Structure and deformation recovery of the thermoplastic polyurethane spherulite

Abstract

We investigated the structure and deformation behavior of the thermoplastic polyurethane (TPU) spherulite by optical microscopy, tensile testing, Hv light scattering, and small angle X-ray scattering. The TPU spherulite structure obtained by melt crystallization was coarse consisting of bundle-like structure containing hard segment (HS) lamellar domain in which the HS domains were stacked and the HS chain direction was perpendicular to the longitudinal axis of the HS domain. By stretching, the spherulite was deformed to ellipsoidal one and the stacked HS lamellar domains were tilted in the stretching direction. The deformed spherulite and the tilted HS domain in the spherulite were recovered to the unstretched state by retraction. The recovery of the structure is ascribed to the characteristic spherulite structure consisting of rubbery soft segment matrix physically cross-linked with the stacked HS domain.

Dynamic Monte Carlo simulations of strain-induced crystallization in multiblock copolymers: effects of dilution

“…19 Polyurethane spherulites showed a good deformation recovery, which has been attributed to the physical crosslinking in the domains rich of soft blocks. 20 Three stages of elasticity during the cyclic deformation of segmental polyether and polyamide copolymers have been observed, 21 and the reversible and irreversible mechanical responses have been discussed with the possible crystallization in soft blocks. 22,23 The asynchronous fracture of polyurethane elastomers has been attributed to a heterogeneous distribution of hydrogen bonding in the hard block domains, implying the diverse stabilities of crystallites.…”

High-Strength Heat-Elongated Thermoplastic Polyurethane Elastomer Consisting of a Stacked Domain Structure

“…Thermoplastic polyurethane (TPU) is one of the most-used elastomers, with versatile thermoplastic and elastomeric properties [ 1 ]. TPU has superior mechanical properties such as high elongation, toughness, and strain recovery [ 2 , 3 , 4 , 5 ]. The characteristic mechanical behavior of TPU is attributed to the sequenced crystalline hard segment (HS) and amorphous soft segment (SS).…”

Filmes formados simultaneamente às sínteses de poliuretanos: celulose microcristalina e óleo de mamona como polióis

“…As micrografias das superfícies de fratura para os filmes PUCOpMDI, não cristalinos (CRIST;SCHULTZ, 2016). Quando os feixes são observados, é possível encontrar os domínios HS empilhados no interior destes, de modo que as regiões SS estão orientadas em direção perpendicular aos domínios HS(YANAGIHARA et al, 2017).…”

“…domínios cristalinos, e de "segmentos flexíveis" (soft segments, SS), poli(tetrametileno éter)glicol (PTMG), que normalmente constituem a região não cristalina, através da cristalização por fusão. As esferulitas apresentaram diâmetro de aproximadamente 30 µm(YANAGIHARA et al, 2017). A forma e organização dessas esferulitas são representadas esquematicamente na Figura 25.Figura 25 -Ilustração esquemática da estrutura morfológica de esferulitas Fonte: Yanagihara et al, 2017.…”