This study demonstrates sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) for robust bioconversion of corn stalks. With only about 3% sodium bisulfite charge on corn stalks and 30 min pretreatment at temperature 180°C, SPORL can achieve near complete cellulose conversion to glucose in 48h enzymatic hydrolysis. Sulfuric acid charge has great effect on SPORL pretreatment. Enzymatic cellulose conversion of substrate increased with the increase in acid charge under the studied conditions. Bisulfite with different counter-ions can be used in the SPORL. Magnesium as counter ion was found to be more effective on enzymatic hydrolysis of substrate than sodium or ammonium.

TDI as main isocyanate, IPDI as end-capping reagent, waterborne polyurethane (WPU) surface-sizing agent have been obtained by a pre–polymerization process. WPU were mixed with starch SSA in different proportion and a composite sizing agent obtained. It is indicated the water resistance, gloss and folding resistance of WPU/starch sized papers are much higher than starch sized papers. The ink absorption obviously decreases and the mechanical properties wholly increase. WPU/starch composite emulsions is a new kind of surface sizing agent having broad development prospects.

TDI as main isocyanate, IPDI as end-capping reagent, waterborne polyurethane emulsions (WPUs) surface-sizing agent have been obtained. The properties of WPUs and papers sized by WPUs with different DMPA content, different NCO/OH molar ratio and nNCOTDI/nNCOIPDI are systematically examined. The results show that WPUs are new kinds of surface sizing agents with good properties. The water resistance, surface gloss and smoothness of papers sized by WPUs have dramatically increased. The folding endurance, tearing resistance and tensile strength of WPU sized papers are observed to increase obviously.

In order to select rational screw parameters for improving the pulping quality, efficiency and reducing specific energy, the paper studied the effects of the rotational speed of screw, lead number of reverse thread and slot width of reverse flight of the twin screw pulping extruder (TSPE) on specific energy, flux and pulping quality (reject rate, fiber length and fine component content) in the processes of extrusion mechanical pulping. The experimental results show that synthetically considering and pulping quality the efficiency, the screw rotational speed of 300 r/min–400 r/min is more appropriate. For poplar chips, the lead number should be greater than or equal to six. And for cotton stalks and wheat straws, the lead number should be no less than seven. For the combination screws of multiple extrusion zones, the slot width of the ultimate extrusion zone plays a decisive role on the fiber length. In addition, the slot width can also adjust the barrel pressure and the axial force of the screws. The work of the paper is significant for optimum design of the TSPE.