PBAT foam achieves high resilience and low shrinkage through TPU blending and epoxy chain extender

Research background and core findings

Biodegradable polyadipate butylene terephthalate (PBAT) foam is considered as a sustainable alternative to petroleum based foam, but its poor resilience and severe shrinkage after foaming limit its practical application. A study published in the Journal of Applied Polymer Science proposed a simple and effective strategy: blending PBAT with thermoplastic polyurethane (TPU) elastomers and introducing epoxy based chain extenders (CE) as reactive compatibilizers. Research has shown that the epoxy group of CE can react with the carboxyl and hydroxyl end groups of PBAT and TPU to form graft copolymers in situ, significantly enhancing interfacial adhesion. Rheological analysis confirms that the melt strength and elasticity of the blend treated with compatibilization have been effectively improved.

Key data and performance

• Thanks to the synergistic effect of TPU toughening and CE compatibility, the ball rebound rate of PBAT/CE/TPU foam reached 52%, 44.4% higher than that of pure PBAT foam.
• The shrinkage of foam after 24 hours was significantly reduced to only 5.3%.
• SEM observation showed that the foam had a uniform cellular structure, and the TPU dispersed phase was well embedded in the PBAT matrix.

Research has shown that refined pore structures ensure uniform stress distribution, which is crucial for applications that require resilience and dimensional stability.

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Significance to the polymer additives industry

From the perspective of formula design, this study shows the multiple roles of reactive chain extenders in biodegradable polyester foam: not only as compatibilizers to improve the interface bonding between PBAT and TPU, but also to stabilize the cell structure by improving the melt elasticity. This is similar to the idea in the rubber industry of regulating cross-linking networks through vulcanization systems and improving mechanical properties through reinforcing fillers – both balance resilience and dimensional stability through interface and network structure regulation. In the field of tires and rubber, the effect of white carbon black as a reinforcing filler on rolling resistance and wet skid resistance, as well as the protection of long-term properties of materials by anti-aging agents, all rely on fine control of the polymer matrix interface and network structure. The compatibility strategy of epoxy based chain extenders in this study provides a reference chemical pathway for interfacial modification of multiphase polymer systems. Although this study focused on PBAT foam rather than tire rubber, its findings on the relationship between melt strength, cell uniformity and resilience have reference value for understanding the formula design of rubber foam materials and multiphase blends. The application directions proposed by the research include cushioning packaging, sports shoe materials, and automotive interiors, which have clear requirements for resilience and dimensional stability. For the rubber industry, how to improve rebound and shrinkage resistance without sacrificing processing performance remains a continuous concern for formulation engineers.

Information source:High‐Resilience and Anti‐Shrinkage PBAT Foams Enabled by TPU Elastomer Blending and Epoxy‐Based Chain Extender Compatibilization， Organized by Herun Chemical.