Development of a New Totally Biodegradable Film Based on Starch and Nanofibrillated Cellulose for Barrier Properties

Abstract

Starch is a natural, renewable, sustainable, inexpensive, and degradable material which has many advantages and plays important roles in human life. Starch is also a natural polymer available everywhere in the world. Nanofibrillated cellulose (NFC) is a main material to reinforce and increase the properties of composites such as paper and packaging materials. Both of starch and NFC are degradable materials and environmental friendly. In this study, starch was used as a raw material to produce a flexible, transparent and biodegradable film which was compounded by glycerol, plasticizer, and reinforced by NFC. There were three steps which must be practiced to create such kind of film included pre–blends, blends, and films preparation. Starch, glycerol, glycerol/NFC, and added water were mixed together to obtain the pre–blends. The appropriate proportions of these compositions were found to acquire good pre–blends. For this step, there were 7 formulations to prepare the pre-blends. After that, the ready prepared blends were then passed though Brabender mixing to get the blends. Optimum temperature, rotation speed, and time of mixing were investigated and observed carefully in this step in order to achieve transparent and flexible blends. The process to obtain the blends was named as compounding. Later on, transparent, flexible, and thin thickness films were processed by those prepared blends through thermoforming. To complete these properties of films successfully, the suitable temperature, applied forces/pressures, and times of thermoforming must be rightly determined. After the films were completely obtained, they were then characterized some of their properties. Mechanical characterization, water absorption, water vapor permeability and biodegradability were the properties of films which must be determined. The effects of NFC with different amount of pulp oxidation (5, 10, and 15 mmol) and higher or lower content of fibers added in the created films were studied on these properties. There were 2 conditions, 23oC and 50% RH and 7oC and 50% RH, of mechanical characterization which would be tested as water absorption determination had 3 conditions contained 23oC and 50% RH, 23oC and 75% RH, and 7oC and 50% RH. The samples were taken to a laboratory in Valencia, Spain, to experiment and study the capacity of water vapor barrier. Finally, biodegradability property of films under enzymatic activity was analyzed and evaluated