Elastomers nanocomposites

Presents current research activities on new rubbers, thermoplastic elastomers, nanocomposites, biomaterials, and smart polymers, as well as rubber blends, composites, and rubber ingredients... 

Figure 2.8 Photomechanical actuation of MWNT-elastomer composites, a) Bimodal and reversible actuation of a MWNT-elastomer nanocomposite induced by IR irradiation. Reversible expansion occurs at small pre-strains (top) and reversible contraction at large pre-strains (bottom), b) Response to IR irradiation at different values of pre-strain. Raw data on stress measured at fixed sample length of a 1 wt% MWNT-PDMS nanocomposite (different pre-strain curves labeled on the plot). Reprinted by permission from Macmillan Publishers Ltd. ...

As mentioned earlier/ Ahir et al. have studied the photomechanical behavior of three types of MWNT-elastomer nanocomposites irradiated with near-IR light under isostrain conditions, including PDMS, styrene-isoprene-styrene (SIS), and a nematic LCE with a polysiloxane backbone. 

Bokobza, L. Burr, A. Garnaud, G. Perrin, M. Pagnotta, S. (2004) Fibre Reinforcement of Elastomers Nanocomposites Based on Sepiolite and Poly(hydroxyethyl acrylate). Polym. Int. Vol.53, N0.8, pp.1060-1065, ISSN 0959-810 Bonduel, D. Mainil, M. Alexandre, M. Monteverde, F. Dubois, P. (2005) Supvported Coordination Polymerisation A Unique Way to Potent Polyolefin Carbon Nanotube Nanocomposites. Chem. Commun. Vol.l4, No.6, pp.781-783 Bruckner, S. Meille, S. Petraccone, V. Pirozzi, B. (1991) Polymorphism in Isotactic Polypropylene. Prog. Polym. Sci. 16, No.2-3, pp.361-404 Bryning, M. Islam, M Kikkawa, J. Yodh, A. (2005) Very Low Conductivity Threshold in Bulk Isotropic Single-Walled Carbon Nanotube-Epoxy Composites. Ado. Mater. Vol.17, N0.9, pp.1186-1191... 

L. Yang, K. Setyowati, A. Li, S. Gong, J. Chen, Reversible infrared actuation of carbon nanotubes-liquid crystalline elastomer nanocomposites. Adv. Mater. 20, 2271-2275 (2008)... 

C.S. Li, Y. Liu, C.-W. Lo, H.R. Jiang, Reversible white-light actuation of carbon nanotube incorporated liquid crystalline elastomer nanocomposites. Soft Matter 7, 7511-7516 (2011)... 

Thompson, M. R. and Yeung, K. K. 2006. Recyclability of a layered silicate-thermoplastic olefin elastomer nanocomposite. Polymer Degradation and Stability 91 2396-2407. 

Elastomer nanocomposites can better be characterized with the help of NMR studies as illustrated in the introduction section. Solid-state NMR is the best choice as the sample is in the solid state, but the same information is obtained from the liquid state NMR as well, in fact this latter method is rather simple and has better sensitivity and resolution. Both these methods determine the crosslink density of composites from the differences in chemical shift values between the bulk solvent and trapped molecules. Prior to the NMR spectral... 

Figure 17.19 shows typical thermal expansion behavior of a PP/PP-g-MA/MMT/ elastomer nanocomposite from the first and second heating the thermal expansion is a nonlinear function of temperature when viewed over the wide range of —40 °C to 125 °C hence, CTE is reported in the temperature range of 0-30 °C so it can be related to the mechanical properties determined at room temperature (Lee et al. 2006a). For both extruder-made and reactor-made TPO nanocomposites, the CTE along the ED and the TD decreases, whereas CTE along the normal direction (ND) increases as the MMT content is increased. The increase in CTE in the ND is... 

Naderil, G., Razavi-Nouril, M.,Taghizadeh, E., Lafleur, P.G. and Dubois, C. (2011), Preparation of thermoplastic elastomer nanocomposites based on polyamide-6/ polyepichlorohydrin-co-ethylene oxide , Polymer Engineering Science, Vol. 51, No. 2, pp. 278-284. 

Li, C. Liu, Y. Huang, X. Jiang, H. Direct sun-driven artificial heliotropism for solar energy harvesting based on a photo-thermomechanical hquid-crystal elastomer nanocomposite. Funct. Mater. 2012. D01 10.1002/adfm.201202038... 

Introductory paragraphs similar to the above can be found in hundreds of nanocomposite papers. With the exception of reinforced elastomers, nanocomposites have not lived up to expectations. Although claims of modulus enhancement by factors of 10 exist, these claims are offset by measurements that show little or no improvement... The lackluster performance of nanocomposites has been attributed to a number of factors including poor dispersion, poor interfacial load transfer, process-related deficiencies, poor alignment, poor load transfer to the interior of filler bundles, and the fractal nature of filler clusters [5]. 

Yang LQ, Setyowati K, Li A, Gong SQ, Chen J (2008) Reversible infrared actuation of carbon nanotube-liquid crystalline elastomer nanocomposites. Adv Mater 20( 12) 2271-2275. doi 10.1002/adma.200702953... 

Yamashita K, Funato T, Suzuki Y, Teramachi S, Doi Y (2003) Characteristic interactions between poly(hydroxybutyrate) depolymerase and poly [(R)-3-hydroxybutyrate] film studied by a quartz crystal microbalance. Macromol Biosci 3 694—702 Yang L, Setyowati K, Li A, Gong S, Chen J (2008) Reversible infrared actuation of carbon nanotube-liquid crystalline elastomer nanocomposites. Adv Mater 20 2271-2275 Yu C, Shi L, Yao Z, Li D, Majumdar A (2005) Thermal conductance and thermopower of an individual single-wall carbon nanotube. Nano Lett 5 1842-1846 Yu H, Qin Z, Zhou Z (2011) Cellulose nanocrystals as green fillers to improve crystallization and hydrophilic property of poly(3-hydroxybut3uate-co-3-hydroxyvalerate). Prog Nat Sci Mater Int 21 478 84... 

The use of a commercial Cloisite 20A organoclay to prepare SBS-based nanocomposites by melt processing was recently reported [63]. In this case, the nanocomposite morphology was characterized by a combination of intercalated and partly exfoliated clay platelets, with occasional clay aggregates present at higher clay content. For this particular thermoplastic elastomer nanocomposite system, well-dispersed nanoclays lead to enhanced stiffness and ductility, suggesting promising improvements in nanocomposite creep performance. The use of stearic acid as a surface modifier of montmorillonite clay to effectively improve the clay dispersion in the SBS matrix and the mechanical properties of the SBS-clay nanocomposites was reported [64]. 

Halbach TS, Thomann Y, Mulhaupt R (2008) Boehmite nanorod-reinforced-polyethylenes and ethylene/l-octene thermoplastic elastomer nanocomposites prepared by in situ olefin polymerization and melt compounding. J Polym Sci A Polym Chem 46 2755-2765... 

Shia, D. Hui, C.Y. Burnside, S.D. Giannelis, E.P. An interface model for the prediction of Young s modulus of layered silicate elastomer nanocomposites. Polym. Compos. 1998, 19, 608-617. 

Several methods have been reported to prepare elastomer nanocomposites. The preparation techniques are divided into three types based on the elastomer and processing conditions. 

Elastomer nanocomposites with one-dimensional nanofillers have been presented in this chapter. The nature of nanofiller has been altered from nanotube to nanorod, and nanofiber with their suitable chemical modifications required for the improvement of various properties. The dispersion and morphology have been explored for... 

Zha JW, Shehzad K, Li WK, Dang ZM (2013) The effect of aspect ratio on the piezoresistive behavior of the multiwalled carbon nanotubes/lhermoplastic elastomer nanocomposites. J ApplPhys 113 014102... 

Fillers of various dimensions are added to polymers to alter its processability, properties and uses. Such micro and nano composites obtained may have tremendous possibilities in industries and information on their viscoelasticity is very necessary as far as their processing and applicability are concerned. The dynamic properties of filled elastomers have been a subject of active research since they affect the performance of tyres such as skid, traction, and rolling resistance. Elastomer nanocomposites are most important materials characterized by excellent elasticity and flexibility, and are widely used in various applications such as cables, tyres, tubing, dielectric materials and sensors [1-5]. The non linear features observed in filled elastomers upon a simple shear are as follows. The dynamic storage and loss moduli of the composites are only dependent on the dynamic strains and not on the static strain. In the same way the stress strain curves also do not depend on static strain. Moreover the initial modulus under constant strain rate is highly rate dependent whereas the terminal modulus is independent of strain rate. This initial to terminal modulus ratio in the stress-strain curves is the same as the ratio of the dynamic storage moduli obtained at low and high strains. 

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