Structure And Properties Of A Novel Starch-based Surface Sizing Agent

In this work, polyurethane prepolymers (PUP) were synthesized using different types of polyester polyols, and then used to prepare modified thermoplastic starch (TPS) in an intensive mixer. The structure/properties of modified TPS were investigated by using tensile test, Fourier infrared spectroscopy (FTIR), Emission Scanning Electron Microscopy (ESEM), contact angle (CA) and so on. Modified TPS surface sizing agents were prepared with different modified starches. The effects of the types and the weight-average molecular weight (Mw) of polyurethane and the solid content of surface sizing agent on the properties of sizing were also investigated. The results showed that:1. The FTIR and ESEM showed that polyurethanes were cross-linked to starch matrix with urethane linkages.2. Compared to pure starch, the tensile strength, folding endurance, tearing resistance and breaking elongation of papers sizing with CP10 were improved. With increasing solid content of CP10 (from 2% to 4%), the above properties were also improved.3. The tensile strength, folding endurance, tearing resistance and breaking elongation of papers were deceased with increasing polyurethane Mw. Generally, pure starch is hydrophilic, the hydrophobicity of modified starched were improved obviously.4. The CPBA600 showed the best above properties than other surface sizing agents (including oxidized starch by Dafeng Co., Ltd). The CWP and the CPCL showed the similar sizing properties. The tensile strength, tearing resistance and folding endurance of CP10 were lower than that of CWP and CPCL.