International Journal of Polymer Science The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. Effect of Nano-CaCO3 and Talc on Property and Weathering Performance of PP Composites Mon, 22 May 2017 07:40:34 +0000 Wood plastic composites (WPCs) are increasingly being utilized these days due to their excellent mechanical properties and low maintenance cost. Despite these advantages, poor UV resistance and low impact strength are drawbacks. To overcome these shortcomings, coextrusion technology has recently been applied in the production of WPCs and it has been showing good results. However, further research on the combination of different functional enhancements is still needed. This study, therefore, manufactured polypropylene (PP) composites filled with UV stabilizer and inorganic fillers (i.e., nano-CaCO3 and talc) and then investigated the influence of weathering on the mechanical and morphological properties of the filled composites as a function of filler type and content. UV stabilizer effectively protected the filled composites from UV-induced photodegradation. At 2.5 wt% nano-CaCO3 (NCC), the NCC particles were well dispersed in the PP matrix, thereby improving the mechanical properties of the filled composites. The best results were observed in 2.5 wt% NCC and 10 wt% talc hybrid filled composites. The composites prepared by adding UV stabilizer to the PP matrix together with NCC and talc exhibited high mechanical properties and improved weathering resistance, and, thus, the combination of NCC, talc, and UV stabilizer in the PP matrix is applicable for shell layer to be used in coextruded WPCs. Danbee Lee, Seungkyun Kim, Birm-June Kim, Sang-Jin Chun, Sun-Young Lee, and Qinglin Wu Copyright © 2017 Danbee Lee et al. All rights reserved. Dextran-Polyacrylamide as Matrices for Creation of Anticancer Nanocomposite Thu, 18 May 2017 06:16:51 +0000 Drug targeting to specific organs and tissues is one of the crucial endeavors of modern pharmacotherapy. Controlled targeting at the site of action and reduced time of exposure of nontargeted tissues increase the efficacy of the treatment and reduce toxicity and side effects, improving compliance and convenience. Nanocarriers based on the branched copolymers dextran-graft-polyacrylamide were synthesized and characterized and were tested on phagocytic cells. It was shown that these nanoparticles are actively captured by phagocytic cells and that they are not cytotoxic. The polymer nanoparticles loaded with cisplatin at different concentrations from 0.1 to 10 μg/mL yielded dose-dependent decrease in viability of chronic myelogenous leukemia and histiocytic lymphoma cells. The lowest percentage of viable cells was observed for lymphoma cells (22%). Taking into account the fact that our nanoparticles will act mainly on malignant phagocytic cells and do not affect healthy cells, they can thus potentially be used for the therapeutic treatment of tumor cells having phagocytic activity. The effect of nanosilver on cell viability was lower than the one of polymer/cisplatin composite. The data from the cytotoxic studies indicate that nanosilver induces toxicity in cells. However, when the copolymers were conjugated to both nanosilver and cisplatin, such a nanosystem displayed less cytotoxic effect compared to the conjugates of dextran-polyacrylamide and cisplatin. G. Telegeev, N. Kutsevol, V. Chumachenko, A. Naumenko, P. Telegeeva, S. Filipchenko, and Yu. Harahuts Copyright © 2017 G. Telegeev et al. All rights reserved. Evaluation of Shear Strength of Concrete Flat Plates Reinforced with GFRP Plates Thu, 18 May 2017 00:00:00 +0000 The shear performance of concrete flat plates with glass fiber-reinforced polymer (GFRP) plate shear reinforcement was investigated through punching shear tests. Each GFRP plate was embedded in the concrete and included openings to permit the flow of concrete during fabrication. Punching shear tests were conducted on a total of 8 specimens, and the resulting crack and fracture formations, strains, and load-displacement curves were analyzed and compared. The experimental variables considered were the types of shear reinforcement, including steel stirrups or GFRP plates, and the shear reinforcement spacing. The experimental results show that the GFRP shear reinforcement effectively increased the shear strengths of flat plates. Furthermore, the applicability of two formulas was investigated: a modified version of a shear strength formula from ACI 318-14 and the ACI 318-14 fracture prediction formula. Min Sook Kim and Young Hak Lee Copyright © 2017 Min Sook Kim and Young Hak Lee. All rights reserved. Simulation of Chloride Ingress through Surface-Coated Concrete during Migration Test Using Finite-Difference and Finite-Element Method Wed, 17 May 2017 00:00:00 +0000 Polymer surface coatings are commonly used to enhance the corrosion resistance of concrete structures in saline environments to ionic diffusivity; this diffusivity can be determined by migration tests. This paper presents the simulation of the effects of the surface coatings on migration tests by solving the Nernst-Planck/Poisson model using both finite-difference method and finite-element method. These two numerical methods were compared in terms of their accuracy and computational speed. The simulation results indicate that the shapes of ionic profiles after migration tests depend on the effectiveness of surface coatings. This is because highly effective surface coatings can cause a high ionic concentration at the interface between coating and concrete. The simulation results were also compared to homogenized cases where a homogenized diffusion coefficient is employed. The result shows that the homogenized diffusion coefficient cannot represent the diffusivity of the surface-coated concrete. Seyoon Yoon Copyright © 2017 Seyoon Yoon. All rights reserved. Physicochemical and Luminescent Properties of Copolymers Composed of Three Monomers: Polythiophenes Based on 3-Hexylthiophene and 3,4-Ethylenedioxythiophene Thu, 11 May 2017 08:56:44 +0000 The chemical synthesis and physicochemical and luminescent characterizations of polymers based on 3-HT, EDOT, and 2,2′-(9,9-dioctyl-9H-fluorene-2,7-diyl) bisthiophene (fluorene) or (E)-2-(ethyl(4-((4-nitrophenyl)diazenyl)phenyl)amino)ethyl 2-(thiophen-3-yl)acetate (TDR1) are reported. The fluorene unit was bound to the conjugate backbone, while the Disperse Red 1 (DR1) chromophore was present as a pendant group. Characterizations by 1H NMR, FT-IR, DSC-TGA, GPC, UV-vis, cyclic voltammetry, fluorescence quantum yield, excited state lifetime, and two-photon absorption cross-section were carried out. These polymers combined the physicochemical properties of EDOT and 3-HT, such as high electron density, high charge mobility, low oxidation potential, and good processability. The optical properties of these copolymers were highly dependent on the presence of EDOT, the molecular weight, and the regioregularity rather than the presence of the third component (fluorene or TDR1). The good nonlinear absorption and luminescent properties exhibited by these copolymers were exploited to fabricate nanoparticles used as fluorescent tags for the imaging of microstructures. Marco Antonio Ramírez-Gómez, Karla Karina Guzmán-Rabadán, Edgar González-Juárez, Marisol Güizado-Rodríguez, Gabriel Ramos-Ortiz, Jorge Enrique Alba-Rosales, Huehueteotl Panzo-Medrano, Victor Barba, Mario Rodríguez, José Luis Maldonado, and Miguel Ángel Basurto-Pensado Copyright © 2017 Marco Antonio Ramírez-Gómez et al. All rights reserved. A Novel Approach to Improve the Barrier Properties of PET/Clay Nanocomposites Thu, 11 May 2017 07:56:30 +0000 An investigation of oleic acid-modified clay versus plain clay with regard to the physical and barrier properties of PET/clay nanocomposites was performed. Montmorillonite (MMT) and Cloisite 30B nanoclays were modified by long-chain oleic acid and identified as ol-MMT and ol-30B, respectively. Fourier Transformed Infrared Spectroscopy and X-ray diffraction (XRD) results revealed that the fatty acid was associated with the clay surface and that the gallery spacing of the layered silicates was expanded. In the case of ol-MMT, a disordered structure of layered silicates was achieved. TGA results indicated that ol-MMT showed thermal stability and could survive PET processing temperature. The degradation of ol-30B, however, increased after modification because of the presence of oleic acid. PET/clay nanocomposites were prepared with modified ol-MMT and modified ol-30B by using a twin screw extruder. XRD indicated that there was a significant improvement on the dispersion of nanoclays modified with long-chain oleic acid into the PET matrix, and an exfoliated structure was achieved. DSC data also revealed that crystallization behaviors of nanocomposites prepared with oleic acid-modified clays are similar to that of extruded PET. Significant improvements in the mechanical and barrier properties of stretched PET/clay nanocomposites were also achieved. Kazem Majdzadeh-Ardakani, Shahab Zekriardehani, Maria R. Coleman, and Saleh A. Jabarin Copyright © 2017 Kazem Majdzadeh-Ardakani et al. All rights reserved. Prestress Loss of CFL in a Prestressing Process for Strengthening RC Beams Tue, 09 May 2017 07:59:25 +0000 A prestressing system was designed to strengthen reinforced concrete (RC) beams with prestressed carbon fiber laminate (CFL). During different prestressing processes, prestress loss was measured using strain gauges attached on the surface of CFL along the length direction. The prestress loss was 50–68% of the whole prestress loss, which is typically associated with CFL slipping between the grip anchors. Approximately 20–27% of the prestress loss was caused by the elastic shortening of the RC beam. An analytical model using linear-elastic theory was constructed to calculate the prestress loss caused by CFL slipping between the anchors and the elastic shortening of the strengthened beams. The compared results showed that the analytical model of prestress loss can describe the experimental data well. Methods of reducing the prestress loss were also suggested. Compared to other experiments, the prestressing system proposed by this research group was effective because the maximum percentage of prestress loss was 14.9% and the average prestress loss was 12.5%. Xinyan Guo, Dong Liu, Peiyan Huang, and Xiaohong Zheng Copyright © 2017 Xinyan Guo et al. All rights reserved. Sulfate and Calcium Chloride Resistance of Steel/Glass Fiber-Reinforced Polymer Hybrid Panel for Improved Movable Weir Application Thu, 04 May 2017 10:12:56 +0000 This study evaluated the performance of a hybrid panel that can overcome the current problem of corrosion of the steel panels of improved movable weirs when they are exposed to a sulfate and calcium chloride environment such as sea water. A hybrid panel with glass fiber-reinforced polymer (GFRP) layers on both sides of a steel panel means that the central panel is not exposed to the external elements, which can avoid corrosion problems. In this study, to maximize the hybrid panel’s strength and durability, the moisture absorption characteristics and the durability in an accelerated environment were evaluated. The test results were considered to indicate no durability issues as the final absorption ratio was approximately 2.0% or less in all environments. Also, from the accelerated deterioration test results when the steel panel processed by sand blasting was applied in all accelerated deterioration environments, it satisfied the residual strength level of 65% or more. However, in the case without surface processing, upon exposure to MgSO4 solution, it did not satisfy the standard residual strength level of 65%. These results show that sand blasting on the surface of a steel panel is adequate for hybrid panels for improved movable weirs. S.-K. Lee, S.-Y. Yoo, and C.-G. Park Copyright © 2017 S.-K. Lee et al. All rights reserved. The Effect of Masterbatch Recipes on the Homogenization Properties of Injection Molded Parts Wed, 03 May 2017 06:54:25 +0000 Appearance is a key factor in most injection molding applications. Unfortunately, there is no widespread method to objectively test visual appearance, such as color inhomogeneity of the parts or other surface defects. We developed an evaluation method to characterize the color inhomogeneity of injection molded parts. First, we examined manufacturing conditions and masterbatch recipes and then the individual effects of the components and their interactions on homogeneity. László Zsíros, Dániel Török, and József Gábor Kovács Copyright © 2017 László Zsíros et al. All rights reserved. Synthesis of Disentangled Ultra-High Molecular Weight Polyethylene: Influence of Reaction Medium on Material Properties Wed, 03 May 2017 00:00:00 +0000 The polymerization of ethylene to Ultra-High Molecular Weight Polyethylene (UHMWPE) in certain reaction conditions allows synthesis of nascent powders with a considerably lower amount of entanglements: the material obtained is of great interest from both academic and industrial viewpoints. From an academic point of view, it is interesting to follow the evolution of the metastable melt state with the progressive entanglements formation. Industrially, it is valuable to have a solvent-free processing route for the production of high modulus, high strength tapes. Since the polymer synthesis is performed in the presence of a solvent, it is interesting to investigate the influence that the reaction medium can have on the catalyst activity, resultant molecular characteristics, and polymer morphology at the macroscopic as wells as microscopic level. In this paper, we present the effect that two typical polymerization solvents, toluene and heptane, and mixtures of them, have on the catalytic performance and on the polymer properties. The observations are that an unexpected increase of catalyst activity, accompanied by a significant improvement in mechanical properties, is found when using a carefully chosen mixture of solvents. A tentative explanation is given on the basis of the presented results. Giuseppe Forte and Sara Ronca Copyright © 2017 Giuseppe Forte and Sara Ronca. All rights reserved. Effect of Graphite Nanosheets on Properties of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Wed, 03 May 2017 00:00:00 +0000 The influence of different contents, 0.25, 0.50, and 1.00 wt%, of graphite nanosheets (GNS) on the properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanocomposites obtained by solution casting method has been studied. GNS were prepared by three steps: intercalation (chemical exfoliation), expansion (thermal treatment), and the GNS obtainment (physical treatment by ultrasonic exfoliation). X-ray diffraction (XRD), Raman spectroscopy, and field emission gun-scanning electron microscopy (FE-SEM) showed that the physical, chemical, and thermal treatments preserved the graphite sheets structure. XRD and Raman results also showed that GNS were dispersed in the PHBV matrix. The degree of crystallinity (X) of the nanocomposites did not change when the graphite nanosheets were added. However, the GNS acted as nucleation agent for crystallization; that is, in the second heating the samples containing GNS showed two melting peaks. The addition the GNS did not change the thermal stability of the PHBV. Larissa Stieven Montagna, Thaís Larissa do Amaral Montanheiro, João Paulo Barros Machado, Fábio Roberto Passador, Ana Paula Lemes, and Mirabel Cerqueira Rezende Copyright © 2017 Larissa Stieven Montagna et al. All rights reserved. Using Factorial Design Methodology to Assess PLA-g-Ma and Henequen Microfibrillated Cellulose Content on the Mechanical Properties of Poly(lactic acid) Composites Sun, 30 Apr 2017 13:59:06 +0000 In this work, a 22 factorial design was used to study the effect of microfibrillated henequen cellulose fibers (HENCEL) and PLA-g-MA coupling agent contents on the tensile, flexural, and impact mechanical properties and the heat deflection temperature (HDT) of biodegradable PLA composites. The results show that the principal effects of HENCEL and MA are statistically significant for the tensile, flexural, HDT, and impact strength properties of PLA composites. Regarding the interactions between the principle effects, MA-HENCEL, there are differences with respect to the mechanical property; for example, for tensile and flexural mechanical properties, there is a synergistic effect between MA and HENCEL, whereas for HDT and impact strength there is not any. The micromechanical analysis shows an excellent agreement between the measured and the estimated values for both the composite tensile strength and the elastic modulus and only slight deviations were noticed for high microfibrillated cellulose fibers content. The morphological analysis via SEM indicated that the addition of PLA-g-MA improved the fiber-matrix adhesion because of the HENCEL unbounding and pull-out decreases from the PLA matrix. The use of appropriate values of matrix strength and stiffness and considering the improved fiber-matrix adhesion of the coupling agent yield a good agreement between experimental and estimated values. M. Dzul-Cervantes, P. J. Herrera-Franco, T. Tábi, and A. Valadez-Gonzalez Copyright © 2017 M. Dzul-Cervantes et al. All rights reserved. Antimicrobial Polyethylene through Melt Compounding with Quaternary Ammonium Salts Sun, 30 Apr 2017 00:00:00 +0000 Selected mono- and bicationic quats were compounded with polyethylene. The physicochemical surface properties, leaching behavior, and antibacterial activity of such modified samples were investigated. Contact angle measurements and fluorescein binding assays showed the presence of quaternary ammonium groups at the surface. After storing the samples in 50°C warm water for 30 days, several were still antimicrobially active. No correlation between the number of exposed N+ head groups after leaching and the antibacterial activity was observed. There is however a qualitative correlation of the antibacterial activity with the contact angles and surface concentrations of N+ before leaching/storing in warm water. Fernanda F. Rossetti, Konstantin Siegmann, Joachim Köser, Irene Wegner, Ismail Keskin, Götz Schlotterbeck, and Martin Winkler Copyright © 2017 Fernanda F. Rossetti et al. All rights reserved. Apparent Surface Free Energy of Polymer/Paper Composite Material Treated by Air Plasma Thu, 27 Apr 2017 10:05:39 +0000 Surface plasma treatment consists in changes of surface properties without changing internal properties. In this paper composite polymer/paper material is used for production of packaging in cosmetic industry. There are problems with bonding this material at the time of packaging production due to its properties. Composite surface was treated by air plasma for 1, 10, 20, and 30 s. The advancing and receding contact angles of water, formamide, and diiodomethane were measured using both treated and untreated samples. Apparent surface free energy was estimated using the hysteresis (CAH) and Van Oss, Good, Chaudhury approaches (LWAB). Surface roughness was investigated using optical profilometry and identification of after plasma treatment emerging chemical groups was made by means of the XPS (X-ray photoelectron spectroscopy) technique. After plasma treatment the values of contact angles decreased which is particularly evident for polar liquids. Apparent surface free energy increased compared to that of untreated samples. Changes of energy value are due to the electron-donor parameter of energy. This parameter increases as a result of adding polar groups at the time of surface plasma activation. Changes of surface properties are combination of increase of polar chemical functional groups, increase on the surface, and surface roughness increase. Konrad Terpiłowski Copyright © 2017 Konrad Terpiłowski. All rights reserved. Valorization of Agricultural Residues for Cellulose Nanofibrils Production and Their Use in Nanocomposite Manufacturing Sun, 23 Apr 2017 00:00:00 +0000 This paper reports the isolation of cellulose nanofibrils (CNFs) from almond stems, available as agricultural residues. The CNF suspensions were prepared by the combination of chemical and mechanical treatment: the microscopic fibres were firstly isolated by the delignification-bleaching process, followed by TEMPO-mediated oxidation to facilitate the further nanofibrillation using high-pressure homogenization process at 600 bar for 10 passes as a mechanical treatment. The ensuing CNFs were characterized by several methods, such as transmission electron microscopy (TEM), degree of fibrillation, and carboxyl content. Different nanocomposites were prepared by casting-evaporation method from the mixture of CNF suspension in the commercial acrylic latex as a matrix. The effect of CNF loading on mechanical and thermal properties of the composites was then studied. The considerable enhancement of both Young’s modulus and tensile strength was observed, which clearly indicates that the nanocomposites reinforced with the nanofibrils from Prunus amygdalus have promising mechanical properties. Ramzi Khiari Copyright © 2017 Ramzi Khiari. All rights reserved. Biocompatibility Assessment of Poly(lactic acid) Films after Sterilization with Ethylene Oxide in Histological Study In Vivo with Wistar Rats and Cellular Adhesion of Fibroblasts In Vitro Tue, 18 Apr 2017 00:00:00 +0000 Biomaterials must meet certain fundamental requirements for their usage in living beings, such as biocompatibility, bifunctionality, and sterilizability, without having chemical and structural changes. The biocompatibility of poly(lactic acid) (PLA) films, shaped by compression, was evaluated after sterilization by ethylene oxide by a histological in vivo test with Wistar rats and cytotoxicity in cell adhesion in vitro. The cytotoxicity test was performed by the reduction of tetrazolium salt (MTT). Thermal and chemical changes in PLA films concerning the proposed sterilization process and characteristics were not observed to evidence polymer degradation due to sterilization. The analysis of the cytotoxicity by the MTT method has shown that the sterilized PLA films are not cytotoxic. The adhesion and proliferation of fibroblasts on PLA films were homogeneously distributed over the evaluation period, showing an elongated appearance with unnumbered cytoplasmic extensions and cell-cell interactions. By examining the biocompatibility in a histological study, a mild tissue inflammation was observed with the presence of fibrosis in the samples that had been exposed for 21 days in the rats’ bodies. PLA films sterilized with ethylene oxide did not exhibit cell adhesion in vitro and toxicity to the surrounding tissue in vivo and they may be used in future in vivo testing, according to histological findings in Wistar rats in the present study. Michele Savaris, Gustavo L. Braga, Venina dos Santos, Glaucio A. Carvalho, Asdrubal Falavigna, Denise C. Machado, Christian Viezzer, and Rosmary N. Brandalise Copyright © 2017 Michele Savaris et al. All rights reserved. Effects of Genipin Concentration on Cross-Linked Chitosan Scaffolds for Bone Tissue Engineering: Structural Characterization and Evidence of Biocompatibility Features Thu, 13 Apr 2017 08:58:07 +0000 Genipin (GN) is a natural molecule extracted from the fruit of Gardenia jasminoides Ellis according to modern microbiological processes. Genipin is considered as a favorable cross-linking agent due to its low cytotoxicity compared to widely used cross-linkers; it cross-links compounds with primary amine groups such as proteins, collagen, and chitosan. Chitosan is a biocompatible polymer that is currently studied in bone tissue engineering for its capacity to promote growth and mineral-rich matrix deposition by osteoblasts in culture. In this work, two genipin cross-linked chitosan scaffolds for bone repair and regeneration were prepared with different GN concentrations, and their chemical, physical, and biological properties were explored. Scanning electron microscopy and mechanical tests revealed that nonremarkable changes in morphology, porosity, and mechanical strength of scaffolds are induced by increasing the cross-linking degree. Also, the degradation rate was shown to decrease while increasing the cross-linking degree, with the high cross-linking density of the scaffold disabling the hydrolysis activity. Finally, basic biocompatibility was investigated in vitro, by evaluating proliferation of two human-derived cell lines, namely, the MG63 (human immortalized osteosarcoma) and the hMSCs (human mesenchymal stem cells), as suitable cell models for bone tissue engineering applications of biomaterials. Simona Dimida, Amilcare Barca, Nadia Cancelli, Vincenzo De Benedictis, Maria Grazia Raucci, and Christian Demitri Copyright © 2017 Simona Dimida et al. All rights reserved. Micromechanical Characterization of Complex Polypropylene Morphologies by HarmoniX AFM Thu, 06 Apr 2017 00:00:00 +0000 This paper examines the capability of the HarmoniX Atomic Force Microscopy (AFM) technique to draw accurate and reliable micromechanical characterization of complex polymer morphologies generally found in conventional thermoplastic polymers. To that purpose, injection molded polypropylene samples, containing representative morphologies, have been characterized by HarmoniX AFM. Mapping and distributions of mechanical properties of the samples surface are determined and analyzed. Effects of sample preparation and test conditions are also analyzed. Finally, the AFM determination of surface elastic moduli has been compared with that obtained by indentation tests, finding good agreement among the results. S. Liparoti, A. Sorrentino, and V. Speranza Copyright © 2017 S. Liparoti et al. All rights reserved. Characterization of Polymer Surfaces by the Use of Different Wetting Theories Regarding Acid-Base Properties Mon, 03 Apr 2017 08:20:00 +0000 The existing wetting methods for the determination of acid-base properties on solid surfaces are discussed. Striving for a better understanding of the adhesive polymer interactions in adhesively joined polymers, the methods of Berger and van Oss-Chaudhury-Good were found as the most suitable methods for the investigation of wetting on solid polymer surfaces. Methods of nonlinear systems by Della Volpe and Siboni were adapted and evaluated on plastic surfaces. In the context of these investigations various data of the surface free energy as well as its components have been identified for a number of polymer surfaces by application of spatial equation solutions. Eduard Kraus, Lukas Orf, Michael Heilig, Benjamin Baudrit, Irina Starostina, and Oleg Stoyanov Copyright © 2017 Eduard Kraus et al. All rights reserved. Recycled Polypropylene Improved with Thermoplastic Elastomers Thu, 30 Mar 2017 00:00:00 +0000 The use of recycled polypropylene (RPP) as raw material for various industries has been known. However, the mechanical and thermal properties of recycled products are lower than those of raw material. The objective of this study was to obtain and investigate the modified recycled polypropylene (RPP) with commercial elastomers for possible applications. The compounded RPP-based thermoplastic elastomers were investigated in order to determine their thermal properties (melt flow index (MFI), differential scanning calorimetry (DSC), VICAT softening temperature (VST), and heat deflection temperature (HDT)), structural characteristics (optical microscopy, atomic force microscopy (AFM), and X-ray diffraction (XRD)), and mechanical properties (tensile properties, density, and IZOD impact). The RPP compounded with 10% elastomer recorded higher tensile properties than the unmodified RPP. Also, IZOD impact strength increased from  kJ/m2 (registered for RPP) to  kJ/m2 for the PPR/SIS30 compound, while the degree of crystallinity decreased for all compounds. The obtained results recommend the RPP/elastomers compounds both for environmental remediation from postconsumer PP wastes and to realize new goods with high performance for various applications. Ecaterina Matei, Maria Râpă, Árpád Andor Andras, Andra Mihaela Predescu, Cristian Pantilimon, Alexandra Pica, and Cristian Predescu Copyright © 2017 Ecaterina Matei et al. All rights reserved. Rheological Properties in Aqueous Solution for Hydrophobically Modified Polyacrylamides Prepared in Inverse Emulsion Polymerization Wed, 29 Mar 2017 00:00:00 +0000 Inverse emulsion polymerization technique was employed to synthesize hydrophobically modified polyacrylamide polymers with hydrophobe contents near to feed composition. Three different structures were obtained: multisticker, telechelic, and combined. N-Dimethyl-acrylamide (DMAM), n-dodecylacrylamide (DAM), and n-hexadecylacrylamide (HDAM) were used as hydrophobic comonomers. The effect of the hydrophobe length of comonomer, the initial monomer, and surfactant concentrations on shear viscosity was studied. Results show that the molecular weight of copolymer increases with initial monomer concentration and by increasing emulsifier concentration it remained almost constant. Shear viscosity measurements results show that the length of the hydrophobic comonomer augments the hydrophobic interactions causing an increase in viscosity and that the polymer thickening ability is higher for combined polymers. Shirley Carro, Valeria J. Gonzalez-Coronel, Jorge Castillo-Tejas, Hortensia Maldonado-Textle, and Nancy Tepale Copyright © 2017 Shirley Carro et al. All rights reserved. Superabsorbent Polymer Based on Sodium Carboxymethyl Cellulose Grafted Polyacrylic Acid by Inverse Suspension Polymerization Mon, 27 Mar 2017 07:24:22 +0000 A superabsorbent polymer (SAP) based on graft copolymerization of sodium carboxymethyl cellulose and acrylic acid was prepared by inverse suspension polymerization using potassium persulfate as an initiator and N,N′-methylenebisacrylamide as a cross-linker. Experiments were performed at 70°C for 90 min but varying the concentrations of sodium carboxymethyl cellulose (NaCMC), acrylic acid (AA), potassium persulfate (KPS), and N,N′-methylenebisacrylamide (MBA), and also varying % neutralization of AA. The maximum swelling capacity for SAP was 544.95 g/g in distilled water and 44.0 g/g in 0.9% w/v NaCl solution. This near optimal SAP was prepared using 2.0 g/100 mL NaCMC, 1.0 mol/L AA with 70% neutralization, 0.014 mol/L KPS, and 0.01 mol/L MBA. Pairote Klinpituksa and Patchareeya Kosaiyakanon Copyright © 2017 Pairote Klinpituksa and Patchareeya Kosaiyakanon. All rights reserved. Bond-Slip Behavior of Basalt Fiber Reinforced Polymer Bar in Concrete Subjected to Simulated Marine Environment: Effects of BFRP Bar Size, Corrosion Age, and Concrete Strength Sun, 26 Mar 2017 07:45:34 +0000 Basalt Fiber Reinforced Polymer (BFRP) bars have bright potential application in concrete structures subjected to marine environment due to their superior corrosion resistance. Available literatures mainly focused on the mechanical properties of BFRP concrete structures, while the bond-slip behavior of BFRP bars, which is a key factor influencing the safety and service life of ocean concrete structures, has not been clarified yet. In this paper, effects of BFRP bars size, corrosion age, and concrete strength on the bond-slip behavior of BFRP bars in concrete cured in artificial seawater were investigated, and then an improved Bertero, Popov, and Eligehausen (BPE) model was employed to describe the bond-slip behavior of BFRP bars in concrete. The results indicated that the maximum bond stress and corresponding slip decreased gradually with the increase of corrosion age and size of BFRP bars, and ultimate slip also decreased sharply. The ascending segment of bond-slip curve tends to be more rigid and the descending segment tends to be softer after corrosion. A horizontal end in bond-slip curve indicates that the friction between BFRP bars and concrete decreased sharply. Yongmin Yang, Zhaoheng Li, Tongsheng Zhang, Jiangxiong Wei, and Qijun Yu Copyright © 2017 Yongmin Yang et al. All rights reserved. Effect of Quinacridone Pigments on Properties and Morphology of Injection Molded Isotactic Polypropylene Thu, 16 Mar 2017 00:00:00 +0000 Two quinacridone pigments were added (0.01; 0.05; 0.1; 0.5; 1; 2 wt%) to isotactic polypropylene (iPP), and their influence on mechanical and thermomechanical properties were investigated. Complex mechanical and thermomechanical iPP properties analyses, including static tensile test, Dynstat impact resistance measurement, and hardness test, as well as dynamic mechanic thermal analysis (DMTA), were realized in reference to morphological changes of polymeric materials. In order to understand the differences in modification efficiency and changes in polymorphism of polypropylene matrix caused by incorporation of pigments, differential scanning calorimetry (DSC) and wide-angle X-ray scattering (WAXS) experiments were done. Both pigments acted as highly effective nucleating agents that influence morphology and mechanical properties of isotactic polypropylene injection molded samples. Differences between polypropylene samples nucleated by two pigments may be attributed to different heterogeneous nucleation behavior dependent on pigment type. As it was proved by WAXS investigations, the addition of γ-quinacridone (E5B) led to crystallization of polypropylene in hexagonal phase (β-iPP), while for β-quinacridone (ER 02) modified polypropylene no evidence of iPP β-phase was observed. Mateusz Barczewski, Danuta Matykiewicz, and Bartłomiej Hoffmann Copyright © 2017 Mateusz Barczewski et al. All rights reserved. Establishment of Passive Energy Conservation Measure and Economic Evaluation of Fenestration System in Nonresidential Building of Korea Thu, 16 Mar 2017 00:00:00 +0000 ECO2 (building energy efficiency rating program) and passive energy conservation measures (ECMs) were established as a basic study for targeted methodologies and decision support systems development in Korea to meet national regulations. The primary energy consumption and economic evaluation of nonresidential buildings was performed. Passive ECMs were classified as planning and performance elements. The planning elements are the window-to-wall ratio (WWR) and horizontal shading angle. The performance elements are the thermal transmittance (U-value) of the walls, roof, and floor and the U-value and solar heat gain coefficient (SHGC) of windows. This study focused on the window-to-wall ratio and the U-value and solar heat gain coefficient of windows. An economic efficiency database for the constructed alternatives was built; the target building was set and the Passive ECM List for the target building was derived. The energy consumption evaluation and economic evaluation were performed for each of the constructed alternatives, and a methodology for guiding energy efficiency decisions was proposed based on the performance evaluation results, and the optimal Passive ECM List for the target building was derived. Bo-Eun Choi, Ji-Hyun Shin, Jin-Hyun Lee, Sun-Sook Kim, and Young-Hum Cho Copyright © 2017 Bo-Eun Choi et al. All rights reserved. Effect of Oxygen and Initiator Solubility on Admicellar Polymerization of Styrene on Silica Surfaces Wed, 15 Mar 2017 07:34:27 +0000 Although admicellar polymerization has been termed the surface analog of emulsion polymerization, previous reports utilizing free radical-initiated admicellar polymerization relied on high levels of the free radical initiator when compared to emulsion polymerization, likely due to the presence of oxygen in the reported admicellar polymerization systems. Admicellar polymerizations of styrene on the surface of precipitated silica initiated by either a water-soluble or a water-insoluble initiator were studied to determine the effect of dissolved oxygen and free radical initiator solubility on the kinetics, yield, and molecular weight of the polymer formed. Results show that the presence of oxygen reduces the polymer yield and limits molecular weight. The solubility of the initiator also affected the polymer formed in the admicellar polymerization of styrene. While monomer conversions and polymer yield were similar, the molecular weights of polymerizations initiated by a water-soluble initiator were higher than comparable polymerizations initiated by a water-insoluble initiator. Pohlee Cheah, Caitlin N. Bhikha, John H. O’Haver, and Adam E. Smith Copyright © 2017 Pohlee Cheah et al. All rights reserved. A Novel Terpolymer as Fluid Loss Additive for Oil Well Cement Sun, 12 Mar 2017 09:48:03 +0000 A terpolymer comprised of sodium styrene sulfonate (SSS), fumaric acid (FA), and acrylamide (AM) was synthesized by aqueous free radical copolymerization and evaluated as fluid loss additive for oil well cement. The chemical structure and performance of the terpolymer were characterized by Fourier transform infrared (FTIR) spectroscopy and thermal gravimetric analysis (TGA); the molecular weight and its distribution were determined by gel permeation chromatography (GPC). The optimum reaction conditions of polymerization were obtained: a reaction temperature of 50°C, a mass ratio of SSS/FA/AM 4 : 2 : 14, initiator 0.1%, and reaction time of 4 h; characterization indicated that the SSS/FA/AM had a certain molecular weight and excellent temperature-resistant and salt-resistant properties. The results show that SSS/FA/AM has a good fluid loss performance, in which the API fluid loss of the oil cement slurry could be controlled within 100 mL at 160°C. In addition, it had little effect on the cement compressive strength. The results of scanning electron microscopy (SEM) of the filter cake showed that SSS/FA/AM could be adsorbed on the surface of the cement particles and produce a hydrated layer to prevent fluid loss from the oil well cement. Ming Li, Dongbo Xie, Zihan Guo, Ya Lu, and Xiaoyang Guo Copyright © 2017 Ming Li et al. All rights reserved. The Compatibilization Effects of Alkylated-grafted-Graphene Oxide on Polypropylene/Polystyrene Blends Wed, 08 Mar 2017 07:51:37 +0000 Modified graphene oxide (GO) was synthesized by covalently grafted alkylated chains on GO sheets and their compatibilization effects on the morphologies and mechanical properties of immiscible polypropylene/polystyrene (PP/PS) blends were investigated. Alkylated-grafted-GO/PP/PS batches were fabricated by melt-mixing approach and displayed different morphologies with various modified GO loadings. When the content of alkylated-grafted-GO is 0.2 wt%, the tensile strength of obtained composite could reach 17.97 MPa, showing a 36.3% enhancement compared to that of pristine PP/PS, indicating the positive compatibilization of modified GO in polymer blends. Moreover, the mixing order also plays an important role in achieving the desired improvement in properties. Due to the preferential location of modified GO in PP phase, a favorable “transition zone” could be formed at the interfacial region of two polymers when alkylated-grafted-GO was premixed with PS and subsequently mixed with PP, leading to an improvement of compatibilization between two polymers and an enhancement of mechanical properties. However, serious phase separation and declined tensile strength were obtained with a reversed mixing sequence. Yanping Hao, Xin Zhao, Jie Dong, and Qinghua Zhang Copyright © 2017 Yanping Hao et al. All rights reserved. Preparation of a Microporous Polyurethane Film with Negative Surface Charge for siRNA Delivery via Stent Mon, 06 Mar 2017 08:52:02 +0000 Polyurethane (PU) and polyethylene glycol (PEG) were used to prepare a porous stent-covering material for the controlled delivery of small interfering RNA (siRNA). Microporous polymer films were prepared using a blend of polyurethane and water-soluble polyethylene glycol by the solution casting method; the PEG component was extracted in water to make the film microporous. This film was dipped in 2% poly(methyl methacrylate-co-methacrylic acid) solution to coat the polymer film with the anionic polyelectrolyte. The chemical components of the film surface were characterized by Fourier Transform Infrared (FTIR) spectroscopy and its structural morphology was examined by scanning electron microscopy (SEM). The effect of the negatively charged surface after attachment of a fluorescein isothiocyanate- (FITC-) labeled siRNA-polyethyleneimine complex onto the microporous polyurethane film and the controlled release of the complex from the film was investigated by fluorescence microscopy. Fluorescence microscopy showed the PU surface with intense fluorescence by the aggregates of the FITC-labeled-siRNA-PEI complex (measuring up to few microns in size); additionally, the negatively charged PU surface revealed broad and diffuse fluorescence. These results suggest that the construction of negatively charged microporous polyurethane films is feasible and could be applied for enhancing the efficiency of siRNA delivery via a stent-covering polyurethane film. Il-Hoon Cho and Sangsoo Park Copyright © 2017 Il-Hoon Cho and Sangsoo Park. All rights reserved. Functional Polymers for Biointerface Engineering Tue, 28 Feb 2017 13:36:16 +0000 Qiang Wei, Jie He, Weifeng Zhao, and Yin Chen Copyright © 2017 Qiang Wei et al. All rights reserved.