Preparation and properties of polyvinyl alcohol-alkali lignin foam material (PLFM)

In order to improve the current situation of foam material with poor mechanical properties and high cost, increase the utilization of alkali lignin, and prepare foam materials with high performance, we prepared polyvinyl alcohol/alkali lignin foam material (PLFM) based on inorganic foaming principles, with polyvinyl alcohol (PVA) and alkali lignin as raw material and formaldehyde as crosslinking agent, and then measured its relevant performance. The results showed: relative to the amount of PVA, when the mass fraction of alkali lignin was 33%, formaldehyde at 4/5(ml/g), sulfuric acid at 6/5 (ml/g), and solidification temperature was 120 ℃, the maximum tensile strength of the prepared foam material is 25.91 MPa,which is remarkably improved compared to the 4.32 MPa of pure polyvinyl alcohol foam material. Comparing the foam materials prepared with different polymerization degrees of PVA: foam material with PVA0588l is unable to form foam due to lower polymerization degree. Compared with PVA1788-PLFM, the tensile strength of PVA2488-PLFM is better, and the apparent density and water absorbency ratio is smaller. FTIR showed that alkali lignin cross-linked with PVA, mostly in the 5th position of the phenyl ring,and crosslinking effect with PVA2488 is better. SEM showed that PVA2488-PLFM has better pore structure. Regarding thermal performance, DSC showed that lignin as filler exists in PVA1788-PLFM, but not in PVA2488-PLFM, indicating that PVA2488-PLFM possesses better biocompatibility. TG and DTG showed that, the temperature while most intensive thermal weight loss of PVA2488-PLFM happened is 379 ℃,which is higher than that (360 ℃) for PVA1788-PLFM,however weight loss ratio is lower. At the same time, the weight loss ratio of 95.94% is also higher than that (80.13%) of PVA1788-PLFM,indicating that PVA2488-PLFM has good heat resistance, and conducive to thermal degradation. To sum up, PVA2488-PLFM has better performance.