# Mechanical Recyclability of TPS/PVA Blends and Their Comparison with Other Bioplastics

## TL;DR

This study explores the mechanical recyclability of TPS/PVA blends and compares them to other bioplastics like PLA and PHB.

## Contribution

The first study on the mechanical recyclability of TPS/PVA blends up to ten cycles and their comparison with commercial bioplastics.

## Key findings

- TPS/PVA blends retain mechanical performance and toughness after ten recycling cycles.
- Wheat-based TPS/PVA compounds show the highest recycling potential due to less chain scission and syneresis.
- PLA and PHB degrade significantly after few cycles, showing poor recyclability.

## Abstract

Thermoplastic starch-PVA
blends currently present great potential
since they show stable mechanical performance along with the advantage
of compostability and self-biodegradability in the marine environment.
However, one step further could be attained if this ocean-friendly
compound could be mechanically recycled and then promote circular
economy applications before its final composting. The main goal of
this work is to study, for the first time, the mechanical recyclability
of TPS/PVA compounds up to ten cycles, using blends based on potato,
wheat, and cassava starch. Furthermore, the results are compared to
those obtained by reprocessing commercial PLA and PHB compounds. As
the mechanical reprocessing cycles proceed, all TPS/PVA compounds
retain the mechanical performance after ten cycles, and especially
toughness is also maintained. At the same time, there is evidence
of some chain scission in starch, observed in earlier cycles for cassava-based
compounds, although it is ultimately superior in a potato mixture.
Interestingly, the starch syneresis progress as well as some chain
scission allows a stable melt-flow index, up to cycle 10. In addition,
wheat compounds could have the highest recycling potential, with less
chain scission and syneresis, being able to redistribute the plasticizer
in the starch-rich phase, improving its plasticization. Regarding
commercial biopolymers, PLA loses toughness dramatically from cycle
4 and PHB from cycle 1, and the melt-flow index increases sharply,
denoting a significant polymer degradation and poor recyclability
potential.