Improvement of PBAT Processability and Mechanical Performance by Blending with Pine Resin Derivatives for Injection Moulding Rigid Packaging with Enhanced Hydrophobicity.

Cristina Pavon,Marina P Arrieta,Juan López-Martínez,Harrison De La Rosa-Ramírez,Miguel Aldas

doi:10.3390/polym12122891

Cristina Pavon, Marina P Arrieta + Show 3 more

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https://doi.org/10.3390/polym12122891

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Abstract

Polybutylene adipate-co-terephthalate (PBAT) is a biodegradable polymer with good features for packaging applications. However, the mechanical performance and high prices of PBAT limit its current usage at the commercial level. To improve the properties and reduce the cost of PBAT, pine resin derivatives, gum rosin (GR) and pentaerythritol ester of GR (UT), were proposed as sustainable additives. For this purpose, PBAT was blended with 5, 10, and 15 wt.% of additives by melt-extrusion followed by injection moulding. The overall performance of the formulations was assessed by tensile test, microstructural, thermal, and dynamic mechanical thermal analysis. The results showed that although good miscibility of both resins with PBAT matrix was achieved, GR in 10 wt.% showed better interfacial adhesion with the PBAT matrix than UT. The thermal characterization suggested that GR and UT reduce PBAT melting enthalpy and enhance its thermal stability, improving PBAT processability. A 10 wt.% of GR significantly increased the tensile properties of PBAT, while a 15 wt.% of UT maintained PBAT tensile performance. The obtained materials showed higher hydrophobicity than neat PBAT. Thus, GR and UT demonstrated that they are advantageous additives for PBAT–resin compounding for rigid food packaging which are easy to process and adequate for industrial scalability. At the same time, they enhance its mechanical and hydrophobic performance.

Highlights

A mismanagement of the disposal of short term polymers after use joined with the impossibility to handle the problem only by mechanical recycling due to still inefficient waste management programs, the composition of some plastic formulations, and the fact that plastics cannot be recycled forever [1], as well as the resistance to degradation by many plasticPolymers 2020, 12, 2891; doi:10.3390/polym12122891 www.mdpi.com/journal/polymersPolymers 2020, 12, 2891 materials, have led to plastic hoarding in the environment [2,3,4,5]
The production of biodegradable polymers has considerably increased during recent years, for short term applications, such as food packaging materials [5,6], while resulting in a necessary alternative to deal with the environmental problem produced by the accumulation of plastics in the environment
Biopolyesters are positioned in the packaging sector as the most suitable polymers to replace petrol-based plastics in food packaging applications; there are many research studies focused on improving biopolyesters’

Summary

Introduction

A mismanagement of the disposal of short term polymers after use joined with the impossibility to handle the problem only by mechanical recycling due to still inefficient waste management programs, the composition of some plastic formulations (i.e., blends, composites, nanocomposites, etc.), and the fact that plastics cannot be recycled forever [1], as well as the resistance to degradation by many plasticPolymers 2020, 12, 2891; doi:10.3390/polym12122891 www.mdpi.com/journal/polymersPolymers 2020, 12, 2891 materials, have led to plastic hoarding in the environment [2,3,4,5]. Biodegradable polymers present reduced overall performance with respect to traditional petroleum-based counterparts, such as higher sensitivity to humidity and thermal degradation, as well as poor barrier and mechanical performance, which hinder its massive industrial exploitation [8,9,10]. Performance, including poly(lactic acid) (PLA), polyhydroxyalkanoates (PHAs) and its derivatives [11], poli(ε-carpolactone) (PCL), and poly(butylene adipate-co-terephthalate) (PBAT) [12,13,14]. Aliphatic biopolyesters, such as PLA and PHB, have been, to date, the most promising biodegradable polymers for biodegradable or compostable food packaging products [7]. Many research efforts have been focused on biopolyesters modification for extending their industrial application as flexible materials with improved barrier and hydrophobicity performance, such as blending, the addition of fillers and/or nanofillers, surface plasma treatment, or copolymerization [16,18,19]

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