Deterioration in the Physico-Mechanical and Thermal Properties of Biopolymers Due to Reprocessing.

Jamileh Shojaeiarani,Ghazal Vahidi,Chad Rehovsky,Sreekala G Bajwa,Dilpreet S Bajwa

doi:10.3390/polym11010058

Jamileh Shojaeiarani, Ghazal Vahidi + Show 3 more

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https://doi.org/10.3390/polym11010058

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Journal: Polymers	Publication Date: Jan 2, 2019
Citations: 47	License type: CC BY 4.0

Affiliation: North Dakota State University

Abstract

Biopolymers are an emerging class of materials being widely pursued due to their ability to degrade in short periods of time. Understanding and evaluating the recyclability of biopolymers is paramount for their sustainable and efficient use in a cost-effective manner. Recycling has proven to be an important solution, to control environmental and waste management issues. This paper presents the first recycling assessment of Solanyl, Bioflex, polylactic acid (PLA) and PHBV using a melt extrusion process. All biopolymers were subjected to five reprocessing cycles. The thermal and mechanical properties of the biopolymers were investigated by GPC, TGA, DSC, mechanical test, and DMA. The molecular weights of Bioflex and Solanyl showed no susceptible effect of the recycling process, however, a significant reduction was observed in the molecular weight of PLA and PHBV. The inherent thermo-mechanical degradation in PHBV and PLA resulted in 20% and 7% reduction in storage modulus, respectively while minimal reduction was observed in the storage modulus of Bioflex and Solanyl. As expected from the Florry-Fox equation, recycled PLA with a high reduction in molecular weight (78%) experienced 9% reduction in glass transition temperature. Bioflex and Solanyl showed 5% and 2% reduction in molecular weight and experienced only 2% reduction in glass transition temperature. These findings highlight the recyclability potential of Bioflex and Solanyl over PLA and PHBV.

Highlights

There is a huge interest in the development of bio-based materials to lessen the dependency on petroleum-based polymers owing to the growth in environmental concerns, fluctuating crude oil price, and the depletion of fossil fuels [1]
In order to investigate the influence of the successive recycling process on the molecular structure of the polymers, Gel Permeation Chromatography (GPC) analysis was performed and the weight average molecular weight (Mw ), the number average of molecular weight (Mn ), and the molecular weight distribution (Mw /molecular number (Mn) )
The higher decline in Mw was observed in PHBV by 82% reduction, followed by polylactic acid (PLA) by 78%, suggesting the structure of PHBV and PLA are more susceptible to high shear and temperature in comparison with Bioflex and Solanyl

Summary

Introduction

There is a huge interest in the development of bio-based materials to lessen the dependency on petroleum-based polymers owing to the growth in environmental concerns, fluctuating crude oil price, and the depletion of fossil fuels [1]. The packaging industry represents the largest demand for plastic and nearly 70% of the biopolymer global market is attributed to the packaging industry [2]. The short-term or single-use application of packaging materials is of great concern as it leads to the pollution of water. The recycling process is one of the most important alternatives to control environmental and waste management issues. The recycling process is a waste management treatment available to lessen the environmental impact related to the disposal of plastics. Recycling extends the life of polymeric materials but helps the biopolymer market financially by providing circular materials of thermoplastics [3]

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