Preparation and properties of polyvinyl alcohol alkali lignin foam materials with organic foaming agent

According to the principle of organic foaming agent benzene sulfonyl hydrazide (BSH), polyvinyl alcohol (PVA) and wheat straw alkaline lignin, crosslinked by formaldehyde, were used to prepare foaming materials with high performance for improving the reuse of lignin waste from paper industries and the properties of PVA foaming materials (PLFM). Results showed that: PLFM reached the maximum tensile strength (28.94MPa) and the most uniform structure when the amount of foaming agent was 0.5%, formaldehyde 0.8mL/g and alkali lignin 30%, relative to the amount of PVA. The least water absorption was 2.455 and the apparent density remained 0.28g/cm3 when the alkali lignin content was 30%. The water resistance of PLFM decreased as the amount of alkali lignin increased. The crosslinks between components were sufficient and the C-5' was substituted in the central aromatic ring; uniform and micro pores were observed in samples and PLFM was biocompatible. The thermal stability of PLFM did not decrease as more alkali lignin was added and thermal degradation of PLFM was good.