Abstract

Water-blown polyurethane (PU) foams are of enormous technological interest as they are widely applied in various fields, i.e., consumer goods, medicine, automotive or aerospace industries. The discovery of the one-way shape-memory effect in PU foams provided a fresh impetus for extensive investigations on porous polymeric actuators over the past decades. High expansion ratios during the shape-recovery are of special interest when big volume changes are required, for example to fill an aneurysm during micro-invasive surgery or save space during transportation. However, the need to program the foams before each operation cycle could be a drawback impeding the entry of shape-memory polymeric (SMP) foams to our daily life. Here, we showed that a reversible shape-memory effect (rSME) is achievable for polyurethane water-blown semicrystalline foams. We selected commercially available crystallizable poly(ε-caprolactone)-diols of different molecular weight for foams synthesis, followed by investigations of morphology, thermal, thermomechanical and shape-memory properties of obtained compositions. Densities of synthesized foams varied from 110 to 180 kg∙m−3, while peak melting temperatures were composition-dependent and changed from 36 to 47 °C, while the melting temperature interval was around 15 K. All semicrystalline foams exhibited excellent one-way SME with shape-fixity ratios slightly above 100% and shape-recovery ratios from the second cycle of 99%. The composition with broad distribution of molecular weights of poly(ε-caprolactone)-diols exhibited an rSME of about 12% upon cyclic heating and cooling from Tlow = 10 °C and Thigh = 47 °C. We anticipate that our experimental study opens a field of systematic investigation of rSMEs in porous polymeric materials on macro and micro scale and extend the application of water-blown polyurethane foams to, e.g., protective covers with zero thermal expansion or even cushions adjustable to a certain body shape.

Highlights

  • Polyurethane (PU) foams are widely spread in our daily life as a core part of the majority of comfort items, such as cushions or pillows

  • In order to obtain a range of densities and thermal and thermomechanical properties different number average molecular weights and their combinations were used without any change of the processing conditions

  • In In this study, series of of semicrystalline semicrystallinewater-blown water-blown this study,wewereport reportthe thesuccessful successful synthesis synthesis of a series free-rise foams using commerciallyavailable available linear linear poly(ε-caprolactone)-diols poly(ε-caprolactone)-diols crosslinked with free-rise foams using commercially crosslinked with rSMEeffect effectisisachievable achievable for Crosslinked Poly(ε-caprolactone) (cPCL)

Read more

Summary

Introduction

Polyurethane (PU) foams are widely spread in our daily life as a core part of the majority of comfort items, such as cushions or pillows. A series of studies describing polyurethane-based foams with shape-memory effect (SME) has been published [2,3,4], where, flexible when heated, the shape-memory polymer (SMP) foam can be shaped to a desired. 2016, 8, 412 geometry can be stored during a required period and the recovery of the 2 oforiginal form,Polymers the introduced shape of the SMP-foam can be triggered by regulating the ambient temperature. The shaping to shaped to a desired form, the introduced geometry can be stored during a required period and the a temporary form is commonly referred to as programming step. A SMP-foam is recovery of the original shape of the SMP-foam can be triggered by regulating the ambient heated during programming to a Tprog until foam’s softening and compressed to a temporary shape

Objectives
Methods
Results
Conclusion

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.