International Journal of Polymer Science The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Dynamics Analysis of the Melt Conveying Process in a Novel Extruder Tue, 01 Dec 2015 08:21:34 +0000 This study investigates dynamics of the melt conveying process in a novel extruder in which a polymer experiences a primarily elongational deformation field. The working principle of the novel extruder is completely different from that of conventional screw extruders. At the last stage of polymer processing in the proposed novel extruder, melt is conveyed through feeding and discharging processes. Here we present a mathematical model to analyze dynamics in the melt conveying process. Melt extrusion is primarily influenced by the position of vane chamber and the structural parameters of the novel extruder such as eccentricity. Zan Huang Copyright © 2015 Zan Huang. All rights reserved. Application of Microbial Biopolymers as an Alternative Construction Binder for Earth Buildings in Underdeveloped Countries Sun, 29 Nov 2015 13:31:45 +0000 Earth buildings are still a common type of residence for one-third of the world’s population. However, these buildings are not durable or resistant against earthquakes and floods, and this amplifies their potential harm to humans. Earthen construction without soil binders (e.g., cement) is known to result in poor strength and durability performance of earth buildings. Failure to use construction binders is related to the imbalance in binder prices in different countries. In particular, the price of cement in Africa, Middle East, and Southwest Asia countries is extremely high relative to the global trend of consumer goods and accounts for the limited usage of cement in those regions. Moreover, environmental concerns regarding cement usage have recently risen due to high CO2 emissions. Meanwhile, biopolymers have been introduced as an alternative binder for soil strengthening. Previous studies and feasibility attempts in this area show that the mechanical properties (i.e., compressive strength) of biopolymer mixed soil blocks (i.e, both 1% xanthan gum and 1% gellan gum) satisfied the international criteria for binders used in earthen structures. Economic and market analyses have demonstrated that the biopolymer binder has high potential as a self-sufficient local construction binder for earth buildings where the usage of ordinary cement is restricted. Ilhan Chang, Minkyung Jeon, and Gye-Chun Cho Copyright © 2015 Ilhan Chang et al. All rights reserved. Optimized Monitoring of Production of Cellulose Nanowhiskers from Opuntia ficus-indica (Nopal Cactus) Thu, 26 Nov 2015 09:34:21 +0000 Preparation of cellulose nanowhiskers (CNWs) has grown significantly because they are useful for a wide range of applications. Additional advantage in their design requires that they meet the following characteristics: nontoxicity, abundance, sustainability, renewability, and low cost. To address these requirements, nanowhiskers were prepared from Opuntia ficus-indica (nopal) cellulose by acid hydrolysis. Monitoring the process of CNWs preparation is necessary to ensure maximum yield and purity of the end product. In this study, the cellulose preparation was monitored by analyzing microscopic morphology by SEM; the purity degree was determined by fluorescence microscopy as a novel and rapid technique, and FTIR spectroscopy was used for confirmation. The additional parameters that monitored the process were the crystallinity index by X-ray diffraction and the size of the particle by dynamic light scattering (DLS). Nopal cellulose was found to be comparable to commercial microcrystalline cellulose. The use of Opuntia ficus-indica is a viable alternative for the production of highly pure CNWs and the strategy to supervise the preparation process was rapid. Horacio Vieyra, Ulises Figueroa-López, Andrea Guevara-Morales, Berenice Vergara-Porras, Eduardo San Martín-Martínez, and Miguel Ángel Aguilar-Mendez Copyright © 2015 Horacio Vieyra et al. All rights reserved. Microbial Cellulose Production from Bacteria Isolated from Rotten Fruit Mon, 23 Nov 2015 16:32:20 +0000 Microbial cellulose, an exopolysaccharide produced by bacteria, has unique structural and mechanical properties and is highly pure compared to plant cellulose. Present study represents isolation, identification, and screening of cellulose producing bacteria and further process optimization. Isolation of thirty cellulose producers was carried out from natural sources like rotten fruits and rotten vegetables. The bacterial isolates obtained from rotten pomegranate, rotten sweet potato, and rotten potato were identified as Gluconacetobacter sp. RV28, Enterobacter sp. RV11, and Pseudomonas sp. RV14 through morphological and biochemical analysis. Optimization studies were conducted for process parameters like inoculum density, temperature, pH, agitation, and carbon and nitrogen sources using Gluconacetobacter sp. RV28. The strain produced 4.7 g/L of cellulose at optimum growth conditions of temperature (30°C), pH (6.0), sucrose (2%), peptone (0.5%), and inoculum density (5%). Characterization of microbial cellulose was done by scanning electron microscopy (SEM). B. E. Rangaswamy, K. P. Vanitha, and Basavaraj S. Hungund Copyright © 2015 B. E. Rangaswamy et al. All rights reserved. Shrinkage Behaviour of Fibre Reinforced Concrete with Recycled Tyre Polymer Fibres Mon, 16 Nov 2015 10:44:59 +0000 Different types of fibres are often used in concrete to prevent microcracking due to shrinkage, and polypropylene fibres are among the most often used ones. If not prevented, microcracks can lead to the development of larger cracks as drying shrinkage occurs, enabling penetration of aggressive substances from the environment and reducing durability of concrete structures. The hypothesis of the present research is that polypropylene fibres, used in concrete for controlling formation of microcracks due to shrinkage, can be replaced with recycled polymer fibres obtained from end-of-life tyres. To test the hypothesis, concrete mixtures containing polypropylene fibres and recycled tyre polymer fibres were prepared and tested. Experimental programme focused on autogenous, free, and restrained shrinkage. It was shown that PP fibres can be substituted with higher amount of recycled tyre polymer fibres obtaining concrete with similar shrinkage behaviour. The results indicate promising possibilities of using recycled tyre polymer fibres in concrete products. At the same time, such applications would contribute to solving the problem of waste tyre disposal. Marijana Serdar, Ana Baričević, Marija Jelčić Rukavina, Martina Pezer, Dubravka Bjegović, and Nina Štirmer Copyright © 2015 Marijana Serdar et al. All rights reserved. Direct Synthesis of Hyperbranched Poly(acrylic acid-co-3-hydroxypropionate) Thu, 12 Nov 2015 11:18:48 +0000 Hyperbranched poly(acrylic acid-co-3-hydroxypropionate) (PAcHP) was synthesized by base-catalyzed hydrogen transfer polymerization of acrylic acid through one step. The copolymers obtained through solution and bulk polymerization were insoluble in water and all organic solvents tried. Structural and compositional characterizations of hyperbranched PAcHP were performed by using FTIR, solid 13C-NMR, TGA, and titrimetric analysis. Acrylate fraction of the hyperbranched PAcHP obtained via bulk polymerization was determined as 60–65% by comparing TGA curves of hyperbranched PAcHP and pure poly(3-hydroxy propionate) (PHP). However, analytical titration of the same sample revealed that acrylic acid units were about 47.3%. The results obtained from TGA and analytical titration were used to evaluate the chemical structure of the copolymer. Hyperbranched PAcHP exhibited hydrogel properties. Swelling behavior of the copolymer was investigated at a wide pH range and ionic strength. The dynamic swelling profiles of hyperbranched PAcHP exhibited a fast swelling behavior in the first hour and achieved the equilibrium state within 12 h in PBS. Depending on the conditions, the copolymers exhibited swelling ratios up to 2100%. As the copolymer has easily biodegradable propionate and versatile functional acrylic acid units, it can be used as not only biodegradable material in medical applications but also raw material in personal care commodities. Efkan Çatıker and Tahsin Filik Copyright © 2015 Efkan Çatıker and Tahsin Filik. All rights reserved. Food Polymers Functionality and Applications Wed, 11 Nov 2015 07:08:57 +0000 Xingxun Liu, Fengwei Xie, Xiaoxi Li, Sumei Zhou, and Liyan Chen Copyright © 2015 Xingxun Liu et al. All rights reserved. Feasibility of Using High-Performance Steel Fibre Reinforced Concrete for Simplifying Reinforcement Details of Critical Members Mon, 09 Nov 2015 16:06:04 +0000 This paper addresses the effects of hooked-end steel fibre contents on the mechanical properties of high-performance concrete (HPC) and investigates the feasibility of utilizing steel fibres to simplify the complicated reinforcement detailing of critical HPC members under high shear stress. Mechanical properties of HPCs with specified compressive strength of 60 and 100 MPa include the flow, air content, compressive strength, and flexural strength. The effectiveness of 1.50% steel fibre content on the shear behaviour of diagonally reinforced concrete coupling beam without additional transverse reinforcement was investigated to alleviate complex reinforcing details for the full section confinement of diagonal bar groups. The test results revealed the incorporation of steel fibres significantly affected the mechanical properties of the HPCs. For diagonally reinforced coupling beam (SFRCCB) without additional transverse reinforcement, the addition of 1.5% steel fibre content into 60 MPa HPC coupling beam provides similar cracking and structural behaviours compared to those of diagonally reinforced coupling beam (CCB) with full section confinement details. However, the ductility of SFRCCB was less than that of CCB. It is recommended that both stirrups and steel fibre should be used for fully confining the diagonal bar groups of coupling beams to achieve the ductile behaviour. Seok-Joon Jang, Dae-Hyun Kang, Kyung-Lim Ahn, Wan-Shin Park, Sun-Woong Kim, and Hyun-Do Yun Copyright © 2015 Seok-Joon Jang et al. All rights reserved. Simulation and Experimental Validation of the Hot Embossing Process of Poly(lactic-co-glycolic acid) Microstructures Sun, 08 Nov 2015 08:29:49 +0000 The microstructures were fabricated by hot embossing method using biodegradable material PLGA poly(lactic-co-glycolic acid), to serve as the drug carriers in the drug delivery system. The embossing process was studied in a combination of simulations and experiments. Firstly, the viscoelastic model of PLGA was built after testing the material properties. Secondly, the hot embossing process was simulated by ABAQUS finite element software. The deformation rules of PLGA during hot embossing were then achieved. The pressures inside the PLGA materials were different at various places during hot embossing, which lead to the differences of the filling speeds. As a result, the inner structures were easier to get formed than the outer structures. And the fluidity of PGLA would increase with the raising temperature, which however caused serious material overflow. Finally the hot embossing experiments were presented to verify the simulation results. Agreed with the filling rules of the simulation, enough duration was necessary to let the outer corners of the microstructures be formed completely. Moreover the trapped air in the grooves was compressed into small bubbles at the corners. It was also found that the material overflow could be prevented in the use of nonisothermal hot embossing method. Xiaopeng Wang, Wei Li, and Tianning Chen Copyright © 2015 Xiaopeng Wang et al. All rights reserved. Experiment Research on Bonding Effect of Poly(lactic-co-glycolic acid) Device by Surface Treatment Method Mon, 02 Nov 2015 07:35:28 +0000 According to the low temperature and high effective bonding problem of microdevices made of degradable polymer PLGA, chemical, plasma, and UV irradiation method are used to study the experimental surface treatment of PLGA films and microdevices bonding process. The results show that all three methods can reduce the surface contact angle of PLGA films, the contact angle increases with time at room temperature, and the PLGA films contact angle is almost unchanged under refrigeration. The PLGA film bonding temperature is significantly reduced after UV irradiation, and the bonding interfaces also generate diffusion cross linking layer are dense and uniform. Xiaopeng Wang, Kun Lian, and Tianning Chen Copyright © 2015 Xiaopeng Wang et al. All rights reserved. Two-Dimensional FTIR as a Tool to Study the Chemical Interactions within Cellulose-Ionic Liquid Solutions Sun, 01 Nov 2015 14:22:37 +0000 In this study two-dimensional FTIR analysis was applied to understand the temperature effects on processing cellulose solutions in imidazolium-based ionic liquids. Analysis of the imidazolium ion νC2–H peak revealed hydrogen bonding within cellulose solutions to be dynamic on heating and cooling. The extent of hydrogen bonding was stronger on heating, consistent with greater ion mobility at higher temperature when the ionic liquid network structure is broken. At ambient temperatures a blue shifted νC2–H peak was indicative of greater cation-anion interactions, consistent with the ionic liquid network structure. Both cellulose and water further impact the extent of hydrogen bonding in these solutions. The FTIR spectral changes appeared gradual with temperature and contrast shear induced rheology changes which were observed on heating above 70°C and cooling below 40°C. The influence of cellulose on solution viscosity was not distinguished on initial heating as the ionic liquid network structure dominates rheology behaviour. On cooling, the quantity of cellulose has a greater influence on solution rheology. Outcomes suggest processing cellulose in ionic liquids above 40°C and to reduce the impacts of cation-anion effects and enhance solubilisation, processing should be done at 70°C. Kalyani Kathirgamanathan, Warren J. Grigsby, Jafar Al-Hakkak, and Neil R. Edmonds Copyright © 2015 Kalyani Kathirgamanathan et al. All rights reserved. Prediction of Mold Spoilage for Soy/Polyethylene Composite Fibers Sun, 01 Nov 2015 09:11:08 +0000 Mold spoilage was determined over 109 days on soy/PE fibers held under controlled temperatures (T) ranging from 10°C to 40°C and water activities from 0.11 to 0.98. Water activities were created in sealed containers using saturated salt solutions and placed in temperature-controlled incubators. Soy/PE fibers that were held at 0.823 or higher exhibited mold growth at all temperatures. As postulated, increased water activity (greater than 0.89) and temperature (higher than 25°C) accelerated mold growth on soy/PE fibers. A slower mold growth was observed on soy/PE fibers that were held at 0.87 and 10°C. A Weibull model was employed to fit the observed logarithmic values of , and an interaction term and was chosen as the final model as it gave the best fit to the raw mold growth data. These growth models predict the expected mold-free storage period of soy/PE fibers when exposed to various environmental temperatures and humidities. Chinmay Naphade, Inyee Han, Sam Lukubira, Amod Ogale, James Rieck, and Paul Dawson Copyright © 2015 Chinmay Naphade et al. All rights reserved. Preparation and Bioactivity Properties of a Novel Composite Membrane of Fructose Mediated β-Tricalcium Pyrophosphate/(Polyethylene Glycol/Chitosan) for Guided Tissue Regeneration Sun, 01 Nov 2015 09:05:01 +0000 A novel composite membrane of β-tricalcium pyrophosphate (β-TCP) and fructose- (F-) mediated chitosan/poly(ethylene glycol) (CS/PEG) was prepared by thermally induced phase separation technique. The prepared composite membranes were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The mechanical property, swelling, degradation, and cytotoxicity of the composite membranes were evaluated in vitro with respect to its potential for use as biodegradable guided tissue regeneration (GTR) membrane. In vitro degradation tests showed the composite membrane with a controllable degradation rate when changing the β-TCP content. The incorporation of β-TCP granules also caused a significant enhancement of tensile strength. When β-TCP content is controlled to 50 wt%, homogeneous composite membranes with well mechanical property and enzymatic degradation rate can be obtained. Cytotoxicity assay demonstrates that the composite membranes were nontoxic and had very good cell compatibility. Most importantly, the release of calcium ions and glucosamine from the composite membranes was proved to increase the cell proliferation of NIH3T3. The results of this study have indicated that this novel F-β-TCP/CS/PEG composite can be a suitable material for GTR applications. Jian-Wen Wang, Min-Hsiung Hon, Yi-Ming Kuo, and Mei-Hui Chung Copyright © 2015 Jian-Wen Wang et al. All rights reserved. An Investigation of the Effect of Chitosan on Isothermal Crystallization, Thermal Decomposition, and Melt Index of Biodegradable Poly(L-lactic acid) Thu, 29 Oct 2015 12:38:51 +0000 Biodegradable chitosan (CS) was introduced into another biodegradable poly(L-lactic acid) (PLLA) to prepare the PLLA/CS composites, and the effect of CS on thermal behavior and melt index of PLLA was investigated using modern testing technologies including optical depolarizer, thermogravimetric analysis instrument, and melt index instrument. The relevant testing results showed that both crystallization temperature and CS concentration affected the isothermal crystallization behavior of PLLA. Compared to neat PLLA, the t1/2 of PLLA/5% CS decreased from 2991.54 s to the minimum value 208.76 s at 105°C. However, the t1/2 of PLLA/CS composites in high crystallization temperature zone was different from that in low crystallization temperature zone. The increase of CS concentration and heating rate made the thermal decomposition temperature of PLLA/CS composites shift to higher temperature. The melt index results indicated that 3% CS made the fluidity of PLLA become better. Yan-Hua Cai and Li-Sha Zhao Copyright © 2015 Yan-Hua Cai and Li-Sha Zhao. All rights reserved. Chemical Recycling of PET Wastes with Different Catalysts Thu, 29 Oct 2015 09:34:11 +0000 Chemical recycling of polyethylene terephthalate, known as PET, has been the subject of increased interest as a valuable feedstock for different chemical processes. In this work, glycolysis of PET waste granules was carried out using excess ethylene glycol in the presence of different simple chemicals acting as catalysts, which are, namely, categorized in ionic liquids, metal salts, hydrotalcites, and enzymes. From every category, some materials as a sample were used, and the one which is going to bring the best result is noted. The effect of some parameters such as temperature, pressure, amount of sample, material ratio, and stirring rate was investigated. As a result we compared the best of each category with the others and final result is shown. Mohammad Khoonkari, Amir Hossein Haghighi, Yahya Sefidbakht, Khadijeh Shekoohi, and Abolfazl Ghaderian Copyright © 2015 Mohammad Khoonkari et al. All rights reserved. Chitosan and Cystatin/Lysozyme Preparation as Protective Edible Films Components Wed, 28 Oct 2015 11:21:09 +0000 This work characterizes biological, physical, and chemical properties of films formed from an aqueous solution of hydroxypropyl methylcellulose (HPMC), with different concentrations of chitosan (CH) and bioactive cystatin/lysozyme preparation (C/L). The properties of biocomposites were examined by Dynamic Mechanical Analysis (DMA), Fourier’s transfer infrared spectroscopy (FTIR), water vapour permeability (WVP), and tensile testing. Antimicrobial activity against Micrococcus flavus, Bacillus cereus, Escherichia coli, Pseudomonas fluorescens, and Candida famata was conducted. Films glass transition and storage modulus were dependent on the C/L and CH concentration. Modulus values decreased during the temperature scan and with higher reagents levels. An increase of CH and C/L concentrations in the films resulted in a decrease in tensile strength from 2.62 to 1.08 MPa. It suggests the hydrolyzing influence of C/L, also observed in smaller peak size of α relaxation. C/L addition caused shifting to higher temperature. DMA and FTIR analysis proved that HPMC and CH are compatible polymers. Water resistance was improved with rising CH concentration from to . The highest inhibition zone in M. flavus and C. famata was recorded at the highest concentration of CH and C/L. Anna Zimoch-Korzycka, Antoine Rouilly, Łukasz Bobak, Andrzej Jarmoluk, and Michał Korzycki Copyright © 2015 Anna Zimoch-Korzycka et al. All rights reserved. Natural Fiber Reinforced Polymer Composites Wed, 28 Oct 2015 08:33:56 +0000 Md. Saiful Islam, Adriana Kovalcik, Mahbub Hasan, and Vijay Kumar Thakur Copyright © 2015 Md. Saiful Islam et al. All rights reserved. Ionic Liquid-Facilitated Preparation of Lignocellulosic Composites Mon, 26 Oct 2015 13:01:39 +0000 Lignocellulosic composites (LCs) were prepared by partially dissolving cotton along with steam exploded Aspen wood and burlap fabric reinforcements utilizing an ionic liquid (IL) solvent. Two methods of preparation were employed. In the first method, a controlled amount of IL was added to preassembled dry matrix of cotton and Aspen wood with a burlap weave reinforcement. In the second method, IL solvent, cotton, and Aspen wood were mixed to produce a thick paste matrix that was subsequently pressed into the burlap weave reinforcement. The IL-based solvent was removed via water soaking, and the flexural and tensile properties of the LCs were examined. In this study, the matrix paste method produced a superior LC. Variables such as processing time (IL interaction time) and fabric weaves were found to influence the mechanical properties of the LCs. Although significant process optimization can still be realized, the mechanical properties of several of the LCs fabricated in this study were comparable to injection molded test specimens of neat high density polyethylene or neat polypropylene. Brent Tisserat, Erik Larson, David Gray, Nathaniel Dexter, Carl Meunier, Lena Moore, and Luke Haverhals Copyright © 2015 Brent Tisserat et al. All rights reserved. Characterization on the Properties of Jute Fiber at Different Portions Mon, 26 Oct 2015 11:24:35 +0000 Natural fibers are environment-friendly, biodegradable, nonabrasive, and less costly and exhibit high initial modulus and high moisture absorption. However, they have nonuniformity in their mechanical, physical, chemical, and thermal properties at different portions. For this reason, long jute fiber was cut into three different portions and subsequently characterized using single fiber tensile test, differential scanning calorimetric, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy according to top, middle, and cutting portions. The crystallinity and moisture content were measured by XRD data and moisture absorption test of the different portions of the raw jute fiber, respectively. The middle portion had better mechanical, thermal, chemical, and crystalline properties compared to the other two portions of the jute fiber. The diameter gradually became thinner from cutting to top portions. Thus the middle portion of jute fiber would be the better choice while being used as reinforcement in composites. Sweety Shahinur, Mahbub Hasan, Qumrul Ahsan, Dilip Kumar Saha, and Md. Saiful Islam Copyright © 2015 Sweety Shahinur et al. All rights reserved. Synthesis of Cotton from Tossa Jute Fiber and Comparison with Original Cotton Mon, 26 Oct 2015 08:38:21 +0000 Cotton fibers were synthesized from tossa jute and characteristics were compared with original cotton by using FTIR and TGA. The FTIR results indicated that the peak intensity of OH group from jute cotton fibers occurred at 3336 cm−1 whereas the peak intensity of original cotton fibers occurred at 3338 cm−1. This indicated that the synthesized cotton fiber properties were very similar to the original cotton fibers. The TGA result showed that maximum rate of mass loss, the onset of decomposition, end of decomposition, and activation energy of synthesized cotton were higher than original cotton. The activation energy of jute cotton fibers was higher than the original cotton fibers. Md. Mizanur Rahman, Md. Rezaur Rahman, Sinin Hamdan, Md. Faruk Hossen, Josephine Chang Hui Lai, and Fui Kiew Liew Copyright © 2015 Md. Mizanur Rahman et al. All rights reserved. Effect of Rubberwood Content on Biodegradability of Poly(butylene succinate) Biocomposites Mon, 26 Oct 2015 07:11:34 +0000 Poly(butylene succinate) (PBS) biocomposites incorporated with rubberwood powder (RWP) were fabricated with various RWP weight fractions (i.e., 0 to 40% wt) by injection moulding process. The soil burial test was employed to examine the biodegradability of such biocomposites under outdoor environment for 60 days. The physical appearance, percentage weight loss, chemical structure, and mechanical properties before and after the soil burial test were determined. Apparent changes in physical appearance of the biocomposites from optical micrographs were detected in terms of surface morphology and colour. The percentage of crystallinity of PBS/RWP biocomposites was studied by the X-ray diffraction (XRD) technique, and the XRD pattern revealed a decrease in percentage of crystallinity due to enhancing RWP weight fractions. This may be attributed to a presence of rubberwood powders providing more disordered molecular chain arrangement of PBS matrix and also an agglomeration of the rubberwood powder content at greater concentration as seen in SEM micrographs. With increasing RWP weight fractions and burial time, the results exhibited a considerable change in chemical structure (essentially ester linkage due to biodegradation mechanism of PBS), relatively greater percentage weight loss, and a substantial decrease in flexural properties. Consequently, the results indicate that incorporating RWP enhances biodegradability of PBS/RWP biocomposites; that is, the biodegradation rate of biocomposites increases with increasing RWP weight fractions and burial time. Hemhong Anankaphong, Duanghathai Pentrakoon, and Jirawut Junkasem Copyright © 2015 Hemhong Anankaphong et al. All rights reserved. Thermal Degradation and Damping Characteristic of UV Irradiated Biopolymer Sun, 25 Oct 2015 12:32:48 +0000 Biopolymer made from renewable material is one of the most important groups of polymer because of its versatility in application. In this study, biopolymers based on waste vegetable oil were synthesized and cross-link with commercial polymethane polyphenyl isocyanate (known as BF). The BF was compressed by using hot compression moulding technique at 90°C based on the evaporation of volatile matter, known as compress biopolymer (CB). Treatment with titanium dioxide (TiO2) was found to affect the physical property of compressed biopolymer composite (CBC). The characterization of thermal degradation, activation energy, morphology structure, density, vibration, and damping of CB were determined after UV irradiation exposure. This is to evaluate the photo- and thermal stability of the treated CB or CBC. The vibration and damping characteristic of CBC samples is significantly increased with the increasing of UV irradiation time, lowest thickness, and percentages of TiO2 loading at the frequency range of 15–25 Hz due to the potential of the sample to dissipate energy during the oscillation harmonic system. The damping property of CBC was improved markedly upon prolonged exposure to UV irradiation. Anika Zafiah M. Rus and Nik Normunira Mat Hassan Copyright © 2015 Anika Zafiah M. Rus and Nik Normunira Mat Hassan. All rights reserved. Obtaining a Flexible Film Elaborated from Cassava Thermoplastic Starch and Polylactic Acid Sun, 25 Oct 2015 11:47:53 +0000 A flexible film was obtained from a blend of cassava thermoplastic starch and polylactic acid, using maleic anhydride as coupling agent. For this, an experimental design with three factors was used: polylactic acid content, coupling agent content, and temperature profile of the blown extrusion. It was found that the three factors generated significant differences on the response variables of tensile mechanical properties individually as in their triple interaction. Differential scanning calorimetry (DSC) was used by understanding the behavior of thermal properties of TPS/PLA blends with and without coupling agent, finding similar results between both. From this, the combination with 28% polylactic acid, 0.87% coupling agent, and 155.75°C temperature profile permitted the obtaining of a material with outstanding mechanical properties and offered advantages from the economic point of view. Germán A. Arboleda, Camilo E. Montilla, Héctor S. Villada, and Giovanni A. Varona Copyright © 2015 Germán A. Arboleda et al. All rights reserved. Suitability of Aquatic Plant Fibers for Handmade Papermaking Sun, 25 Oct 2015 11:39:29 +0000 Increasing concerns for future fiber supplies in pulp and paper industries has shifted interest in nonwood sources from agriculture residues and aquatic plants. Aquatic plants with short growth cycles, in abundance, and with low lignin are a potential fiber source. Five aquatic plant species, Cyperus digitatus, Cyperus halpan, Cyperus rotundus, Scirpus grossus, and Typha angustifolia, were examined for fiber dimensions and chemical composition (cellulose, lignin) and compared with other nonwood plants. All aquatic plants possessed short (length, 0.71–0.83 mm) and thin (diameter, 9.13–12.11 µm) fibers, narrow lumen (diameter, 4.32–7.30 µm), and thin cell wall (thickness, 2.25–2.83 µm) compared with most other nonwood plants. Slenderness ratio ranged from 73.77 to 89.34 with Typha angustifolia having the highest ratio. Except for Scirpus grossus, the flexibility coefficient ranged from 52.91 to 58.08. Scirpus grossus has low Runkel ratio, 0.84 ± 0.17. Fiber characteristics, short and thin fibers, Slenderness ratio >60, flexibility coefficient within 50–75, and Runkel ratio <1, are suitable for papermaking. Cellulose content of Cyperus rotundus (42.58 ± 1.32%), Scirpus grossus (36.21 ± 2.81%), and Typha angustifolia (44.05 ± 0.49%) >34% is suitable for pulp and papermaking. Lignin content in aquatic plants in the present study ranged 9.54–20.04% and below the wood lignin content of <23–30% encountered in pulp and papermaking. Handmade paper sheets produced for paperboard, craft, and decorative purposes are with permissible tensile strength, breaking length, and low moisture content. Nordiah Bidin, Muta Harah Zakaria, Japar Sidik Bujang, and Nur Aznadia Abdul Aziz Copyright © 2015 Nordiah Bidin et al. All rights reserved. Water Absorption Behaviour and Its Effect on the Mechanical Properties of Flax Fibre Reinforced Bioepoxy Composites Sun, 25 Oct 2015 11:31:07 +0000 In the context of sustainable development, considerable interest is being shown in the use of natural fibres like as reinforcement in polymer composites and in the development of resins from renewable resources. This paper focuses on eco-friendly and sustainable green composites manufacturing using resin transfer moulding (RTM) process. Flax fibre reinforced bioepoxy composites at different weight fractions (40 and 55 wt%) were prepared in order to study the effect of water absorption on their mechanical properties. Water absorption test was carried out by immersion specimens in water bath at room temperature for a time duration. The process of water absorption of these composites was found to approach Fickian diffusion behavior. Diffusion coefficients and maximum water uptake values were evaluated; the results showed that both increased with an increase in fibre content. Tensile and flexural properties of water immersed specimens were evaluated and compared to dry composite specimens. The results suggest that swelling of flax fibres due to water absorption can have positive effects on mechanical properties of the composite material. The results of this study showed that RTM process could be used to manufacture natural fibre reinforced composites with good mechanical properties even for potential applications in a humid environment. E. Muñoz and J. A. García-Manrique Copyright © 2015 E. Muñoz and J. A. García-Manrique. All rights reserved. Water Absorption and Thermomechanical Characterization of Extruded Starch/Poly(lactic acid)/Agave Bagasse Fiber Bioplastic Composites Sun, 25 Oct 2015 08:26:06 +0000 Water absorption and thermomechanical behavior of composites based on thermoplastic starch (TPS) are presented in this work, wherein the concentration of agave bagasse fibers (ABF, 0–15 wt%) and poly(lactic acid) (PLA, 0–30 wt%) is varied. Glycerol (G) is used as starch (S) plasticizer to form TPS. Starch stands as the polymer matrix (70/30 wt/wt, S/G). The results show that TPS hygroscopicity decreases as PLA and fiber content increase. Storage, stress-strain, and flexural moduli increase with PLA and/or agave bagasse fibers (ABF) content while impact resistance decreases. The TPS glass transition temperature increases with ABF content and decreases with PLA content. Micrographs of the studied biocomposites show a stratified brittle surface with a rigid fiber fracture. F. J. Aranda-García, R. González-Núñez, C. F. Jasso-Gastinel, and E. Mendizábal Copyright © 2015 F. J. Aranda-García et al. All rights reserved. Influence of Chitosan Coating on Mechanical Stability of Biopolymer Carriers with Probiotic Starter Culture in Fermented Whey Beverages Wed, 21 Oct 2015 14:32:36 +0000 The aim of this study was to improve the mechanical stability of biopolymer carriers and cell viability with addition of chitosan coating during fermentation process and product storage. Dairy starter culture (1% (w/v)) was diluted in whey and mixed with sodium alginate solution and the beads were made using extrusion technique. The mechanical stability of coated and uncoated beads, the release behavior, and the viability of encapsulated probiotic dairy starter culture in fermented whey beverages were analyzed. The mechanical properties of the beads were determined according to force-displacement and engineering stress-strain curves obtained after compression testing. It was observed that addition of chitosan as a coating on the beads as well as the fermentation process increased the elastic modulus of the calcium alginate-whey beads and cell survival. The current study revealed that the coating did not significantly improve the viability of probiotics during the fermentation but had an important influence on preservation of the strength of the carrier during storage. Our results indicate that whey-based substrate has positive effect on the mechanical stability of biopolymer beads with encapsulated probiotics. Nataša S. Obradović, Tanja Ž. Krunić, Kata T. Trifković, Maja Lj. Bulatović, Marko P. Rakin, Marica B. Rakin, and Branko M. Bugarski Copyright © 2015 Nataša S. Obradović et al. All rights reserved. Shear Strength of Unreinforced Masonry Wall Retrofitted with Fiber Reinforced Polymer and Hybrid Sheet Wed, 21 Oct 2015 13:09:06 +0000 Unreinforced masonry (URM) structures represent a significant portion of existing historical structures around the world. Recent earthquakes have shown the need for seismic retrofitting for URM structures. Various types of strengthening methods have been used for URM structures. In particular, a strengthening technique using externally bonded (EB) fiber reinforced polymer (FRP) composites has attracted engineers since EB FRP materials effectively enhance the shear strength of URM walls with negligible change to cross-sectional area and weight of the walls. Research has been extensively conducted to determine characteristics of URM walls strengthened with EB FRP materials. However, it is still difficult to determine an appropriate retrofitting level due to the complexity of mechanical behavior of strengthened URM walls. In this study, in-plane behavior under lateral loading was, therefore, investigated on a full-scale nonstrengthened URM wall and URM walls retrofitted with two different FRP materials: carbon (CFRP) and hybrid (HFRP) sheets. The test results indicated that both FRP composites were effective in increasing shear strength in comparison with the control specimen. However, better performance was obtained with HFRP compared to CFRP. In addition, an equation for estimating effective strain was proposed, and the theoretical results were in good agreement with the experimental ones. Yun-Cheul Choi, Hyun-Ki Choi, Dongkeun Lee, and Chang Sik Choi Copyright © 2015 Yun-Cheul Choi et al. All rights reserved. Prediction of Flexural Capacity of RC Beams Strengthened in Flexure with FRP Fabric and Cementitious Matrix Wed, 21 Oct 2015 11:06:01 +0000 This paper presents both experimental and analytical research results for predicting the flexural capacity of reinforced concrete (RC) beams strengthened in flexure with fabric reinforced cementitious matrix (FRCM). In order to assess the efficiency of the FRCM-strengthening method, six beams were strengthened in flexure with FRCM composite having different amounts and layers of FRP fabric and were tested under four-point loading. From test results, it was confirmed that the slippage between the FRP fabric and matrix occurs at a high strain level, and all of the FRCM-strengthened beams failed by the debonding of the FRCM. Additionally, a new bond strength model for FRCM considering the slippage between fabric and matrix was proposed, using a test database to predict the strengthening performance of the FRCM composite. The prediction of the proposed bond strength model agreed well with the debonding loads of the test database. Kyusan Jung, Kinam Hong, Sanghoon Han, Jaekyu Park, and Jaehyun Kim Copyright © 2015 Kyusan Jung et al. All rights reserved. Rheological Behavior of Renewable Polyethylene (HDPE) Composites and Sponge Gourd (Luffa cylindrica) Residue Mon, 19 Oct 2015 12:56:09 +0000 The present study reports the results of rheological behavior of renewable composites, based on a matrix of high density polyethylene (HDPE), made from ethanol distilled from sugarcane, and lignocellulose filler from waste generated in the processing of sponge gourds for bathing use. The composites were prepared with 10, 20, 30, and 40%wt of filler in a twin-screw extruder. The materials were analyzed in a parallel plate rheometer and a melt-flow indexer. The composite morphology was determined by scanning electron microscopy. The composite viscosity increased with filler content, suggesting possible formation of filler agglomerates. This result was confirmed by Cole-Cole diagrams. Viviane Alves Escócio, Elen Beatriz Acordi Vasques Pacheco, Ana Lucia Nazareth da Silva, André de Paula Cavalcante, and Leila Léa Yuan Visconte Copyright © 2015 Viviane Alves Escócio et al. All rights reserved.