Tensile Strength Values Research Articles

Fabrication of Novel Polyurethane matrix-based Functional Composites with Enhanced Mechanical Performance

Thermoplastic polyurethane (TPU) has gained significant interest in several fields, including automobile steering wheels, and the electronics sector due to their easier processability, abrasive resistance, and self-lubricating performances. However, their strong inherent flammability and significant smoke and heat production during burning limit their industrial applications. Therefore, its applicability can be enhanced with the addition of high-strength reinforcement and making them antibacterial and flame-retardant. This research is designed to examine the influence of zirconium phosphate (ZrP) and zinc oxide (ZnO) nanoparticles on the novel polyurethane/glass fiber reinforced composites for flame retardant and antibacterial applications with improved mechanical performance. Three different types of novel polyurethane (PU1, PU2, PU3) matrices were prepared using different recipes, and 7% ZrP and 5% ZnO nanoparticles were added to the polyurethane matrices separately, and their corresponding composite samples were fabricated using glass reinforcement. Mechanical i.e., Charpy impact, hardness and tensile, and functional i.e., flame retardancy (FR) and antibacterial tests were performed to compare their performance. Mechanical testing results showed that PU3-based composite samples showed the highest values of impact force, hardness, and tensile strength in both ZrP and ZnO nanoparticle-based composite samples. Furthermore, 7% ZrP-PU3 composite exhibited the best performance of flame retardancy due to the presence of hexamethylene diisocyanates (HDI) content. Likewise, the 5% ZnO-PU3-based composite exhibited the highest antibacterial activity along with enhanced mechanical performance.

Dissimilar MIG Welding Optimization of C20 and SUS201 by Taguchi Method

This study looks at how welding intensity, speed, voltage, and stick-out affect the structural and mechanical characteristics of metal inert gas (MIG) welding on SUS 201 stainless steel and C20 steel. The Taguchi method is used to optimize the study’s experiment findings. The results show that the welding current has a more significant effect on the tensile test than the welding voltage, stick-out, and welding speed. Welding voltage has the lowest influence. In addition to the base metals’ ferrite, pearlite, and austenite phases, the weld bead area contains martensite and bainite microstructures. The optimal parameters for the ultimate tensile strength (UTS), yield strength, and elongation values are a 110 amp welding current, 15 V of voltage, a 500 mm.min−1 welding speed, and a 10 mm stick-out. The confirmed UTS, yield strength, and elongation values are 452.78 MPa, 374.65 MPa, and 38.55%, respectively, comparable with the expected value derived using the Taguchi method. In the flexural test, the welding current is the most critical element affecting flexural strength. A welding current of 110 amp, an arc voltage of 15 V, a welding speed of 500 mm.min−1, and a stick-out of 12 mm are the ideal values for flexural strength. The flexural strength, confirmed at 1756.78 MPa, is more than that of the other samples. The study’s conclusions can offer more details regarding the dissimilar welding industry.

Prediction of Tensile Properties of Natural Fiber Reinforced PP Hybrid Composites by Facca-Kortschot-Yan (FKY) and Palsule Equations

Abstract Natural fiber reinforced polymer hybrid composites are advanced materials for commercial and engineering applications. Rule of hybrid mixtures has been applied to develop Facca-Kortschot-Yan (FKY) Equation and Palsule equation for predicting tensile strength and modulus of these hybrid polymer composites. This study predicts the values of tensile strength and modulus of a few natural fibers reinforced polypropylene hybrid composites by these two equations and compares them with the reported experimental values.

Experimental study of natural fiber Jute reinforced by metal wires and its using as patch on semi-elliptical defected of the API X52 pipelines corroded according to ratio a/t

The aim of this study is to evaluate the efficiency of a hybrid patch of Jute with/without Glass fiber reinforced with Steel wire for repairing defective API X52 pipeline. Five specimens were tested using Jute fiber, Glass fiber and Steel wire to enhance the mechanical properties according to ASTM 3039 and D790 standards. The experimental results showed that the effects of hybrid materials (synthetic and natural) for repairing API X52 pipeline defect depend on the nature of the patch and the properties of the adhesive (polyester resin) by increasing the tensile strength and bending load. In the first step, specimen S5 was selected due to its distinctive mechanical properties, which revealed maximum values of tensile strength, toughness and bending load respectively 47.42014 MPa, 2357.42 kJ/m3 and 488.3 N. In the second step, the selected sample (S5) was used as a patch to repair API X52 pipeline, which has semi-elliptical defects where the bending load is 31.4246 kN. According to the obtained results, the patch efficiency is 103% for defects with a/t < 0.3, which can be, restored 100% of the mechanical properties. There fore, repairing API X52 pipeline using hybrid patch (Jute reinforced with Steel wires) with shallower defects can be a successful technique.

Synthesis and characterization of novel carboxymethyl tamarind kernel gum - Poly (vinyl alcohol)/guar gum-based hydrogel film loaded with ciprofloxacin for biomedical applications

The current study delineates the synthesis of hydrogel films comprised of carboxymethyl tamarind kernel gum (CMTKG), poly (vinyl alcohol) (PVA), and guar gum (GG) using glutaraldehyde (GL) as cross-linker. The hydrogel films were evaluated in terms of equilibrium swelling ratio (ESR), moisture content, thickness, wetting analysis, thermal, and mechanical analysis. The tensile strength value lies in the range of 95.80 to 149.07 MPa while elongation at break value lies in the range of 1.51 to 5.20 %. The FTIR spectroscopy confirmed the presence of hydrogen bonding between CMTKG, PVA, and GG components of hydrogel film. FE-SEM micrographs indicated the rough surfaces of hydrogel film. TGA-DTA analysis confirmed that the thermal stability of hydrogel film was found to be increased by incorporating the ciprofloxacin (CFX) drug into the hydrogel matrix. CFX was embedded in the best-swelled hydrogel film and in-vitro drug release behavior was studied at alkaline pH 7.4 phosphate buffer solution. It was found that the maximum drug release was to be 73 % after 24 h at pH 7.4. Moreover, the release data was fitted in various kinetic models such as the First-order, Higuchi, and Korsmeyer-Peppas models. The best-fitted Korsmeyer-Peppas model suggested that the release of the drug follows Fickian diffusion and the value of diffusion exponent (n) was determined to be 0.38. The cytocompatibility of the hydrogel film was analyzed by MTT assay while the antibacterial behavior of the hydrogel film against E. coli and S. aureus showed clear zone of inhibition area. Thus, the overall results indicated that CMTKG/PVA/GG hydrogel film have potential to be used in the biomedical applications.

Utilizing Nata de Pina for Hydrogel Synthesis: Effects of Citric Acid on Hydrogel Characteristics

Abstract The increasing production of pineapples will produce waste that’s increasing anyway. To optimize the utilization of pineapple skin waste One solution is to use the pineapple skin waste To be used as the main material for making nata de pina. Nata de pina is fiber cellulose on the surface of pineapple medium from the results of Acetobacter xylinum bacterial metabolism. The resulting cellulose is then used as a basic material manufacture of natural polimer as hydrogel. The research stage consists of 3 stages, namely making Nata de Pina, the manufacture of hydrogels as well as the characterization of the resulting hydrogels. The method used in hydrogel synthesis is chemical crosslinking with citric acid as a crosslinking agent. Variable variations performed in This study is the use of citric acid concentrations of 35%,37,5%,40%, and 42.5%. Nata de Pina-based hydrogel was successfully synthesized. Hydrogels based on Nata de Pina were successfully synthesized. It is shown based on the results of the FTIR test that the hydrogel has a C=O group that proving that there has been a cross-linking between cellulose and citric acid. The resulting hydrogel has good antibacterial activity against bacteria-positive and negative grams. The best results are shown by hydrogels with 40% concentration where the hydrogel has a maximum tensile strength value by 11.4 MPa. This study aim the innovative use of Nata de Pina, a byproduct of pineapple peel waste, as a novel material for hydrogel synthesis. By employing citric acid as a crosslinking agent, we investigated the effects on the hydrogel’s mechanical and swelling properties. Our findings demonstrate the potential of Nata de Pina-based hydrogels in sustainable material applications, offering an eco-friendly alternative to synthetic polymers.

Functional Silsesquioxanes-Tailoring Hydrophobicity and Anti-Ice Properties of Polylactide in 3D Printing Applications.

To explore the tailoring of hydrophobicity in 3D-printed polylactide (PLA) composites for advanced applications using additive manufacturing (AM), this study focuses on the use of Fused Deposition Modeling (FDM) 3D printing. PLA, a material derived from renewable sources, is favored for its eco-friendliness and user accessibility. Nonetheless, PLA's inherent hydrophilic properties result in moisture absorption, negatively affecting its performance. This research aims to modify PLA with organosilicon compounds to enhance its hydrophobic and anti-icing properties. Incorporating fluorinated siloxane derivatives led to significant increases in water contact angles by up to 39%, signifying successful hydrophobic modification. Mechanical testing demonstrated that the addition of organosilicon additives did not compromise the tensile strength of PLA and, in some instances, improved impact resistance, especially with the use of OSS-4OFP:2HEX:2TMOS, which resulted in an increase in the tensile strength value of 25% and increased impact strength by 20% compared to neat PLA. Differential scanning calorimetry (DSC) analysis indicated that the modified PLA exhibited reduced cold crystallization temperatures without altering the glass transition or melting temperatures. These results suggest that organosilicon-modified PLA has the potential to expand the material's application in producing moisture and ice-resistant 3D-printed prototypes for various industrial uses, thereby facilitating the creation of more durable and versatile 3D-printed components.

Experimental study of shielding gas concentration on mechanical properties of stainless steel alloy parts using wire and arc additive manufacturing

Wire Arc Additive Manufacturing (WAAM) is an emerging three-dimensional fabrication technology that enables higher deposition rate, material savings, and near net-shape. In this study, various shielding gas concentration (SGC) of argon (Ar) and carbon-di-oxide (CO2) was employed to fabricate 316L using Cold Metal Transfer (CMT) WAAM process. Microstructure characteristics and mechanical properties of thick-walled parts were studied. Microstructure studies show a combination of columnar and equiaxed grains in various regions. Microhardness results exhibit the uneven distribution of hardness value from bottom to top region along the building direction and the values are ranging between185 and 240 HV. Tensile studies indicates the both horizontal and vertical direction samples secures the higher ultimate tensile strength (UTS), yield strength (YS) and elongation (EL) values and confirmed the isotropic properties. Fractography studies prove ductile fracture with the evidence of dimples and enough plastic deformation. From the experimental results, the SGC-2 possesses finer solidification structure and higher mechanical properties than the other samples. The as-fabricated WAAM parts possess higher mechanical properties than the 316L parts fabricated via casting and wrought parts.

EXPERIMENTAL AND OPTIMIZATION-BASED ANALYSIS TO MAXIMIZE MECHANICAL-RELATED ATTRIBUTES OF FRICTION STIR WELDED CDA101 CU ALLOY JOINTS

This paper deals with the identification of optimized process parameters for FSW of 6[Formula: see text]mm thick CDA 101 Cu alloy plates. Three distinctive parameters, the tool’s traverse speed, rotational speed, axial load, have been considered as self-reliant variables for formulating a numerical model based on nonlinear regression-type approach, with the objective of anticipating mechanical attributes of joints. From the surface- and contour-type plots, it was revealed that the axial load in combination with rotational speed has played a dominant role in influencing the tensile and yield strength of the CDA101 Cu alloy joints. At the same time, the traverse speed of the tool has played a dominant role in enhancing the ductility of the CDA101 joints through the generation of ample volumes of frictional heat, which in turn have facilitated both coarsening of grain structures and softening of materials in an ideal manner. Employing tool rotational speed, traverse speed and axial load in the ranges of 1750–1900[Formula: see text]rpm, 23–27[Formula: see text]mm/min and 5.75–6.5[Formula: see text]kN, respectively, was found to enhance the tensile strength of the CDA101 Cu alloy joints. FSW process parameters attained through the numerical meta-model of RSM have led to the attainment of the highest value of tensile strength of 209.5[Formula: see text]MPa together with a 141.4[Formula: see text]MPa yield strength with very minimal fitting errors of 0.28% and 0.52%, respectively. A collection of additional experimental data has been employed to verify the formulated empirical-based formula and additionally, an entirely different optimization technique namely PSO (i.e. particle swarm optimization) was implemented for comparison and validation purposes. The formulated meta-model of RSM generated the largest value of % of elongation of 14.23%, though the relative percent error was around 1.988%, which was slightly larger than that of the value (i.e. 14.11%) generated by PSO, with a relative error of 0.58%.

Elimination of cracks in Al–Zn–Mg–Cu alloy by addition of TiO2 in selective laser melting

7050 aluminium alloy is widely used in aerospace industry due to its excellent mechanical properties. 7050 aluminium alloy belongs to Al–Zn–Mg–Cu alloy. Due to the formation of cracks in selective laser melting (SLM) forming of Al–Zn–Mg–Cu alloys, 7050 aluminium alloy is difficult to be applied to forming and manufacturing in this technological field. In order to solve this critical problem, in this paper, titanium dioxide (TiO2) powder was mixed with 7050 aluminium alloy using ball milling method to achieve the effect of eliminating cracks. The cracks in the specimens completely disappeared when the TiO2 additions were 1.5 wt% and 2 wt%. With the addition of TiO2, the grains gradually changed from coarse columnar crystals to fine equiaxed crystals. Combined with the temperature field simulation, the grain refinement and crack elimination mechanism of TiO2 in SLM forming were analysed. The grain refinement is attributed to the formation of Al3Ti. The crack elimination was attributed to the reduction of the intergranular solid-liquid channel length. The maximum values of tensile strength and elongation of 7050 aluminium alloy formed by SLM are achieved at 2 wt% of TiO2. The values are 389 MPa and 8.8 %. The better mechanical properties were attributed to the synergistic effect of crack elimination, Hall-Petch, and Orowan strengthening. This study provides experimental guidance for the preparation of crack-free 7050 aluminium alloy.

Profile of a Composite Based on Bacterial Cellulose and Polyvinyl Alcohol as a Drug Release Matrix for Tetracycline Hydrochloride

Bacterial cellulose (BC) is a natural polymer with good mechanical properties and hydrophilicity. Polyvinyl alcohol (PVA) is a synthetic polymer widely used in medicine. Both have been researched for their potential in drug release and acceptance. This study aims to determine the role of BC and PVA as drug release matrices for tetracycline hydrochloride (TCH), with additional fillers such as graphite (G) and TiO2. The results showed that the composites with BC matrix had lower mechanical properties than those with PVA matrix, with tensile strength values of 6.4075 and 17.446 MPa, respectively. However, the BC matrix was superior in porosity and swelling ability. The drug release testing of TCH from the composites showed that the appropriate model to describe drug release in BC matrix composites was in zero order, while the PVA matrix was in first order. The antibacterial activity of the composites on both matrices was tested against Staphylococcus aureus. The results indicate that both composites have potential applications in promising biomedical fields.

Variations in Size of Sugarcane Bagasse Fiber as Raw Material for Making Environmentally Friendly Plates

Plastic is a material that is often used as a storage medium, equipment and also furniture to support human activities, but plastic is not easily broken down by the environment. Bioplastic technology is one of the efforts made to address the problem of plastic packaging which can pollute the environment. Environmentally friendly plates, bioplastic products made from tapioca, glycerol and sugar cane bagasse. This research aims to determine the effect of variations in the size of bagasse on tensile strength, elongation at break, water resistance and biodegradability of environmentally friendly plates and to obtain the best formulation of varying sizes of bagasse as raw material for making environmentally friendly plates. This research used a Completely Randomized Design (CRD) with one factor, namely variation in the size of the bagasse. The results of this research show that there is a real influence between tensile strength, water resistance and biodegradability, however, in the elongation test, variations in bagasse did not have a significant effect. Tensile strength values range from 20.00 N/mm2 to 47.72 N/mm2. The largest elongation value is 4.08%. The highest water resistance is at room temperature, namely 88.86% with a degree of curvature of 16⁰ and in water with a temperature of 60⁰C, namely 85.02% with a degree of curvature of 18.75⁰. Variations in the size of bagasse also affect the biodegradability of environmentally friendly plates which ranges from 11.77% to 14.65%. The best treatment is a sample with a variety of bagasse sizes of 60 mesh, because it has high strength compared to other samples.

Sodium alginate edible films incorporating cactus pear extract: antimicrobial, chemical, and mechanical properties

The potential benefits of biodegradable and functional food packaging materials have garnered increasing attention in recent years. Sodium alginate (SA), a commonly utilized polysaccharide, is particularly noteworthy for producing biodegradable films for food packaging. This study aimed to investigate SA-based edible films enriched with various proportions of cactus pear peel extract (CPPE). We assessed the films and extracts for total phenolic content, antimicrobial and antioxidant activities, as well as mechanical properties. Cactus pear peels powder (CPPP) exhibited higher contents of total polyphenols (1243.82 mg GAE/100 g), total flavonoids (18.92 mg QE/100 g), and betalains (2.28 mg/100 g). The main constituents detected were catechol, pyrogallol, catechin, and alpha-coumaric acid, with concentrations of 1013.82, 223.45, 148.21, and 101.02 ppm, respectively, contributing about 45.71%, 9.85%, 6.54%, and 4.46% of the total phenolic compounds. The thickness of the SA films increased from 0.220 mm to 0.265 mm. The tensile strength values ranged from 1.98 to 3.12, while the elongation at break values for SA-CPPE films decreased relative to the plain SA film. Moreover, the inclusion of CPPE improved the barrier characteristics (with water vapor permeability values for SA films with 1%, 2%, and 3% CPPE ranging from 0.72 × 10−5 g·h−1·m−1·Pa−1 to 1.68 × 10−5 g·h−1·m−1·Pa−1) and induced variations in flexibility and resistance. The plain SA film did not exhibit any inhibitory activity against bacteria and fungi. However, the inclusion of CPPE in alginate films showed favorable antibacterial properties, which improved progressively with increasing CPPE concentration. These findings highlight the potential of incorporating active alginate-based films in food preservation.

Synthesis Of Biofoam Based On Glucomannan Porang And Polyvinyl Alcohol (PVA) With The Addition of Seaweed Dregs

Biofoam (Biodegradable foam) is an alternative packaging to Styrofoam made from natural raw materials that can be biodegraded in the soil. Biofoam is generally made from 3 constituent materials in the form of main ingredients in the form of starch or other similar materials, plasticizers such as PVA and also fillers in the form of fibers containing cellulose. The purpose of this study was to determine the effect of the combination of porang glucomannan, PVA and seaweed pulp on biofoam and to determine the best formulation and characteristics of the biofoam samples made.. The technique of making biofoam was done using baking technique with 9 different treatments. Each treatment was repeated 3x and observations were made on biofoam structure, mechanical properties testing (tensile strength, elongation and young modulus), water absorption test, and biodegradation test. The results showed that Polyvinyl Alcohol plays a role in the formation of a hollow biofoam structure. The thickness parameter value for each treatment was 0.628-1.939 mm. The tensile strength value of each treatment has a value ranging from 15.989-35.265 N/mm². The elongation value for each treatment ranged from 25.719-76.427%. The young modulus value for each treatment ranged from 0.343-0.896 N/mm². The water absorption value of each treatment obtained values ranging from 35.81-77.12%. And the value of testing biodegradation parameters obtained values ranging from 8.68-32.18%. So that the best treatment obtained using the multiple attribute method is the A3B1 treatment (PVA 15% and the ratio of seaweed pulp concentration to glucomannan 1: 2).

End-grain bonding of spruce timber at low curing temperatures – effects on tensile strength and how to improve

ABSTRACT The end-grain bonding of timber components using Timber Structures 3.0 technology (TS3) represents an emerging construction method in the field of timber engineering. For onsite applications, research is being conducted to determine how low temperatures during the curing process affect the bonding and to explore potential methods of mitigating any adverse impacts. The current research results reveal that low curing temperatures detrimentally influence the mechanical properties of the bond. Conversely, investigations into bonding with heated casting resin as a means to counteract the effects of low curing temperatures demonstrate highly beneficial outcomes. Overall, this study provides design-relevant tensile strength values, which, when coupled with suitable application strategies, enable effective bonding under low ambient temperatures. Future investigations will delve deeper into the failure mechanism (adhesion – cohesion) as it relates to curing temperature variations.

Development of hydroxyapatite/poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/gelatin composite nanofibers to improve bone‐forming cell proliferation and mineral deposition

AbstractCalcium phosphate hydroxyapatite (HA) was successfully incorporated into poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/gelatin (PHBV/GEL) nanofibers through an electrospinning process in a hexafluoroisopropanol solvent (HFIP). The PHBV/GEL was electrospun and collected using a rotating metallic network to develop highly ordered nonwoven mats. The effects of HA addition on the morphologies of the obtained fibers were investigated using SEM. The average diameter of the fibers ranged around 700–900 nm, depending on the HA content. From a mechanical perspective, the addition of HA nanoparticles showed variations in tensile strength and elastic modulus values. The lowest tensile strength measured for neat PHBV/GEL was 0.37 ± 0.08 MPa with an elastic modulus of 9.45 ± 0.65 MPa, whereas the highest tensile strength reported for 5% HA‐loaded PHBV/GEL mats was 1.1 ± 0.4 MPa with an elastic modulus of 16.9 ± 0.39 MPa. In addition, cell viability, and mineral deposition were also studied using MC3T3‐E1 pre‐osteoblasts. The in vitro experiment results showed that the HA loaded‐PHBV/GEL mats provide optimal conditions for cell growth and osteogenic differentiation of MC3T3‐E1 cells. This study reveals the potential of PHBV/GEL/HA matrices in the development of novel guided bone‐regeneration (GBR) membranes for orthopedic and craniomaxillofacial surgery, by providing favorable structural features for attachment, growth, and differentiation of osteoblast cells.Highlights Simple and cheap electrospinning strategy toward network‐like fibrous mats. Microstructure, mechanical, and biological features were evaluated. Electrospun PHBV/GEL/HA promoted calcium phosphate deposition by MC3T3‐E1 cells.

Influence of Plant Additives on Antimicrobial Properties of Glass-Fabric-Reinforced Epoxy Composites Used in Railway Transport.

The aim of this research was to explore the innovative use of natural additives, containing phytochemicals with proven antimicrobial effects, in the production of epoxy-glass composites. This study was based on information regarding the antimicrobial effects of phytochemicals present in Cistus incanus, Zingiber officinale, and Armoracia rusticana. The additives were subjected to a gas chromatography (GC) analysis to determine their composition, and, subsequently, they were used to prepare resin mixtures and to produce epoxy-glass composites. Samples of the modified materials were tested against E. coli, S. aureus, and C. albicans. In addition, flammability and durability tests were also performed. It was found that the strongest biocidal properties were demonstrated by the material with the addition of cistus, which caused a reduction of microorganisms by 2.13 log units (S. aureus), 1.51 log units (E. coli), and 0.81 log units (C. albicans). The same material also achieved the most favorable results of strength tests, with the values of flexural strength and tensile strength reaching 390 MPa and 280 MPa, respectively. Public transport is a place particularly exposed to various types of pathogens. Currently, there are no solutions on the railway market that involve the use of composites modified in this respect.

Effect of intermetallic compounds on the mechanical properties of Cu/Al clad sheets with an SS304 interlayer

Annealing treatments were conducted on Cu/Al clad sheets incorporating a 304 stainless steel (SS304) interlayer to investigate the impact of intermetallic compounds (IMCs) on the mechanical properties of these clad sheets with an interfacial layer. Additionally, the mechanisms of interfacial strengthening and crack propagation behavior were examined. It was found that the best overall performance was achieved for samples annealed at 200 °C, showing tensile strength, fracture elongation, and peeling strength values of 219 MPa, 7.19 %, and 19.6 N/mm, respectively. For the rolled clad sheet, cracks typically initiated at the edges of the SS304 fragments, accompanied by minor residual holes and stress concentrations. Post-annealing, the Cu and Al layers underwent varying degrees of recovery and recrystallization, and element diffusion increased, leading to improvements in elongation and interfacial bonding strength of the clad sheets. As the thickness of the IMCs grew, the interfacial crack propagation path shifted to the Al2Cu/AlCu interface within the IMC layer, significantly reducing the bonding strength.

Optimizing foaming agent concentration and recycled fine aggregate content to enhance mechanical and durable properties of foam concrete mixes

This research explores the impact of using recycled fine aggregates from construction and demolition wastes (CD-RFA) through the replacement of natural sand in proportion of 0 %, 10 %, 30 %, 50 %, 70 %, and 100 % for making foam concrete mixes. Protein based foaming agent was diluted with water in ratios of 1:20, 1:40 and 1:60. It was found that with the increase in the proportion of recycled fines, the porosity, sorptivity and water absorption of foam concrete mixes increases significantly. At the same time, a downward trend in the mechanical characteristics was noted. However, the obtained values of compressive strength, flexural strength, and split tensile strength of 22.35, 5.68 and 2.27 MPa were found to be well within the ACI 523 R 2014 recommended ranges of 8–22, 3–6.4 and 1–2.2 MPa, respectively. Hardened density, abrasion resistance, and resistance to sulphates and chlorides attack showed perceptible decline. The present study recommends the replacement of natural sand up to 50 % with CD-RFA. The foam concrete mix prepared using recycled fines will help clearance of a large quantities of CD wastes, thereby benefiting the environment and ecology.

The physicomechanical optimization and antimicrobial properties of the Ɛ-polylysine/ZnO nanoparticles loaded active packaging films

Response surface methodology (RSM) was used to evaluation the effects of Ɛ-polylysine (Ɛ-PL: 0–5 wt%) and zinc oxide nanoparticle (ZnO: 0–5 wt%) on the physico-mechanical properties of the gelatin/polyvinyl alcohol (G/PVA) based nanocomposite packaging films. Using Design-Expert 7.0.0 software, numerical and graphical improvements were also carried out. The optimization was focused on increasing the values of the ultimate tensile strength (UTS), strain at break (SAB), Young's modulus (YM), and lightness (L), and reducing the values of the water vapor permeability (WVP), yellowness index (YI), and overall color difference (∆E). The overall optimal concentrations of ZnO and Ɛ-PL were 1.00 (wt%) and 4.30 (wt%), respectively, with a maximum desirability of 75 %. Additionally, the microstructure, surface topography, interactions, and distribution quality of ZnO nanoparticles and Ɛ-PL in the biopolymer matrix were analyzed using Scanning Electron Microscopy, Atomic Force Microscopy, Fourier Transform Infrared Spectroscopy, and X-ray diffraction measurements. The result of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) confirmed improved thermal stability of nanocomposite films containing ZnO nanoparticles and Ɛ-PL. MIC test showed that ZnO and Ɛ-PL were effective against E. coli, S. aureus, P. fluorescence, and S. typhimurium at the concentration of 2–3 and 10–12 mg/mL, respectively. The antimicrobial activity of G/PVA nanocomposites containing ZnO, Ɛ-PL, and ZnO/Ɛ-PL against E. coli was more than S. aureus.