Abstract:

Acetic acid lignin(AAL) was isolated from acetic acid pulping waste liquor. The structure of acetic acid lignin was characterized by Fourier infrared spectroscopy(FTIR)and ³¹P-NMR spectrum.And the molecular mass distribution of acetic acid lignin was determined on a gel permeation chromatography (GPC). Rigid polyurethane foams were prepared from acetic acid lignin,polyether polyol and toluene diisocyanate in the presence of catalyst,silicone surfactant and foaming agent. Thermal stability and physical characteristics of AAL-based polyurethane foams were determined by TGA /DSC and compression tests, respectively. And the cell structure of AAL-based PUF was observed by scanning electron microscopy (SEM). The results showed that the acetic acid lignin contained highly reactive hydroxyl groups as reactive chemical reaction sites and can be used to replace part of polyols in the synthesis of polyurethane foams.The polyurethane foam presented better compressive strength.When AAL content was 5%,the compression strength was 1.325 MPa,which was higher 63% than pure PU foams. And the compression modulus reached the maximum, which was 0.181 MPa.The most rapid degradation temperature of AAL-based polyurethane foam decreased with AAL contents increasing.The glass transition temperature had no distinct change .The SEM images suggested that the polyurethane foam containing acetic acid lignin had smooth surface and homogeneous foam structure.

Key words: acetic acid pulping, acetic acid lignin(AAL), rigid polyurethane foam