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

Dengfeng Zhou,1,2

Daiyuan Li,1

Menglei Liu,3

Xianshuai Zhong,4

Huige Wei,1*Email

Zhe Wang,5

Qinglong Jiang,6

Fusheng Jin3

Dapeng Cui7*Email

1 Tianjin Key Laboratory of Brine Chemical Engineering and Resource Eco-utilization, College of Chemical Engineering and Materials Science, Tianjin University of Science and Technology, Tianjin, 300457, China

2 CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, No. 11 Zhongguancun Beiyitiao, Beijing 100190, China

3 QinHuangDao Tabacco Machinery Co., Ltd, Qinhuangdao, Hebei, 066000, China

4 Huayou New Energy (Quzhou) Science & Technology Co., Ltd., Huayou New Energy Industry Group, Quzhou, 324000, China

5 Chemistry Department, Oakland University, Rochester, MI, 48309, USA

6 Department of Chemistry and Physics, University of Arkansas, Pine Bluff, Arkansas 71601, USA

7 College of Light Industry Science and Engineering

Tianjin University of Science and Technology, Tianjin, 300457, China

Abstract

Cross-linked porous starch has become a subject of research interest recently. The degree of cross-linking and the freeze-thaw stability are critical for cross-linked porous starch with respect to their 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 cross-linked 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 (mNaOH/mpcs), the mass ratio of NaCl to PCS (mNaCl/mpcs), the temperature (Ta), and the reaction time (ta)) and the cross-linking reaction (the ratio of ECH volume to the mass of PCS (VECH/mpcs), the ratio of solution volume to the mass of PCS (Vs/mpcs), pH value, the temperature (Tc), and the reaction time (tc)) on the cross-linking degree and freeze-thaw stability of c-PCS were investigated in details. Results show that the optimum conditions for the pre-alkalization and cross-linking reaction to obtain c-PCS are as follows: mNaCl/mpcs is 0.06, mNaOH/mpcs is 0.02, Ta is 40 °C and ta is 1.0 h, VECH/mpcs is 0.003 (mL/g), Vs/mpcs is 7 (mL/g), pH is 10, Tc is 20 °C, and tc 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.

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