Fabrication of poly(acrylic acid)/chitosan/linseed mucilage films: Thermal and mechanical properties

The use of biodegradable polymers in the plastics industry has been increasing in recent years. The study of the chemical, physical, thermal, and mechanical properties of films based on biodegradable components is of interest to technologists because these properties determine their applicability for food packaging. In this work, films based on natural polymers such as linseed mucilage (LM) and chitosan (CH), as well as poly(acrylic acid) (PAA) were obtained through the casting method and using V-50 as the initiator. The films were characterized through Fourier Transform Infrared spectroscopy, and thermogravimetric analysis, and their water absorption and swelling capacity, and thermal and mechanical properties were determined. Homogenous flexible, translucid, amber-colored films, with low absorption and solubility in water were obtained. It was demonstrated through Fourier Transform Infrared analysis the chemical interaction between C-H, C=O, and C-O chemical groups of LM, CH, and PAA. In addition, films showed high resistance to thermal decomposition between 125 and 425 degrees C. The mechanical tests of tension allowed the composition of LM in the film, the behavior variates between a plastic and/or elastic material and with tensile strength (Rm) values between 10.8 and 16.4 MPa and elastic modulus (E) values between 56.2 and 169.2 GPa, we observed that at higher quantities of LM and thickness, both E and Rm tend to increase, while %EL decreases. This led us to conclude that the material transitioned from ductile and malleable to rigid and brittle. The films obtained with different ratios of LM/CH/PAA may exhibit a semi-interpenetrating polymeric networking type morphology.