Formulating Bioplastic Composites for Biodegradability, Recycling, and Performance: A Review

Society’s wish list for future packaging systems is placing some daunting challenges upon researchers: In addition to protecting contents during storage and shipping, the material must not bio-accumulate, and it should be readily recyclable by using practical processing steps. This article considers strategies employing bio-based plastics and reviews published information relative to their performance. Though bioplastics such as poly(lactic acid) (PLA) and poly(hydroxybutyrate) (PHB) can be prepared from plant materials, their default properties are generally inferior to those of popular synthetic plastics. In addition, some bioplastics are not easily decomposed in soil or seawater, and the polymers can undergo chemical breakdown during recycling. This review considers strategies to overcome such challenges, including the use of biodegradable cellulose-based reinforcing particles. In addition to contributing to strength, the cellulose can swell the bioplastic, allowing enzymatic attack. The rate-controlling step in bioplastic degradation also can be abiotic, i.e. not involving enzymes. Though there is much more work to be done, much progress has been achieved in formulating bioplastic composites that are biodegradable, recyclable, and higher in strength compared to the neat polymer. Emphasis in this review is placed on PLA and PHB, but not to the exclusion of other bioplastic matrix materials.