The 2012 World Congress on Advances in Civil, Environmental, and Materials Research (ACEM’ 12)Seoul, Korea, August 26-30, 2012

Preparation, characterization, and properties of nanofillers based thermoplastic polyurethane nanocomposites

Aruna Kumar Barick1), Ji-Yoen Jung2), Young-Wook Chang3), and

Deba Kumar Tripathy4)

1), 2), 3) Polymer Nano Materials Laboratory, Department of Chemical Engineering, Hanyang University, Ansan 426-791, Gyeonggi, South Korea

4) Pro-Vice Chancellor, School of Technology, Kalinga Institute of Industrial Technology University, Bhubaneswar 751 024, Odisha, India

3) ywchang@hanyang.ac.kr

ABSTRACT The nanofillers (nanoclay (NC), carbon nanofiber (CNF), and carbon nanotube (CNT) based thermoplastic polyurethane (TPU) nanocomposites were prepared by melt intercalation technique followed by compression molding. The nanostructure morphology of the prepared nanocomposites was visualized through transmission electron microscope (TEM). The representative microphotographs showed that the nanofillers are homogeneously dispersed within the TPU matrix. The thermal and dynamic mechanical properties of the TPU nanocomposites were analyzed using thermo-gravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The TGA study found out that the thermal stability of the nanocomposites was significantly increases with increase in filler loading, which is attributed to the rigidity of the nanofillers and very good interfacial interactions between TPU matrix and nanofillers. The storage modulus (E') and dynamic glass transition temperature (Tg) of the TPU matrix are significantly enhanced by the incorporation of nanofillers due to the strong reinforcing effect imparted by the nanofillers. 1. INTRODUCTION Polymer nanocomposites have received outstanding importance in the present decade because of their broad range of high performance applications in various areas of engineering and technology due to their special material properties. The new class of polymer nanocomposites based on nanofillers (nanoclays, nanofibers, nanotubes, nanoparticles, etc) has received enormous attentions from academicians, researchers, and industrial personnel from the very inception of its 1) Postdoctoral Researcher 2) Postgraduate Student 3) Professor 4) Professor

discovery (Pavlidou and Papaspyrides, 2008; Moniruzzaman and Winey, 2006; Thostenson et al., 2005; Ray and Okamoto, 2003). Polymer nanocomposites are a novel class of composite materials where one part of the constituents i.e. dispersed phase has dimensions in the range of 1–102 nm. A great interest is dedicated to nanofiller based polymeric materials, which exhibit excellent enhancement in macroscopic material properties (mechanical, thermal, dynamic mechanical, electrical and many more) at very low filler contents and can therefore be used for the development of a next generation nanocomposite materials. The improvement of material properties of nanofillers reinforced polymer nanocomposites is assigned to their nanometer dimensional features i.e. the extraordinarily high surface area of the dispersed nanofiller and the unique microstructure characteristics that make them excellent candidature as reinforcing materials for polymers in multifunctional nanocomposites. 2. EXPERIMENTAL 2.1 Materials Commercial biomedical grade cyclo-aliphatic polyether based TPU (Tecoflex® EG 80A injection grade) used as the matrix material for this work was supplied by Lubrizol Advanced Materials, Inc., Thermedics™ Polymer Products, Ohio, USA. Commercial organically modified layered silicate (Cloisite 30B) used in this study was procured from the Southern Clay Products, Inc., Texas, USA. Heat-treated low-density vapor-grown carbon nanofiber (PR-24-HHT-XT-LD) was procured from Pyrograf® Products, Inc. an affiliate of Applied Sciences, Inc., Ohio, USA. Carboxyl functionalized multi-walled carbon nanotube (COOH–MWNT) of 95 weight percent (wt%) purity contains 3.86 wt% –COOH groups used for the research work were supplied by Cheap Tubes, Inc., Vermont, USA. 2.2 Methods Polymer nanocomposites based on TPU and nanofillers were prepared by melt intercalation technique using Thermo Scientific Haake PolyLab OS Rheomix (Thermo Electron Corporation, Massachusetts, USA). The mixing of samples was carried out at temperature of 185 °C with a rotor speed of 100 rpm. The mixing time for nanoclay filled system is 6 min as well as nanofiber and nanotube filled system is 8 min. Varying amount of nanoclay (1, 3, 5, 7, and 9 wt%), nanofiber (1, 4, 7, 10, and 15 wt%), and nanotube (0.5, 2.5, and 5.0 wt%) were added to the TPU matrix. The TPU pellets and nanoclay were dried in a vacuum oven at 80 °C for 6 h and 12 h, respectively prior to mixing for the evaporation of moisture if any in the supplied materials. The nanofiber and nanotube samples were dried at 120 °C in a preheated vacuum oven for 24 h before processing. The compounds were cut into small pieces and specimens of 2 mm thick sheet for all the compositions were prepared using compression molding machine (Moore Press, GE Moore and Son, Birmingham, UK) at 185 °C for 3 min with an applied pressure of 5 MPa. The compression molded sheets were cooled to room

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