Films Based on Mater-Bi® Compatibilized with Pine Resin Derivatives: Optical, Barrier, and Disintegration Properties

Miguel Aldas,Juan López-Martínez,Marina Patricia Arrieta,José Miguel Ferri,Cristina Pavon

doi:10.3390/polym13091506

Miguel Aldas, Juan López-Martínez + Show 3 more

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https://doi.org/10.3390/polym13091506

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Abstract

Mater-Bi® NF866 (MB) was blended with gum rosin and two pentaerythritol esters of gum rosin (labeled as LF and UT), as additives, to produce biobased and compostable films for food packaging or agricultural mulch films. The films were prepared by blending MB with 5, 10, and 15 wt.% of each additive. The obtained films were characterized by optical, colorimetric, wettability, and oxygen barrier properties. Moreover, the additives and the MB-based films were disintegrated under composting conditions and the effect of each additive on the biodegradation rate was studied. All films were homogeneous and optically transparent. The color of the films tended to yellow tones due to the addition of pine resin derivatives. All the formulated films presented a complete UV-transmittance blocking effect in the UVA and UVB region, and those with 5 wt.% of pine resin derivatives increased the MB hydrophobicity. Low amounts of resins tend to maintain the oxygen transmission rate (OTR) values of the neat MB, due to its good solubilizing and compatibilizing effects. The disintegration under composting conditions test revealed that gum rosin completely disintegrates in about 90 days, while UT degrades 80% and LF degrades 5%, over 180 days of incubation. As expected, the same tendency was obtained for the disintegration of the studied films, although Mater-Bi® reach 28% of disintegrability over the 180 days of the composting test.

Highlights

Introduction published maps and institutional affilBiodegradable plastics films have risen as a solution for the use of non-renewable resources and the solid waste disposal management of conventional non-biodegradable polymers when recycling is impractical or not economical [1,2,3]
Starch can be plasticized during extrusion, where the combination of shear, temperature, and plasticizers allows the disruption of the native crystalline granular structure leading to an amorphous plasticized starch so-called thermoplastic starch (TPS) [3,9]
The homogeneous distribution of pine resins in MB polymeric matrix was corroborated by FESEM and all film formulations resulted mostly homogenous with no phase separation (Figure S1 in the Supplementary Materials), in good agreement with injection molded MB-based materials developed in previous works [19,30]

Summary

Introduction

Biodegradable plastics films have risen as a solution for the use of non-renewable resources and the solid waste disposal management of conventional non-biodegradable polymers when recycling is impractical or not economical [1,2,3]. Biodegradable plastics are typically derived from renewable materials such as starch or cellulose and can be disposed by composting or anaerobic digestion to reduce landfilling [4,5]. Starch-based plastics have gained great attention due to their biodegradability, renewability, and low cost [6,7]. Starch can be plasticized during extrusion, where the combination of shear, temperature, and plasticizers allows the disruption of the native crystalline granular structure leading to an amorphous plasticized starch so-called thermoplastic starch (TPS) [3,9]. Thermoplastic starch offers the advantage that it can be processed by extrusion, injection molding, iations

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