Tensile Elastic Modulus Research Articles

Effect of particle size on the properties of avocado pear wood fiber/low-density polyethylene composite enhanced by pretreatment

Abstract The work entailed the influence of particle size on the characteristics and water absorption resistance of avocado pear wood fiber/low-density polyethylene (APWF/LDPE) composite enhanced by pretreatment. The fiber particle of 100, 80, 60, 40, and 20 mesh (150, 180, 250, 425, and 850 µm) for the avocado wood fiber (APWF) was infused in the resin. Each particle of the fiber with fiber content of 5–25 wt% for the untreated, pretreated with NaOH, NaOH + CH3COOH, and NaOH + CH3COOH + MAPE was intermixed in the resin to produce the APWF/LDPE composites, respectively. The APWF/LDPE composites were analyzed on the properties, water absorption resistance, Fourier transform infra-red, and scanning electron microscopy. The study exhibited that mechanical properties and water absorption resistance of the APWF/LDPE composite were improved at lower particle of the fiber triggered by treatment. The best properties were confirmed at 150 µm of APWF pretreated with NaOH + CH3COOH + MAPE when compounded with the resin. These were proportional to 15.92 MPa, 0.867 GPa, 41.39 MPa, 0.662 GPa, 683 Pa, 84.04 kJ m−2, and 2.44 % for tensile strength, elastic modulus, flexural strength, bending modulus, Brinell hardness, impact strength, and water absorption resistance, respectively. The APWF/LDPE composite for NaOH + CH3COOH + MAPE pretreated is recommended for interior cabinet of an automobile.

Design value of tensile strength of raw bamboo

Bamboo has the advantages of a short growth cycle, good mechanical properties, energy savings, and environmental protection. It is regarded as a new building material with great development potential and application prospects. However, current research on the design values of raw bamboo materials is lacking. In this study, the design value of tensile strength of raw bamboo material was determined by a tensile test of the raw bamboo material, and the statistical values of the tensile strength and elastic modulus of the raw bamboo material were obtained. The standard value and resistance uncertainty statistical parameters of the tensile strength of the raw bamboo material were determined. Considering different load combinations and load effect ratios, the relationship between the reliability index and the resistance component coefficient and the optimal resistance partial coefficient under different load combinations were obtained, and the design value of the tensile strength of the raw bamboo material was obtained.

Assessing the engineering properties of massive self-compacting geopolymer concretes utilising the Taguchi method

In this article, the potential of employing self-compacting geopolymer concrete in massive elements has been investigated. The main binder consisted of 85% ground granulated blast furnace slag and 15% fly ash. An alkaline solution of sodium hydroxide and sodium silicate was utilised. The effects of four parameters (binder content, water-to-binder [W/B] ratio, Na2O% and coarse-to-fine aggregate [C/F] ratio) on the fresh, mechanical and thermal properties of Massive Self-Compacting Geopolymer Concrete (MSCGC) mixes were evaluated. Taguchi’s design of experiments was used to minimise the number of trial mixes. The heat of geopolymerisation of MSCGCs was monitored using a semi-adiabatic chamber and then applied to concrete samples using a temperature match curing system. The maximum compressive and splitting tensile strengths and modulus of elasticity were 62.7 MPa, 5.04 MPa and 33.26 GPa, respectively. Binder content was identified as the most significant parameter affecting the thermal and mechanical properties of the mixtures. The impact of the C/F ratio was greater than the W/B ratio on the thermal characteristics. The results of a numerical analysis reveal that although a higher binder content enhances the mechanical properties of the MSCGCs, it leads to an increased risk of cracking owing to greater heat production.

Developing a sustainable self-compacting geopolymer concrete with 100% geopolymer-coated recycled concrete aggregate replacement

PurposeConcrete, the second most used material in the world, surpassed only by water, relies on a vast amount of cement. The process of cement production emits substantial amounts of carbon dioxide (CO2). Consequently, it is crucial to search for cement alternatives. Geopolymer concrete (GC) uses industrial by-product material instead of traditional cement, which not only reduces CO2 emissions but also enhances concrete durability. On the other hand, the disposal of concrete waste in the landfills represents a significant environmental challenge, emphasising the urgent need for sustainable solutions. This study aimed to investigate waste concrete's best form and rate as the alternative aggregates in self-compacting and ambient-cured GC to preserve natural resources, reduce construction and demolition waste and decrease pertinent CO2 emissions. The binding material employed in this research encompasses fly ash, slag, micro fly ash and anhydrous sodium metasilicate as an alkali activator. It also introduces the best treatment method to improve the recycled concrete aggregate (RCA) quality.Design/methodology/approachA total of25%, 50% and 100% of coarse aggregates are replaced with RCAs to cast self-compacting geopolymer concrete (SCGC) and assess the impact of RCA on the fresh, hardened and water absorption properties of the ambient-cured GC. Geopolymer slurry was used for coating RCAs and the authors examined the effect of one-day and seven-day cured coated RCA. The mechanical properties (compressive strength, splitting tensile strength and modulus of elasticity), rheological properties (slump flow, T500 and J-ring) and total water absorption of RCA-based SCGC were studied. The microstructural and chemical compositions of the concrete mixes were studied by the methods of energy dispersive X-Ray and scanning electron microscopy.FindingsIt is evident from the test observations that 100% replacement of natural aggregate with coated RCA using geopolymer slurry containing fly ash, slag, micro fly ash and anhydrous sodium metasilicate cured for one day before mixing enhances the concrete's quality and complies with the flowability requirements. Assessment is based on the fresh and hardened properties of the SCGC with various RCA contents and coating periods. The fresh properties of the mix with a seven-day curing time for coated RCA did not meet the requirements for self-compacting concrete, while this mix demonstrated better compressive strength (31.61 MPa) and modulus of elasticity (15.39 GPa) compared to 29.36 MPa and 9.8 GPa, respectively, for the mix with one-day cured coated RCA. However, incorporating one-day-cured coated RCA in SCGC demonstrated better splitting tensile strength (2.32 MPa) and water absorption (15.16%).Research limitations/implicationsA potential limitation of this study on SCGC with coated RCAs is the focus on the short-term behaviour of this concrete. This limited time frame may not meet the long-term requirements for ensuring the sustained durability of the structures throughout their service life.Originality/valueThis paper highlights the treatment technique of coating RCA with geopolymer slurry for casting SCGC.

Mechanical properties prediction of ductile iron with spherical graphite using multi-scale finite element model

In this paper, using the multi-scale finite element method, the effect of graphite particles on the mechanical behavior of ductile iron has been investigated under tensile loading. For this purpose, taking into account the spherical geometric shape of the graphite phase and considering a specific volume fraction, these spheres are randomly placed in the whole body and a two-component composite material is created. As a next step, a micromechanical model of these materials is developed by defining the mechanical properties of the matrix and graphites as well as their interfaces. The mechanical properties of the matrix are simulated using the Ramberg-Osgood elastic-plastic model. By simulation in ABAQUS software and using nonlinear dynamic analysis, the effects of volume percentages and adhesion of graphite particles with matrix on the direct tensile load-displacement behavior of ductile iron were investigated. The results of experimental tests were used to verify the results of the numerical model. The weight percentage of graphite particles has a significant effect on the tensile strength and elastic modulus of these cast irons. The results show that with the increase in the amount of graphite particles, the tensile strength of cast iron increases up to a certain value and then reverses. With 21% graphite particles, the maximum tensile strength of ductile iron is 601 MPa. Compared with a pure sample of cast iron, the tensile strength increases by approximately 13.4% for this weight percentage of graphite particles.

Study Of High Performance Concrete Using Local Materials (Fly Ash Of Pltu Labuhan Angin, Mount Sinabung Volcanic Ash And Silica Sand) On The Mechanical Properties Of Concrete

Currently in Indonesia a lot of construction work and concrete is one that is widely used. In the development of concrete construction technology, especially in Indonesia, it is necessary to have concrete capable of carrying high loads using available materials. The development of high quality concrete has 3 levels, namely High Strength Concrete (HSC), High Performance Concrete (HPC) and Ultra High Performance Concrete (UHPC). Against the background of future needs, in this study experiments were carried out in a concrete laboratory to obtain high performance concrete mixes with local materials. At the experimental stage, testing of tools and materials, concrete mix, casting, slump test, manufacture of specimens, maintenance, checking of unit weight, compressive strength test, split tensile strength and modulus of elasticity was carried out. In that study there were 11 variations. Furthermore, the test results were analyzed by the data to draw conclusions. The results showed that the average compressive strength of concrete at 3 days of age was relatively high, namely 53.8 MPa which could be used for fast precision work. In variation 11 mixture (PCC Cement, Silica Fume, Sand Mesh 35-60, Silica Mesh 325, Water, Viscocrete Superplasticizer 8670 MN, Fly Ash 7% and Polypropylene Fiber 0.2%) tested for 28 days, the compressive strength reached 87.5 MPa, so it can be said as HPC concrete. In this study it was concluded that the use of local materials, Sinabung Volcanic Ash waste and fly ash can improve the quality of concrete and can also reduce environmental pollution.

Integration of wood-based components – Cellulose nanofibrils and tannic acid - into a poly(vinyl alcohol) matrix to improve functional properties

Poly(vinyl alcohol) (PVA) biocomposite films reinforced with cellulose nanofibrils (CNF) and biologically active tannic acid (TA) were prepared. The influence of different concentrations of CNF and TA in the PVA polymer matrix was investigated in terms of mechanical properties, thermal properties and hydrophobicity improvement of the prepared films. The results showed that in all cases the addition of CNF and TA improved the values of tensile strength and elastic modulus. The PVA film with 10 % CNF exhibited a 30 % higher tensile strength, and the three-component PVA film with 2 % CNF and 10 % TA (P2C10T) exhibited a 40 % higher tensile strength compared to the neat PVA film. The thermal properties (Tg, Tonset) of the PVA biocomposite films were greatly improved, with a significant effect observed for the three-component PVA films. The Tg of the PVA film with 10 % CNF and 10 % TA was 87 °C, 12 °C higher than that of the neat PVA film. For three-component PVA biocomposites with 4 % and 6 % CNF and with all weight percentages of TA, the Tonset shifted to a higher temperature range by about 30 °C compared to the neat PVA film. The PVA film with 2 % CNF and 10 % TA exhibited about a 20° higher contact angle than the neat PVA film. Moreover, the addition of both fillers to the PVA matrix resulted in PVA biocomposites with lower water absorption. PVA film with 10 % TA absorbed about 90 % less water and PVA film with 10 % CNF and 10 % TA absorbed about 80 % less water than the neat PVA film after the films were soaked in water for one hour. The better properties of the composite films produced are due to hydrogen and ester bonds between the components of the composite, which was confirmed by FT-IR spectroscopy. Antioxidant effective films were also obtained due to the biologically active TA to the PVA and PVA/CNF systems.

Study on deterioration mechanism of granite with a natural single weak surface after freeze-thaw treatment

Natural weak plane of rock is a great threat to the stability of the rock project in cold areas due to the freeze-thaw environment. However, the effect of both weak plane and freeze-thaw cycles is rarely considered. This paper investigated the deterioration mechanism of granite with a natural single weak surface after 0, 20, 40, and 60freezing-thawing cycles. Experimental results show that as the number of freeze-thaw cycles increased, the peak strength of samples decreased while the axial strain gradually increased. The weak plane angle has a significant impact on the sample strength. The strength and elastic modulus changed in a ‘U' shape with the increase of weak plane angle. The samples exhibited a shift from brittle failure to ductile failure with the increase of freeze-thaw cycles. A theoretical model for predicting rock strength is proposed with consideration of weak plane and freeze-thaw effects by combining the single weak plane theory with the decay function. The proposed model is verified by experimental data. The predicted values based on the proposed model match well with experimental data. Samples with lower porosity but higher tensile strength and elastic modulus have larger frost resistance. The research results can provide a scientific basis for the safety assessment of geotechnical engineering in cold regions.

Determinating optimum combination of ageing and manufacturing parameters for laminated composites using response surface methodology

This study mainly focuses on the effects of ageing and manufacturing parameters on the water absorption behaviour and mechanical characteristics of the glass-fibre reinforced polymer (GFRP) composites, and multiple optimizations of these parameters based on the quasi-static mechanical properties and low-velocity impact performances. Utilizing response surface methodology (RSM), an experimental design was executed varying curing temperature (20-100°C), ageing temperature (20-70°C) and salinity (3-35%). After 59-days ageing period, gravimetric, tensile and low-velocity impact tests were conducted to assess weight gain at saturation, changes in tensile strength, elasticity modulus, peak force and peak energy. Tensile fracture surfaces of aged and un-aged samples were examined using scanning electron microscopy. ANOVA results indicated the adequacy of RSM models, supported by high R2 (>80%) and R2adj (>65%) and proper residual distribution. Gravimetric tests revealed that higher curing and ageing temperatures resulted in greater water sorption-induced weight gain, while elevated salinity had the opposite effect. Ageing temperature and salinity are the most influential factors on tensile strength change. Optimal mechanical properties, minimizing differences between aged and un-aged samples, were achieved at 100°C curing temperature, 20°C ageing temperature and 19.8% salinity. Data from this study can be a valuable reference for designing GFRP composites, particularly in marine applications.

Enhancement mechanism of epoxy resin by polyacrylic acid-modified 3D porous graphene: A microscopic and molecular dynamics perspective

Graphene is a two-dimensional nanomaterial with remarkable strength and is a highly effective enhancer in polymer materials. However, the mechanisms underlying the enhancement between the enhancer and the base material remain uncertain. In this study, we have successfully prepared advanced epoxy nanocomposites by grafting polyacrylic acid onto 3D porous graphene (3DG). The covalent functionalization of 3DG has proven to be highly effective in preventing its aggregation within the epoxy matrix. The mechanical test results demonstrated a substantial enhancement in the tensile strength (41.04%), elastic modulus (43.23%), and impact strength (370.88%) of the epoxy resin upon the incorporation of polyacrylic acid-modified graphene (PAAMG). The fracture surfaces of the composites were examined using scanning electron microscopy, which provided insights into the enhancer's mechanism of enhancement. Notably, employing a range of molecular dynamic simulations and analyses, we found that PAAMG exhibits the ability to bifurcate cracks, thereby improving the mechanical properties of the material.

Room-to-low temperature thermo-mechanical behavior and corresponding constitutive model of liquid oxygen compatible epoxy composites

The room-to-low temperature (RT-LT) mechanical behavior of liquid oxygen-compatible epoxy composites (LOC-EP) is of great importance in the strength analysis of lightweight liquid oxygen tanks. This article first explores the tensile-compressive mechanical behaviors of LOC-EP from RT down to −183 °C. The results show that compared with RT, the tensile strength, compressive strength, and elastic modulus at −183 °C increase by 44%, 109%, and 160% respectively. Secondly, based on the theories of molecular chain freezing degree and yield surface extension, a ductile-brittle transition T of −60 °C and a completely brittle T of −90 °C are obtained sequentially. Moreover, a universal thermal-mechanical constitutive model for EP is derived, and the constitutive model parameters of LOC-EP from RT to −183 °C are fitted and calibrated using Matlab. Finally, the proposed constitutive model is introduced into Abaqus through a user subroutine. On the one hand, three-dimensional one-element analyses demonstrate that the simulation curves are highly consistent with the experimental and Matlab-fitted curves (errors less than 3%) with good convergence/accuracy. On the other hand, the fracture modes obtained from macroscopic simulations of tensile and compressive specimens are also coherent with the experimental fracture modes.

Properties of Macadam Stabilized with Cement and Asphalt Emulsion

The cracking of cement-stabilized macadam (CSM) reflects to the asphalt layer, which is one of the reasons for the failure of pavement performance and structure. Adding asphalt emulsion to CSM can effectively prevent the formation of cracks. The primary purpose of this article is to reveal the effect of asphalt emulsions on the performance of CSM by adding different contents of asphalt emulsion. For this purpose, tests of unconfined compressive strength (UCS), flexural tensile strength (FTS), elastic modulus, and frost resistance were performed on CSM with gradations of CSM-5 and CSM-10 (the maximum particle sizes of the macadam in the gradation composition are 5 mm and 10 mm), respectively. The test results showed that the UCS of CSM decreased with the increment of asphalt emulsion content. The FTS and elastic modulus of CSM increased with the content of asphalt emulsion. Based on the FTS test results, the frost resistance coefficient Km1, defined according to the CSM splitting strength prior to and subsequent to freeze–thaw, was used to evaluate the frost resistance. The test results showed that the frost resistance of CSM improved with the increase in asphalt emulsion content for the same cement content. In conclusion, adding asphalt emulsion to CSM has positive effects on the FTS, elastic modulus, and frost resistance. Therefore, for the purpose of maintaining the UCS value of CSM, the content of cement should be considered at the same time as the controlling of the content of asphalt emulsion.

Three-dimensional structural characterization and mechanical properties of bamboo parenchyma tissue

Bamboo is predominantly composed of parenchyma and fibers, with parenchyma constituting approximately 52% of the bamboo culm wall. The bamboo fibers function as the primary load-bearing elements, its structure and performance have been studied in detail. However, investigations concerning the structure and mechanical properties of parenchyma tissue remain limited. Consequently, this study focuses on the comprehensive characterization of the three-dimensional (3D) structure of bamboo parenchyma. Additionally, the study encompasses the evaluation of tensile and compressive properties of parenchyma tissue, along with an analysis and discourse on failure mechanisms. Parenchyma cells can be categorized into two types: long cells, accounting for approximately 89.37%, and short cells. The measured tensile strength and elastic modulus of the parenchyma tissue are 48.81 MPa and 706.48 MPa, respectively. The propagation of cracks leading to tensile failure predominantly occurs along the middle lamella, accompanied by partial penetration through cell walls. Concerning parenchyma tissue compression, three discernible stages can be identified: the elastic stage, plateau stage, and densification stage. The axial load-bearing capacity of parenchyma tissue exceeds that of the tangential and radial orientations. Axial compressive strength and elastic modulus of the parenchyma are measured at 18.82 MPa and 5.24 GPa, respectively. Compression failure modes in parenchyma tissue encompass compression bending and cell fracture, shear failure of the middle lamella, and detachment and debonding of the cell wall. The comprehensive structural and mechanical parameters derived from this investigation provide valuable insights for the development of numerical models and understanding the various mechanical properties of bamboo.

A double-layer cellulose/pectin-soy protein isolate-pomegranate peel extract micro/nanofiber dressing for acceleration of wound healing

Multi-layered wound dressings can closely mimic the hierarchical structure of the skin. Herein, a double-layer dressing material is fabricated through electrospinning, comprised of a nanofibrous structure as a healing-support layer or the bottom layer (BL) containing pectin (Pec), soy protein isolate (SPI), pomegranate peel extract (P), and a cellulose (Cel) microfiber layer as a protective/monitoring layer or top layer (TL). The formation of a fine bilayer structure was confirmed using scanning electron microscopy. Cel/Pec-SPI-P dressing showed a 60.05 % weight loss during 7 days of immersion in phosphate buffered solution. The ultimate tensile strength, elastic modulus, and elongation at break for different dressings were within the range of 3.14–3.57 MPa, 32.26–36.58 MPa, and 59.04–63.19 %, respectively. The release of SPI and phenolic compounds from dressings were measured and their antibacterial activity was evaluated. The fabricated dressing was non-cytotoxic following exposure to human keratinocyte cells. The Cel/Pec-SPI-P dressing exhibited excellent cell adhesion and migration as well as angiogenesis. More importantly, in vivo experiments on Cel/Pec-SPI-P dressings showed faster epidermal layer formation, blood vessel generation, collagen deposition, and a faster wound healing rate. Overall, it is anticipated that the Cel/Pec-SPI-P bilayer dressing facilitates wound treatment and can be a promising approach for clinical use.

The influence of phenolic resin modified by cardanol on improving the processability of PVC

Polyvinyl chloride (PVC) is a kind of plastic widely used in different industries, and it is a hard and brittle polymer that requires the use of plasticizers to improve processability. Phthalates are small molecule plasticizers of PVC, which are easy to volatilize and migrate while improving the processing properties of PVC. We propose alternatives based on phenolic resin prepolymer modified by cardanol (CPF), which were added to PVC as reactive plasticizer and can improve the processability of PVC. The effects of CPF on the rheological properties and migration resistance of plasticized PVC were studied, and the changes in the physical properties of blends were also discussed. The results showed that the viscosity of PVC melt can be reduced by two orders of magnitude by adding 30 wt% prepolymers at 180°C compared with PVC without CPF, which indicated that CPF can be used to reduce the processing temperature of PVC. The test results of migration resistance showed that the mass loss rate of the blend with 30 wt% prepolymers was less than 1 wt% after curing, however, the mass loss rate of the blend with 30 wt% dioctyl phthalate (DOP) was more than 12% after 5 days of testing. When the PVC/CPF mass ratio was between 60/40-70/30, the maximum values of tensile strength and elastic modulus are 64.4 MPa and 3.2 GPa, respectively, which showed the addition of CPF could significantly improve the tensile strength and elastic modulus of the blend system compared with PVC without CPF. Especially, the thermal stability of CPF is better than that of DOP, CPF exhibits the maximum thermal decomposition temperature (410°C), higher than that of DOP (170°C), which can adapt to higher processing temperature.

Mechanical properties and compressive constitutive model of steel fiber-reinforced geopolymer concrete

Geopolymer concrete is an environmentally friendly material, and the addition of steel fibers can overcome its brittleness and improve its performance, which has broad application prospects. However, there are currently few studies on the comparative analysis of mechanical properties between steel fiber-reinforced geopolymer concrete (SFGPC) and steel fiber-reinforced ordinary Portland concrete (SFOPC), as well as uniaxial compressive constitutive models for SFGPC. Therefore, 144 cubes and 36 prisms were tested for SFGPC and SFOPC. The main variables were the volume content of steel fibers (0 %, 0.5 %, 1 %, 1.5 %, and 2 %), curing age (7 and 28 days), and water-to-binder ratio (0.45, 0.5, and 0.55). The slump, failure pattern, compressive strength, splitting tensile strength, elastic modulus, peak strain, toughness index, and compressive stress−strain curves were obtained. The results indicate that with the increase of steel fiber content, the compressive strength, splitting tensile strength, peak strain, and toughness index of SFGPC increase, while the elastic modulus remains almost unchanged. Compared with the plain geopolymer concrete, the above corresponding indexes of SFGPC with 1 % steel fiber content can be increased by 9.9 %, 20.5 %, 23.3 %, and 52.2 %, respectively. The 7-day compressive and tensile strengths of SFGPC can reach about 80 % of the 28-day strengths. Under the same conditions, SFGPC exhibits higher strength, peak strain, and lower elastic modulus than SFOPC. The scanning electron microscope (SEM) test results show that the geopolymer matrix has a denser structure and a tighter bond with steel fibers than the cement matrix. Based on the plain geopolymer concrete, formulas for mechanical indexes and a uniaxial compressive stress−strain model of SFGPC were proposed.

Development and characterization of peppermint essential oil/rice husk fibre/ corn starch active biocomposite film and its performance on bread preservation

Active packaging with antimicrobial characteristics can inhibit bacterial growth and prolong the shelf life of packaged food products. Numerous attempts have been made to develop biobased eco-friendly polymer packaging films to minimize the utilization of synthetic antimicrobial packaging. However, polymer-based packaging has limited physio-mechanical properties, making it a poor candidate for packaging applications. In this study, an antimicrobial fibre-reinforced biocomposite was fabricated using rice husk fibre (RH) in the starch matrix to enhance the properties of packaging film. Peppermint essential oil (PEO), extracted from peppermint leaves, was incorporated into the film to enable antimicrobial properties. Rice husk fibre was varied from 10% to 50%, PEO ranged from 1% to 6%, and influence on various properties of biocomposite film was analysed. Developed biocomposite films were evaluated using XRD, FT-IR, SEM, water contact angle, and surface roughness. Furthermore, mechanical properties, water solubility, moisture content, colour properties, and optical barrier properties of biocomposite film were also calculated. In mechanical properties, biocomposite film that has 10% rice husk fibres, and 1% PEO showed the maximum tensile strength and elastic modulus of 2.25 MPa, and 57.4 MPa, respectively. In the biodegradability test, the degradation rate was reduced with reinforcing rice husk fibres and incorporation of PEO. The fabricated biocomposite films exhibit a zone of inhibition against Gram-positive bacteria (S. aureus and B. subtilis) as well as Gram-negative bacteria (E. coli and K. pneumoniae). Moreover, fabricated biocomposite was used as bread packaging and compared with synthetic and open packaging for shelf-life analysis. In observation, it was found that it has increased the shelf life of packed bread and reduced the growth of food-borne microbes in bread. This fabricated antimicrobial biocomposite is an eco-friendly packaging film that may reduce the food wastage and environmental impact of packaging materials by utilizing agricultural waste.

Investigation of mechanical properties of plastic composites produced using wood and eggshell

In this study, it is aimed to produce wood plastic composite material with eggshell additives and to investigate the mechanical properties of these materials. Mechanical properties such as tensile strength and modulus of elasticity, elongation at break, flexural strength and modulus of elasticity and impact resistance of new materials produced by adding eggshell to wood plastic composite at different rates were investigated. It was determined that tensile strength values gradually decreased due to the increase in the amount of eggshell in the composites produced. The modulus of elasticity of the composite material in tensile strength increases with the increase in the amount of eggshell in the mixture. With the increase of the eggshell ratio used, the elongation values of the plastic composite at break are reduced. The eggshell material used in wood plastic composite reduces the bending strength of the material. The eggshell reduces the modulus of elasticity of the composite material in bending. The eggshell composite material did not cause a significant change in impact resistance.

Development and characterization of an active starch-based film as a chlorogenic acid delivery system

Given its health benefits for the human body, chlorogenic acid (CA) offers promising applications in the food industry. However, the instability and low bioavailability of CA remain to be solved. In this paper, a starch-based film prepared by the homogenization and solution-casting method was used as an effective carrier to alleviate these problems. Homogenization (10–50 MPa) reduced the starch paste viscosity and its particle sizes from 21.64 to 7.68 μm, which promoted the starch recrystallization and induced chemical cross-links between starch-CA, as confirmed by the FTIR result with an appearance of a new CO peak at about 1716 cm−1. Accordingly, the rapidly digestible starch content of the film was reduced to 27.83 % and the CA encapsulation efficiency was increased to 99.08 % (from 65.88 %). As a result, the film system extended CA's release time beyond 4 h and significantly increased the heat-treated CA's antioxidant activity. Besides, the tensile strength and elastic modulus of the film were also improved to 6.29 MPa (from 1.63 MPa) and 160.98 MPa (from 12.02 MPa), respectively, by homogenization. In conclusion, the developed active starch-based film could be used as an edible film for the production of functional food or active food packaging.

Low molarity geopolymer concrete: Effects on compressive strength, elastic modulus, sorptivity and chloride migration

The present study explores the application of low molarity geopolymer concrete for structural applications. In this context, 35 compositions with 4 M and 6 M NaOH concentrations have been developed to yield compressive strength ranging from 10 to 40 MPa. The flow values at low water to binder (w/b) ratio are shown to be influenced by molarity of NaOH while it remains range bound at higher w/b ratio. The effect of curing conditions reveals low reactivity rate under ambient conditions with significant enhancements at elevated curing conditions. Three compositions with compressive strength of 30 ± 2 MPa have been further investigated for tensile strength, elastic modulus, plastic strain, sorptivity and chloride migration. The results reveal that despite similar compressive strength, the mix compositions have significant impact on the fresh and hardened properties indicating possibility of multiparameter optimization. The development of low molarity geopolymer concrete with possibility to optimize other structural/durability parameters in addition to compressive strength would enhance sustainability, economy and structural performance of geopolymer concrete.