Experimental Parameters Affecting Cross-Linking Density and Free-Thaw Stability of Cross-Linked Porous Starch

Abstract

Cross-linked porous starch has become a subject of research interest recently. The degree of cross-linking and the freezethaw stability are critical for cross-linked porous starch with respect to its practical applications. Herein, cross-linked porous corn starch (c-PCS) was prepared by the pre-alkalization of porous corn starch (PCS) using NaCl/NaOH which was then crosslinked using epichlorohydrin (ECH). The effects of key experimental parameters involved in both the pre-alkalization process (i.e., the mass ratio of NaOH to PCS (m NaOH /m pcs ), the mass ratio of NaCl to PCS (m NaCl /m pcs ), the temperature (T a ), and the reaction time (t a )) and the cross-linking reaction (the ratio of ECH volume to the mass of PCS (V ECH /m pcs ), the ratio of solution volume to the mass of PCS (V s /m pcs ), pH value, the temperature (T c ), and the reaction time (t c )) on the cross-linking degree and freeze-thaw stability of c-PCS were investigated in details. Results show that optimum conditions for the pre-alkalization and cross-linking reaction to obtain c-PCS are as follows: m NaCl /m pcs is 0.06, m NaOH /m pcs is 0.02, T a is 40 °C and t a is 1.0 h, V ECH /m pcs is 0.003 (mL/g), V s /m pcs is 7 (mL/g), pH is 10, T c is 20 °C, and t c is 3.0 h. The morphology, crystalline structure and thermal stability of the as-obtained c-PCS were also investigated, suggesting that the surface became rougher, the crystallinity was decreased, and the thermal stability was enhanced resulting from the cross-linking reaction.

Reinforced Hydroxylated Boron Nitride on Porous Sulfonated Poly(ether sulfone) with Excellent Electrolyte Properties for H2/O2 Fuel Cells

“…The porous structure possesses interconnected microstructures that act as the proton transporting channels from one polymer domain to another and afford the continuous proton migration along with the polymer matrix. This porous structure is a promising practical approach for constructing PEM with the tunable porosity and well-interconnected nanostructure; however, the drawback of thermo-mechanical properties is still the primary concern in the porous polymer. − …”