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Two shot solution polymerized natural rubber/polyethylene oxide (NR/PEO) block copolymers are used as chelating exchanger for the metal ions Mn(II) and Fe(II). The polymer - metal ion chelates are prepared via solution batch adsorption method and are subjected to various characterisation techniques. Adsorption studies shows 96 and 63 % complexation for Mn(II) and Fe(III) ions, respectively. The 72 helical conformation of PEO and metal-etheric oxygen coordination are confirmed by FT-IR spectroscopy. The XRD results revealed the complete miscibility of metal ions and semi-crystalline nature of samples. The EDX analysis confirmed the presence of metal ions in the polymer chelates. Surface morphology is also studied using SEM and TEM techniques.

As the ever rising world population has led to increasing energy demand, it is necessary to develop efficient materials for energy storage applications. The enhancement of dielectric permittivity plays a significant role for designing materials for energy storage applications. Hence, composites with high dielectric permittivity are presently getting interest in academic and industrial research fields. In the present study, reduced graphene oxide (RGO) was compounded with plasticized poly (vinyl chloride) to obtain flexible composites which show both high dielectric permittivity and low dielectric loss. An enhancement of 57% in dielectric constant was obtained after the addition of RGO to poly (vinyl chloride). This enhancement can be attributed to the increased number of interfaces of polymer and filler that was observed by transmission electron microscopy. The interfacial polarization in the heterogeneous interface plays an important role in imparting dielectric performance. Effective dielectric permittivity values of the composites calculated using theoretical equations were found to be lower than the experimental values. The nanocomposites were also tested for the permeability of O2 which is very important for fabrication of energy storage devices. The permeability was decreased by 53% when compared to pristine poly (vinyl chloride). Hence, the enhanced dielectric permittivity as well as the impermeability to oxygen makes this material a suitable candidate for energy storage applications.

Improving the properties of polyvinyl chloride matrix by the incorporation of carbonaceous filler by melt mixing is an unusual thought in the polymer research. Here we incorporated reduced graphene oxide (RGO) as a filler into plasticized polyvinyl chloride (PPVC) matrix by melt mixing, an eco-friendly method. The effect of addition of filler in the morphology of the PPVC nanocomposites was analyzed by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM) and Raman spectroscopy. The mechanical response of the nanocomposites to an applied stress was studied. A 50% improvement in mechanical properties was obtained at a low filler loading. A decrease in elongation was observed at higher RGO loading. The dynamic mechanical analysis (DMA) of the nanocomposites indicated an increase in glass transition temperature of the PVC up on the addition of RGO. This has confirmed the confinement of PVC chains at the graphene surface. As a result, the storage modulus of the nanocomposites showed an increase up on the addition of the nanofiller. Theoretical values of the storage modulus were calculated using various theoretical equations. The effectiveness of filler on the storage modulus is estimated and is found to be consistent with the results obtained experimentally. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers

Two shot solution polymerised NR/PEO block copolymer (BC) was used as an absorbent in this study. This polymer has got polyethylene oxide (PEO) immobilised on hydrophobic natural rubber and it was used for complexation studies with the selected 3d transition metal ions. The prepared complexes were subjected to various analytical techniques such as energy dispersive X-ray spectroscopy (EDX), Fourier Transform infrared spectroscopy(FTIR), Raman spectroscopy, X-ray diffraction (XRD) studies, extended X-ray absorption fine structure (EXAFS) analysis and X-ray absorption near edge spectroscopy (XANES). EDX analysis confirms presence of the respective metal ion in each complex. FTIR spectroscopy reveals the 72 helical conformation of polyethylene oxide segments in BC which is retained with some deformation upon complexation. The BC-metal ion interaction is confirmed by broadening of the C-O-C triplet peak. XRD analysis revealed that PEO lattice undergoes expansion during complexation inorder to accommodate the respective metal ion. From the EXAFS results it was observed that each metal ion shows only one peak that corresponds to the oxygen shell indicating the presence of only one type of metal ion bonding. The EXAFS gives hexa coordinated pattern for Co(II), Ni(II) and Zn(II) complexes while a tetra coordination for the Cu(II) complex. Metal-oxygen distance in a given complex is constant and unique which varies with the metal ion. XANES shows a distorted octahedral symmetry (Oh) with sp3d2 hybridisation for the hexa coordinated complexes and a square planar symmetry with dsp2 hybridisation for the tetra coordinated complex. Feasibility of 1 s → 3d transition confirms +2 oxidation state of the metal ions. The combined result of EXAFS and FTIR shows the best fit structure of the complexes in which metal ions are encapsulated within the PEO helical tunnel.

Segmented polyurethanes based on toluene diisocyanate (TDI) with three different chain extender diols, viz., propylene glycol (PG), 1,4-butanediol (1,4-BDO), and 1,3-butanediol (1,3-BDO) were synthesized by a two-step, solution polymerization method. These different NR-b-PU block copolymers were incorporated into PVC at various compositions by the solution blending method. These blend systems were subjected to FTIR analysis, DSC, tensile testing, tensile impact measurements, and tensile impact fracture studies by SEM. It was observed that systems showed modification in tensile impact properties. Optimum impact properties were shown at concentrations 6–8% of the block copolymer. At higher compositions there is deterioration in impact properties. High impact properties showed by these blends are attributed to the optimum level of compatibility achieved between the blend components. Tensile impact fracture studies revealed that failure pattern for these blend system transitioned from brittle to ductile fracture. Blends up to 10 wt% of block copolymer showed partially compatible heterogeneous nature exhibiting domain morphology. Blends with higher block copolymer content showed deterioration in tensile strength, modulus, yield strength, and tensile impact strength due to higher particle size of the agglomerated rubber soft segments of the block copolymer.

Magnesium oxide (MgO) nano particle was synthesized by ultrasound assisted one pot method and thus synthesized nano MgO was mixed with poly(vinyl alcohol) (PVA) to prepare the polymer nano composite. The influence of the nano sized MgO on the structural modification of PVA was evaluated. The particle size and morphology of MgO was confirmed by High Resolution Transmission Electron Microscopy (HRTEM). The properties of PVA/MgO nano composite materials were characterized by Fourier Transform Infrared analysis (FTIR), Thermogravimetric analysis (TGA) and Differential scanning calorimetry (DSC) like analytical tools.

Thermal stability of solution-cast blends of poly(vinylchloride) and NR-b-PU block copolymers of three different chain extender diols was studied by thermogravimetry. Thermal degradation of individual components and their blends were investigated with special reference to blend ratio. As the block copolymer content in the blends increased their thermal stability was also found to increase. Enhanced thermal stability of PVC is believed due to the favorable interaction with PVC and the PU hard segments of the block copolymer. DTG curves were used for the determination of different stages involved in the degradation. Activation energy for degradation was determined from Coats–Redfern plot.

Five series of block copolymers were synthesized from hydroxyl-terminated liquid natural rubber (HTNR) and polyurethane (PU) oligomers, from various diols and diphenyl methane-4,4′-diisocyanate (MDI). They were characterized by mechanical testing and fracture studies (SEM analysis). The block copolymer characteristics were assessed on the basis of the composition and the type of extender diols. Mechanical properties were found to be strongly dependent on the copolymer composition in all the series. Tensile properties were found to improve with the hard segment content. At low hard segment content samples resemble flexible elastomers whereas at high hard segment content they behave as rigid plastics. Where bisphenol A (BPA) is used as the extender diol sample rigidity was higher compared to the samples with aliphatic diols which is attributed to the presence of aromatic ring system in the former samples. Fracture mechanism was found to vary from ductile fracture to rigid and brittle fracture as the hard segment content increased. Fractography also shows the presence of some beads disposed on the sample surface which could be the uncombined polyurethane homopolymer fractions.

The ultrasound (US) assisted one pot method has used to synthesize CuO nanoparticles. The fourier transform infrared spectroscopy (FTIR) spectrum shows a characteristic peak of metal–oxygen bond at 535 cm−1, which confirms the CuO formation. The high resolution transmission electron microscope (HRTEM) images of the synthesized nano-CuO confirms the size of nanorods with the length of approximately 25–30 nm, and its breadth is less than one nanometer. X-ray diffraction (XRD) pattern of CuO can be readily assigned to those of crystalline CuO, indicating the formation of single-phase CuO with monoclinic structure. The synthesized nano-CuO is mixed with poly(vinyl alcohol) (PVA) to prepare the PVA/CuO nanocomposite to improve the thermal stability of PVA. Their physico-chemical properties are examined by means of FTIR, XRD, differential scanning calorimetry, thermogravimetric analysis, HRTEM, and scanning electron microscope (SEM) techniques.

Five series of block copolymers based on natural rubber and polyurethane were prepared from hydroxyl terminated liquid natural rubber (HTNR) and polyurethane (PU) formed by the reaction of diphenyl methane—4,4′—diisocyanate (MDI) with a chain extender diol, viz., ethylene glycol (EG)/propylene glycol (PG)/1,4-butane diol (1,4-BDO)/1,3-butane diol (1,3-BDO)/bisphenol A (BPA), by solution polymerization. Structural characterization of the block copolymers was done by infrared (IR) analysis. Thermal studies and kinetic analysis on thermal degradation of the block copolymers were undertaken with the view of characterizing them. Energy of activation and entropy change for the degradation were determined and a probable mechanism for the solid state degradation was suggested which corresponds to a three dimensional diffusion mechanism. DSC analysis has been used for the study of microphase separation in the block copolymers. Thermal transition of the hard segment significantly varies with the extender diol which highlights the effect of extender diol structure on the chain stiffening mechanism. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Liquid natural rubber of different molecular masses L-LNR, and H-LNR were subjected to varying degree of epoxidation (L-ELNR-10, L-ELNR-20, L-ELNR-30, L-ELNR-40, L-ELNR-50, H-LNR-20, and H-LNR-50) and the products were incorporated into PVC at various compositions by the solution blending method. These blend systems were subjected to tensile testing, tensile impact measurements, and SEM studies. It was observed that blends with L-ELNR-20 showed highest impact strength modification, followed by L-ELNR-10 and L-ELNR-30. High impact properties showed by these blends are attributed to the optimum level of compatibility existing between the blend components. Tensile impact fracture studies revealed that the failure pattern for this blend system is intermediate between the brittle fracture of rigid PVC and ductile fracture of PVC/L-ELNR-50 samples. Blends up to 30 mol % of epoxidation showed partially compatible heterogeneous nature exhibiting domain morphology. Blends of liquid rubber with higher degree of epoxidation showed deterioration in tensile strength, modulus, yield strength, and tensile impact strength due to plasticization of PVC caused by the higher polar interaction between PVC chains and the oxirane rings. Effect of ELNR molecular weight was studied and it is found that the impact modification is higher for the L-ELNR blends compared to the H-ELNR blends. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Soluble block copolymers from toluene diisocyanate (TDI), with chain extender diols, viz., propylene glycol (PG), 1,4-butane diol (1,4-BDO) and 1,3-butane diol (1,3-BDO), were synthesised for the first time by solution polymerisation. Maintaining low hard segment content and keeping optimum NCO/OH ratio, formation of linear, flexible elastomers is achieved. They were characterised by spectral, thermal, microscopic and stress–strain analysis. The dilute solution properties of these block copolymers dissolved in tetrahydrofuran (THF) are studied by viscometry and gel permeation chromatography (GPC). IR and NMR spectral data support the notion that a chemical reaction leads to block copolymerisation. Differential scanning calorimetric (DSC) analysis showed a soft segment glass transition temperature around −58°C and a hard segment glass transition temperature between 75 and 70°C for these samples. This observation and two-stage thermal decomposition of the samples in thermogravimetric analysis (TGA) clearly indicate that the block copolymers are completely phase-segregated systems. SEM indicates the amorphous heterophase morphology of the samples.

Liquid natural rubber of two different molecular masses, viz., $\overline{\text{M}}_{\text{W}} = 4900$ and 9500, each with epoxidation of 20 and 50 mol % (L-ELNR-20, L-ELNR-50, and H-ELNR-20, H-ELNR-50) were prepared and blended with polyvinyl chloride (PVC). Miscibility of these blend systems was studied with special reference to blend ratio, mol % of epoxidation and effect of molecular mass of the liquid rubber by various techniques such as stress – strain measurement, SEM studies and DSC analysis. It was observed that PVC/L-ELNR-50 and PVC/H-ELNR-50 systems were homogenous and miscible compared to PVC/L-ELNR-20 and PVC/H-ELNR-20 blends and the maximum modification in properties was found for the former systems. Results of blends with 20 mol % epoxidised liquid rubber showed that the components are only partially miscible and hence they are heterogeneous systems. Miscibility achieved with an increase in mol per cent epoxidation of the liquid rubber is explained on the basis of the higher polar interaction between the blend components. Analysis of the blends also revealed that the lower molecular mass epoxidised rubber is aiding better property modifications than the higher molecular mass rubber. This is explained by the fact that rubber with lower chain length provides greater penetration into the PVC interstices enabling better solubilisation of the PVC segments.

The thermal behaviour of a series of solution-cast blends of polyvinyl chloride/epoxidised liquid natural rubber (ELNR) of different mole percentage of epoxidation has been examined using thermogravimetric analysis. Thermal degradation is found to occur through a two-step route in which the first step corresponds to the dehydrochlorination of PVC to form a polyene and the second step is attributed to the decomposition of the ELNR and the polyene. Introduction of 20 and 50 mol% of epoxy group into the liquid NR is found to enhance the thermal stability of PVC. Probable mechanisms of degradation have been suggested on the basis of the kinetic analysis of the degradation studies. It is found that the mechanism is influenced by the epoxy content of the blend system. Activation energy for the degradation and the entropy change have also been reported.

Polyvinyl chloride (PVC) has been blended with masticated natural rubber (NR5) in the presence of a compatibiliser. A block copolymer of NR and polyurethane (PU) based on propylene glycol (PG) and toluene diisocyanate (TDI) was used as the compatibiliser. Compatibilising effect of this block copolymer on PVC/NR5 (90/10) blend system was investigated by solution viscometry and optical microscopy. Testing and analysis of the blends showed that the mechanical and morphological properties are functions of compatibiliser concentration. Incorporation of 10 parts of NR5 into PVC caused deterioration of tensile properties of the latter, which were recovered on the addition of 1.5 weight per cent of the compatibiliser. Besides, the tensile impact strength of PVC gets improved greatly. This was attributed to the enhanced interfacial adhesion between PVC and NR caused by the compatibiliser. The modification at the interface leads to finer and uniform distribution of NR domains in the PVC matrix.

A series of segmented block copolymers was prepared by the chain extension of hydroxyl terminated liquid natural rubber (HTNR) with polyurethane oligomers derived from toluene diisocyanate (TDI) and 1,3-butane diol at varying NCO/OH ratio. The previously reported two-step method of synthesis was modified to get improved products. This was done by optimizing the formation of polyurethane oligomers in the first step of the synthesis. All the samples were characterized by solubility testing, DSC, tensile testing, etching studies, and SEM. The data obtained were correlated to the structural features of the block copolymers. It was found that NCO/OH ratio played an important role in determining the structural variations in the block copolymers. POLYM. ENG. SCI. 46:1812–1821, 2006. © 2006 Society of Plastics Engineers

Soluble block copolymers based on natural rubber and polyurethane oligomers derived from 1,3 butane diol and toluene diisocyanate were synthesized for the first time. The dilute solution properties of these block copolymers dissolved in tetrahydrofuran (THF) were studied by viscometry and gel permeation chromatography (GPC). The Mark–Houwink constants K and a of the block copolymer system were determined by the molecular weight data from GPC combined with the viscosity data. Both the values were found to be in the range usually given by flexible elastomers. The intrinsic viscosity values were found to decrease successively with a decrease in the NCO/OH ratio from 1.12 to 1.05. The unperturbed chain parameters, Kθ and B were determined from the viscosity data. The Kθ calculated was used to get the unperturbed end-to-end distance and radius of gyration of the block copolymer systems in THF. The viscosity data were also used to study the chain conformation in dilute solutions. It was found that the molecules adopt a compressed core and shell conformation in which the higher molecular weight component, NR, forms the shell, which compresses the PU core. All the block copolymers assume a compressed segregated core and shell model which changes to a partially segregated core and shell conformation, or partially Gaussian conformation, at the transition temperature located at 70 °C. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2104–2111, 2006

A series of (NR/PU) block copolymers (BCs) was prepared from toluene diisocyanate (TDI), 1,3-butane diol (1,3-BDO), and hydroxyl-terminated liquid natural rubber (HTNR), by solution polymerisation. The swelling characteristics of the BCs were investigated. Diffusion profile in various solvents and the sorption kinetics were studied. Arrhenius and thermodynamic parameters were evaluated from the diffusion data. Finally, the influence of NCO/OH ratio on the swelling behaviour was also studied. The equilibrium sorption value (Q∞) decreased with increasing NCO/OH ratio for all the BCs. The samples have higher uptake of solvents with solubility parameter within a small range centred about 9 (cal/cm3)1/2. Highly polar and non-polar solvents show minimum uptake. It was observed that polarity factor predominates in the solvent transport through the present block copolymer systems. The sorption behavior is also found to vary with the NCO/OH ratio employed in the preparation of polyurethane (PU) oligomers.

The equilibrium swelling experiments of block copolymers based on natural rubber (NR) as soft segment and polyurethane (PU) derived from toluene diisocyanate (TDI) and 1,3-butane diol (1,3-BDO) as hard segment were performed in various solvents. Block copolymers with different NCO/OH ratio, viz., from 1.26 to 1.96 were employed in this study. The crosslink densities are found to vary with the NCO/OH ratio employed in the synthesis of the samples. The sorption behaviour is also found to vary with the NCO/OH ratio. The equilibrium swelling experiments have been used to determine the molecular parameters such as molecular mass between crosslinks, crosslink density, polymer–solvent interaction parameter, etc. The equilibrium swelling values were also used to calculate the solubility parameter values of the block copolymers.

Segmented block copolymers were synthesized from hydroxyl-terminated liquid natural rubber and polyurethane oligomers based on Bisphenol A and toluene diisocyanate by one-shot and two-shot processes in solution. Structural features were characterized by infrared and nuclear magnetic resonance spectroscopic analysis. The spectra of the one-shot materials were identical with those of the two-shot materials, indicating their chemical identity. The soft segment Tg was well defined and almost invariant around −64°C, but the hard segment Tg varied from 75 to 105°C as the hard segment content increased from 30 to 60 wt %. Two relaxation temperatures were observed for each sample in dynamic mechanical analysis (DMA). These observations and the two-stage thermal decomposition by random nucleation mechanism, as investigated in thermogravimetric analysis unambiguously confirmed complete phase segregation in these materials. The scanning electron microscopy and optical micrographs showed well-defined domains dispersed in a matrix, indicating the two-phase morphology. Systematic changes in hardness and tensile properties with hard segment content were also observed. The samples behaved like soft elastomers at lower hard segment content, toughened plastics at high hard segment content, and rigid elastomers at intermediate compositions. Variations in hardness and tear strength were consistent with this behavior. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 706–721, 1999

A series of segmented block copolymers of NR and 1,3-butanediol–toluene diisocyanate oligomers have been synthesized with varying hard segment content. The synthesis has been carried out by one-shot and two-shot processes in solution. The products were characterized by spectral analysis, thermal and mechanical analysis, SEM and optical microscopy. They are found to be amorphous materials having no potential for hydrogen bonding between the `hard' and `soft' segments. Their two-phase morphology has been deduced from SEM and optical micrographs and established by DMA and thermal studies. DSC analysis shows a soft segment glass transition temperature at −62±2°C and hard segment glass transitions between 70° and 100°C, depending on the polyurethane content. The T g values determined by the dynamic mechanical analysis are significantly higher than these values. The thermogravimetric analysis indicates a two-stage thermal decomposition of the materials by random nucleation mechanism and corresponds to the two phases present in the block copolymer. Depending on the proportion of the continuous and dispersed phases, the block coolymers behave like quasi-elastomers at lower hard segment concentrations and brittle plastics at higher hard segment contents. This variation in mechanical behaviour is consistent with the sample morphology. Materials synthesized by the two-shot process are found to possess better mechanical properties than the one-shot products, presumably due to a more systematic ordering of the different segments in the former.

The extent of compatibility of the blend solutions poly(vinyl chloride)-liquid natural blends (PVC-LNR), PVC-expodized LNR-20 (PVC-ELNR-20), and PVC-ELNR-50 has been studied using an ultrasonic technique. The variation of ultrasonic velocity with composition is nonlinear in the case of blends of PVC-LNR and PVC-ELNR-20, showing incompatibility. The ultrasonic velocity versus composition plot for PVC-ELNR-50 showed linear behavior showing compatibility. The above behavior was confirmed by heat of mixing calculations as well as ultrasonic attenuation measurements.

The morphology and properties of heterogeneous poly(methyl methacrylate)/natural rubber blends have been modified by the addition of a graft copolymer of natural rubber and poly(methyl methacrylate) (NR-g-PMMA). The morphology has been studied as a function of copolymer concentration. A sharp decrease in the dispersed domain size was observed by the addition of a few per cent of the copolymer followed by leveling off at higher concentrations. The compatibilizer increases the interfacial adhesion by the formation of micro-bridges with the matrix. The effects of homopolymer molecular weights, processing conditions, and mode of addition on the morphology of the dispersed phase have been investigated. The experimental results are compared with the theoretical predictions of Noolandi and Hong. Attempts have been made to explain the conformation of the graft copolymer at the interface. The changes in mechanical properties of the blends as a result of the addition of the compatibilizer were related to the morphology of the blends.

Nickel oxide (NiO) nano particle is synthesized by Ultrasound assisted one pot method and thus synthesized nano NiO is mixed with poly(vinyl alcohol) (PVA) to prepare the PVA/NiO nanocomposite. The influence of the composition on the structural modification on the composite is evaluated. The particle size and morphology of NiO nano material is confirmed by HRTEM. The structure and properties of the PVA/NiO nanocomposite material are characterized by FTIR, XRD, UV–Visible spectroscopy, DSC, TGA, and HRTEM. The synthesized PVA nanocomposite underwent hydrolytic oxidation reaction assisted by the effect of nano-sized NiO. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Nanosized manganese oxide was synthesized with help of ultrasound and its polymer nanocomposite with poly (vinyl alcohol) was prepared. The incorporated nanosized manganese oxide is involved in the surface catalytic effect on PVA matrix. Nanosized manganese oxide and its polymer composite were characterized by FTIR, XRD, DSC, TGA, SEM and HRTEM methods. This PVA- Mn3O4 nanocomposite system has improved thermally resistant than pristine PVA.