Preparation and Properties of Starch/Carboxymethyl Cellulose/Glycerol Degradable Composite Films

Starch/carboxymethyl cellulose(CMC)/glycerol composite film was fabricated with a casting method by mixing starch CMC and glycerol used as a plasticizer. The structure of the composite film was characterized by SEM, XRD, and FT-IR, and the mechanics, light transmittance, water absorption, and degradation properties of the composite film were studied. The effect of different glycerol addition levels(based on the total dry mass of starch and CMC, 0-30%) on the structure and properties of the composite film were mainly investigated. The results showed that starch, CMC, and glycerol were physically blended, and the addition of glycerol improved the compatibility of the system. The more glycerol added, the smoother fracture surface of the composite film was achieved. As the glycerol addition increased, the elongation at break of the composite film significantly increased. When the addition increased from 0 to 30%, the elongation at break increased from 3.39% to 46.23%, which was an increase of 12.6 times. The transmittance, water absorption, and water vapor permeability(WVP) of the composite film increased with increase of glycerol addition. When the addition was 20%, the maximum transmittance at 600 nm reached 79.42%, and the WVP and water absorption were 5.14×10^-11 g/(m · s · Pa) and 25.46%, respectively. The increase of glycerol addition in the system could also accelerate the degradation rate of the composite film. When the glycerol addition was 20%, the composite film almost completely degraded within 9 days. The results showed that the mechanical, optical and degradable properties of starch/CMC/glycerol composite film were better when the glycerol content was 20%, which could meet the performance requirements of food packaging film.