Study on Chain Extension Blending Modification and Foaming Behavior of Thermoplastic Polyamide Elastomer

Area of Science:

• Materials Science
• Polymer Chemistry
• Foam Technology

Background:

• Thermoplastic polyamide elastomers (TPAE) often exhibit high shrinkage rates in melt foaming.
• Improving melt foaming properties and reducing material shrinkage are critical for TPAE applications.

Purpose of the Study:

• To enhance melt foaming properties of TPAE using styrene maleic anhydride copolymer (SMA).
• To reduce the shrinkage rate of foamed TPAE materials through in situ reactive blending with polyamide 6 (PA6).

Main Methods:

• In situ reactive blending of TPAE and PA6 using SMA as a chain extender.
• Characterization of rheological and crystalline properties using rotational rheometry and differential scanning calorimetry.
• Melt batch foaming experiments utilizing CO2 as the foaming agent.

Main Results:

• Addition of PA6 decreased the melting enthalpy and crystallinity of modified TPAE, aiding gas penetration and reducing cell pressure effects.
• Increased PA6 content formed a micro-cross-linked structure, enhancing storage modulus and strain recovery.
• Foaming temperature range and recovery performance were significantly improved, with shrinkage reduced to <10% and expansion ratios reaching 11-13 times.

Conclusions:

• SMA-modified TPAE with PA6 shows improved melt foaming characteristics, including reduced shrinkage and enhanced expansion.
• The balance between reduced crystallinity and increased modulus is key to achieving superior foam properties.
• This approach offers a viable method for producing high-performance foamed TPAE materials.