Journal of Polymers The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Preparation and Antiflame Performance of Expandable Graphite Modified with Sodium Hexametaphosphate Mon, 27 Jul 2015 13:35:26 +0000 A kind of polyphosphate modified expandable graphite (EGp) was prepared in graphite oxidation and intercalation reaction with KMnO4 as oxidant, H2SO4 as intercalator, and sodium hexametaphosphate (SHMP) as assistant intercalator. The feasible mass ratio of C : KMnO4 : H2SO4 (98%) : SHMP was determined as 1.0 : 0.3 : 4.5 : 0.6, H2SO4 was diluted to 77 wt% before intercalation reaction, and the reaction lasted for 40 min at 40°C. Expanded volume and initial expansion temperature of the prepared EGp reached 600 mL/g (at 800°C) and 151°C, respectively. X-ray diffraction spectroscopy testified the intercalation and layer structure of EGp, and Fourier transform infrared spectroscopy illuminated the intercalated functional groups. Flame retardance of the prepared EGp and the referenced EG (with only H2SO4 as intercalator) for linear low density polyethylene (LLDPE) was also investigated. Addition of 30 wt% EGp to the polymer improved the limiting oxygen index (LOI) from 17.5 to 27.3%. On the other hand, the LOI of the same amount of the referenced EG was only 24.6%. Assistant intercalation of SHMP improved the dilatability and flame retardancy. Hongmei Zhao, Xiuyan Pang, and Zhixiao Zhai Copyright © 2015 Hongmei Zhao et al. All rights reserved. Oxidative Coupling Copolymerization of 2,6-Dimethylphenol and Dihydroxynaphthalene Affording Poly(phenylene oxide) Derivatives Thu, 16 Jul 2015 10:40:59 +0000 The oxidative coupling copolymerization between 2,6-dimethylphenol (DMP) and dihydroxynaphthalenes, such as the 2,3- and 2,6-dihydroxynaphthalenes (2,3- and 2,6-DHN), was carried out using a Cu catalyst under an O2 atmosphere. The polymerization was significantly affected by the structure of the comonomer, and the copolymers were efficiently obtained during the copolymerization of DMP and 2,6-DHN. The obtained copolymers containing hydroxyl groups of the DHN unit were further transformed into polymers containing ester and urethane groups. The obtained copolymers containing various functional groups showed a very different solubility from that of the homopolymer of DMP. Shigeki Habaue, Ryosuke Ito, Ken Okumura, and Yuki Takamushi Copyright © 2015 Shigeki Habaue et al. All rights reserved. Model for Charge Transport in Ferroelectric Nanocomposite Film Mon, 23 Mar 2015 08:42:21 +0000 This paper describes 3D particle-in-cell simulation of charge injection and transport through nanocomposite film comprised of ferroelectric ceramic nanofillers in an amorphous polymer matrix and/or semicrystalline ferroelectric polymer with varying degrees of crystallinity. The classical electrical double layer model for a monopolar core is extended to represent the nanofiller/nanocrystallite by replacing it with a dipolar core. Charge injection at the electrodes assumes metal-polymer Schottky emission at low to moderate fields and Fowler-Nordheim tunneling at high fields. Injected particles propagate via field-dependent Poole-Frenkel mobility. The simulation algorithm uses a boundary integral equation method for solution of the Poisson equation coupled with a second-order predictor-corrector scheme for robust time integration of the equations of motion. The stability criterion of the explicit algorithm conforms to the Courant-Friedrichs-Levy limit assuring robust and rapid convergence. Simulation results for BaTiO3 nanofiller in amorphous polymer matrix and semicrystalline PVDF with varying degrees of crystallinity indicate that charge transport behavior depends on nanoparticle polarization with antiparallel orientation showing the highest conduction and therefore the lowest level of charge trapping in the interaction zone. Charge attachment to nanofillers and nanocrystallites increases with vol% loading or degree of crystallinity and saturates at 30–40 vol% for the set of simulation parameters. Meng H. Lean and Wei-Ping L. Chu Copyright © 2015 Meng H. Lean and Wei-Ping L. Chu. All rights reserved. Cyclic Oligolactic Acid in Direct Polycondensation PLLA and Its Extraction with Organic Solvent Tue, 25 Nov 2014 11:16:57 +0000 The contents of poly(L-lactic acid) (PLLA) prepared by direct condensation polymerization without using a catalyst were studied. 1H NMR and mass spectrometry analyses suggested that PLLA contained cyclic oligo(L-lactic acid) (c-OLLA) with 3–20 repeat units. Notably, only c-OLLA was extracted and isolated using hexane or cyclohexane at 4°C; thus the hydrophobicity, topology, and temperature dependence of the solubility of the obtained PLLA enabled the selective extraction of c-OLLA. The effect of cyclic compounds on direct polycondensation and the potential for c-OLLA to form molecular inclusion complexes were also discussed. Keiichiro Nomura, Yuta Nakatsuchi, Ryugo Shinmura, Sommai Pivsa-Art, Weraporn Pivsa-Art, Yuji Aso, and Hitomi Ohara Copyright © 2014 Keiichiro Nomura et al. All rights reserved. Kinetic Studies on Saponification of Poly(ethylene terephthalate) Waste Powder Using Conductivity Measurements Mon, 25 Aug 2014 09:15:45 +0000 Conductometric measurement technique has been deployed to study the kinetic behavior during the reaction of poly(ethylene terepthalate) (PET) and NaOH. A laboratory made arrangement with facility of continuous stirring was used to carry out experiments at desired temperature. With conductometry, the determination of kinetic as well as thermodynamic parameters becomes more simple and faster as compared to gravimetry. Chemical kinetics of this reaction shows that it is a second order reaction with reaction rate constant  g−1 s−1 at 70°C. The specific reaction rates of the saponification reaction in the temperature range at various temperatures (50–80°C) were determined. From the data, thermodynamic parameters such as activation energy, Arrhenius constant (frequency factor), activation enthalpy, activation entropy, and free energy of activation obtained were 54.2 KJ g−1,  min−1, 90.8 KJ g−1, 126.5 JK−1 g−1, and 49.9 KJ g−1, respectively. Dilip B. Patil, Vijendra Batra, and Sushil B. Kapoor Copyright © 2014 Dilip B. Patil et al. All rights reserved. The Effects of Antioxidants Content on Mechanical Properties and Water Absorption Behaviour of Biocomposites Prepared by Single Screw Extrusion Process Wed, 04 Jun 2014 12:03:53 +0000 The performance of hybrid fillers between rice husk and sawdust filled recycled high density polyethylene (rHDPE) with the presence of antioxidants (IRGANOX 1010 and IRGAFOS 169, with the ratio of 1 : 1) was investigated. The biocomposites with 30 wt% of matrix and around 70 wt% of hybrid fillers (rice husk and sawdust) and different antioxidants’ contents (0 to 0.7 wt%) were prepared with single screw extruder. Increasing the amount of antioxidants in biocomposites reduced the modulus of elasticity and modulus of rupture on flexural testing. The addition of antioxidants increased the tensile and impact strength of biocomposites. From the study, samples with 0.5 wt% of antioxidants produce the most reasonable strength and elasticity of biocomposites. Furthermore, the effect of antioxidants content on water uptake was minimal. This might be caused by the enhanced interfacial bonding between the polymer matrix and hybrid fillers, as shown from the morphology by using scanning electron microscopy (SEM). Mohd Hafizuddin Ab Ghani, Mohd Nazry Salleh, Ruey Shan Chen, Sahrim Ahmad, Mohd Rashid Yusof Hamid, Ismail Hanafi, and Nishata Royan Rajendran Royan Copyright © 2014 Mohd Hafizuddin Ab Ghani et al. All rights reserved. Edible Polymers: Challenges and Opportunities Mon, 05 May 2014 13:09:35 +0000 Edible polymers have established substantial deliberation in modern eons because of their benefits comprising use as edible materials over synthetic polymers. This could contribute to the reduction of environmental contamination. Edible polymers can practically diminish the complexity and thus improve the recyclability of materials, compared to the more traditional non-environmentally friendly materials and may be able to substitute such synthetic polymers. A synthetic hydrogel polymer unlocked a new possibility for development of films, coatings, extrudable pellets, and synthetic nanopolymers, particularly designed for medical, agricultural, and industrial fields. Edible polymers offer many advantages for delivering drugs and tissue engineering. Edible polymer technology helps food industries to make their products more attractive and safe to use. Novel edible materials have been derived from many natural sources that have conventionally been regarded as discarded materials. The objective of this review is to provide a comprehensive introduction to edible polymers by providing descriptions in terms of their origin, properties, and potential uses. Subhas C. Shit and Pathik M. Shah Copyright © 2014 Subhas C. Shit and Pathik M. Shah. All rights reserved. Dielectric Spectroscopy of Nanostructured Polypyrrole-NiO Composites Sun, 04 May 2014 13:41:41 +0000 Conducting polypyrrole-nickel oxide (polypyrrole-NiO) composites were synthesized by in situ deposition technique by placing different weight percentages of NiO powder (10, 20, 30, 40, and 50%) during the polymerisation of pyrrole. The polypyrrole-NiO composites were later characterised with Fourier transform infrared spectroscopy (FTIR) which confirms the presence of polypyrrole in the composite. AC conductivity was studied in the frequency range from 102 to 107 Hz. From these studies it is found that AC conductivity remains constant at low frequency and increases rapidly at higher frequency, which is the characteristic behavior of disordered materials. The dielectric behavior of these composites was also investigated in the frequency range 102–107 Hz. It is observed from these studies that the dielectric constant and dielectric tangent loss decrease exponentially with frequency. The composites exhibit a low value of dielectric loss at higher frequency. Syeda Seema and M. V. N. Ambika Prasad Copyright © 2014 Syeda Seema and M. V. N. Ambika Prasad. All rights reserved. Permittivity and Electromagnetic Interference Shielding Investigations of Activated Charcoal Loaded Acrylic Coating Compositions Sun, 04 May 2014 13:36:26 +0000 Acrylic resin (AR) based electromagnetic interference (EMI) shielding composites have been prepared by incorporation of up to 30 wt% activated charcoal (AC) in AR matrix. These composites have been characterized by XRD, Raman spectroscopy, scanning electron microscopy, dielectric, and EMI shielding measurement techniques. XRD patterns and Raman studies confirm the incorporation of AC particles inside AR matrix and suggest possible interactions between phases. The SEM images show that incorporation of AC particles leads to systematic change in the morphology of composites especially the formation of porous structure. The dielectric measurements show that 30 wt% AC loading composite display higher relative permittivity value (~79) compared to pristine AR (~5). Further, the porous structure, electrical conductivity, and permittivity value contribute towards EMI shielding effectiveness value of −36 dB (attenuation of >99.9% of incident radiation) for these composites, thereby demonstrating their suitability for making efficient EMI shielding coatings. Sharief ud Din Khan, Manju Arora, M. A. Wahab, and Parveen Saini Copyright © 2014 Sharief ud Din Khan et al. All rights reserved. Main Chain Noncentrosymmetric Hydrogen Bonded Macromolecules Incorporating Aniline, Alkanol, and Alkanoic Acid Hydrogen Bond Donors Sun, 27 Apr 2014 12:01:57 +0000 The syntheses and characterization of three noncentrosymmetric main chain hydrogen bonded macromolecules which incorporate aniline, alkanoic acid, and alkanol hydrogen bond donor units are reported. These macromolecules participate in weak intermolecular hydrogen bonding as demonstrated using attenuated total reflectance (ATR) FTIR. The phase transitions of these macromolecules depend on the identity of the hydrogen bond donor. Jeremy R. Wolf Copyright © 2014 Jeremy R. Wolf. All rights reserved. Effect of MWCNT on Thermal, Mechanical, and Morphological Properties of Polybutylene Terephthalate/Polycarbonate Blends Thu, 24 Apr 2014 07:25:52 +0000 This paper evaluated the effect of multiwall carbon nanotube (MWCNT) on the properties of PBT/PC blends. The nanocomposites were obtained by melt blending MWCNT in the weight percentages 0.15, 0.3, and 0.45 wt% with PBT/PC blends in a high performance corotating twin screw extruder. Samples were characterized by tensile testing, dynamic mechanical analysis, thermal analysis, scanning electron microscopy, and X-ray diffraction. Concentrations of PBT and PC are optimized as 80 : 20 based on mechanical properties. A small amount of MWCNT shows better increase in the thermal and mechanical properties of the blends of PBT/PC nanocomposite when compared to nanoclays or inorganic fillers. The ultimate tensile strength of the nanocomposites increased from 54 MPa to 85 MPa with addition of MWCNT up to 0.3% and then decreased.The tensile modulus values were increased to about 60% and the flexural modulus was more than about 80%. The impact strength was also improved with 20% PC to about 60% and with 0.15% MWCNT to about 50%. The HDT also improved from 127°C to 205°C. It can be seen from XRD result that the crystallinity of PBT is less affected by incorporating MWCNT. The crystallizing temperature was increased and the MWCNT may act as a strong nucleating agent. C. P. Rejisha, S. Soundararajan, N. Sivapatham, and K. Palanivelu Copyright © 2014 C. P. Rejisha et al. All rights reserved. New Semi-IPN Hydrogels Based on Cellulose for Biomedical Application Tue, 22 Apr 2014 11:58:29 +0000 Cellulose pulp, obtained from a paper industry, has been dissolved in PEG/NaOH system and the resulting solution has been polymerized in the presence of monomer acrylic acid (AA) and crosslinker N,N′ methylene bisacrylamide via free radical polymerization. The Cell/PEG/poly (SA) ternary semi-IPN hydrogel, so prepared, was characterized by FTIR and TG analysis. The dynamic water uptake of various hydrogels, having different compositions, was investigated in the physiological buffer of pH 7.4 at 37°C. The various hydrogels exhibited chain-relaxation controlled swelling behavior. The uptake data was best interpreted by Schott kinetic model. The various diffusion coefficients, that is, initial , average , and late time , were also calculated using the dynamic water uptake data. The hydrogels showed fair pH and salt-dependent swelling behavior. S. K. Bajpai and M. P. Swarnkar Copyright © 2014 S. K. Bajpai and M. P. Swarnkar. All rights reserved. Thermal Stability and Kinetic Study of Isotactic Polypropylene/Algerian Bentonite Nanocomposites Prepared via Melt Blending Wed, 16 Apr 2014 12:33:20 +0000 Isotactic polypropylene (iPP)/bentonite nanocomposites were prepared via melt blending using bentonite clay originated from Maghnia (Algeria). This clay was, at a first stage, used in its pure form (PBT) and then organically modified by Hexadecyl ammonium chloride (OBT). The effect of Maghnia bentonite dispersion on the iPP matrix was investigated by X-ray diffraction (XRD) and transmission electronic microscopy (TEM). DSC results evidenced that unmodified or organomodified bentonite can act as a nucleating agent increasing the rate of crystallites formation. Moreover, a thermogravimetry analysis confirmed a significant enhanced thermal stability of IPP/clay nanocomposites compared to pure IPP. The Flynn-Wall-Ozawa and Tang methods were applied to determine the activation energy of the degradation process. The apparent activation energy   of thermal degradation for IPP/clay nanocomposites was much higher than that of virgin iPP. Comparatively to PBT, results indicate that OBT has an important effect on pure iPP thermal stability. Tensile modulus, tensile strength, and elongation at break were also measured and compared with those of pure iPP. Fayçal Benhacine, Farida Yahiaoui, and Assia Siham Hadj-Hamou Copyright © 2014 Fayçal Benhacine et al. All rights reserved. Thermal Degradation Studies of Terpolymer Derived from 2-Aminothiophenol, Hexamethylenediamine, and Formaldehyde Mon, 14 Apr 2014 11:36:23 +0000 Terpolymer (2-ATPHMDAF-I) has been synthesized by the condensation of 2-aminothiophenol and hexamethylenediamine with formaldehyde in the presence of 2 M hydrochloric acid as a catalyst with 1 : 1 : 2 molar proportion of reacting monomers. The structure of newly synthesized terpolymer has been elucidated and confirmed on the basis of elemental analysis and various spectral techniques, that is, UV-visible, FT-IR, and 1H-NMR spectroscopy. Number average molecular weight () has been determined by conductometric titration in nonaqueous medium. The viscosity measurements in dimethyl sulfoxide (DMSO) have been carried out to ascertain the characteristic functions and constants. The studies have been further extended to nonisothermal thermogravimetric analysis for determination of their mode of decomposition and relative thermal stability. Activation energy , order of reaction , and frequency factor were calculated by Friedman, Chang, Sharp-Wentworth and Freeman-Carroll methods. Activation energy calculated by Friedman and Chang methods are in close agreement with each other while the results obtained from Freeman-Carroll and Sharp-Wentworth’s methods are found to be in a similar order. P. U. Belsare, A. B. Zade, P. P. Kalbende, and M. S. Dhore Copyright © 2014 P. U. Belsare et al. All rights reserved. Studies on Structural and Conducting Properties of Goethite Nanoparticles Doped HPMC Polymer Films Tue, 08 Apr 2014 09:10:32 +0000 We have carried out systematic studies on Goethite nanoparticles doped (dispersed) HPMC polymer films to quantify the changes in their structural properties, the conductivity, and IR absorbance of films. It is observed that the addition of nanoparticles has significant influence on changing structural parameters and hence enhancing the conductivity of the polymer composite considerably. These polymer composites are water soluble. Thejas Gopal Krishne Urs, Mahadevaiah Dasaiah, and Rudrappa Somashekar Copyright © 2014 Thejas Gopal Krishne Urs et al. All rights reserved. Synthesis and Characterization of Polyesteramide Hot Melt Adhesive from Low Purity Dimer Acid, Ethylenediamine, and Ethanolamine Mon, 07 Apr 2014 11:49:24 +0000 Polyesteramide hot melt adhesive (HMA) was synthesized using low purity dimer acid (composition: 3% linoleic acid, 75% dimer acid, and 22% trimer acid), ethanolamine, and ethylenediamine. Ethanolamine was added as a partial replacement (10, 20, and 30%) of ethylenediamine. Prepared HMAs were characterized for acid value, amine value, hydroxyl value, Fourier transform infrared spectroscopy, mechanical (tensile strength, percentage strain at brea, and shore D hardness), thermal (glass transition temperature, melting temperature, enthalpy of melting, crystallization temperature, and enthalpy of crystallization), rheological (viscosity versus shear rate and viscosity versus time), and adhesion properties (T-peel strength and lap shear strength). Replacement of ethylenediamine by ethanolamine replaced certain amide linkages by ester linkages, decreasing the intermolecular hydrogen bonding, leading to decrease in the crystallinity of the material, and thus the mechanical, thermal, adhesion, and rheological properties. However, HMAs prepared using ethanolamine will have better low temperature flexibility due to low glass transition temperature and better adhesion process due to the lower viscosity. Pravin G. Kadam, Parth Vaidya, and Shashank T. Mhaske Copyright © 2014 Pravin G. Kadam et al. All rights reserved. Characterization by Confocal Laser Scanning Microscopy of the Phase Composition at Interfaces in Thick Films of Polymer Blends Sun, 30 Mar 2014 07:32:40 +0000 Confocal Laser Scanning Microscopy (CLSM) has been used as a fast, user-friendly, and noninvasive tool for characterizing the phase composition differences at the substrate and air interfaces in thick films of polymer blends. A clearly different phase composition at the blend/glass interface and at the blend/air interface has been detected. We show that PCBM preferentially accumulates at the glass/blend interface, while P3HT preferentially accumulates at the blend/air interface, by comparing the integrated signal intensity of the luminescence coming from both interfaces. Our results demonstrate that CLSM can be used conveniently for the fast identification of a preferential phase segregation at interfaces in polymer blends. This is useful in the research field on devices (like sensors or planar waveguides) that are based on very thick layers (thickness higher than 1 μm). Sandro Lattante, Andrea Perulli, and Marco Anni Copyright © 2014 Sandro Lattante et al. All rights reserved. Synthesis, Characterization, and Biodegradation Studies of Poly(1,4-cyclohexanedimethylene-adipate-carbonate)s Tue, 25 Mar 2014 11:48:45 +0000 Aliphatic/alicyclic poly(1,4-cyclohexanedimethylene-adipate-carbonate)s (PCACs) were synthesized by a transesterification from 1,4-cyclohexamethylendimethanol (1,4-CHDM), adipic acid (AA), diethyl carbonate (DEC), and titanium butoxide Ti(OBu)4 as a transesterification catalyst. The synthesized PCACs were characterized by the Fourier transform infrared (FTIR), X-ray diffraction analysis (XRD), solubility, solution viscosity, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscope (SEM) for their structural, physical, thermal, and morphological investigation. The structure of synthesized PCACs was confirmed by FTIR. All TGA curves of PCACs shows 10% weight loss above 270°C, and they reveal good thermal stability. Biodegradability of PCACs was investigated by hydrolytic degradation at (pH 7.2 and 11.5), enzymatic degradation using Rhizopus delemar lips at 37°C in phosphate buffer solution (PBS), and soil burial degradation at 30°C. The hydrolytic degradation shows the greater rate of weight loss in PBS at pH-11.5 than pH-7.2. The hydrolytic and soil burial degradation shows faster rate of weight loss as compared to enzymatic degradation. Biodegradation rate of PCACs follows the order: PCAC-20 > PCAC-40 > PCAC-60. SEM images show that degradation occurred all over the film surface, creating holes and cracks. These biodegradable PCACs may be able to replace conventional polymer in the fabrication of packaging film in near future. Ajay S. Chandure, Ganesh S. Bhusari, and Suresh S. Umare Copyright © 2014 Ajay S. Chandure et al. All rights reserved. Optimization of Variables for Aqueous Extraction of Gum from Grewia mollis Powder Sun, 23 Mar 2014 12:26:58 +0000 Grewia gum is a polysaccharide derived from the inner stem bark of the edible plant Grewia mollis. Juss (family Tiliaceae). It is a savanna shrub that grows wildly but is usually cultivated in Nigeria and Northern part of Cameroon. The main goal of the present study was to investigate the effect of aqueous extraction conditions on the extraction yield and physicochemical properties of the Grewia mollis. The studied aqueous extraction variables were water/powder (W/P) ratio (10 : 1–80 : 1 w/p), temperature (25.0–85.0∘C), time (1–3 h), and pH (4.0–10.0). The results indicated that the aqueous extraction variables exhibited the least significant () effect on the yield and the viscosity of the gum. The result shows that the ratio of extraction is the main factor affecting the extraction of gum. The optimized extraction condition for higher viscosity was at the powder/water ratio of 1 : 55.4, pH of 7, time of 1 h, and temperature of 50∘C. However, the optimized extraction condition for higher yield was at the powder/water ratio of 1 : 80, pH of 4, time of 3 h, and temperature of . Emmanuel Panyoo Akdowa, Thaddee Boudjeko, Alice Louise Woguia, Nicolas Njintang-Yanou, Claire Gaiani, Joel Scher, and Carl Moses F. Mbofung Copyright © 2014 Emmanuel Panyoo Akdowa et al. All rights reserved. Effect of Acetylation on Stability to Retrogradation of Starch Extracted from Wild Polynesian Arrowroot (Tacca leontopetaloides (L.) Kuntze) for Utilization as Adhesive on Paper Thu, 13 Mar 2014 12:41:11 +0000 Starch was isolated from T. leontopetaloides tubers, chemically modified by acetylation with varying amounts of acetic anhydride. Monolayer of the ten acetylated and control starch powders was exposed on roof top for five weeks and pastes of both exposed and unexposed (control) samples were prepared with distilled water (1 : 3 w/w). The effects of acetylation, degree of substitution (DS), and exposure to sunlight were investigated to evaluate the retrogradation tendency of the adhesive pastes from changes in syneresis, tack strength, optical clarity, viscosity, gelation time, and drying time. The results obtained showed that all the adhesive properties studied were affected by both DS and exposure to sunlight. While tack strength, viscosity, and drying time were found to increase with increase in DS, syneresis, optical clarity, and gelation time were found to decrease with increase in DS. Increase in tack strength and reduction in syneresis imply that the acetylation treatment has made T. leontopetaloides starch more suitable for use in remoistenable adhesive applications. The reduction in syneresis, optical clarity, and gelation time with increase in DS was attributed to the strengthening of the bonds between the amylose and amylopectin molecules, preventing water leaching out of the starch granules. Hamza Abba, Abdulqadir Ibrahim, Gideon A. Shallangwa, Sani Uba, and Yakubu A. Dallatu Copyright © 2014 Hamza Abba et al. All rights reserved. Amphiphilic Fluorescent Well-Defined Living Polymer from Indole-3-Carboxaldehyde and 4-Bromo-1, 8-Naphthalic Anhydride: Synthesis and Characterization Mon, 10 Mar 2014 13:06:56 +0000 We reported a well-defined amphiphilic fluorescent polymer bearing indole repeating units with naphthalimide pendants obtained by ATRP followed by chemical modification. The obtained polymer poly (N-allyl indole-2-(4-hydroxybutyl)-1, 8-naphthalimide) (PAIHN) was characterized by 1H NMR, FTIR, and GPC. The polymer showed a specific fluorescence emission maximum at 538 nm excited at 435 nm in aqueous solution. The amphiphilic nature of the polymer was investigated in aqueous solution using two spectroscopic methods, namely, absorption and emission spectroscopy. The Critical Miceller Concentration values obtained by UV-visible and fluorescence are in good agreement with each other. The micelles were characterized by TEM at concentration of 0.014 mg/mL. The polymer PAIHN prepared after tweaking exhibits green fluorescence at 538 nm due to the significant effect of naphthalimide moieties, whereas before tweaking the polymer poly (1-allyl indole-3-carbaldehyde) (PAIC) exhibits blue fluorescence at 425 nm due to indole repeating units of the polymer. Ambika Srivastava, Pooja Singh, Arti Srivastava, and Rajesh Kumar Copyright © 2014 Ambika Srivastava et al. All rights reserved. Preparation and Characterization of Talc Filled Thermoplastic Polyurethane/Polypropylene Blends Mon, 03 Mar 2014 12:31:56 +0000 The effect of the addition of talc on the morphology and thermal properties of blends of thermoplastic polyurethane (TPU) and polypropylene (PP) was investigated. The blends of TPU and PP are incompatible because of large differences in polarities between the nonpolar crystalline PP and polar TPU and high interfacial tensions. The interaction between TPU and PP can be improved by using talc as reinforcing filler. The morphology was observed by means of scanning electron microscopy (SEM). The thermal properties of the neat polymers and unfilled and talc filled TPU/PP blends were studied by using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The addition of talc in TPU/PP blends improved miscibility in all investigated TPU/T/PP blends. The DSC results for talc filled TPU/PP blends show that the degree of crystallinity increased, which is due to the nucleating effect induced by talc particles. The reason for the increased storage modulus of blends with the incorporation of talc is due to the improved interface between polymers and filler. According to TGA results, the addition of talc enhanced thermal stability. The homogeneity of the talc filled TPU/PP blends is better than unfilled TPU/PP blends. Emi Govorčin Bajsić, Vesna Rek, and Ivana Ćosić Copyright © 2014 Emi Govorčin Bajsić et al. All rights reserved. Synthesis, Characterization, and Electrical Properties of Poly(azophenyleneazo-2,4-diamino-1,5-phenylenes) Sun, 23 Feb 2014 09:13:52 +0000 Poly(azophenyleneazo-2,4-diamino-1,5-phenylenes) were synthesized via diazotization of m- and p-phenylenediamine and azocoupling with m-phenylenediamine. It is found that, simultaneously, dihydrobenztriazolic units were formed as a result of cyclization reaction between amino and azo groups located in ortho position to each other. Oxidation of poly(azo-p-phenyleneazo-2,4-diamino-1,5-phenylene) was carried out and new polymer with benzotriazolic units in the main polymer chain was obtained. The conductivities of obtained polymers doped with iodine were increased with doping levels increase from 10−9–5 × 10−8 S/m to 0,1–0,6 S/m. A. H. Durgaryan, R. H. Arakelyan, N. A. Durgaran, and E. E. Matinyan Copyright © 2014 A. H. Durgaryan et al. All rights reserved. Microstructural and Mechanical Studies of PVA Doped with ZnO and WO3 Composites Films Tue, 21 Jan 2014 13:54:58 +0000 Polymer composites of ZnO and WO3 nanoparticles doped polyvinyl alcohol (PVA) matrix have been prepared using solvent casting method. The microstructural properties of prepared films were studied using FTIR, XRD, SEM, and EDAX techniques. In the doped PVA, many irregular shifts in the FTIR spectra have been observed and these shifts in bands can be understood on the basis of intra/intermolecular hydrogen bonding with the adjacent OH group of PVA. The chemical composition, phase homogeneity, and morphology of the polymer composites of the polymer film were studied using EDAX and SEM. These data indicate that the distribution of nanosized ZnO and WO3 dopants is uniform and confirm the presence of ZnO and WO3 in the film. The crystal structure and crystallinity of polymer composites were studied by XRD. It was found that the change in structural repositioning and crystallinity of the composites takes place due to the interaction of dopants and also due to complex formation. The mechanical studies of doped polymer films were carried out using universal testing machine (UTM) at room temperature, indicating that the addition of the ZnO and WO3 with weight percentage concentration equal to 14% increases the tensile strength and Young’s modulus. N. B. Rithin Kumar, Vincent Crasta, Rajashekar F. Bhajantri, and B. M. Praveen Copyright © 2014 N. B. Rithin Kumar et al. All rights reserved. Poly Meta-Aminophenol: Chemical Synthesis, Characterization and Ac Impedance Study Sun, 19 Jan 2014 12:26:44 +0000 The present work is an investigation of AC impedance behaviour of poly(meta-aminophenol). The polymer was prepared by oxidative chemical polymerization of meta-aminophenol in aqueous HCl using ammonium persulfate as an oxidant at 0–3°C. The synthesized polymer was characterized by GPC, Elemental analysis, UV-VIS-NIR, FT-IR, 1H NMR, XRD, SEM, and TGA-DTA. The AC conductivity and dielectric response were measured at a temperature range from 303 to 383 K in the frequency range of 20 Hz to 106 Hz. The AC conductivity data could be described by the relation , where the parameter “” and values decrease in the entire range of study and hence follow Correlated Barrier Hopping conduction mechanism. Both dielectric constant and dielectric loss increase with the decrease of frequency exhibiting strong interfacial polarization at low frequency and the dissipation factor also decreases with frequency. Complex electric modulus and dissipation factor exhibit two relaxation peaks, indicating two-phase structure as indicated by a bimodal distribution of relaxation process. The activation energies corresponding to these two relaxation processes were found to be 0.07 and 0.1 eV. Thenmozhi Gopalasamy, Mohanraj Gopalswamy, Madhusudhana Gopichand, and Jayasanthi Raj Copyright © 2014 Thenmozhi Gopalasamy et al. All rights reserved. Role of Hard-Acid/Hard-Base Interaction on Structural and Dielectric Behavior of Solid Polymer Electrolytes Based on Chitosan-XCF3SO3 (X = Li+, Na+, Ag+) Thu, 16 Jan 2014 09:58:09 +0000 Solid films of pure chitosan, chitosan-LiCF3SO3, chitosan-NaCF3SO3, and chitosan-AgCF3SO3 were prepared using solution cast technique. The influence of cation size on the chitosan structure has been investigated by X-ray diffraction technique. The interaction between the alkali metal ions and the donor atoms of chitosan polymer is a strong hard-acid/hard-base interaction. It was found that the intensity of crystalline peaks of chitosan decreases with increase of cation size. The impedance analysis shows that ionic transport is high for the high amorphous system. The second semicircle in - plots and the surface plasmonic resonance (SPR) peaks in chitosan-AgCF3SO3 sample system reveal the formations of silver metal nanoparticles. It was found that the high amorphous sample exhibits the high dielectric constant and dielectric loss values. The increase of dielectric constant and dielectric loss with temperature for chitosan-salt membranes indicated an increase of charge carrier concentration. Shujahadeen B. Aziz and Zul Hazrin Z. Abidin Copyright © 2014 Shujahadeen B. Aziz and Zul Hazrin Z. Abidin. All rights reserved. Adsorption of Chromium(VI) from Aqueous Solutions by Coffee Polyphenol-Formaldehyde/Acetaldehyde Resins Thu, 26 Dec 2013 14:25:08 +0000 Removal of chromium(VI) from wastewater is essential as it is toxic. Thus, removal of chromium(VI) was performed using coffee polyphenol-formaldehyde/acetaldehyde resins as adsorbents. Adsorbent resins were prepared by condensation of decaffeinated coffee powder with formaldehyde/acetaldehyde and used for the removal of Cr(VI) ions from aqueous solutions. A simple and sensitive solid phase extraction procedure was applied for the determination of chromium at trace levels by spectroscopic method using 1,5-diphenylcarbazide reagent. The adsorption of Cr(VI) on the coffee polyphenol-formaldehyde/acetaldehyde resins was monitored by FTIR and EDX analysis. The metal adsorption parameters such as contact time, pH, Cr(VI) ion concentration, and adsorbent dose were investigated. For Cr(VI), the maximum adsorption capacity of coffee polyphenol-formaldehyde resins was 98% at pH 2. The experimental results showed that Cr(VI) bound strongly with coffee polyphenol-formaldehyde/acetaldehyde resins and utilization of resins could be improved greatly by reuse. Khudbudin Mulani, Siona Daniels, Kishor Rajdeo, Sanjeev Tambe, and Nayaku Chavan Copyright © 2013 Khudbudin Mulani et al. All rights reserved. Structure/Property Relationships of Poly(L-lactic Acid)/Mesoporous Silica Nanocomposites Tue, 24 Dec 2013 08:59:46 +0000 Biodegradable poly(L-lactic acid) (PLLA)/mesoporous silica nanocomposites were prepared by grafting L-lactic acid oligomer onto silanol groups at the surface of mesoporous silica (SBA-15). The infrared results showed that the lactic acid oligomer was grafted onto the mesoporous silica. Surface characterization of mesoporous silica proved that the grafted oligomer blocked the entry of nitrogen into the mesopores. Thermal analysis measurements showed evidence that, once mixed with PLLA, SBA-15 not only nucleated the PLLA but also increased the total amount of crystallinity. Neat PLLA and its nanocomposites crystallized in the same crystal habit and, as expected, PLLA had a defined periodicity compared with the nanocomposites. This was because the grafted macromolecules on silica tended to cover the lamellar crystalline order. The g-SBA-15 nanoparticles improved the tensile moduli, increasing also the tensile strength of the resultant nanocomposites. Overall, the silica concentration tended to form a brittle material. Javier Gudiño-Rivera, Francisco J. Medellín-Rodríguez, Carlos Ávila-Orta, Alma G. Palestino-Escobedo, and Saúl Sánchez-Valdés Copyright © 2013 Javier Gudiño-Rivera et al. All rights reserved. Creep and Recovery Behavior of Compression Molded Low Density Polyethylene/Cellulose Composites Wed, 18 Dec 2013 10:12:17 +0000 Low density polyethylene (LDPE) is an important industrial material because it is durable, light-weight, easily processed and characteristically inert, but its everyday use is hazardous to the environment. The solution to this seems to consist of incorporation of biopolymers in the structure of LDPE to form composites. Compression molded composites at different cellulose loading were subjected to creep tests at 30, 40, 50, and 60°C. The samples were displaced for 12 minutes and allowed to recover for 12 minutes. Creep behavior of the polymer composites was governed by temperature, time, and cellulose loading. Creep performance decreased with increase in temperature and improved with cellulose loading while creep modulus decreased with increase in time and temperature. Time temperature superposition was used to predict the long time (up to 106 s) creep behavior of the samples. William-Landel-Ferry (WLF) model offered a better description of the shift factors based on the short term data that was used to predict the long time behavior of the polymer composites by shifting the curves along the logarithmic time axis. The deformation was dependent on free volume. Martin M. Riara, Abdallah S. Merenga, and Charles M. Migwi Copyright © 2013 Martin M. Riara et al. All rights reserved. Optimization of Cultural Conditions for Production of Extracellular Polymeric Substances (EPS) by Serpentine Rhizobacterium Cupriavidus pauculus KPS 201 Mon, 09 Dec 2013 10:16:21 +0000 Extracellular polymeric substances (EPS) are complex biopolymers produced by a wide array of microorganisms for protection against dessication, aggregation, adhesion, and expression of virulence. Growth associated production of EPS by Ni-resistant Cupriavidus pauculus KPS 201 was determined in batch culture using sodium gluconate as the sole carbon source. The optimum pH and temperature for EPS production were 6.5 and 25°C, respectively. Optimal EPS yield (118 μg/mL) was attained at 0.35% Na-gluconate after 72 h of growth. Cupriavidus KPS 201 cells also utilized glutamate, acetate, pyruvate, fumarate, malate, malonate, formate, citrate, and succinate for EPS production. Although EPS production was positively influenced by the increase of nitrogen and phosphate in the growth medium, it was negatively influenced by nickel ions. Compositional analysis of the purified EPS showed that it is a homopolymer of rhamnose containing uronic acid, protein, and nucleic acid. Presence of lipids was also detected with spectroscopy. Non-destructive EPS mediated biofilm formation of KPS 201 was also visualized by epifluorescence microscopy. Arundhati Pal and A. K. Paul Copyright © 2013 Arundhati Pal and A. K. Paul. All rights reserved.