Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE In this work, we report the synthesis of disulphide-linked polyurethane and its blending with Eri silk to obtain a homogeneous blend. The study examined how disulfide linkages influence the rheological behaviour and thermal properties of the blend, revealing a lower glass transition temperature and potential for use at sub-zero temperatures. Subsequently, the optimized blend was spun into fibers using an in-house wet-spinning method, demonstrating its practical applicability for fibre production.

ABSTRACT
The study demonstrates a polyurethane (PU) and Eri silk blend with excellent performance in ultra-low temperature conditions, highlighting its potential for extreme cold environments. PU is a versatile polymer known for its ability to be formed into various structures, making it ideal for numerous applications. Incorporation of disulfide bonds introduces dynamic covalent linkages, enhancing the flexibility of the polymer network. Eri silk has excellent thermal insulation and moisture-wicking features, making it an ideal choice for blending with polyurethane. Herein, we report a synthesis approach achieving a homogeneous blend of PU/Eri silk using trifluoroacetic acid as solvent. The optimized composition resulted in low glass transition temperature (T
g) of blend, overcoming Eri silk's inherently higher T
g. An in-house wet spinning method was adopted to form uniform fibers from the blend solution. The smooth morphology was examined by SEM, while T
g was evaluated from DSC. DMA analysis in torsional mode demonstrated the viscoelastic behavior of the PU/Eri silk blend, while DMA in tensile mode was used to assess its suitability for low-temperature applications. The results suggest that the PU/Eri silk blend has potential for applications requiring flexibility under low-temperature conditions.