ABSTRACT In this work, the surface of synthetic nanosized Mg-substituted fluorapatite particles was modified with biodegradable diacid N-trimellitylimido-L-leucine as a coupling agent in methanol. Furthermore, different contents of N-trimellitylimido-L-leucine-modified Mg-substituted fluorapatite were doped into polyvinylpyrrolidone/L-leucine-modified montmorillonite material to prepare novel ternary polyvinylpyrrolidone/modified montmorillonite/N-trimellitylimido-L-leucine-Mg-substituted fluorapatite nanocomposites by an efficient sonication process. Nanocomposite containing 5 wt% modified montmorillonite and 3, 5, and 7 wt% N-trimellitylimido-L-leucine-modified Mg-substituted fluorapatite contents were prepared and labeled as polyvinylpyrrolidone/modified montmorillonite/N-trimellitylimido-L-leucine-Mg-substituted fluorapatite 3, polyvinylpyrrolidone/modified montmorillonite/N-trimellitylimido-L-leucine-Mg-substituted fluorapatite 5, and polyvinylpyrrolidone/modified montmorillonite/N-trimellitylimido-L-leucine-Mg-substituted fluorapatite 7, respectively. The structure and morphology of the aforesaid products were characterized by different analytical apparatuses. GRAPHICAL ABSTRACT
ABSTRACT Poly(lactic acid) (PLA) was melt blended with thermoplastic elastomer, maleic anhydride grafted poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS-g-MA) copolymer with varied concentration (10–40 wt%) using twin screw extruder. Dynamic rheological behavior of PLA/SEBS-g-MA blends investigated a transition from liquid-like behavior to solid-like behavior in the composition range of 10–20 wt% of SEBS-g-MA. The capillary rheometer analysis showed enhanced shear viscosity with increase in SEBS-g-MA content. At 10 wt% of SEBS-g-MA, a maximum in the non-essential work of fracture was observed which reflects resistance to crack propagation. Scanning electron microscopy revealed a transition in deformation mechanisms from voids, to fibrillation and cavitation. GRAPHICAL ABSTRACT
A ladder-type poly(3,4-ethylenedioxythiophene)-poly (ethylene glycol)-polyurethane (PEDOT-PEG-PU) supramolecular network was successfully synthesized using graft copolymerization of hydroxymethyl-EDOT with isocyanate-terminated PEG-PU prepolymer. PEDOT functionalized as the frame for a ladder-type supramolecular structure and PEG-PU as the rung. The successful formation of supramolecular network was confirmed by analyzing the Fourier transform infrared spectroscopy (FTIR). A series of PEDOT-PEG-PU gel polymer electrolyte by linking the LiClO4 were prepared as a function of [O/Li+] ratios. The pH effect of their electrical capacitances was investigated using cyclic voltammetry. Ionic conductivities of different PEDOT-PEG-PU/Li+ complexes at a fixed pH were also evaluated through impedance analysis. [GRAPHICS] .
Cellulose fiber-reinforced composite has received great attention due to the high strength, stiffness, biodegradability, and renewability of the excellent natural biomaterials. Cellulose nanofibers for the development of organic-inorganic hybrid composite is relatively new filed of research. Cellulose macro and nanofibers can be used as reinforcement in the hybrid composite because of improved mechanical, thermal, optical, electrical, morphological, and biological properties. The hybrid nanocomposites were synthesized by an in situ sol-gel process in the presence of coupling agent. The sol-gel process has definitely proven its potential by providing the synthesis of various functional organic-inorganic hybrid nanocomposites through an in situ sol-gel process. The hybrid nanocomposites have been prompted by the ability to control the morphology of final materials. The photoluminescence spectral studies indicate that the emission shifts toward higher wavelength (326-532nm) accompanied by a reduction in impurity centers with increasing concentration of poly(vinyl alcohol)-TiO2 and hybrid nanocomposite. The final nanostructured TiO2 hybrid nanocomposites with particle size ranging from 0.32 to 20nm were characterized by Field -emission transmission electron microscopy (FE-TEM) analysis. Furthermore, cellulose-poly(vinyl alcohol)-nano-TiO2 hybrid composite was characterized by Fourier transform infrared, X-ray diffraction, UV, Thermogravimetric analysis (TGA), Differential scanning calorimetry (DSC), FE-SEM-EDX, Field-emission scanning electron microscopy (FE-SEM), and FE-TEM analysis. The different analysis results of the hybrid composite indicate the optical transparency, optical properties, T-g, crystallinity, thermal stability, and controlled morphology of hybrid nanocrystalline composites. Finally, the cellulose-poly(vinyl alcohol)nano-TiO2 hybrid nanocomposites were tested against pathogens such as Gram-positive Bacteria Bacillus cereus and Gram-negative Escherichia coli for antimicrobial activity. These results show that the hybrid composite exhibited excellent antimicrobial properties against pathogens. [GRAPHICS] .
The impedance of well-characterized KI-incorporated glucosyl carboxonium ion-based biopolymer crust electrolytes up to a maximum 2.7wt% was measured using electrical impedance spectroscopy. Enhanced ionic conductivity of 2.3657x10(-2)Scm(-1) on the addition of 2.7wt% of KI was observed in contrast to earlier reported value for pure GCI of 4.5278x10(-4)Scm(-1). This is attributed due to the increased concentration of KI in the system and is corroborated with increased ion density (n), mobility (mu), and diffusion coefficients (D). Dielectric and modulus study shows the capacitive nature of electrolyte. Fabricated dye-sensitized solar cell using pure glucosyl carboxonium ion crust and KI-incorporated glucosyl carboxonium ion crust shows the efficiency of 1.19% for pure and shows the efficiency of 2.14% for 2.6wt% of KI in glucosyl carboxonium ion at 1 sun condition. [GRAPHICS] .
The present work is aimed to synthesize a novel series of linear polyamides (PAs) 4a–d based on di(thiazolyl-thiophenylidene)cyclyhexanone as well as carries aliphatic and aromatic species in the polymer main backbones. The polymerization process was occurred by solution polycondensation technique by the interaction of the newly synthesized monomer 3 with adepoyl, sebacoyl, terphthaloyl, and isophthaloyldiacid chlorides. Before polymerization, the structure of monomer 3 was confirmed by elemental and spectral analyses. The structures of polymers were also investigated by elemental, spectral analysis, thermal analysis, and Field-Emission Scanning Electron Microscopy (FE-SEM) micrographs. Film draw temperatures for all the polymers were evaluated in the range 509.0–542.3°C. Here, the heavy metallic sensors are developed with the polyamide-fabricated glassy carbon electrode (GCE) by reliable current vs. voltage technique. A thin layer of PA onto GCE was fabricated with conducting coating agents (5% nafion) to fabricate a selective heavy metal ions, Cu2+ sensor in short response time in phosphate buffer phase. The fabricated sensor was also exhibited higher sensitivity, lower detection limit, large dynamic concentration ranges, long-term stability, and improved electrochemical performances toward Cu2+ sensor. The calibration plot is linear (r2: 0.9956) over the large Cu2+ ion concentration ranges (1.0 nM to 10.0 mM). The sensitivity and detection limit is 3.4177 µA cm−2 µM−1 and 0.36 nM (signal-to-noise ratio of 3) respectively. This novel effort is initiated a well-organized way of efficient cationic sensor improvement with conductive polymers for heavy metallic pollutants in environmental and health-care fields in large scales.
In this work, poly(L-lactic acid) film was coated with SiOx by the plasma-enhanced chemical vapor deposition with different deposition times. Compared with the neat poly(L-lactic acid) film, the oxygen (O-2), carbon dioxide (CO2), nitrogen (N-2), and water vapor permeability of the poly(L-lactic acid)/SiO(x)60 film (depositing for 60min) decreased by 40.7, 30.6, 58.7, and 53.4% at 25 degrees C, respectively. After treated by the SiOx deposition, the gas permselectivity of the poly(L-lactic acid)/SiO(x)60 film, such as (CO2/O-2), (O-2/N-2), and (CO2/N-2), increased by 17.2, 43.9, and 67.5% at 25 degrees C, respectively. In addition, Young's modulus and tensile strength of poly(L-lactic acid)/SiO(x)60 film increased by 107.2 and 49.3%, respectively. Moreover, the poly(L-lactic acid)/SiO(x)60 films still kept good toughness with an elongation at break of 50.7%. [GRAPHICS] .
Ring-opening polymerization of epsilon-caprolactone was performed at 130 degrees C, under partial vacuum in the presence of stannous octoate as the catalyst and 1,4-butanediol as the initiator. After the termination of polymerization by deionized water, a hydroxyl group formed at the end of the polymer chains. Structure of the synthetic poly(epsilon-caprolactone)-diols (PCL-diol), molecular weight, polydispersity index, and Cell viability were evaluated. Very narrow distribution in the molecular weight obtained for PCL-diols is due to a new method for synthesis. It was shown that by the increase in PCL-diols, the compatibility of human mesenchymal stem cells grew up. [GRAPHICS] .
This up-to-date review comprehends the research performed on three important types of thermoplastic polymers, i.e., polyamide, polyimide, and poly(amide-imide). Graphite has been discussed as indispensable nanofiller to form significant categories of polyamide/graphite, polyimide/graphite, and poly(amide-imide)/graphite nanocomposite. Main focus of this review was to outline the properties and potential of these polymers and their composites. Studies have demonstrated considerable enhancement in the strength, thermal, electrical, rheology, and wear properties of these polymers upon graphite addition. Significance of polyamide, polyimide, poly(amide-imide), and graphite-based composites have been discussed keeping in view the challenges and future demands for contemporary technical applications.[GRAPHICS].
Waterborne polyurethane coatings made from castor oil as polyol resource, replacing oil from fossil fuels are attracting lot of recognition during recent decades. In this review, castor oil and its modifications to synthesize various biobased waterborne polyurethane and their nanocomposite systems have been addressed. Various synthesis procedures for waterborne polyurethane dispersions and their applications as a coating material have been described. This review will be helpful to the green research community for selection of monomer and further development of biobased waterborne polyurethane utilizing advanced technology. [GRAPHICS] .
Owing to their complex structural characteristics, 3D woven composites display different mechanical properties and failure modes from traditional composite laminates. The relations between the weaving geometry and main mechanical properties of composites are obtained by studying the internal structures of 3D woven textile. This paper reviews the research on the mechanical behavior such as tension, compression, shear, flexural, and impact properties, and analytical models of 3D woven polymer matrix composites mainly in four major inner structures and discusses the development of mechanical properties and applications of 3D woven fabrics and suggests further studies on aero industry. [GRAPHICS] .
The effect of three different organomodified nanoclays (Cloisite 20A, Cloisite 30B, and Nanomer I28E) as well as the effect of a compatibilizer (PEgMA) was studied, with the purpose of developing greenhouse cover films based on polyethylene/ethylene vinyl acetate blends. Three organomodified clays were analyzed. The influence of organomodifier clay on film optical, morphology, mechanical, and photo-oxidative degradation properties as well as the effect of incorporation of maleic anhydride-grafted polyethylene as a compatibilizer was studied. The combined effect of these nanoclays with two different UV-oxidative protection systems for polyethylene/ethylene vinyl acetate-nanostructured films was evaluated. Two types of UV stabilizer combination systems were studied; one with a combination of heat and light stabilizers of mixture of antioxidants (phenolic and metal deactivator, Irgatec NC66) with hindered amines, Tinuvin 494AR (designated as system-A) and other with a combination of metal deactivator antioxidant, Irganox MD1024 with hindered amines Tinuvin NOR 371 and benzophenones, Chimasorb 81 (designated as system-B). A strong influence is observed in the use of compatibilizing agent, type, and content of nanoclay in the degree of dispersion as well as in the photo-oxidation behavior. The structure obtained is very dependent on the modified clay used; mostly, intercalated-exfoliated clay structure is produced. The induction period for the photodegradation reaction to start is shorter in the samples with the nanoclay than in the pure polymer. There was a difference in the effectiveness of two stabilizing systems used. It was found a better performance for the stabilizer system-A, regardless of the type of clay used. These greenhouse cover films should allow the pass-through of visible light into the greenhouse during day but restrict the pass-through of the infrared radiation out of the greenhouse during night. [GRAPHICS] .
Maleic anhydride-grafted polypropylene (PP-g-MA) was reacted with aniline (NH2C6H5) to produce PP-g-NHC6H5 and used as a compatibilizer in polypropylene/carbon nanotube composites. Infrared spectroscopy (FTIR) and nuclear magnetic resonance confirmed the reaction between PP-g-MA and aniline. PP-g-NHC6H5 resulted a better compatibilizer than PP-g-MA, producing good dispersion and homogeneous distribution of the carbon nanotubes with less agglomerates, as observed by SEM analysis. Improved dispersion and distribution is assumed to be due to the - interactions between the -C6H5 ring in the prepared compatibilizer and the hexagonal carbon structure in the nanotubes. In addition, a higher degree of crystallinity (12%) was promoted, since it was favored by - interactions. This achieved higher crystallinity promoted an increase in tensile modulus, with only slight changes in tensile strength but with an adverse effect on elongation at break. [GRAPHICS] .
An accelerated aging study on silicone rubber exploring the effects of exposure to a functional oil (polyalkylene glycol) at elevated temperature (195 degrees C) is reported in this paper. Variations in mechanical (tensile, tear, hardness) and thermal (conductivity, specific heat capacity) properties were monitored versus aging time while permanent deformation of the rubber was evaluated through creep and recovery measurements. Morphology and surface chemistry of the aged rubber were also investigated through scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy, respectively. Aging had a significant impact on the mechanical properties with the ultimate tensile strength and elongation at break decreasing from 7.4MPa and 2250% in unaged samples to 1.5MPa and 760% in 6-week aged samples, respectively. The tear strength and hardness exhibited an initial increase during the early stages of aging, followed by a decreasing trend. In contrast, the thermal properties did not change significantly and FTIR did not detect any changes in the surface chemistry of the rubber with aging. SEM however, provided evidence of an increase in brittle behavior from the morphology of the fractured surfaces. [GRAPHICS] .
A new type of thermothickening graft copolymer was synthesized through free radical copolymerization and grafting onto technique in aqueous solution. Their molecular structure combines a hydrophilic backbone based on poly(acrylicacid-co-2-acrylamido-2-methylpropane sulfonic acid and thermosensitive side chains based on N,N-diethylacrylamide and N,N-dimethylacrylamide (DMAA). The lower critical solution temperature of poly(N,N-diethylacrylamide) was increased easily by copolymerizing with hydrophilic monomers DMAA. The results demonstrate that the polymers in aqueous solution exhibit a significant increase in viscosity with the temperature rising and their thermothickening behavior is related to various physicochemical parameters such as the concentration of the polymer, shear rate, chemical composition of side chains, salt concentration, and pH value. [GRAPHICS] .
In this paper, new polymer composites were synthesized by template copolymerization of aniline and metanilic acid in the presence of prepared melamine triacetic acid and poly(melamine-co-citric acid) as polyacids and dopants. The properties of the poly(aniline-co-metanilic acid) composites were studied by Fourier transform infrared, X-ray diffraction, scanning electron microscope, CV, and differential scanning calorimeter analysis. The four-point probe technique was used for evaluating the electrical conductivity of the composites. The scanning electron micrographs disclosed that the products had the morphology with agglomerated distorted spherical shapes with the average size of 40-50nm. Also, the solubility of the composites had been improved notably in organic solvents. [GRAPHICS] .
The present study reports the analysis of properties of tamarind gum-based hydroethanolic physical hydrogels. The extent of hydrogen bonding in hydrogels decreased with an increase in tamarind gum content. The hydrogel with the highest tamarind gum content was found to be highly stable in terms of mechanical properties. There was a decrease in the resistive component of the hydrogels with an increase in tamarind gum content. The drug release from the hydrogels increased with an increase in the tamarind gum content. The antimicrobial activity of the drug-loaded hydrogels against Escherichia coli was excellent. [GRAPHICS] .
Novel biodegradable pH and thermal-responsive hydrogels were prepared for controlled drug delivery studies via reaction of chitosan with 4-chloroacetylantipyrine in DMF/H2O, followed by heating of the formed poly [acetylantipyrine-chitosan] with glutaraldehyde as a crosslinking agent to give the hydrogels. These hydrogels were subjected to equilibrium swelling studies at different temperatures (25 degrees C, 37 degrees C and 45 degrees C) in solutions of pH 2.1 and 7.4. Methotrexate (MTX) was entrapped in the hydrogels, and drug release studies were carried out at 37 degrees C in solutions at pH 2.1 and 7.4. [GRAPHICS]
Polyvinylpyrrolidone/polyaniline (PVP/PANI) with additives (TiO2, ZnO, NaCl and Na2SO4) was synthesized. To spread the electric and photoelectric applications of PVP/PANI, its photodegradation under UV irradiation was studied by Fourier transform infrared spectroscopy, diffuse reflectance spectroscopy, water uptake and scanning electron microscopy. Results show that ZnO, TiO2 and NaCl accelerate the photodegradation, respectively, but Na2SO4 stabilized PVP/PANI. The degradation rate of PVP/PANI/tert-butyl alcohol and PVP/PANI/ascorbic acid proved the radical role. Water uptake results show that the power of interactions is in this order: PVP/PANI/Na2SO4 > PVP/PANI/TiO2 > PVP/PANI/ZnO > PVP/PANI > PVP/PANI/NaCl > PVP/PANI/tert-butyl alcohol> PVP/PANI/ascorbic acid. [GRAPHICS] .
In this work in-situ preparation of novel poly(urethane-imide)/graphene, graphene oxide and reduced graphene oxide nanocomposite is reported by the reaction of 4,4 '-diphenylmethane diisocyanate, polypropylene glycol, 3,3',4,4'-benzophenone tetra carboxylic dianhydride and nanomaterials in the loadings levels of 0.5, 1.5, 2.5, and 3.5 pbw in propylene carbonate as an alternative green solvent. The synthesized poly(urethane-imide) nanocomposite was characterized by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy ((HNMR)-H-1), thermogravimetric analysis (TGA), attenuated total reflection (ATR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC), respectively. The resulting nanocomposite showed enhanced thermal stability when compared with pristine and unfilled poly(urethane-imide) sample. [GRAPHICS]
