Polyurethane foam/silica chemical hybrids for shape memory effects
- PDF / 529,720 Bytes
- 7 Pages / 584.957 x 782.986 pts Page_size
- 86 Downloads / 257 Views
S.H. Kwona) Department of Naval Architecture and Ocean Engineering, Pusan National University, Busan 609-735, Korea
H. Park Global Core Research Center for Ships and Offshore Plants, Pusan National University, Busan 609-735, Korea
H.M. Jeong Department of Chemistry, University of Ulsan, Ulsan 680-749, Korea
B.K. Kimb) Department of Polymer Science and Engineering, Pusan National University, Busan 609-735, Korea (Received 24 April 2012; accepted 4 September 2012)
The isocyanate-functionalized silica nanoparticles were chemically incorporated into the polyurethane (PU) during the synthesis of flexible PU foam from polypropylene glycol and toluene diisocyanate following the one-shot method with water as the blowing agent. Chemical incorporations of silica nanoparticles augmented hardness, initial modulus, and strength for tensile and compression loading. As results, shape fixity, shape recovery, and strain energy storage significantly increased with reduced hysteresis loss. It was found that the chemically incorporated silica particles effectively reinforce the PUs with improved dispersion and act as multifunctional cross-links, elastic energy storage, and relaxation retarder, which are beyond the conventional reinforcing filler. The maximum increases of dynamic properties and shape memory performances with 2% silica are an indication that the chemical incorporation is also limited by particle aggregations, though it appears at higher content than the simple blend.
I. INTRODUCTION
When polymers are doped with fillers such as fibers, platelets, tubes, or particles, substantial enhancement in mechanical properties is obtained depending on the amount, degree of dispersion, interfacial adhesion, and the filler geometries. The shape memory (SM) polymer composites provide the materials with high recovery stress as well as novel functions such as electrical conductivity, magnetism, and biofunctionality1 and have received considerable attention over the last decade,2–5 shedding lights on the potential applications in automotive, aerospace, building, electrical, optoelectronic, and biomedical applications.6–8 Among them, the SM performance was most pronounced when the multifunctional fillers were chemically incorporated into the polymer chains.9–11 In this case, fillers act as multifunctional cross-links, strain energy storage, and relaxation retarder as well as the conventional reinforcing fillers. However, so far, the effects have largely been limited to nonfoam materials.
Address all correspondence to these authors. a) e-mail: [email protected] b) e-mail: [email protected] DOI: 10.1557/jmr.2012.334 J. Mater. Res., Vol. 27, No. 22, Nov 28, 2012
http://journals.cambridge.org
Downloaded: 02 Jun 2014
Regarding the polyurethane (PU) foam, SM effects have been reported with regard to the cyclic properties,12 effect of shape holding conditions,13 and for biomedical applications14,15 largely using the commercially available PU foams. On the other hand, flexible PU foam is used in a broad range of applications. The majority of molded foam i
Data Loading...
