Higher Elongation Percentage Research Articles

Optimization of acetylated starch films from purple sweet potato: effect of glycerol, carboxymethylcellulose, and stearic acid

The objective of this study was to ascertain the optimal additive conditions to develop a film from an alternative source of modified starch, using the response surface methodology. The central composite design + points used factors to evaluate the effect of the independent variables (glycerol concentration: 0.3, 0.35, and 0.40 g g−1 starch; carboxymethylcellulose: 0.5, 0.75 and 1 g/5 g starch; stearic acid 0.025, 0.05, and 0.075 g/5 g starch) on the response variables (solubility, swelling, opacity, luminosity, tensile strength, elongation, water vapor permeability, and water activity). A simultaneous optimization was achieved using concentrations of glycerol 0.30 g g−1 starch, CMC 0.32 g/5 g starch, and stearic acid 0.007 g/5 g starch, which generated interesting properties validated through experimentation. Therefore, an ecological film was obtained that can be considered for food coating because it presented a low permeability to water vapor (0.0055 g ms−1MPa−1), a high percentage of elongation (91%), and a decrease in solubility (23%). This will also allow the incorporation of other compounds such as antioxidants, reinforcements, and sensors with favorable results, and with a positive perspective on the use of alternative sources of starch.

Mangosteen peel and seed as antimicrobial and drug delivery in rubber products

AbstractGarcinia mangostana Linn. or mangosteen is a tropical superfruit with an excellent taste. The peel and seed of mangosteen waste can be used in medical, cosmetic, and health‐care applications. Both mangosteen peel and seed have outstanding antibiotic properties and are suitable for use as bio‐fillers in natural rubber latex products such as medical gloves, rubber transdermal patches, rubber toys, and rubber‐health care products. In addition, mangosteen seed composed of griseofulvin polyethylene glycol [(C2H4O2)n]1‐x (C17H17ClO6)x is useful for treating osteoarthritis of the knee, similar to commercial glucosamine (amino sugar). Adding mangosteen peel and mangosteen seed in rubber gloves and rubber patches, respectively, is an alternative form of antimicrobial and drug delivery replacing taking a tablet. This study compared the characteristics and properties of mangosteen peel with silver nitrate (AgNO3) and compared the characteristics and properties of mangosteen seed with commercial glucosamine using the film casting dipping process. The obtained natural rubber latex gloves with added mangosteen peel powder had a good appearance with a high contact angle (resulting in hydrophobicity and low wettability with water equal to 130.67° ± 2.08°), good mechanical properties (high percentage of elongation at break 815.72 ± 54.67%, high tensile strength 64.59 ± 13.54 MPa, good stiffness 296.50 ± 48.32 N/m, and high Young's modulus 29.65 ± 4.83 MPa), and as it was non‐toxic to skin it was suitable for application in medical gloves and transdermal patches. The natural rubber patches added with mangosteen seed had high wettability and good mechanical properties. The Fourier‐transform infrared (FTIR) spectra of mangosteen seed were consistent with the FTIR spectra of commercial glucosamine.

Partially Oriented Yarn (POY) produced from semi-dull via melting spun using an extruder: Effect of die extruder temperature on elongation of the POY

Semi-Dull is a white and slightly opaque polyester type with 0.35 wt% of titanium dioxide (TiO2) content. Whereas, Partially Oriented Yarn (POY) is a type of yarn produced from polyester fibers derived from continuous filament using molten spinning. The used filament fibers have low strength with a very high percentage of elongation. This study aims to analyze the elongation properties of the yarn produced during molten spinning process of raw materials. The yarn produced has 165 denier 96 filaments Semi-Dull POY (i.e. POY 165/96 SDC). In this study, the used raw material is Semi-Dull, which then melted in the extruder machine and spun into Partially Oriented Yarn (POY). The temperatures of the extruder die was varied (i.e. 275, 280, 285°C) and controlled by using a commercial thermal fluid, i.e. DOWTHERM™. The POY samples prepared from the molten spinning process using extruder were then analyzed for their elongation at different extruder die temperatures. The elongation analysis results showed that the elongations of the POY were about 127.17; 137.85; 137.97 % at die temperatures of 275, 280, 285°C, respectively. From the results, it can be concluded that the die temperature has affected the elongation properties of the POY 165/96 SDC yarn.

Fabrication and Characterization of Low Methoxyl Pectin/Gelatin/Carboxymethyl Cellulose Absorbent Hydrogel Film for Wound Dressing Applications

In this study, hydrogel films composed of low methoxyl pectin (LMP), gelatin, and carboxymethyl cellulose (CMC) were fabricated. Glycerin was used as a plasticizer while glutaraldehyde (Glu) and calcium chloride (CaCl2) were used as crosslinking agents in film preparation. Hydrogel films were morphologically characterized and evaluated for mechanical properties. In addition, the investigations for fluid uptake ability, water retention capacity, water vapor transmission rate, and integrity value of the invented films were performed. The results showed that F-Glu-Ca-G30 film demonstrated superior properties when compared to other prepared films. It demonstrated a high percentage of elongation at break (32.80%), fluid uptake ability (88.45% at 2 h), water retention capacity (81.70% at 2 h), water vapor transmission rate (1889 g/m2/day), and integrity value (86.42%). F-Glu-Ca-G30 film was subsequently selected for 10% w/w povidone iodine (PI) loading and tested for anti-Staphylococcus aureus activity using an agar diffusion assay. Notably, F-Glu-Ca-G30-PI film demonstrated a dramatic ability to inhibit microbial growth, when compared to both a blank film and iodine solution control. Our LMP/gelatin/CMC hydrogel film promises to be an effective dressing material with high fluid absorption capacity, fluid holding ability, and water vapor transmission rate. Incorporation of antibiotics such as povidone iodine into the films conferred its antimicrobial property thereby highlighting its potential dermatological use. However, further clinical studies of the application of this hydrogel film as wound dressing material is recommended.

Preparation and partial characterization of films made with dual-modified (acetylation and crosslinking) potato starch.

Starch is an alternative material for the production of biodegradable plastics; however, native starches have drawbacks due to their hydrophilic nature. Chemical modifications such as acetylation and crosslinking are used to broaden the potential end-uses of starch. Dual modification of starches increases their functionality compared to that of starches with similar single modifications. In this study, a dual-modified potato starch (acetylated and crosslinked) was used to produce films by casting. Changes in the arrangement of the amylopectin double helices of dual-modified starch were evident from X-ray diffraction patterns, pasting profiles and thermal properties. The degree of substitution for acetyl groups was low (0.058±0.006) because crosslinking dominated acetylation. Modified starch film had higher elongation percentage (82.81%) than its native counterpart (57.4%), but lower tensile strength (3.51MPa for native and 2.17MPa for dual-modified) and lower crystallinity in fresh and stored films. The sorption isotherms indicated that the dual modification decreased the number of reactive sites for binding water, resulting in a reduction in the monolayer value and a decrease in the solubility and water vapor permeability. Dual modification of starch may be a feasible option for improving the properties of biodegradable starch films. © 2018 Society of Chemical Industry.

The Influence of Annealing Temperature and Soaking Time on the Ductility of SG 255

This study deals with the effect of annealing temperature on the mechanical properties of SG 255 steel. Furthermore it aims to experimentally obtain better mechanical properties in particular ductility with lower annealing temperature and to minimize the cost of the manufacturing. The SG 255 steel is used in manufacturing of domestic LPG cylinder at Halala Company located in Sulaimanyah/Iraq. A number of samples were made according to ISO 6892, and then heat treated with different annealing temperature (850, 900 and 950 ºC). Moreover, the mentioned samples were broken by tensile machine to obtain the required mechanical properties, and to be compared with that of Halala factory. It was shown that higher elongation percentage 34.18%El with lower annealing temperature 900 ºC can be achieved and this leads to decrease the cost of manufacturing without degrading of cylinder’s quality.

Characterization of gelatin/chitosan scaffold blended with aloe vera and snail mucus for biomedical purpose

Biologically active scaffolds used in tissue engineering and regenerative medicine have been generating promising results in skin replacement. The present study aims to test the hypothesis that the incorporation of Aloe vera and snail mucus into scaffolds based on gelatin and chitosan could improve their structure, composition and biodegradability, with a potential effect on bioactivity. Homogeneous pore diameter as well as pore walls in the composite scaffold could be seen in the SEM image. The pores in the scaffolds were interconnected and their sizes ranged from 93 to 296μm. The addition of Aloe vera and snail mucus enlarged the mean pore size with increased porosity and caused changes in the pore architecture. The FTIR analysis has shown good affinity and interaction between the matrix and the Aloe, which may decrease water-binding sites, so this fact hindered the water absorption capacity of the material. The mechanical properties could explain the highest swelling capacity of the snail scaffold, because the high percentage of elongation could facilitate the entry of liquid in it, generating a matrix with plenty of fluid retention. The real innovation in the present work could be the use of these substances (Aloe and snail mucus) for tissue engineering.

Sorbitol-Plasticized and Neutralized Chitosan Membranes as Skin Substitutes

Chitosan is soluble in diluted acid solutions and can easily form films by casting. However, residual acid neutralization should be performed for biomedical applications what may compromise physical and mechanical properties of the films. Thus, plasticizers can be added to improve these properties. The aim of this study was to characterize morphological, barrier and mechanical properties, besides evaluate the in vitro cytotoxicity of sorbitol-plasticized and NaOH-Na2CO3 neutralized chitosan membranes for skin substitute application. Scanning electron microscopy, X-ray diffraction, water vapor permeability and mechanical tests were carried out to characterize the obtained membranes. Moreover, Vero cells were used for in vitro cytotoxicity evaluation. In this paper, we report a non-cytotoxic sorbitol-plasticized chitosan membrane with desirable properties for skin substitution, such as flexibility, water vapor permeability and high percentage of elongation.

Polymer Solar Collectors. A Better Alternative to Heat Water in Mexican Homes

Polymer solar collectors have been developed by the Mexican company Modulo Solar to satisfy the demand of hot water in Mexican households. Traditionally, the solar collectors have been manufactured in aluminum, copper and iron. However, under certain parameters in the number of risers and diameter of manifolds, it's possible to obtain the same thermal performance with polymer collectors of similar size. In addition, due to its high percentage of elongation, polymers can avoid the use of an antifreeze external valve to resist low environmental temperatures.These polymer solar collectors have achieved the functionality specifications required in the Mexican market which are described in the Technical Specification of Thermal Solar Energy for Housing.

Effect of Temperature in Superplastic Forming in Al6063/SiC<sub>p</sub> Composites

Superplastic forming in Al6063/SiCp composites having a wide range of applications in aerospace and automobile industries due to the high strength and wear resistance[7]. High percentage of elongation was obtained only at high temperatures. At high temperatures liquid phase will form in the grain boundaries. Due to the liquid phase, grain boundary sliding was easy to get the Newtonian viscous flow[1]. In composites high ductility was obtained only the temperature more than 560°C. The maximum dome height of 19 mm was obtained at 580°C. Temperature is more than 600°C the material was failed, fracture was occurred.

Jumbo squid ( Dosidicus gigas) mantle collagen: Extraction, characterization, and potential application in the preparation of chitosan–collagen biofilms

Collagen-based biomaterials have been widely used due to its binding capabilities. However the properties and potential use of new collagen sources are still under investigation. Fish by-products are an excellent source of collagen. Thus, acid-soluble collagen (ASC) was extracted, and biochemical and physicochemically characterized from one under-utilized specie, jumbo squid ( Dosidicus gigas). In addition, commercial chitosan (95–50%)-ASC (5–50%) blend films were successfully prepared by casting, and characterized by infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). The molecular masses of the ASC subunits were about 190 kDa, 110 kDa, and 97 kDa, the content of proline and hydroxyproline was 10.9% and 2.8%, respectively. The FT-IR and nuclear magnetic resonance spectra ( 1H NMR) confirmed collagen peptidic crosslinks, and one endothermic peak was found at 119 °C. The FT-IR spectrum showed that chitosan and ASC remain linked into the films mainly due to hydrogen bonding. The 85:15 (chitosan:ASC) ratio was selected for its thermal and mechanical analyses. The thermograms of this film indicated the presence of two peaks, one at 87–98 °C and the other at 142–182 °C. The chitosan:ASC blend produced a transparent and brittle film, with high percentage of elongation at break, and low tensile strength in comparison to chitosan films. D. gigas mantle might be useful as a new source of plasticizer agent in the preparation of biofilms in composites with chitosan.

Quench Sensitivity and its Effect on the Microstructure and Mechanical Properties of an Al-Zn-Mg-Cu Aluminum Alloy

The high mechanical properties in 7xxx aluminum alloy are obtained by controlling the precipitation hardening microstructure. In this work, the relationship between the microstructures and mechanical properties of 7A04 (Al-Zn-Mg-Cu) aluminum alloy during isothermal aging at 140 oC after different quenching rates has been studied in order to find its useful hardening conditions. The as-extruded samples were solution heat treated at 480 oC and cooled in air, 70 oC water, 40 oC water and 0 oC ice water. Tensile test were performed and the ultimate tensile strength and percentage of elongation were obtained. The difference in the amount of precipitates is known by DSC and the morphology of the precipitates is characterized by TEM. The results indicate that the artificial age hardening response is strongly dependent on the quenching rate. Lower quenching rate results in lower tensile strength but higher percentage of elongation in the peak age condition, and this corresponds to the difference in the size and number density of the precipitates. It is concluded that the highest ultimate tensile strength is obtained in the fastest quenching rate in 0 oC ice water (up to 870Ks-1) while stable and high percentage of elongation is achieved in the intermediate quenching rate (about 226 Ks-1).

Mechanical properties and bonding of maxillofacial silicone elastomers

ObjectivesMaxillofacial silicone elastomers are used to replace facial parts lost through disease or trauma. However, these materials do not possess ideal properties. The purpose of this study was to investigate the mechanical properties of recently and previously introduced maxillofacial silicone elastomers and their bond strength to acrylic resin substrate. Materials and methodsSpecimens of three maxillofacial silicone elastomers (TechSil S25, Cosmesil M511, and Cosmesil Z004) were prepared according to manufacturers’ instructions. Tear and tensile strengths, elongation percentage, modulus of elasticity and hardness were evaluated for each material. Shear bond strengths of these silicone elastomers to primed acrylic resin surfaces were evaluated. Data was analyzed with 1-way ANOVA, Bonferroni, and Dunnett's T3 post hoc tests (P<0.05). ResultsThe tensile strength of S25 was higher than M511 and Z004 (P<0.05). Also S25 had higher elongation percentage in comparison to the other materials (P<0.05). Z004 and S25 were harder (P<0.05) than M511. All materials had the same tear strength and modulus of elasticity (P>0.05). Z004 had higher shear bond strength than S25 (P<0.05). There was a positive linear correlation between shear bond strength, and tear strength (r=0.974) and shore A hardness (r=0.717). ConclusionsAll silicone elastomers tested showed desirable properties. TechSil S25 had more favorable combination of high tensile strength and elongation at break, comparable tear strength, and hardness within the favorable range. However, Cosmesil Z004 was more resistant to shear debonding than other silicone elastomers. SignificanceTechSil S25 silicone elastomer has promising properties that favor its use in fabricating maxillofacial prostheses.

Characterization of Fibroin and PEG-Blended Fibroin Matrices for In Vitro Adhesion and Proliferation of Osteoblasts

Silk fibroin protein, isolated from cocoons of the domesticated mulberry silkworm, Bombyx mori, finds extensive application in biomaterial design. In this study, poly(ethylene glycol) (PEG) 4000 has been used for blending fibroin from both B. mori and Antheraea mylitta, the wild tropical non-mulberry silkworm. PEG-blended films have shown marked changes from the pure fibroin films with respect to thermal properties and mechanical properties. FT-IR spectroscopy confirmed incorporation of new functional groups like quinone oximes. Pure fibroin and PEG-blended fibroin films showed biocompatibility with the HOS osteosarcoma cell line. Von Kossa staining confirmed nodule formation due to mineralization and differentiation of osteoblasts on pure and blended matrices. On account of increased surface roughness, higher elongation percentage, higher thermostability and better activity of osteoblasts in terms of intracellular alkaline phosphatase production, PEG-blended A. mylitta fibroin film shows better potential than PEG-blended B. mori fibroin film for use as potential biomaterial.

Properties of AA6061 Processed by Multi-Axial Compressions/Forging (MAC/F)

Multi-axial compressions/forgings (MAC/F) were conducted at room temperature to obtain severe plastic deformation (SPD) of AA6061 alloy. Microhardness measurements taken across the cross-section of each of the MAC/F processed samples indicated that the hardness distribution is nonuniform during initial compressions/forgings and becomes uniform with subsequent compressions. Microhardness and tensile testing showed that the hardness, yield strength, and elongation of the MAC/F processed material followed similar trends to that for AA6061 processed by equal channel angular pressing (ECAP). The MAC/F material exhibited high strain rate sensitivity and high percentage of elongation to failure in the temperature range of 300–350°C. This observation is in agreement with the high formability of SPD-processed AA6061 over the same temperature range.