Chemical Modification of Poly(butylene trans-1,4-cyclohexanedicarboxylate) by Camphor: A New Example of Bio-Based Polyesters for Sustainable Food Packaging.

Giulia Guidotti,Massimo Gazzano,Andrea Munari,Nadia Lotti,Valentina Siracusa,Michelina Soccio,Gianfranco Burzotta

doi:10.3390/polym13162707

Abstract

Among the several actions contributing to the development of a sustainable society, there is the eco-design of new plastic materials with zero environmental impact but that are possibly characterized by properties comparable to those of the traditional fossil-based plastics. This action is particularly urgent for food packaging sector, which involves large volumes of plastic products that quickly become waste. This work aims to contribute to the achievement of this important goal, proposing new bio-based cycloaliphatic polymers based on trans-1,4-cyclohexanedicarboxylic acid and containing different amount of camphoric acid (from 0 to 15 mol %), a cheap and bio-based building block. Such chemical modification was conducted in the melt by avoiding the use of solvents. The so-obtained polymers were processed in the form of films by compression molding. Afterwards, the new and successfully synthesized random copolymers were characterized by molecular (NMR spectroscopy and GPC analysis), thermal (DSC and TGA analyses), diffractometric (wide angle X-ray scattering), mechanical (through tensile tests), and O2 and CO2 barrier point of view together with the parent homopolymer. The article aims to relate the results obtained with the amount of camphoric moiety introduced and to present, the different microstructure in the copolymers in more detail; indeed, in these samples, a different crystalline form developed (the so-called β-PBCE). This latter form was the kinetically favored and less packed one, as proven by the lower equilibrium melting temperature determined for the first time by Baur’s equation.

Highlights

In recent years, the growing attention to the increasingly complex and serious problem of waste management and the push by governments to develop the so-called circular economy has required the growingly careful choice of the various plastic materials that are used for various daily purposes
Among the several actions contributing to the development of a sustainable society, there is the eco-design of new plastic materials with zero environmental impact but that are possibly characterized by properties comparable to those of the traditional fossil-based plastics
The copolymer objects of the study were synthesized starting from two different diacids: 1,4-cyclohexanedicarboxylic acid (1,4-CHDA) (Scheme 1A) and (1R,3S)-(+)camphoric acid (CA) (Scheme 1B) together with 1,4-butanediol (BD) (Scheme 1C)

Summary

Introduction

The growing attention to the increasingly complex and serious problem of waste management and the push by governments to develop the so-called circular economy has required the growingly careful choice of the various plastic materials that are used for various daily purposes. The principles of circular economy and green chemistry require a low environmental impact of the entire life cycle of materials, starting from raw materials and production processes up to disposal. The choice fell onto renewable sources as an alternative to fossil ones, which can give life to eco-sustainable materials, the so-called bioplastics, obtained through green synthetic processes limiting the use of solvents and low greenhouse gas emissions

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