Abstract
Carboxymethyl cellulose, a hydrophobic derivative from cellulose that can be prepared from different biomass, has been widely applied in food, medicine, chemical, and other industries. In this work, carboxymethyl cellulose was used as the additive to improve the hydrophobicity and strength of carboxylated starch film, which is prepared from starch catalyzed by bio-α-amylase. This study investigated the effects of different bio-α-amylase dosages (starch 0.5%, starch 1%) and different activation times (10, 30 min) on starch to prepare the carboxylated starch. The effects of different carboxymethyl cellulose content on the carboxylated starch film were investigated by analysis viscosity, fourier-transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, x-ray powder diffraction, scanning electron microscope, and contact angle. The results showed that preparing carboxylated starch using activated starch increased the carboxyl content, which could improve the effectiveness of the activated enzyme compared to prolonging the activation time. The carboxyl starch prepared by enzyme catalysis had a lower gelatinization temperature, and enzyme activation destroyed the crystallization area of the starch, thus facilitating the carboxylation reaction. The addition of 15% carboxymethyl cellulose improved the mechanical properties of the prepared film with maximum tensile strength of 44.8 MPa. Carboxymethyl cellulose effectively improved the hydrophobicity of the starch film with the addition amount of 10–30%, while hydrophobic property was stable at 66.8° when the addition amount was exceeded to 35%. In this work, it can be found that carboxymethyl cellulose improve the mechanical and hydrophobic properties of starch film, laying the foundation for the application of carboxylated starch materials.
Highlights
Cellulose has abundant reserves, low price, environmental protection, and wide application
Carboxymethyl cellulose was used as the additive to improve the hydrophobicity and strength of carboxylated starch film, which is prepared from starch catalyzed by bio-α-amylase
Activated enzyme was more effective at increasing the carboxyl content than was prolonging the activation time of the enzyme
Summary
Low price, environmental protection, and wide application. A large number of functional groups, such as carboxyl and hydroxyl, make the technical requirements of the CMC modification process simple, and performance improvement can be achieved with low modification costs. Studies have shown that the addition of CMC can improve the mechanical properties, transparency, and thermal stability of the material (Tasaso, 2015; Huang et al, 2017; Mansur et al, 2017; Kontturi and Spirk, 2019). In the preparation of an electrode film, the addition of CMC can improve the plasticity of the composite film (Ekramulmahmud et al, 2005; Ampaiwong et al, 2019; Nazrin et al, 2020). CMC is used as the basic material for performance improvement, and the starch film is modified to obtain better material performance
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