In situ reactive compatibilization of polylactic acid (PLA) and thermoplastic starch (TPS) blends; synthesis and evaluation of extrusion blown films thereof

• Published in: Industrial crops and products 2019-12, Vol.141, p.111748, Article 111748
• Main Authors: Palai, Bishwabhusana, Biswal, Manoranjan, Mohanty, Smita, Nayak, Sanjay Kumar
• Format: Article
• Language: English
• Subjects: Biodegradable; Blown film; Grafting; PLA; TPS
• ISSN: 0926-6690; 1872-633X
• DOI: 10.1016/j.indcrop.2019.111748

•Thermoplasticized starch (TPS) was obtained from native cassava and maize starch.•PLA/TPS blown films were prepared via in situ compatibilization through chemical grafting technique.•Chemical grafting favoured the dispersion and processibility of blown films.•Elongation and tear resistance of the blown film enhanced.•Incorporation of TPS increased the crystallization rate of the blend system. Biodegradable compositions of polylactic acid (PLA) and thermoplasticized starch (TPS) were prepared using in situ compatibilization process using a twin screw extruder followed by extrusion blown film process. TPS obtained from maize and cassava starch were blended with PLA to prepare the PLA/TPS blend at variable content ranging from 5 to 30 wt%. In situ compatibilization was accomplished with chemical grafting of glycidyl methacrylate (GMA) in the presence of benzoyl peroxide (BPO) as free radical initiator. An in depth study on the morphological, mechanical, barrier, optical and antislip properties of blown films were evaluated. FTIR analysis showed the interaction between PLA and TPS phase in presence of GMA. The thermal analysis employing DSC confirmed increased crystallization rate of PLA with the incorporation of TPS. Mechanical properties reported a moderate decrease in tensile modulus and strength compared to virgin PLA films. However, the percentage of elongation of the films containing 30 wt% of both cassava and maize starch increased to the tune of 68.62%; 144.4% and 25.49%; 38.8% respectively in the machine and transverse direction respectively. The films also exhibited improved permeability of oxygen to the tune of 41.7% and 38.1%. Furthermore, a twofold increment in water vapour permeability was observed for both cassava and maize starch films obtained from 30 wt% of TPS loadings.