# UHMWPE-Assisted Melt Strength Enhancement of Recycled PLA for Lightweight Foaming

## TL;DR

Adding UHMWPE to recycled PLA improves its melt strength and allows for lightweight, high-performance foams suitable for insulation and packaging.

## Contribution

A novel method to enhance recycled PLA's melt strength using UHMWPE for foam production.

## Key findings

- UHMWPE/PLA composites showed a 5.3-fold increase in melt strength compared to recycled PLA.
- Composite foams achieved a thermal conductivity of 0.019 W m–1 K–1 and a density of 0.217 g cm–3.
- The method uses standard techniques, making it scalable for industrial applications.

## Abstract

Increased utilization
of biodegradable polymers to achieve
sustainability
and decrease the carbon footprint is connected with a necessity to
find an effective way of their reutilization. Polylactic acid (PLA),
and generally all biodegradable polymers, undergoes significant degradation
during reprocessing cycles, leading to inferior products when compared
with the original material. Here, ultrahigh molecular weight polyethylene
(UHMWPE) was incorporated as a reinforcing phase to create a polymer–polymer
composite capable of restoring and enhancing the melt strength of
recycled PLA. While recycled PLA lost melt strength during reprocessing,
limiting its foamability, the UHMWPE/PLA composites exhibited up to
a 5.3-fold increase in melt strength, enabling stable cell growth
and expansion during foaming. The composite foams also showed a substantial
reduction in thermal conductivity to 0.019 W m–1 K–1 and a lower density of 0.217 g cm–3. These improvements originate from the unique combination of UHMWPE/PLA
composite and filler morphology within the PLA matrix, which reinforces
the PLA melt and suppresses cell coalescence. The approach under discussion
relies on standard blending and foaming techniques, thus offering
a simple and scalable route for the conversion of reprocessed and
recycled PLA into high-performance, highly expanded foams. These foams
can be used for thermal insulation, protective packaging and lightweight
structural applications.