Fatigue Characteristics of Poly(ether-b-amide) Elastomers during Cyclic Dynamic Tests and the Underlying Microstructural Evolution

Abstract

The dynamic fatigue behavior of the poly­(ether-b-amide) (PEBA) elastomers was characterized by a combination of step increase load test (SILT), step increase strain test (SIST), and single load dynamic creep (SLDC). PEBA had crystalline hard segments of polyamide 12 (PA12) and soft segments of poly­(tetramethylene oxide) (PTMO). The crystalline morphologies before and after the tests were studied by ex situ wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS). Fast stress relaxation can be seen under the applied strain well below than the elongation at break. Remarkable dynamic creep can be observed under the applied load triggering yielding of the specimen, which is substantially less than the ultimate tensile strength. Although the presence of high content of amorphous PTMO renders high entropic elasticity, the disintegration of the crystalline hard domains of PA12 is expected to determine the relaxation rate, creep rate, and modulus, as strain-induced crystallization in soft domains did not occur and no trace was found by WAXD. SAXS patterns showed that the orientation of the PA12 lamellae at lower stresses or strains can largely be restored. However, the fractured and highly aligned PA12 lamellae resulted in classic four-point or two-lobe SAXS patterns, which implied the underlying microstructural changes after the cyclic dynamic tests.

Supercritical foaming of novel poly(ether‐b‐amide) elastomer and compression property characterization

“…Compared with pure PA6 and chain‐extended PA6, long‐chain branched PA6 foams exhibit smaller cell diameters, higher cell densities, and a wider foaming temperature window 20 . Novel PEBAs with PA1012 as HS have been developed, of which the structure–property relationship was extensively studied 21–23 . The diacid and diamine monomer for PA1012 HS could be prepared by microbial fermentation of alkanes, and derived from castor oil respectively, thus PA1012 has the characteristics of lower carbon footprint than crude oil‐based PA12 and comparable mechanical properties, thus it could be a good alternative for PA12 or PA11‐based PEBAs.…”

Introducing the I&ECR Virtual Collection of Industrial and Industrially Relevant Research (2022–2023)

“…The Applied Chemistry topic area is represented with research articles across a diverse breadth of research and development topics including: foam injection molding, the preparation of mesoporous aluminosilicates, multinational studies of the catalytic pyrolysis of linear low-density polyethylene (LLDPE) in fluidized-bed reactors, and poly­(ether- b -amide) (PEBA) elastomer fatigue, an interesting longitudinal study of the optimal storage conditions for cannabis crops from New Zealand, and studies of lactate based plasticizers for polyvinyl chloride (PVC) and polylactic acid (PLA) polymers, and methyl ethyl ketone (MEK) peroxide synthesis in a continuous flow regime …”