Making of PLA Based Biodegradable TPEs (Thermoplastic Elastomers)

PLA-based thermoplastic elastomers (TPEs) are generally produced as either polymer blends or block copolymers that integrate rigid PLA segments with softer, more flexible segments. Common methodologies include:

PLA + biodegradable polyesters: The combination of PLA with aliphatic polyesters results in flexible and compostable materials. For instance, PLA/PBAT (poly(butylene adipate-co-terephthalate)) blends, such as those found in BASF’s ecovio® line, utilize PLA as the continuous phase and PBAT (or Ecoflex) as the soft phase. Additionally, blends of PLA with PCL (polycaprolactone) or PHB (polyhydroxybutyrate) have been investigated to enhance ductility.

PLA + natural rubber or resin: Furthermore, PLA can be melt-blended or chemically reacted with rubbery polymers. Formulations incorporating natural rubber (NR) or epoxidized natural rubber (ENR) produce thermoplastic elastomers (TPEs) characterized by high elasticity. Some studies have also explored blending PLA with thermoplastic polyurethane (TPU) segments derived from PLA-based polyols to create PLA–PU block copolymers (ABA triblocks) that exhibit soft elastomeric properties. Generally, these blends position PLA as the hard block while employing a flexible biodegradable polyol or rubber as the soft block.

PLA copolymers and plasticized PLA: Ring-opening polymerization has produced multiblock copolymers like PLA–PCL–PLA or PLA–PEG–PLA that behave as elastomers. Low-molecular-weight PLA oligomers or bio-based plasticizers (e.g. citrate esters) can be added to PLA to increase chain mobility, though true TPE grades usually use co-polymers or blends.

Other bio-based blends: Some TPEs incorporate thermoplastic starch (TPS) or cellulose fibers with PLA to yield softer composites. For example, Green Dot’s Terratek® Flex is a starch-based compostable elastomer (not PLA-based, but illustrative of bio-elastomers). In general, any blend that uses >50% PLA and meets compostable standards can be considered a PLA-based TPE.

In summary, commercial PLA-TPE formulations include PLA blended with compostable polyester elastomers (PBAT/Ecoflex, PCL, PHAs) or with rubbery segments (NR, TPU from PLA polyols). For instance, FKuR’s Bio-Flex® grades are proprietary PLA-based copolyesters (often PLA/PBAT) fully biodegradable and compostable. These PLA blends typically contain >50–80% renewable PLA content, with the soft component providing rubber-like elasticity.


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Author
Dr. Subhas C. Shit
Trainer, Polymerupdate Academy
Ex principal Director - Central Institute of Plastics Engineering & Technology (CIPET)