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Nanocomposites based on natural rubber latex as the matrix and naturally occurring tubular shaped nanoclay, halloysite nanotubes (HNTs) as the reinforcing phase were prepared through co-coagulation method. XRD, morphology, mechanical, and solvent transport properties of the nanocomposites with special reference to weight percentage of nanoclay were analyzed and discussed in detail. Matrix-filler interaction was estimated from Kraus, Cunneen-Russell, and Lorentz-Park plots. Theoretical estimation of reinforcement effect revealed a better interaction between rubber and filler at lower concentration of filler. At higher loading properties decreased due to the formation of filler-filler networks than polymer-filler networks resulting in the reduction of aspect ratio of fillers. Properties of nanocomposites depend on the aspect ratio and volume fraction of reinforcing filler. Morphological analyses of the nanocomposites were done in detail from scanning electron micrographs. Theoretical modulus of nanocomposites was computed using different composite theories by varying the aspect ratio of filler and compared with experimental data. A good agreement between experimental and theoretical values was observed at lower concentration of filler. Solvent transport properties of nanocomposites were found to decrease at lower concentration of HNT because of the tortuosity of the path. POLYM. COMPOS., 37:602-611, 2016. © 2014 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Conductive carbon black (CCB), carbon nanotubes (CNT) and its hybrids are introduced into the natural rubber (NR) matrix aiming to explore the effect of filler ratio on the transport properties. Solvent transport of NR is found to decrease for hybrid filler systems as compared to single filler incorporated systems. Kinetic parameters of solvent transport behavior of filled NR systems are analyzed using various kinetic models. Upon the computation of kinetic parameters of transport data, it is found that the Peppas-Sahlin model is in good agreement with experimental observations, which suggests that the transport mechanism is diffusion controlled. Rubber-filler interaction parameters are computed and analyzed from the swelling experiments using Kraus, Cunneen-Russel, and Lorenz-Park equations. [ABSTRACT FROM AUTHOR]

The versatility and potential have framed natural rubber (NR) nanocomposites as the focal point in the polymer research field and industry. Currently, NR nanocomposites filled with hybrid nanostructures is an interesting area than single filler or conventional filler systems. Halloysite nanotube (HNT) and bentonite clay are well-studied potential fillers of polymers. This work is an attempt to study the effect of hybrid filler system of HNT and organically modified bentonite nanoclay (NC) in the properties of NR. NR/HNT-NC systems with varied filler concentrations were prepared in a two-roll mixing mill. Properties such as cure characteristics, morphology, mechanical, thermal, and transport behavior were analyzed in detail. The prepared composites had better wear properties than gum vulcanizates. Improvement in physical properties was observed due to the increased contact surface area between the filler and the matrix. The nanocomposite with 2 wt% hybrid filler shows a 31% decrease in abrasion loss compared to neat NR composite. Apparently, 4 wt% of hybrid filler could improve modulus at 300% strain and tear by approximately 57% and 14%, respectively. The ability to withstand high strain was evident from the improved crack growth resistance as observed in micrographs. Lorenz–Park plots were employed to analyze the rubber–filler interaction. The activation energy of thermal degradation was calculated using Coats–Redfern equation. [ABSTRACT FROM AUTHOR]

Permselective polymeric membranes are important materials for the efficient separation of organic solvents and azeotropic mixtures. In this work, we address an effective strategy to the fabrication of novel high-performance membranes of crosslinked poly(vinyl alcohol) (PVA) by incorporating chemically modified cage-structured polyhedral oligomeric silsesquioxane (m-POSS) through solution casting method. The fabricated PVA/m-POSS system showed excellent mechanical stability as well as good pervaporation performance for the separation of isopropanol (IPA)-water azeotropic mixture. Scanning electron micrographs and atomic force microscopy analysis revealed the homogeneous dispersion of m-POSS in PVA matrix. Differential scanning calorimetric studies showed the rigidification of crosslinked PVA matrix by the incorporation of m-POSS. Tensile strength and Young's modulus of PVA matrix were increased remarkably to 200% and 740%, respectively, in the presence of 5 wt% of m-POSS. Moreover, the membranes exhibited excellent water selectivity, hydrophilicity and excellent anti-fouling properties compared to traditional hydrophilic membranes. At lower filler loading (1.0 wt%), 300% and 200% increase in selectivity and permeance were observed for PVA/m-POSS system over crosslinked PVA. The excellent mechanical properties and other comprehensive properties revealed the potential of the PVA/m-POSS system for the effective separation of azeotropic IPA-water mixture. Modified Maxwell-Stefan model was applied for the theoretical estimation of permeation flux and it was in good agreement with the experimental findings. [ABSTRACT FROM AUTHOR]

Organically modified halloysite nanotube (HNT) containing polysulfone (PSU) membranes were fabricated by the wet phase inversion method. Organic modification of HNT was carried out using telehelic polyetheramine inorder to overcome the poor dispersion of HNT in PSU matrix. Telehelic polyetheramine acts as a dispersing agent and a hydrophilic modifier. FTIR results revealed the hydrogen bond formation between -SO2 of PSU and -NH2 of modified HNT. Based on the obtained results of contact angle measurements, the wettability of membranes were found to increase with the weight percentage of HNT in the presence of polyetheramine. At higher loading of filler the water uptake was found to be increasing due to the aggregation of nanotubes. Porosity values substantiate the results obtained for contact angle and water uptake measurements. Thermogravimetric results showed that the thermal stability of polysulfone (PSU)/HNT nanocomposite membranes decreased when compared to neat PSU due to the presence of aliphatic chain of polyetheramine. [ABSTRACT FROM AUTHOR]