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Non‐solvent induced phase separation (NIPS) method was employed to fabricate biodegradable poly(lactic acid) (PLA) nanocomposite membranes. Morphological studies using scanning electron microscopy revealed that all the membranes prepared display asymmetric structures comprising finger‐like macropores. The incorporation of modified polyhedral oligomeric silsesquioxane (POSS) particles into the PLA matrix resulted in enhanced crystallinity, mechanical, and thermal properties. Annealing of the membranes was performed to explore the influence of temperature on the morphology and properties. After annealing, membranes become more thin and compact, and drastic enhancement in crystallinity is also observed. Consequently, Young's modulus experiences a significant improvement. The reduction in oil absorption capacity after annealing can be attributed to the higher level of crystallinity, reduced porosity, and smaller pore diameter observed in the annealed membranes. Additionally, the unannealed PLA nanocomposite membranes demonstrated exceptional oil absorption capacity, reaching approximately 88%. It is foreseeable that these PLA/POSS nanocomposite membranes possess the potential to be utilized as effective tools for oil–water separation, offering the advantage of mitigating secondary pollution. [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]

Conducting elastomers are highly desirable in the present world because of their major applications in the electronic industry. Conductive carbon black (CCB) is a conventional reinforcing filler commonly used in elastomers to modify the mechanical as well as electrical properties. The present study focuses on the experimental and theoretical computation of filler reinforcement, dielectric, mechanical, dynamic mechanical, and surface morphology of natural rubber (NR)/CCB composites. Two step processing method is adopted to attain homogeneous dispersion of filler in the matrix: preparation of NR/CCB masterbatch through melt mixing using internal mixer followed by compounding in a two‐ roll mill. Improved DC conductivity in the order of 10−6 was obtained at higher filler loading indicating the formation of a continuous conductive network in the matrix. Percolation threshold was computed using Power law equation and obtained a value of 0.154 vol%. Theoretical predictions of mechanical modulus and tensile strength were done using rule of mixtures, Einstein, Guth and Kerner models and Nicolais‐Narkis and Kuneri‐Geil models respectively. A remarkable change in tensile strength is observed for NR as a function of the weight percentage of CCB; it is increased to 26.3 ± 0.9 MPa at 20 phr CCB from 17.1 ± 0.9 MPa for NR. [ABSTRACT FROM AUTHOR]

In this work, the thermal degradation of functionalized cage structured polyhedral oligomeric silsesquioxane (POSS) incorporated poly(vinyl alcohol) (PVA) and poly(vinyl alcohol)‐poly (ethylene oxide) (PEO) blend membranes were discussed. PVA‐PEO/POSS and cross‐linked PVA/POSS systems exhibited excellent improvement in thermal stability at lower loading of POSS as compared to pure PVA and uncross‐linked PVA/POSS system. Uncross‐linked PVA and PVA/POSS systems exhibited mainly two degradation steps. However, cross‐linked PVA/POSS systems showed more degradation steps due to the formation of 3‐dimentional network structure in the polymer. The mechanical stability of PVA/POSS and PVA‐PEO/POSS systems at hydrated state were analyzed and observed a remarkable stability even in the wet condition. [ABSTRACT FROM AUTHOR]

The present work reports the effect of various organically functionalized polyhedral oligomeric silsesquioxane (POSS) particles on the gas transport properties (N2, O2, and CO2 molecules) in poly(vinyl alcohol) (PVA) membranes. The incorporation of polyethylene glycol‐POSS (PEG‐POSS), octa‐tetramethylammonium‐POSS (Octa‐TMA‐POSS) and m‐POSS (Octa‐TMA‐POSS molecule was modified using cetyltrimethyl ammonium bromide) led to the enhancement in CO2 separation performance of PVA, among which, PEG‐POSS exhibited highest CO2 separation due to the dipole‐quadrupolar interaction of CO2 with ethylene oxide group in POSS. Octa‐TMA‐POSS and m‐POSS reduced the O2 and N2 permeability of the PVA membrane due to the reduction in the number of permeating pathways as compared to pure PVA. Free volume of the membranes was evaluated by positron annihilation lifetime spectroscopic (PALS) and coincidence Doppler broadening measurements. PALS confirms the increase in polymer free volume in PVA/POSS system due to the presence of rigid and spherical POSS molecule, which could enter in the polymer chain and provide viable pathway for molecular transport. Maxwel–Wagner–Sillar and Higuchi models were applied for the theoretical prediction of permeability of the fabricated membranes. [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]

Polymer membrane based gas transport and pervaporation processes are fast growing areas in separation technology and have received wide attention as areas of 'clean technology'. Mechanically stable novel polyhedral oligomeric silsesquioxane (POSS) embedded poly(vinyl alcohol) (PVA)/poly(ethylene oxide) (PEO) blend membranes were prepared by solution blending followed by casting. The addition of carboxymethyl cellulose enhanced the interfacial activities of the PVA and PEO blends. The peripheral organic substituent on POSS plays a key role in achieving compatibility with polymers whereas the rigid Si–O–Si core of POSS imparts high mechanical strength. Compared to PVA membrane, poly(ethylene glycol) and octa(tetramethylammonium) functionalized POSS embedded PVA/PEO membranes exhibit 680% and 580% enhancement in Young's modulus as well as 130% and 140% improvement in tensile strength respectively. The Einstein, Kerner and Frankel–Acrivos models were applied to compare the experimental and theoretical Young's modulus of PVA‐PEO/POSS membranes. The presence of an ethylene oxide tail on POSS as well as PEO in the blend membrane enhances the CO2 affinity of the membrane. The presence of a hydrophilic functional group on the POSS improves the hydrophilicity of the membrane and produces more binding sites for water molecules in the membrane during the pervaporation separation of a tetrahydrofuran–water azeotropic mixture. The transport properties of the membrane are further elucidated by means of free volume defect analysis carried out by positron annihilation lifetime spectroscopy and coincidence Doppler broadening spectroscopy. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

ABSTRACT An effective amphiphilic polyhedral oligomeric silsesquioxane (POSS) encapsulated poly(vinyl alcohol) (PVA) nanocomposite was successfully fabricated by solution blending method. Anionic octa(tetramethylammonium) (Octa-TMA) and poly(ethylene glycol) (PEG) were used as cage side groups in POSS (Octa-TMA-POSS and PEG-POSS) for the present study. Transmission electron microscopic analysis revealed the uniform dispersion of POSS in the PVA matrix. Crystallinity of PVA/POSS system was computed from differential scanning calorimetric studies. The effect of POSS on the mechanical, dynamic mechanical, and dielectric properties of PVA has been analyzed and discussed in detail with respect to the weight percentage of POSS. The incorporation of POSS in PVA matrix remarkably enhances the Young's modulus of the matrix. The viscoelastic properties such as storage modulus, loss modulus, damping behavior, and glass transition temperature of the membranes were evaluated. The relaxation corresponding to the crystal-crystal slippage characteristic of semicrystalline polymers were observed in storage modulus curves of PVA/POSS system, suggesting the crystalline nature of matrix even in the presence of POSS. Less polar, inert, and stiff inorganic center core of POSS contributes to the reduced energy dissipation and dielectric constant of PVA/POSS system. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45447. [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]

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]