International Journal of Polymer Science The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Improved Thrombin Hemostat Using the Cross-Linked Gelatin by Microbial Transglutaminase Thu, 21 May 2015 07:28:16 +0000 It is well known that the thrombin obtained from animal is available in clinical treatment, which plays an important role in hemostasis and the treatment of hemorrhagic diseases. However, how to achieve complete hemostasis in 2 min is still a challenge. In this report, the thrombin hemostatic has been improved using the cross-linked gelatin by microbial transglutaminase, and its efficacy was demonstrated by the vitro experiment. Compared with the traditional thrombin hemostatic the clotting time with the improved hemostat is significantly shorter. It may rapidly stop blood loss, which would provide a simple, safe, and cost-effective surgical sealant. Tengfei Yu, Yuepeng Guan, Xia Xie, Yaqin Huang, and Jie Tang Copyright © 2015 Tengfei Yu et al. All rights reserved. Development of a Layer-by-Layer Assembled Film on Hydrogel for Ocular Drug Delivery Wed, 20 May 2015 06:47:43 +0000 Hydrogel is a kind of attractive drug carriers because of its good biocompatibility and transparency. But traditional hydrogel showed some restrictions in its application in ocular drug delivery. A simple surface modification technique based on layer-by-layer (LbL) self-assembled multilayer for ocular drug delivery was developed in this work. Polycarboxymethyl-β-cyclodextrin (poly(CM-β-CD))/poly-l-lysine (PLL) multilayer film was designed and constructed for ocular drug delivery, since β-CD showed good drug delivery property. The properties such as the contact angle and transparency varied a little with the deposition of poly(CM-β-CD)/PLL multilayer. Orfloxacin and puerarin were loaded into multilayer during the self-assembly procedure by two methods, which were tracked by the largest drug absorbance of UV spectrum. The loaded drug amount by incorporating drugs into poly(CM-β-CD) solution was larger than that by incorporating drugs into PLL solution. The loaded drug in the multilayer could gradually be released from multilayer in some period either for orfloxacin or for puerarin. The drug release behavior was influenced by drug loading method and pH value of released medium. Moreover, the balanced released drug amount by incorporating drugs into poly(CM-β-CD) solution is much smaller than that by incorporating drugs into PLL solution. Pin Chen, Xin Wang, Yan Dong, and Xiaohong Hu Copyright © 2015 Pin Chen et al. All rights reserved. End-Group Evaluation of HEMA Initiated Poly(-caprolactone) Macromonomers via Enzymatic Ring-Opening Polymerization Tue, 19 May 2015 13:47:45 +0000 Poly(ε-caprolactone) (PCL) macromonomers comprising acrylate end-functionality were synthesized via enzymatic ring-opening polymerization (eROP) by utilizing commercially available Candida antarctica Lipase B (CALB), Novozyme-435. 2-Hydroxyethyl methacrylate (HEMA) was purposed to be the nucleophilic initiator in eROP. The side reactions generated due to the cleavage of ester bonds in HEMA and the growing polymer chains were investigated through altering polymerization period, initiator concentration, temperature, and enzyme concentration. 1H NMR evaluations showed that minimum quantities of side reactions were in lower temperatures, initiator concentration, enzyme concentration, and lower monomer conversions. Gel permeation chromatography (GPC) results revealed that lower polydispersity along with number-average molecular weight of end-functionalized PCL macromonomers was obtained depending on higher initiator/monomer ratios, lower temperature (60°C), enzyme concentration (100 mg), and/or polymerization time (2 h). Furthermore, 0.1 HEMA/ε-caprolactone (CL) ratio had higher molecular weight than 0.5 HEMA/CL ratio, while keeping a close value of methacrylate transfer, total methacrylate end-groups, and lower polyester transfer. N. Ugur Kaya and Y. Avcibasi Guvenilir Copyright © 2015 N. Ugur Kaya and Y. Avcibasi Guvenilir. All rights reserved. Characterization and Cell Culture of a Grafted Chitosan Scaffold for Tissue Engineering Tue, 19 May 2015 11:36:50 +0000 Poly(vinyl alcohol) (PVA) was grafted to chitosan to form a porous scaffold. The PVA-g-chitosan 3D scaffold was then observed by Fourier transform infrared spectroscopy (FT-IR). The water absorbency of PVA-g-chitosan was increased 370% by grafting. Scanning electron microscope (SEM) observations of the material revealed that the 3D scaffold is highly porous when formed using a homogenizer at 300 rpm. Compression testing demonstrated that as the amount of chitosan increases, the strength of the 3D scaffold strength reached showed that, by increasing the amount of chitosan, the strength of the 3D scaffold could be increased to 16 × 10−1 MPa. Over 35 days of enzymatic degradation, the 3D scaffold was degraded by various enzymes at rates of up to 10%. In vitro tests showed good cell proliferation and growth in the 3D scaffold. Wen-Chuan Hsieh, Jiun-Jia Liau, and Yi-Jhong Li Copyright © 2015 Wen-Chuan Hsieh et al. All rights reserved. Microstructure, Mechanical, and Biological Properties of Porous Poly(vinylidene fluoride) Scaffolds Fabricated by Selective Laser Sintering Mon, 18 May 2015 15:01:30 +0000 Porous poly(vinylidene fluoride) (PVDF) scaffolds were prepared by selective laser sintering. The effects of laser energy density, ranging from 0.66 to 2.16 J/mm2, on microstructure and mechanical properties were investigated. At low energy density levels, PVDF particles could fuse well and the structure becomes dense with the increase of the energy density. Smoke and defects (such as holes) were observed when the energy density increased above 1.56 J/mm2 which indicated decomposition of the PVDF powder. The scaffolds appeared to be light yellow and there was a reduction in tensile strength. The fabricated scaffolds were immersed into simulated body fluid for different time to evaluate biostability. In addition, MG63 cells were seeded and cultured for different days on the scaffolds. The testing results showed that the cells grew and spread well, indicating that PVDF scaffolds had good biocompatibility. Wei Huang, Pei Feng, Chengde Gao, Xiong Shuai, Tao Xiao, Cijun Shuai, and Shuping Peng Copyright © 2015 Wei Huang et al. All rights reserved. Effect of Particle Size of Additives on the Flammability and Mechanical Properties of Intumescent Flame Retarded Polypropylene Compounds Mon, 18 May 2015 13:12:58 +0000 The effect of particle size reduction of the components of a common intumescent flame retardant system, consisting of pentaerythritol (PER) and ammonium polyphosphate (APP) in a weight ratio of 1 to 2, was investigated on the flammability and mechanical performance of flame retarded polypropylene (PP) compounds. Additives of reduced particle size were obtained by ball milling. In the case of PER, the significant reduction of particle size resulted in inferior flame retardant and mechanical performance, while the systems containing milled APP noticeably outperformed the reference intumescent system containing as-received additives. The beneficial effect of the particle size reduction of APP is explained by the better distribution of the particles in the polymer matrix and by the modified degradation mechanism which results in the formation of an effectively protecting carbonaceous foam accompanied with improved mechanical resistance. Nevertheless, 10% higher tensile strength was measured for the flame retarded PP compound when as-received APP was substituted by milled APP. Katalin Bocz, Tamás Krain, and György Marosi Copyright © 2015 Katalin Bocz et al. All rights reserved. Chemical Modifications of Starch: Microwave Effect Sun, 17 May 2015 07:56:44 +0000 This paper presents basic methods of starch chemical modification, the effect of microwave radiation on the modification process, and the physicochemical properties of starch. It has been shown that the modifications contribute to improvement of the material performance and likewise to significant improvement of its mechanical properties. As a result, more and more extensive use of starch is possible in various industries. In addition, methods of oxidized starch and starch esters preparation are discussed. Properties of microwave radiation and its impact on starch (with particular regard to modifications described in literature) are characterized. Kamila Lewicka, Przemysław Siemion, and Piotr Kurcok Copyright © 2015 Kamila Lewicka et al. All rights reserved. Potential Environmental Benefits of Ultralight Particleboards with Biobased Foam Cores Thu, 14 May 2015 13:39:10 +0000 A new generation of ultralight particleboards (ULPB) with an expanded foam core layer produced in an in-line foaming step is under development. The environmental impacts of three types of ULPB containing foam based on 100% polylactic acid (PLA), 100% expanded polystyrene, and 50% PLA/50% polymethyl methacrylate, as well as a conventional particleboard (PB), have been compared in an LCA. Two approaches were chosen for the assessment: first, the “EPD-approach” in accordance with EN 15804 for EPD of building materials and second, a holistic-approach which allows an expansion of the system boundaries in order to forecast the consequences of a broader replacement of PB with ULPB. The results show that most of the environmental impacts are related to raw materials and end-of-life stages. Both approaches show that the exchange of PB with ULPB with a foam core based on PLA leads to a reduction of greenhouse gas emissions. On the other hand, the PLA is responsible for higher ecotoxicity results in comparison to non-bio-based polymers mainly due to agricultural processes. Both approaches allowed the drafting of complementary advisories for environmental impact reduction addressed to the developers. Christelle Ganne-Chédeville and Stefan Diederichs Copyright © 2015 Christelle Ganne-Chédeville and Stefan Diederichs. All rights reserved. The Mechanical Aspects of Formation and Application of PDMS Bilayers Rolled into a Cylindrical Structure Wed, 13 May 2015 09:44:10 +0000 A polydimethylsiloxane (PDMS) film with its surface being oxidized by a plasma treatment or a UV-ozone (UVO) treatment, that is, a bilayer made of PDMS and its oxidized surface layer, is known to roll into a cylindrical structure upon exposure to the chloroform vapor due to the mismatch in the swelling ratio between PDMS and the oxidized layer by the chloroform vapor. Here we analyzed the formation of the rolled bilayer with the mechanical aspects: how the mismatch in the swelling ratio of the bilayer induces rolling of the bilayer, why any form of trigger that breaks the symmetry in the in-plane stress level is needed to roll the bilayer uniaxially, why the rolled bilayer does not unroll in the dry state when there is no more mismatch in the swelling ratio, and how the measured curvature of rolled bilayer matches well with the prediction by the theory. Moreover, for the use of the rolled bilayer as the channel of the microfluidic device, we examined whether the rolled bilayer deforms or unrolls by the flow of the aqueous solution that exerts the circumferential stress on the rolled bilayer. Dongwon Kang, Hyeonji Yu, and Jungwook Kim Copyright © 2015 Dongwon Kang et al. All rights reserved. Physical, Physicochemical, Mechanical, and Structural Characterization of Films Based on Gelatin/Glycerol and Carbon Nanotubes Wed, 13 May 2015 07:16:33 +0000 A new method to prepare glycerol/gelatin based films, by doping the film with carbon nanotubes (CNTs) and sodium dodecyl sulfate (SDS), was proposed. SDS was used to disperse CNTs in gelatin/glycerol films as follows: gelatin/glycerol (GG) incubated with equal concentrations of CNT and SDS; GG with 0.001% w/w CNT/SDS; GG with 0.002% CNT/SDS and GG with 0.004% CNT/SDS. Diffractograms of CNT/SDS /glycerol films showed an amorphous structure, being consistent with thermograms involving temperature and fusion enthalpy. Mechanical tests showed 30% increase in elongation at break of GG with 0.004% CNT/SDS, with respect to gelatin/glycerol/SDS control. Samples with CNT had increased water vapor permeability (WVP). The film fractal dimension indicated that, with the addition of the highest concentration of CNT, films with a homogeneous surface were obtained, with probable nanotube inclusion in the protein matrix. According to the results, the easy method used to prepare gelatin composite materials gave place to films with better physical, mechanical, and thermal properties. Israel Sifuentes-Nieves, Rodolfo Rendón-Villalobos, Antonio Jiménez-Aparicio, Brenda Hildeliza Camacho-Díaz, Gustavo Fidel Gutiérrez López, and Javier Solorza-Feria Copyright © 2015 Israel Sifuentes-Nieves et al. All rights reserved. Physicochemical Properties of Calcium Phosphate Based Coating on Gutta-Percha Root Canal Filling Wed, 06 May 2015 09:12:32 +0000 Dental Gutta-percha (GP) is a polymer based standard root canal filling material that has been widely used in dentistry. However, it has an inadequate sealing ability and adhesion to root dentin. The aim of this study is to coat GP with a bioactive material to enhance its sealing ability and adhesion to the root sealer and subsequently to the root dentin. The choice of coating method is limited by the nature of GP as it requires a technique that is not governed by high temperatures or uses organic solvents. In this study, biomimetic coating technique using 1.5 Tas-simulated body fluids (SBF) was employed to coat the treated GP cones. The coated samples were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray Diffraction (XRD), and field emission scanning electron microscope (FESEM). The presence of hydroxyl, carbonate, and phosphate groups was detected by FTIR while the formation of hydroxyapatite (HA)/calcium phosphate was confirmed with XRD. FESEM revealed uniform, thin, and crystalline HA calcium phosphate coating. The adhesion of the coating to the GP substrate was assessed with microscratch technique. It was viable with cohesive failure mode. In conclusion, Tas-SBF is able to coat pretreated GP cones with a crystalline apatitic calcium phosphate layer. Afaf Al-Haddad, Muralithran G. Kutty, Noor Hayaty Abu Kasim, and Zeti Adura Che Ab Aziz Copyright © 2015 Afaf Al-Haddad et al. All rights reserved. Effect of Alginate Lyase on Biofilm-Grown Helicobacter pylori Probed by Atomic Force Microscopy Wed, 06 May 2015 06:59:57 +0000 Helicobacter pylori (H. pylori) is a microorganism with a pronounced capability of adaptation under environmental stress solicitations. Its persistence and antimicrobial resistance to the drugs commonly used in the anti-H. pylori therapy are associated with the development of a biofilm mainly composed of DNA, proteins, and polysaccharides. A fundamental step to increase the success of clinical treatments is the development of new strategies and molecules able to interfere with the biofilm architecture and thus able to enhance the effects of antibiotics. By using Atomic Force Microscopy and Scanning Electron Microscopy we analyzed the effects of the alginate lyase (AlgL), an enzyme able to degrade a wide class of polysaccharides, on the H. pylori shape, surface morphology, and biofilm adhesion properties. We demonstrated that AlgL generates a noticeable loss of H. pylori coccoid form in favor of the bacillary form and reduces the H. pylori extracellular polymeric substances (EPS). Alessandro Maiorana, Francesca Bugli, Massimiliano Papi, Riccardo Torelli, Gabriele Ciasca, Giuseppe Maulucci, Valentina Palmieri, Margherita Cacaci, Francesco Paroni Sterbini, Brunella Posteraro, Maurizio Sanguinetti, and Marco De Spirito Copyright © 2015 Alessandro Maiorana et al. All rights reserved. Highlight on the Mathematical Modeling of Controlled Free Radical Polymerization Tue, 05 May 2015 05:44:24 +0000 Over the last quarter century, controlled free radical polymerization (CFRP) has received great attention by the researchers of polymer science and engineering. In addition to the experimental studies, many publications in the literature dealt with the modeling of CFRP processes. A review of acknowledged and well-received researches on mathematical modeling in the area of CFRP is presented in this work. Three main categories of CFRP (namely, ATRP, RAFT, and NMP) are taken into consideration in the review. The different techniques used in modeling CFRP processes are also enumerated with more emphasis on Monte Carlo simulation and the method of moments. The review provides a better understanding of the processes and the recent efforts to model CFRP. Mamdouh A. Al-Harthi Copyright © 2015 Mamdouh A. Al-Harthi. All rights reserved. Improving Mechanical Properties of Thermoset Biocomposites by Fiber Coating or Organic Oil Addition Sun, 03 May 2015 14:34:57 +0000 Two different thermoset biocomposite systems are experimented in this study with the hope to improve their mechanical properties. Fiberglass and hemp, in form of fabrics, are used to reinforce the thermoset polymer matrix, which includes a traditional epoxy resin and a linseed oil-based bioresin (UVL). The fiber/polymer matrix interface is modified using two different approaches: adding a plant-based oil (pine or linseed) to the polymer matrix or coating the fibers with 3-(aminopropyl)triethoxysilane (APTES) prior to integrating them into the polymer matrix. Epoxy resin is cured using an amine-based initiator, whereas UVL resin is cured under ultraviolet light. Results show that hemp fibers with APTES prime coat used in either epoxy or UVL matrix exhibit some potential improvements in the composite’s mechanical properties including tensile strength, modulus of elasticity, and ductility. It is also found that adding oil to the epoxy matrix reinforced with fiberglass mostly improves the material’s modulus of elasticity while maintaining its tensile strength and ductility. However, adding oil to the epoxy matrix reinforced with hemp doubles the material’s ductility while slightly reducing its tensile strength and modulus of elasticity. Truc T. Ngo, James G. Kohl, Tawni Paradise, Autumn Khalily, and Duane L. Simonson Copyright © 2015 Truc T. Ngo et al. All rights reserved. Isolation, Structural Characterization, and Valorization of Pectic Substances from Algerian Argan Tree Leaves (Argania spinosa (L.) Skeels) Tue, 28 Apr 2015 07:04:00 +0000 Pectic polysaccharides were solubilized from Algerian argan tree leaves by sequential extraction with water at 100°C (water-soluble pectin; AL-WSP) and EDTA solution at 80°C (chelating-soluble pectin; AL-CSP). Both AL-WSP and AL-CSP were rich in arabinose (28% and 74.5%, resp.) and had a high content of uronic acid (38.5% and 21.5%, resp.). Pectic substances were deesterified and fractionated by anion exchange chromatography, giving five fractions for each extract. Most of the fractions were characterized by methylation analysis and then analyzed by 13C nuclear magnetic resonance spectroscopy. The results showed that AL-WSP consisted of rhamnogalacturonan type I, with arabinan and galactan branching at the O-4 position of the main rhamnose chain, while AL-CSP consisted of rhamnogalacturonan type I and a block of homogalacturonan. Antioxidant activities of AL-WSP and AL-CSP were evaluated by electronic spin resonance. The results showed that the antioxidant potential of AL-WSP (8.1%) and AL-CSP (−1.2%) was significantly lower than that of vitamin E. Kadda Hachem, Abderrahmane Labani, and Meriem Kaid-Harche Copyright © 2015 Kadda Hachem et al. All rights reserved. Third-Order Nonlinear Optical Behavior of Novel Polythiophene Derivatives Functionalized with Disperse Red 19 Chromophore Thu, 23 Apr 2015 07:36:12 +0000 Two copolymers of 3-alkylthiophene (alkyl = hexyl, octyl) and a thiophene functionalized with disperse red 19 (TDR19) as chromophore side chain were synthesized by oxidative polymerization. The synthetic procedure was easy to perform, cost-effective, and highly versatile. The molecular structure, molecular weight distribution, film morphology, and optical and thermal properties of these polythiophene derivatives were determined by NMR, FT-IR, UV-Vis GPC, DSC-TGA, and AFM. The third-order nonlinear optical response of these materials was performed with nanosecond and femtosecond laser pulses by using the third-harmonic generation (THG) and Z-scan techniques at infrared wavelengths of 1300 and 800 nm, respectively. From these experiments it was observed that although the TRD19 incorporation into the side chain of the copolymers was lower than 5%, it was sufficient to increase their nonlinear response in solid state. For instance, the third-order nonlinear electric susceptibility () of solid thin films made of these copolymers exhibited an increment of nearly 60% when TDR19 incorporation increased from 3% to 5%. In solution, the copolymers exhibited similar two-photon absorption cross sections with a maximum value of 8545 GM and 233 GM (1 GM = 10−50 cm4 s) per repeated monomeric unit. Marilú Chávez-Castillo, Arelis Ledesma-Juárez, Marisol Güizado-Rodríguez, Jesús Castrellón-Uribe, Gabriel Ramos-Ortiz, Mario Rodríguez, José-Luis Maldonado, Jorge-Antonio Guerrero-Álvarez, and Victor Barba Copyright © 2015 Marilú Chávez-Castillo et al. All rights reserved. Aminoalkylated Merrifield Resins Reticulated by Tris-(2-chloroethyl) Phosphate for Cadmium, Copper, and Iron (II) Extraction Sun, 19 Apr 2015 17:03:25 +0000 We aimed to synthesize novel substituted polymers bearing functional groups to chelate heavy metals during depollution applications. Three polyamine functionalized Merrifield resins were prepared via ethylenediamine (EDA), diethylenetriamine (DETA), and triethylenetetramine (TETA) modifications named, respectively, MR-EDA, MR-DETA, and MR-TETA. The aminoalkylated polymers were subsequently reticulated by tris-(2-chloroethyl) phosphate (TCEP) to obtain new polymeric resins called, respectively, MR-EDA-TCEP, MR-DETA-TCEP, and MR-TETA-TCEP. The obtained resins were characterized via attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), elemental analysis (EA), and thermogravimetric (TGA), thermodynamic (DTA), and differential thermogravimetric (DTG) analysis. The synthesized resins were then assayed to evaluate their efficiency to extract metallic ions such as Cd2+, Cu2+, and Fe2+ from aqueous solutions. Mokhtar Dardouri, Fayçel Ammari, and Faouzi Meganem Copyright © 2015 Mokhtar Dardouri et al. All rights reserved. Reducing Water Vapor Permeability of Poly(lactic acid) Film and Bottle through Layer-by-Layer Deposition of Green-Processed Cellulose Nanocrystals and Chitosan Wed, 08 Apr 2015 13:20:06 +0000 Layer-by-layer electrostatic self-assembly technique was applied to improve the barrier properties of poly(lactic acid) (PLA) films and bottles. The LbL process was carried out by the alternate adsorption of chitosan (CH) (polycation) and cellulose nanocrystals (CNC) produced via ultrasonic treatment. Four bilayers (on each side) of chitosan and cellulose nanocrystals caused 29 and 26% improvement in barrier properties in case of films and bottles, respectively. According to the results the LbL process with CH and CNC offered a transparent “green” barrier coating on PLA substrates. Katalin Halász, Yanin Hosakun, and Levente Csóka Copyright © 2015 Katalin Halász et al. All rights reserved. Characterization of Olfactory Ensheathing Glial Cells Cultured on Polyurethane/Polylactide Electrospun Nonwovens Tue, 31 Mar 2015 14:24:54 +0000 The aim of this research was to evaluate novel biomaterials for neural regeneration. The investigated materials were composed of polyurethane (PU) and polylactide (PLDL) blended at three different w/w ratios, that is, 5/5, 6/4, and 8/2 of PU/PLDL. Ultrathin fibrous scaffolds were prepared using electrospinning. The scaffolds were investigated for their applicability for nerve regeneration by culturing rat olfactory ensheathing glial cells. Cells were cultured on the materials for seven days, during which cellular morphology, phenotype, and metabolic activity were analysed. SEM analysis of the fabricated fibrous scaffolds showed fibers of a diameter mainly lower than 600 μm with unimportant volume of protrusions situated along the fibers, with nonsignificant differences between all analysed materials. Cells cultured on the materials showed differences in their morphology and metabolic activity, depending on the blend composition. The most proper morphology, with numerous p75+ and GFAP+ cells present, was observed in the sample 6/4, whereas the highest metabolic activity was measured in the sample 5/5. However, none of the investigated samples showed cytotoxicity or negatively influenced cellular morphology. Therefore, the novel electrospun fibrous materials may be considered for regenerative medicine applications, and especially when contacting with highly sensitive nervous cells. Jakub Grzesiak, Ryszard Fryczkowski, Anna Lis, Dariusz Szarek, Jadwiga Laska, and Krzysztof Marycz Copyright © 2015 Jakub Grzesiak et al. All rights reserved. The Synthesis of the Locating Substitution Derivatives of Chitosan by Click Reaction at the 6-Position of Chitin Mon, 30 Mar 2015 08:17:20 +0000 A novel method to prepare the macrocyclic compound locating substitution derivatives of chitosan was investigated, by using cyclodextrin as the model of macrocyclic compound. The method combines the advantages of activated 6-OH of chitin and high efficiency of click reaction. Chitin C6-OH p-toluenesulfonate (CTN-6-OTs) was generated and subsequently transferred to chitin C6-N3 via nucleophilic substitution. Afterwards, β-cyclodextrin was immobilized at 6-OH of chitin via click reaction to afford CTN-6-CD. Ultimately, CTS-6-CD was obtained by removing the acetyl group of chitin unit. The structures and properties of these products were characterized by FTIR, TG, and XRD, respectively. It was found that CTN-6-CD synthesized at the optimum conditions has an immobilized loading of  mol/g and that of the corresponding CTS-6-CD, generated by removal of the acetyl group, was  mol/g. Yu Chen, Yanchun Ye, Yanyan Jing, YuanYuan Gao, Yanwen Guo, and Huimin Tan Copyright © 2015 Yu Chen et al. All rights reserved. Preparation and Properties of Cross-Linked Starch Nanocrystals/Polylactic Acid Nanocomposites Sun, 29 Mar 2015 12:34:03 +0000 Cross-linked starch nanocrystals (CStN)/polylactic acid (PLA) nanocomposites were prepared by blending CStN and PLA, wherein CStN were homogeneously dispersed in the nanocomposites. The structure and morphology of the nanocomposites were studied through FTIR, XRD, and SEM. The results of mechanical test showed that the strength and toughness of the nanocomposites could be improved when the additive amount of hydrophobic CStN was 3% (weight ratio). Meanwhile, the microstructures of tensile fracture surface showed that CStN were uniformly dispersed in PLA matrix, and the tensile fracture surface was presented as ductile fracture. Moreover, water vapor permeability experiments illustrated that the addition of CStN reduced the water vapor permeability of PLA nanocomposites, so CStN have some resistance to water vapor. Those above indicated that CStN have functions of reinforcement and toughness in PLA matrix; therefore, they are expected to be used as functional additives in polymer matrix such as PLA, polycaprolactone (PCL), and polybutylene succinate (PBS). Zuodong Yin, Jiliang Zeng, Cai Wang, and Zelin Pan Copyright © 2015 Zuodong Yin et al. All rights reserved. Synthesis of Chitosan Oligomers/Propolis/Silver Nanoparticles Composite Systems and Study of Their Activity against Diplodia seriata Sun, 29 Mar 2015 11:39:16 +0000 The synthesis and characterization of composites of oligomeric chitosan with propolis extract which allow the incorporation of a third component (silver nanoparticles) are reported, together with their application in aqueous or hydroalcoholic solutions with a view to the formation of adhesive substances or nanofilms for the protection of vineyards against harmful xylophagous fungi. The antimicrobial properties of the association of the two biological products or those resulting from the incorporation of silver nanoparticles (NPs) are studied and discussed. The efficacy of the chitosan oligomers/propolis/silver NPs ternary system is assessed in vitro for Diplodia fungi. A preliminary study on the convenience of replacing propolis with gentisic acid is also presented. Petruta Mihaela Matei, Pablo Martín-Ramos, Mercedes Sánchez-Báscones, Salvador Hernández-Navarro, Adriana Correa-Guimaraes, Luis M. Navas-Gracia, Cassyo Araujo Rufino, M. Carmen Ramos-Sánchez, and Jesús Martín-Gil Copyright © 2015 Petruta Mihaela Matei et al. All rights reserved. Polyols Prepared from Ring-Opening Epoxidized Soybean Oil by a Castor Oil-Based Fatty Diol Sun, 29 Mar 2015 08:38:08 +0000 Several biorenewable vegetable oil-based polyols with different molecular weights and various hydroxyl functionalities were successfully prepared by ring-opening epoxidized soybean oil with a castor oil-based fatty diol. It was found that several factors, including reaction time, reaction temperature, and molar ratios between epoxidized soybean oil and castor oil diol, affect structures and rheology behaviors of the final polyols. Proton NMR, FT-IR, GPC, and rheometry results revealed that the hydroxyl functionalities, molecular weight, and viscosity of the polyols could be tailored by controlling the above-mentioned factors. Besides, the role of solvents in the epoxy ring-opening process was investigated as well. Jing Zhang, Ji Jun Tang, and Jiao Xia Zhang Copyright © 2015 Jing Zhang et al. All rights reserved. Evaluating Lignin-Rich Residues from Biochemical Ethanol Production of Wheat Straw and Olive Tree Pruning by FTIR and 2D-NMR Thu, 26 Mar 2015 12:56:24 +0000 Lignin-rich residues from the cellulose-based industry are traditionally incinerated for internal energy use. The future biorefineries that convert cellulosic biomass into biofuels will generate more lignin than necessary for internal energy use, and therefore value-added products from lignin could be produced. In this context, a good understanding of lignin is necessary prior to its valorization. The present study focused on the characterization of lignin-rich residues from biochemical ethanol production, including steam explosion, saccharification, and fermentation, of wheat straw and olive tree pruning. In addition to the composition and purity, the lignin structures (S/G ratio, interunit linkages) were investigated by spectroscopy techniques such as FTIR and 2D-NMR. Together with the high lignin content, both residues contained significant amounts of carbohydrates, mainly glucose and protein. Wheat straw lignin showed a very low S/G ratio associated with p-hydroxycinnamates (p-coumarate and ferulate), whereas a strong predominance of S over G units was observed for olive tree pruning lignin. The main interunit linkages present in both lignins were β-O- ethers followed by resinols and phenylcoumarans. These structural characteristics determine the use of these lignins in respect to their valorization. José I. Santos, Raquel Martín-Sampedro, Úrsula Fillat, José M. Oliva, María J. Negro, Mercedes Ballesteros, María E. Eugenio, and David Ibarra Copyright © 2015 José I. Santos et al. All rights reserved. Encapsulation of Phase Change Materials Using Layer-by-Layer Assembled Polyelectrolytes Wed, 25 Mar 2015 14:05:57 +0000 Phase change materials absorb the thermal energy when changing their phases (e.g., solid-to-liquid) at constant temperatures to achieve the latent heat storage. The major drawbacks such as limited thermal conductivity and leakage prevent the PCMs from wide application in desired areas. In this work, an environmentally friendly and low cost approach, layer-by-layer (LbL) assembly technique, was applied to build up ultrathin shells to encapsulate the PCMs and therefore to regulate their changes in volume when the phase change occurs. Generally, the oppositely charged strong polyelectrolytes Poly(diallyldimethylammonium chloride) (PDADMAC) and Poly(4-styrenesulfonic acid) sodium salt (PSS) were employed to fabricate multilayer shells on emulsified octadecane droplets using either bovine serum albumin (BSA) or sodium dodecyl sulfate (SDS) as surfactant. Specifically, using BSA as the surfactant, polyelectrolyte encapsulated octadecane spheres in size of ∼500 nm were obtained, with good shell integrity, high octadecane content (91.3% by mass), and good thermal stability after cycles of thermal treatments. Qiangying Yi, Gleb B. Sukhorokov, Jin Ma, Xiaobo Yang, and Zhongwei Gu Copyright © 2015 Qiangying Yi et al. All rights reserved. Elution of Monomers from Provisional Composite Materials Wed, 25 Mar 2015 12:58:52 +0000 The aim of this study was to evaluate the elution of substances from different materials used for the manufacturing of temporary indirect restorations, after storage in saliva and ethanol 75%. 10 samples of three chemically cured materials (Protemp 3 Garant, Systemp.c&b, and Trim) and one light-cured material (Clip F) were stored in saliva and ethanol 75% for 24 h, 7, and days 28 days. From the storage media at each time period, samples were prepared and analysed by LC-MS/MS, in order to access the elution of monomers. The results differed among the materials ( ≤ 0.05). No monomers were detected in the samples of Protemp 3 Garant and Clip F. Substances were detected only in ethanol samples of Systemp.c&b and Trim. The amount of BisGMA, TEGDMA, and UDMA 2 released from Systemp.c&b was higher compared to Trim. Storage time affected the release of substances ( ≤ 0.05). The highest release was observed within the first 24 h. It can be concluded that provisional resin composite materials do not show high release of monomers and this release is material dependent. However, the detection of additional peaks during the analysis, suggesting the formation of by-products of the eluted substances, may not be in favour of these materials with respect to their toxicity. Simon Daniel Schulz, Tobias Laquai, Klaus Kümmerer, Richard Bolek, Volker Mersch-Sundermann, and Olga Polydorou Copyright © 2015 Simon Daniel Schulz et al. All rights reserved. Characterization of Strong and Crystalline Polyvinyl Alcohol/Montmorillonite Films Prepared by Layer-by-Layer Deposition Method Wed, 18 Mar 2015 09:33:48 +0000 The preparation of a high-strength and highly crystalline nanocomposite with a layered structure by the use of layer-by-layer deposition (LbL) method from polyvinyl alcohol (PVOH) and montmorillonite (MMT) platelets is reported. The crystallinity and interactions between the components were studied by the use of Fourier transform infrared spectroscopy (FT-IR), wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The nanocomposite film structure was investigated by the use of scanning electron microscope (SEM) and atomic force microscopy (AFM). The stiffness of the LbL PVOH/MMT film was significantly higher compared to pure PVOH and conventional PVOH/MMT nanocomposite. The structural and thermal studies on thin PVOH/MMT films indicated the enhanced crystallinity of the polymer. S. Gaidukov, I. Danilenko, and G. Gaidukova Copyright © 2015 S. Gaidukov et al. All rights reserved. Improved Mechanical Properties of Compatibilized Polypropylene/Polyamide-12 Blends Mon, 16 Mar 2015 12:09:21 +0000 Compatibilized blends of polypropylene (PP) and polyamide-12 (PA12) as a second component were obtained by direct injection molding having first added 20% maleic anhydride-modified copolymer (PP-g-MA) to the PP, which produced partially grafted PP (gPP). A nucleating effect of the PA12 took place on the cooling crystallization of the gPP, and a second crystallization peak of the gPP appeared in the PA12-rich blends, indicating changes in the crystalline morphology. There was a slight drop in the PA12 crystallinity of the compatible blends, whereas the crystallinity of the gPP increased significantly in the PA12-rich blends. The overall reduction in the dispersed phase particle size together with the clear increase in ductility when gPP was used instead of PP proved that compatibilization occurred. Young’s modulus of the blends showed synergistic behavior. This is proposed to be both due to a change in the crystalline morphology of the blends on the one hand and, on the other, in the PA12-rich blends, to the clear increase in the crystallinity of the gPP phase, which may, in turn, have been responsible for the increase in its continuity and its contribution to the modulus. Nora Aranburu and José Ignacio Eguiazábal Copyright © 2015 Nora Aranburu and José Ignacio Eguiazábal. All rights reserved. Effect of pH and Monomer Dosing Rate in the Anionic Polymerization of Ethyl Cyanoacrylate in Semicontinuous Operation Wed, 11 Mar 2015 06:40:00 +0000 Nanoparticles of poly(ethyl cyanoacrylate) with more than 10% solids content were prepared by semicontinuous heterophase polymerization at monomer-starved conditions varying the initial pH in the interval of 1–1.75 and at two monomer dosing rates. Measurements by scanning-transmission electron microscopy allowed us to identify an inverse dependence of particle size on pH. Furthermore, all the polymerizations conducted at the slower monomer dosing rate rendered two particle populations, with the larger one formed from the aggregation of a fraction of the smaller particles. It was believed that the so slow addition of the monomer caused the formation of very small but instable particles, thereby a fraction of which aggregated to reduce the total interface particles-aqueous phase, increasing the latex stability. An increase in the monomer dosing rate led to larger and more stable particles in such way that only one population of nanoparticles with around 40 nm in average diameter was obtained. Hened Saade, Suleidi Torres, Cynthia Barrera, Julieta Sánchez, Yolanda Garza, and Raúl G. López Copyright © 2015 Hened Saade et al. All rights reserved. Microphase Separation of a PS-b-PFS Block Copolymer via Solvent Annealing: Effect of Solvent, Substrate, and Exposure Time on Morphology Mon, 09 Mar 2015 06:43:35 +0000 Block copolymer (BCP) lithography makes use of the microphase separation properties of BCPs to pattern ordered nanoscale features over large areas. This work presents the microphase separation of an asymmetric polystyrene-block-poly(ferrocenyl dimethylsilane) (PS-b-PFS) BCP that allows ordered arrays of nanostructures to be formed by spin casting PS-b-PFS on substrates and subsequent solvent annealing. The effects of the solvent annealing conditions on self-assembly and structural stability are discussed. Colm T. O’Mahony, Dipu Borah, and Michael A. Morris Copyright © 2015 Colm T. O’Mahony et al. All rights reserved.