration (based on total weight of lignosulfonate and water) was 50%. Effects of degradation temperature, reaction time, and H₂O₂ dosage on number average molecular weight (M_w) and weight average molecular weight (M_n) of oxidatively degraded lignosulfonate (ODL) were investigated. The optimal degradation conditions were: temperature was about 60 degrees C, reaction time 2 h, and H₂O₂ concentration (based on weight of lignosulfonate) 6 wt%, where M_w and M_n attained a minimum 998 and 493, respectively. Foaming resol resin modified with ODL was synthesized under an alkaline condition. Phenolic foam made from modified resol resin (30 wt% replacement of phenol by ODL) and other chemicals possessed satisfied properties.