An Experimental Study on the Influence of Different Cooling Methods on the Mechanical Properties of PVA Fiber-Reinforced High-Strength Concrete after High-Temperature Action.

High-strength concrete (HSC) has a high compressive strength, high density, excellent durability, and seepage resistance, but its deformation ability is weak. Adding fibers can improve the physical and mechanical properties of HSC. Additionally, the HSC structure may face the threat of fire. In the process of fire extinguishing, the damage mechanism of high-temperature-resistant concrete is complicated due to the different contact conditions with water at different locations. Hence, it is essential to conduct pertinent research on the behavior of fiber-reinforced HSC with different cooling methods after high-temperature action. In this paper, polyvinyl alcohol fiber (PVA fiber) was selected to be added into the HSC to carry out high-temperature experimental research, so as to explore the apparent changes, failure pattern, and mass loss rate of the fiber-reinforced HSC using different cooling methods and analyze the influence of its residual compressive strength and flexural strength. The test results suggest that, with the increase in heating temperature, the color of the specimen's surface transitions from dark blue-gray to white, and the quantity of surface cracks on the specimen gradually rises. The mechanical strength gradually decreases as the heating temperature increases. At a consistent heating temperature, the mechanical strength initially rises, and then falls with an increase in fiber content. The maximum compressive strength and flexural strength were achieved at PVA fiber contents of 0.2% and 0.3%, respectively. For different temperatures and fiber contents, the mechanical strength after natural cooling is generally higher than that after immersion cooling. In addition, X-ray polycrystalline diffractometry (XRD) and scanning electron microscopy (SEM) tests were conducted to analyze the compositional alterations and microstructure of the fiber-reinforced HSC following high-temperature exposure, accompanied by an explanation of the factors influencing the alterations in the physical and mechanical properties. Therefore, the findings of this study can serve as a valuable reference for the utilization of HSC in engineering structures and contribute to the advancement of HSC technology.

Properties and release behavior of sodium alginate-based nanocomposite active films: Effects of particle size of IRMOF-3.

Nanoparticles are used as fillers to improve the properties of biopolymers, and their particle size is an important parameter. This work aims to investigate the effect of particle size of isoreticular metal-organic framework-3 (IRMOF-3) on the mechanical, physical, and release properties of sodium alginate (SA)-based composite active film. In our study, IRMOF-3 with six different particle sizes was synthesized by introducing additives. IRMOF-3 loading with carvacrol (IRMOF-3/CA nanoparticles) was incorporated into the SA matrix to prepare the composite film. The characterization and testing results of films showed that the particle size of nanoparticles affected the physical morphology and chemical structure of the film. Especially smaller nanoparticles uniformly dispersed into the SA matrix more easily, forming a denser and more stable spatial network structure with SA, which could more significantly improve the tensile strength, water vapor barrier, and hydrophobic properties of the film (P < 0.05). In addition, the CA release rate from the active film could be significantly reduced by about 33.90 % even when the smallest particle size of the IRMOF-3/CA nanoparticles was added. Therefore, when IRMOF-3/CA is used as the nano-filler to develop SA-based active film, its particle size has a potential influence on the properties of the film.

Effect of alkali treatment on mechanical and water absorption properties of biodegradable wheat-straw/glass fiber reinforced epoxy hybrid composites: A sustainable alternative for conventional materials.

Fiber-reinforced polymer composites are preferred over conventional materials because of their superior strength and modulus. Previously limited due to high manufacturing costs, synthetic fibers have been replaced by some natural fibers, such as waste wheat straw fibers. Here, epoxy-based polymer composites' mechanical and physical properties have been investigated, focusing on fiber weight ratios for both treated and untreated fiber. The research found that treated fibers display more effective mechanical qualities than untreated fibers, with a higher tensile strength of 54.4 MPa. The untreated Wheat Straw-Glass fiber reinforced composite has a less tensile strength of 26.3 MPa (10 wt% fiber). Pure resin-based composite has the most minor tensile strength at 1.52 MPa. The highest flexural strength obtained for hybrid composite is 88.76 MPa for treated fiber with epoxy resin and 49.6 MPa for untreated 30 wt % fiber. At the same time, the sole epoxy resin composite has the lowest value of 10.60 MPa. Untreated fiber (30 wt%) has the highest impact energy of 8J. Untreated wheat straw fiber absorbs more water due to its hydrophilic nature. In contrast, treated fiber exhibits better bonding and minimal water content, and the sole epoxy resin composite exhibits hydrophobic properties, resulting in less water absorption. The treated fiber displays better bonding than the untreated fiber throughout the SEM analysis. Wheat Straw fiber is mainly used for biodegradable plastic formation, housing construction, building materials, etc.

Precision Engineering of Chondrocyte Microenvironments: Investigating the Optimal Reaction Conditions for Type B Gelatin Methacrylate Hydrogel Matrix for TC28a2 Cells.

Gelatin methacrylate (GelMA) is a photocrosslinkable biomaterial that has gained widespread use in tissue engineering due to its favorable biological attributes and customizable physical and mechanical traits. While GelMA is compatible with various cell types, distinct cellular responses are observed within GelMA hydrogels. As such, tailoring hydrogels for specific applications has become imperative. Thus, our objective was to develop GelMA hydrogels tailored to enhance cell viability specifically for TC28a2 chondrocytes in a three-dimensional (3D) cell culture setting. We investigated GelMA synthesis using PBS and 0.25M CB buffer, analyzed the mechanical and physical traits of GelMA hydrogels, and evaluated how varying GelMA crosslinking conditions (GelMA concentration, photoinitiator concentration, and UV exposure time) affected the viability of TC28a2 chondrocytes. The results revealed that GelMA synthesis using 0.25M CB buffer led to a greater degree of methacrylation compared to PBS buffer, and the LAP photoinitiator demonstrated superior efficacy for GelMA gelation compared to Irgacure 2959. Additionally, the stiffness, porosity, and swelling degree of GelMA hydrogels were predominantly affected by GelMA concentration, while cell viability was impacted by all crosslinking conditions, decreasing notably with increasing GelMA concentration, photoinitiator concentration, and UV exposure time. This study facilitated the optimization of crosslinking conditions to enhance cell viability within GelMA hydrogels, a critical aspect for diverse biomedical applications.

Evaluation of the Mechanical and Physical Properties of Maxillofacial Silicone Type A-2186 Impregnated with a Hybrid Chitosan-TiO2 Nanocomposite Subjected to Different Accelerated Aging Conditions.

The effects of incorporating a pioneer chitosan-TiO2 nanocomposite on the mechanical and physical properties of room-temperature vulcanization (RTV) maxillofacial A-2186 silicone under accelerated aging protocols were rigorously examined. This investigation utilized 450 samples distributed across five distinct silicone classifications and assessed their attributes, such as tensile strength, elongation, tear strength, hardness, and surface roughness, before and after various accelerated aging processes. Statistical methodologies, including a one-way ANOVA, Tukey's HSD, and Dunnett's T3, were employed based on the homogeneity of variance, and several key results were obtained. Silicones infused with 1 wt.% chitosan-TiO2 showed enhanced tensile strength across various aging procedures. Moreover, the 1 wt.% TiO2/Chitosan noncombination (TC) and 2 wt.% TiO2 compositions exhibited pronounced improvements in the elongation percentage. A consistent rise was evident across all silicone categories regarding tear strength, with the 1 wt.% chitosan-TiO2 variant being prominent under certain conditions. Variations in hardness were observed, with the 1 wt.% TC and 3 wt.% chitosan samples showing distinctive responses to certain conditions. Although most samples displayed a decreased surface roughness upon aging, the 1 wt.% chitosan-TiO2 variant frequently countered this trend. This investigation provides insights into the potential of the chitosan-TiO2 nanocomposite to influence silicone properties under aging conditions.

Tannic Acid as a Green Cross-linker for Biomaterial Applications.

Plant-derived tannic acid as a green material can play an important role in improving the mechanical and physical properties of biomaterials. Tannic acid can be used as an antioxidant, antimicrobial, and cross-linking agent in biomaterial products due to its unique functional groups. Its active phenolic groups can react with biomaterial functional groups to form bonds that improve performance. In this review, the mechanism of effectiveness of tannic acid as a natural crosslinker in improving the properties of biomaterials for various applications, such as tissue engineering, tissue adhesives, drug delivery, wound healing, and toxicity studies, has been investigated. In general, tannic acid can be a suitable alternative to synthetic crosslinkers in biomaterial applications.

Radial Variability of Selected Physical and Mechanical Parameters of Juvenile Paulownia Wood from Extensive Cultivation in Central Europe-Case Study.

The research on Paulownia cultivation and wood properties is up to date in many countries. However, there are no data on the properties of this wood defined on a microscale, on microtome samples. The main aim of this study was to find the best valorization path for the wood of Paulownia Shang Tong Hybrid F1 from an extensively cultivated plantation established in April 2017 in Poland by determining the tensile strength, the wood density, the strength-to-density ratio, and the modulus of elasticity on a cross-section of the trunk. The wood was collected from extensive plantation, where production is based on the natural resources of the habitat and ambient weather conditions, which is the opposite to the intensive cultivation model, which is the recommended model of Paulownia cultivation. The results of this study show that the mean density of the analyzed samples was approximately 210 kg/m3 when the mean value of the modulus of elasticity (MOE) was approximately 2400 MPa. The mean result for the tensile strength ratio to density was 11.25 km. In the case of anatomical structure, the increasing trend with age was noticed both in fiber and vessel characteristics. The study results provide unique data worldwide about Paulownia wood's properties based on a cross-section of the trunk, from plantations cultivated in conditions which are not recommended by seedlings producers. The obtained data indicate that the Paulownia wood (examined) from the cultivation in this study has a technical quality similar to that of model-intensive agricultural plantations.

A review on recent eco-friendly strategies to utilize rice straw in construction industry: pathways from bane to boon.

With the growing demand, a large amount of paddy has been harvested by growers leaving behind the stubble (left over rice straw), which is being a big burden on the farmers for its management. For the easy access, the burning of stubble has been opted which in turn results in the deterioration of the environment. To mitigate this problem, rice straw utilization strategies should be opted. Therefore, in this review article, the strategies of utilizing rice straw in fiber or ash form to manufacture construction materials have been summarized. The manuscript also considers the method of productions, variability in raw materials, and various mechanical/physical properties of construction materials targeted. Further, the financial aspects related to utilization of rice straw and rice straw ash are also encoded at last. This review will be helpful to expedite the research in this field and may also be used for startups related to various product development using straw in the local areas, which may depreciate the burning of straw in the field and its environmental effects.

Experimental Investigation on the Mechanical and Physical Properties of Glass/Jute Hybrid Laminates.

Natural fibres have been partly substituting synthetic fibres in polymer composites due to their renewable character and many other advantages, and sometimes, they can be hybridized into a single composite for a better combination of properties. This work aims to study the effect of hybridization and stacking sequence on the mechanical and physical properties of the glass/jute laminates. For that, pure jute, pure glass and glass/jute hybrids were manufactured by vacuum infusion process using orthophthalic polyester resin. The composites were characterized via C-scan analysis, density, volume fraction of constituents and optical microscopy analyses. Mechanical properties were obtained from tensile, compression and shear tests. The longitudinal properties were higher than transverse properties for all laminates. The hybrids presented intermediate density and mechanical properties compared to pure glass and pure jute laminates. The hybrids produced similar density and tensile modulus, but with small differences in tensile strength and compressive strength which were justified based on variations in resin and void content due to the influence of the stacking sequence (glass/jute interlayer regions). In addition, the pure glass and the hybrid laminates displayed acceptable failure morphology in the in-plane shear test, but not the pure jute laminate.

High Amylose-Based Bio Composites: Structures, Functions and Applications.

As biodegradable and eco-friendly bio-resources, polysaccharides from a wide range of sources show steadily increasing interest. The increasing fossil-based production of materials are heavily associated with environmental and climate concerns, these biopolymers are addressing such concerns in important areas such as food and biomedical applications. Among polysaccharides, high amylose starch (HAS) has made major progress to marketable products due to its unique properties and enhanced nutritional values in food applications. While high amylose-maize, wheat, barley and potato are commercially available, HAS variants of other crops have been developed recently and is expected to be commercially available in the near future. This review edifies various forms and processing techniques used to produce HAS-based polymers and composites addressing their favorable properties as compared to normal starch. Low toxic and high compatibility natural plasticizers are of great concern in the processing of HAS. Further emphasis, is also given to some essential film properties such as mechanical and barrier properties for HAS-based materials. The functionality of HAS-based functionality can be improved by using different fillers as well as by modulating the inherent structures of HAS. We also identify specific opportunities for HAS-based food and biomedical fabrications aiming to produce cheaper, better, and more eco-friendly materials. We acknowledge that a multidisciplinary approach is required to achieve further improvement of HAS-based products providing entirely new types of sustainable materials.

Facile preparation of collagen fiber-glycerol-carboxymethyl cellulose composite film by immersing method.

Carboxymethyl cellulose (CMC) and glycerol were added by immersing neutralized collagen fiber paste into CMC/glycerol aqueous solutions with different mass ratios, forming composite films. CMC decreased the glycerol adsorption by 49.5%. The presence of CMC formed rougher film surface and more compact internal structure. Glycerol increased the distances between collagen molecules and decreased the relative triple helix contents. The tensile strength and Young's modulus of film in dry condition maximum respectively increased by 125% and 277% with the immersion in CMC (1.5%)/glycerol (4%) solution, compared to the sample immersed into pure glycerol solution, but mechanical properties decreased at high glycerol content. Besides, lower wet mechanical strength was observed as the addition of CMC, corresponding to the higher water swelling ratio of film. CMC also improved the shrinkage stability under boiling and the thermostability of film at a fixed glycerol level, but higher glycerol content caused the decrease of denaturation temperature of film.

Physical and Mechanical Properties of Thermally-Modified Beech Wood Impregnated with Silver Nano-Suspension and Their Relationship with the Crystallinity of Cellulose.

The aim of this study was to investigate the physical and mechanical properties of thermally modified beech wood impregnated with silver nano-suspension and to examine their relationship with the crystallinity of cellulose. Specimens were impregnated with a 400 ppm nanosilver suspension (NS); at least, 90% of silver nano-particles ranged between 20 and 100 nano-meters. Heat treatment took place in a laboratory oven at three temperatures, namely 145, 165, and 185 °C. Physical properties and mechanical properties of treated wood demonstrated statistically insignificant fluctuations at low temperatures compared to control specimens. On the other hand, an increase of temperature to 185 °C had a significant effect on all properties. Physical properties (volumetric swelling and water absorption) and mechanical properties (MOR and MOE) of treated wood demonstrated statistically insignificant fluctuations at low temperatures compared to control specimens. This degradation ultimately resulted in significant decrease in MOR, impact strength, and physical properties. However, thermal modification at 185 °C did not seem to cause significant fluctuations in MOE and compression strength parallel to grain. As a consequence of the thermal modification, part of amorphous cellulose was changed to crystalline cellulose. At low temperatures an increased crystallinity caused some of the properties to be improved. Crystallinity also demonstrated a decrease in NS-HT185 in comparison to HT185 treatment. TCr indices in specimens thermally treated at 145 °C revealed a significant increase as a result of impregnation with nanosilver suspension. This improvement in TCr index resulted in a noticeable increase in MOR and MOE values. Other properties did not show significant fluctuations, suggesting that the effect of the increased crystallinity and cross-linking in lignin was more than the negative effect of the low cell-wall polymer degradation caused by thermal modification. Change of amorphous cellulose to crystalline cellulose, as well as cross-linking in lignin, partially ameliorated the negative effects of thermal degradation at higher temperatures and therefore, compression parallel to grain and modulus of elasticity did not decrease significantly. Overall, it can be concluded that increased crystallinity and cross-linking in lignin can compensate for some decreased properties caused by thermal modification, but it would be significantly dependent on the temperature under which modification is carried out. Impregnating specimens with silver nano-suspension prior to thermal modification enhanced the effects of thermal modification as a result of improved thermal conductivity.

Mechanical and Physical Properties of Oriented Strand Lumber (OSL): The Effect of Fortification Level of Nanowollastonite on UF Resin.

The aim of this work is to investigate the effect of the fortification level of nanowollastonite on urea-formaldehyde resin (UF) and its effect on mechanical and physical properties of oriented strand lumbers (OSL). Two resin contents are applied, namely, 8% and 10%. Nanowollastonite is mixed with the resin at two levels (10% and 20%). It is found that the fortification of UF resin with 10% nanowollastonite can be considered as an optimum level. When nanowollastonite content is higher (that is, 20%), higher volume of UF resin is left over from the process of sticking the strips together, and therefore is absorbed by wollastonite nanofibers. The mechanism involved in the fortification of UF resin with nanowollastonite, which results in an improvement of thickness swelling values, can be attributed to the following two main factors: (i) nanowollastonite compounds making active bonds with the cellulose hydroxyl groups, putting them out of reach for bonding with the water molecules and (ii) high thermal conductivity coefficient of wollastonite improving the transfer of heat to different layers of the OSL mat, facilitating better and more complete resin curing. Since nanowollastonite contributes to making bonds between the wood strips, which consequently improves physical and mechanical properties, its use can be safely recommended in the OSL production process to improve the physical and mechanical properties of the panel.

Effect of carboxylic acids as compatibilizer agent on mechanical properties of thermoplastic starch and polypropylene blends.

In this work, polypropylene/thermoplastic starch (PP/TPS) blends were prepared as an alternative material to use in disposable packaging, reducing the negative polymeric environmental impact. Unfortunately, this material displays morphological characteristics typical of immiscible polymer blends and a compatibilizer agent is needed. Three different carboxyl acids: myristic (C14), palmitic (C16) and stearic acids (C18) were used as natural compatibilizer agent (NCA). The effects of NCA on the mechanical, physical, thermal and morphological properties of PP/TPS blends were investigated and compared against PP/TPS with and without PP-grafted maleic anhydride (PPgMA). When compared to PP/TPS, blends with C18, PPgMA and C14 presented an improvement of 25, 22 and 17% in tensile strength at break and of 180, 194 and 259% in elongation at break, respectively. The highest increase, 54%, in the impact strength was achieved with C14 incorporation. Improvements could be seen, through scanning electron microscopy (SEM) images, in the compatibility between the immiscible components by acids incorporation. These results showed that carboxylic acids, specifically C14, could be used as compatibilizer agent and could substitute PPgMA.

Determination of the mechanical and physical properties of cartilage by coupling poroelastic-based finite element models of indentation with artificial neural networks.

One of the most widely used techniques to determine the mechanical properties of cartilage is based on indentation tests and interpretation of the obtained force-time or displacement-time data. In the current computational approaches, one needs to simulate the indentation test with finite element models and use an optimization algorithm to estimate the mechanical properties of cartilage. The modeling procedure is cumbersome, and the simulations need to be repeated for every new experiment. For the first time, we propose a method for fast and accurate estimation of the mechanical and physical properties of cartilage as a poroelastic material with the aid of artificial neural networks. In our study, we used finite element models to simulate the indentation for poroelastic materials with wide combinations of mechanical and physical properties. The obtained force-time curves are then divided into three parts: the first two parts of the data is used for training and validation of an artificial neural network, while the third part is used for testing the trained network. The trained neural network receives the force-time curves as the input and provides the properties of cartilage as the output. We observed that the trained network could accurately predict the properties of cartilage within the range of properties for which it was trained. The mechanical and physical properties of cartilage could therefore be estimated very fast, since no additional finite element modeling is required once the neural network is trained. The robustness of the trained artificial neural network in determining the properties of cartilage based on noisy force-time data was assessed by introducing noise to the simulated force-time data. We found that the training procedure could be optimized so as to maximize the robustness of the neural network against noisy force-time data.

Developing a Sealing Material: Effect of Epoxy Modification on Specific Physical and Mechanical Properties.

To develop a matched sealing material for socket rehabilitation of grey cast iron pipes, an epoxy resin is modified by the addition of different components to improve the flexibility. Three different modifications are made by adding ethylene-propylene diene monomer (EPDM) rubber powder, reactive liquid polymer (ATBN) and epoxidized modifier. In this paper the effect of the modification method as well as the influence of absorption of water on the mechanical and physical properties are analyzed in terms of: tensile strength, modulus of elasticity, adhesion performance, pressure resistance, glass transition temperature and water content. A comparison with neat epoxy shows for all materials that the modulus of elasticity and strength decrease. Unlike other tested modification methods, the modification with rubber powder did not enhance the flexibility. All materials absorb water and a plasticization effect arises with further changes of mechanical and physical properties. The application of the sealant on the grey cast iron leads to a reduction of the strain at break (in comparison to the common tensile test of the pure materials) and has to be evaluated. The main requirement of pressure resistance up to 1 MPa was tested on two chosen materials. Both materials fulfill this requirement.