Tensile Breaking Research Articles

Use of carboxymethyl cellulose in polyurethane synthesis for thermal applications

This research utilizes carboxymethyl cellulose (CMC) as a renewable feedstock in polyurethane synthesis, offering improved thermal stability and potential for biomedical applications. In this study, a series of CMC-based polyurethanes was synthesized by using a step-growth polymerization reaction. The initial step involved the reaction of isophorone diisocyanate (IPDI) with hydroxy-terminated polybutadiene (HTPB) to prepare an isocyanate (-NCO) terminated prepolymer. Then, this prepolymer was extended using a combination of chain extenders, namely 1,4-butanediol and CMC, to produce the final polyurethanes. Five different samples of polyurethanes were prepared using varying mole ratios of chain extenders (CMC and 1,4-butanediol). The developed polyurethanes were characterized through Fourier transform infrared (FTIR) spectroscopy and proton nuclear resonance (1H NMR). The thermal degradation behaviour of the CMC-based polyurethanes was observed by using thermogravimetric analysis (TGA), while the molecular weight of the samples was determined by using Gel permeation chromatography (GPC). The results showed that polyurethanes prepared using CMC as a natural chain extender, in place of petrochemical-derived 1,4-butanediol, exhibited improved thermal stability and higher molecular weights. Notably, MWF-5 exhibited the highest tensile strength and breaking strain among all the samples, while MWF-1 showed the lowest values.

A universal strategy for decoupling stiffness and extensibility of polymer networks.

Since the invention of polymer networks such as cross-linked natural rubber in the 19th century, it has been a dogma that stiffer networks are less stretchable. We report a universal strategy for decoupling the stiffness and extensibility of single-network elastomers. Instead of using linear polymers as network strands, we use foldable bottlebrush polymers, which feature a collapsed backbone grafted with many linear side chains. Upon elongation, the collapsed backbone unfolds to release stored length, enabling remarkable extensibility. By contrast, the network elastic modulus is inversely proportional to network strand mass and is determined by the side chains. We validate this concept by creating single-network elastomers with nearly constant Young's modulus (30 kilopascals) while increasing tensile breaking strain by 40-fold, from 20 to 800%. We show that this strategy applies to networks of different polymer species and topologies. Our discovery opens an avenue for developing polymeric materials with extraordinary mechanical properties.

Achieving superior low-temperature mechanical performances by nacre-like alternating microlayered structures in PP/POE-based pipes

The poor low-temperature mechanical performance significantly constrains the use of polypropylene (PP) pipe in frigid climates. Here, the PP/POE-based pipes were successfully manufactured using an independently-developed microlayer pipe coextrusion technology, including 8-, 32–, 128-, and 512-layer. The low-temperature mechanical performance of the 512-layer pipe is significantly improved, compared with the blend pipe, its drop hammer impact damage energy and axial tensile breaking energy are increased by 200% and 1100%, respectively. The results from DSC, WAXD, and SAXS indicate that all the microlayer pipes and the blend pipe have almost the same crystal structure. Therefore, the unparalleled low-temperature mechanical performance is attributable to the ultrathin microlayer structures, which dissipated energy by morphological variation of the dispersed phase POE and the effective initiation and termination of craze. Briefly, the self-developed microlayer pipe coextrusion technology provides an effective strategy for the preparation of low-temperature mechanical performance robust PP pipe, and provides a simple and universal method for building an ideal polymer pipe material.

Enhancing the strength of tissue paper through pulp fractionation and stratified forming

Abstract The potential of combining stratified paper forming with pulp fractionation was investigated to improve the balance between low density, which enhances water absorbency and softness, and the dry strength of tissue papers. The selected fractionation approaches allowed us to separate especially stiff, low-fibrillated fibers (A fractions) from flexible, fibrillated fibers containing fines (detached segments of fibers, fibrils, or lamellae fragments) (B fractions). After characterizing the morphological properties of each fiber fraction, 20 g/m2 model papers were produced with and without wet pressing to tune the paper density. At a density of 0.3 g/cm³, the tensile breaking stress of B papers was at least three times higher than that of A papers. The strain at break of B papers was also close to two times higher than that of A papers. Interestingly, bilayer papers A/B exhibited breaking stress values intermediate between those of A and B papers, while native pulp papers, i.e., without fractionation and stratified forming, followed the trend of A papers. Notably, bi-layering the paper improved the breaking stress by up to twice as much without increasing the paper density, which could be highly beneficial in improving the balance of properties in tissue paper grades.

Low Fibrillation Lyocell Fiber: Analysis of Fiber and its Crosslinking Agent

AbstractIn this paper, the hydrolysis process of Dichlorohydroxytriazine (NHDT) under alkaline conditions are studied. A qualitative and quantitative method for the determination of HNDT and its hydrolysis products are established, which further clarified the hydrolysis mechanism of NHDT. Under alkaline conditions, the hydrolysis products are mainly compound 4, compound 6 and chloride (Cl−). The hydrolysis rate of NHDT at different NaOH concentration and temperature is studied. This research can be used to guide the high efficiency preparation of low fibrillation Lyocell fiber. According to the quantitative detection of wet abrasion numbers and the qualitative analysis of the fiber by SEM after slapping, it is concluded that the low fibrillation Lyocell fiber is less prone to fibrillation under the combined action of wet state and mechanical force. Due to hydrolysis of the unreacted second chlorine resulting in harmful products on the low fibrillation Lyocell fiber, the fibrillation propensity increased with the increase of storage time. The mechanical properties of low fibrillation Lyocell fiber prepared under different fiber states are studied. The tensile breaking strength of low fibrillation Lyocell fiber prepared in the form of sequentially arranged fiber bundles are better, which is closely related to the fiber surface.

A novel and sustainable approach to efficiently modify cotton material via a physical flash-explosion with sub- or SCF-CO2 as medium

A novel and eco-friendly approach to modify natural cotton fiber by flash-explosion with a sub- or supercritical fluid of carbon dioxide (sub- or SCF-CO2) for improving its structure and properties was constructed for the first time. The achieved results demonstrate that remarkable improvements in the coloration performance of cotton fiber by 71.1 % and the water retention by 1001.2 % against the control could be readily available by employing the flashily-explosion method at a recommended condition with 4-cycle explosion in sub- or SCF-CO2, and system temperature, fluid treatment duration and explosion number exhibited much more pronounced positive influences among all parameters. Additionally, minimal influences from the supercritical explosion on cotton fiber micronaire value, thermal property and tensile breaking strength were also observed. The scanning electron microscopy (SEM) and porosity investigations clearly show that plenty of micropores and/or strip fissures were formed on the fiber surfaces and their inner phases, and notably improved fiber surface area, pore volume and size were also obtained after a subsupercritical flash-explosion. Nuclear magnetic resonance hydrogen spectroscopy (1H NMR) and Fourier transform infrared spectroscopy (FT-IR) analysis disclose that numbers of hydrogen bonds between the fiber macrochains and/or from their intramolecular chains were broken by generating numerous free hydroxyl groups, which reasonably supported the improvements of the dye uptake behaviors and water retention properties, etc. The Energy-dispersive X-ray spectroscopy (EDS) analysis on the fiber cross-sections further confirms that a loosening of the inner aggregation structure of the cotton fiber was achieved after a flash explosion by significantly enhancing its coloration performance, etc. This innovative approach provides a promising idea and possibility as an alternative to chemical methods via mechanically and physically modifying fiber or other materials with sub- or SCF-CO2 fluid in an eco-friendly and sustainable manner.

A one-pot strategy for modifying the surface of Ti3C2Tx MXene

Surface modification of MXenes significantly expands their potential for a wide range of applications. Here, we demonstrate a one-pot spontaneous polymerization of acrylic acid onto MXene sheet surfaces using an aryl diazonium coupling agent (nitrobenzene diazonium salt) as an approach to tune MXene interfacial properties. We use this formation of polymer coatings as a coagulation strategy for spinning fibers from liquid crystal MXene dispersions, obtaining densified free-standing fibers with tensile strength and breaking energy of ∼155 MPa and ∼4.5 MJ m−3. This simple method potentially offers a scalable approach for fabricating functional MXene macroarchitectures.

Research on high-velocity ballistic impact of para-aramid sateen fabric with ZnO nanorods oriented to the development of soft body armor

This study introduces an innovative approach of utilizing ZnO nanorod growing technology to the sateen fabric in order to improve its ballistic performance. Through SEM, FTIR, XRD and XPS analyses, ZnO nanorods with majority length of 1000–1500 nm and fineness of 200–600 nm have been deposited on the surface of sateen fabric surface Compared the fabric with ZnO nanorods (S-11-Nrs) with its neat counterpart, the mechanical properties of S-11-Nrs are increased, especially the inter-filament friction and fabric tensile breaking strength. However, in the impact process, the number of filaments involved in the impact is reduced and the filaments are mainly failure by the shear action of the bullets. Due to these positive and negative effects, the energy absorption of S-11-Nrs displays inferior ballistic energy absorption. Nevertheless, at lower areal density, in the non-perforation test, S-11-Nrs presents less BFS and shows better resistance to the consecutive shotting process compared with the neat fabric. The reason is that the increase of inter-filament friction limits the movement of filaments and thus results in less BFS. In addition, the flexibility, air permeability and moisture permeability are still kept. This research offers valuable insights for the design and development of comfortable soft body armor.

Preparation and Application of a Novel Liquid Oxygen-Compatible Epoxy Resin of Fluorinated Glycidyl Amine with Low Viscosity

A liquid oxygen-compatible epoxy resin of fluorinated glycidyl amine (TFEPA) with a low viscosity of 260 mPa·s in a wide range of temperatures, from room temperature to 150 °C, was synthesized and used to decrease the viscosity of phosphorus-containing bisphenol F epoxy resins. And the forming process and application performances of this resin system and its composite were investigated. The viscosity of the bisphenol F resin was decreased from 4925 to 749 mPa·s at 45 °C by mixing with 10 wt.% TFEPA, which was enough for the filament winding process. Moreover, the processing temperature and time windows were increased by 73% and 186%, respectively. After crosslinking, the liquid oxygen compatibility was preserved, and its tensile strength, elastic modulus, and breaking elongation at −196 °C were 133.31 MPa, 6.59 GPa, and 2.36%, respectively, which were similar to those without TFEPA. And the flexural strength and modulus were 276.14 MPa and 7.29 GPa, respectively, increasing by 21.73% in strain energy at flexural breaking, indicating an enhanced toughness derived from TFEPA. Based on this resin system, the flexural strength and toughness of its composite at −196 °C were 862.73 MPa and 6.88 MJ/m3, respectively, increasing by 4.46% and 10.79%, respectively.

Analyzing the Strelitzia Juncea Cellulosic Fibers Mechanical Properties’ Experimental Data Using Various Statistical Methods

ABSTRACT Manufacturing composites using natural fibers support the development of more ecologically friendly applications in many industrial areas, including sports equipment, wind turbine blades, construction materials, packaging, medical devices, and prosthetics. To investigate the tests’ number (N) impact on the fibers’ tensile behavior, newly developed fibers from the Strelitzia juncea (SJ) plant are being studied for their mechanical properties using various statistical laws. This study aims to assess the SJ fibers’ performance with a gauge length of 50 mm under quasi-static stress conditions. 150 SJ fibers were tensile tested in five groups (30, 60, 90, 120, and 150) to determine the N impact on the fibers’ tensile strength, break deformation, and Young’s modulus. Weibull and log-normal distributions were used to study statistically the mechanical properties results, and their dispersion was investigated and quantified using least squares and maximum likelihood prediction model with a confidence level of 95%.

Experimental study on the blast resistance of polyurea-coated aramid fabrics

This paper investigates overpressure attenuation capacity and failure mechanism of the polyurea-coated aramid fabric (PCAF) subjected to air-blast loading experimentally. The peak overpressure, arrival time and positive pressure duration of shock waves on the blast and back side of PCAFs were obtained in tests and analyzed. In addition, the failure mode and mechanism were revealed with the electron scanning microscope (SEM), meanwhile the effect of polyurea type, coating position and thickness ratio on the blast resistance were discussed. The results show that in the cases of scaled distances of 1.84 and 2.32 m/kg1/3, PCAFs, one-layer polyurea coated on three-layer aramid woven fabrics, can attenuate the peak overpressure by about 70 %, delay the arrival time by about 0.7 ms, and shorten the positive pressure duration by 10 %-50 %. This is due to the increased out-of plane stiffness and closure of interweaving apertures of the aramid fabric. Furthermore, perforation is the main failure mode of aramid fabrics, in which the tensile breakage in weft yarn and the frictional slip in warp yarn, while the failure modes of PCAF mainly include fracture and exfoliation, with both weft and warp yarns breakage and polyurea failure. It was concluded that the degree of infiltration between the polyurea and fabric affects mechanical properties of the fiber, changing the failure mode of PCAF. In terms of the extent of damage, the PCAF exhibits a superior blast resistance when the polyurea coated on the back side. The blast resistance of PCAF increases first then decreases with an increase in the thickness of the polyurea layer under the same areal density.

Sustainable Plastics with High Performance and Convenient Processibility.

Designing and making sustainable plastics is especially urgent to reduce their ecological and environmental impacts. However, it remains challenging to construct plastics with simultaneous high sustainability and outstanding comprehensive performance. Here, a composite strategy of in situ polymerizing a petroleum-based monomer with the presence of an industrialized bio-derived polymer in a quasi-solvent-free system is introduced, affording the plastic with excellent mechanical robustness, impressive thermal and solvent stability, as well as low energy, consumes during production, processing, and recycling. Particularly, the plastic can be easily processed into diverse shapes through 3D printing, injection molding, etc. during polymerization and further reprocessed into other complex structures via eco-friendly hydrosetting. In addition, the plastic is mechanically robust with Young's modulus of up to 3.7GPa and tensile breaking strength of up to 150.2MPa, superior to many commercially available plastics and other sustainable plastics. It is revealed that hierarchical hydrogen bonds in plastic predominate the well-balanced sustainability and performance. This work provides a new path for fabricating high-performance sustainable plastic toward practical applications, contributing to the circular economy.

Factors affecting the tensile strength of bituminous geomembrane seams

The tensile shear strength, break location, and constant tensile load failure times are examined for seams made from one 4 mm-thick bituminous geomembrane (BGM) product, with corresponding observations specific to that material. In short-term tests, failure is observed within the sheet material once the seam strength exceeded 0.8 times that of the sheet material. The effects of seam thickness reduction and overlap width on seam strength are examined for two methods of seaming. Seams with a short-term strength meeting or exceeding 80% of the sheet strength are subjected to constant tensile loads between 18 and 55% of sheet ultimate strength and the time to failure is reported. The relationship between short-term seam strength and time to failure under sustained load and thickness reduction and squeeze-out is investigated. Constant tensile load testing is proposed as a construction quality assurance procedure to assess the degree of geotextile engagement of field seams.

Recrystallization behavior and strengthening mechanism of friction stir welded T-joint of Ti80 titanium alloy

In this study, Ti80 titanium alloy T-joints were produced by friction stir welding (FSW), and the joint temperature and residual stress distribution of the joints were analyzed by numerical simulation based on the ABAQUS platform, and the correlation between microstructure and performance of FSWed T-joint was investigated. The results show that the SZ is lamellar α grains due to the fact that the peak temperature of all joints exceeds β phase transus. The deformation and dynamic recrystallization behavior take place in the β phase region. During the subsequent cooling stage, the acicular α/α' phase is precipitated from refined prior β phase. The non-uniform heating and cooling results in the significant microstructure differences in the weld thickness direction. The top and middle of the SZ are composed of basketweave structure, while the bottom of the SZ shows a bimodal structure. The microhardness distribution along the skin shows a higher value in the weld area, and the weakest area is located in the HAZ due to recovery, resulting in a significant reduction in dislocation density of the weld. The tensile specimen breaks in the HAZ when it is stretched along the skin direction, while it breaks in a direction parallel to the skin when it is stretched along the stringer. The fracture mechanism of the joint changes from a hybrid mode of ductile and brittle fracture to ductile fracture as the rotation speed increases from 600 rpm to 750 rpm.

Predicting Weld Quality in Duplex Stainless Steel Butt Joints During Laser Beam Welding: A Hybrid DNN-HEVA Approach

Duplex stainless steel (DSS) welding is critical for producing structures and components in a variety of industries. Because traditional optimization approaches cannot manage the complexity of welding, additional solutions must be investigated. This study addresses the need for a systematic exploration of the welding parameters affecting the quality and performance of DSS butt joints, specifically employing fiber laser welding. This study focuses on butt joints in UNS S32304 and 304L using a fiber laser. Welding process parameters were systematically varied, including laser power, scanning speed, beam diameter, and focal position. To efficiently examine the parameters in the design space, the response surface methodology (RSM) with Box–Behnken design (BBD) was used. The combination of the specific parameter values used in the 7th run (Laser Power: 1600 W, Scanning Speed: 2000 mm/min, Beam Diameter: 1.5 [Formula: see text]m, Focal Position: 30 mm) led to better yield point stress (YPS), maximum tensile stress (MTS), break stress (BS) and reduction in area (RA). ANOVA and lack of fit analysis confirmed the significance of the experiment. In particular, the selected welding parameters significantly influenced all responses. A hybrid machine learning method of deep neural network (DNN) and human eye vision algorithm (HEVA) was used for predicting weld quality during laser beam welding (LBW). The hybrid DNN-HEVA consistently outperformed other optimization methods (RSM-BBD, FNN, CNN, and RNN) across key welding quality parameters. High [Formula: see text]2 values (0.9922, 0.9962, 0.9983, and 0.9907) indicated a strong correlation between predicted and actual values for all calculated responses. Lower RMSE, MSE, and MAE values were also highlighted in the precision of predicted values to the experimental data.

Study on the Aging Characteristics of a ±500 kV Composite Dead-End Insulator in Longtime Service.

Composite insulators have been widely used in power grids due to their excellent electrical-external-insulation performance. Long-term operation at high voltage levels accelerates the aging of composite insulators; however, there is a scarcity of research on aged composite insulators operating at 500 kV for over ten years. In this paper, the mechanical, electrical, and microscopic properties were tested on different sheds along a 500 kV composite insulator that had been running for 18 years. Additionally, the results were compared with a new insulator and the standards for live insulator operation. The results showed that the aging of the high-voltage end of composite insulators was the most serious. The results of the physical properties test indicated that the insulator's hardness was compliant but its tensile strength and break elongation did not meet standards. Under wet conditions, the pollution flashover voltage decreases by about 50% compared to the new insulator. Combined with the microscopic test results, the shed skeleton structure could be damaged and the filler might be lost during the aging process of polydimethylsiloxane (PDMS). The hardness of the insulator would increase by the precipitation of inorganic silicon; however, inorganic silicon might destroy the hydrophobicity and other properties of insulator sheds. These results can provide theoretical references for insulator life prediction and operation protection.

Construction of fully bio‐based flame retardant and antibacterial coating on polyester fabric with chitosan and ammonium phytate

AbstractIn this work, a flame retardant and antibacterial coating was constructed on the surface of polyester (PET) fabric by a simple layer‐by‐layer self‐assembly method based on chitosan (CS) and ammonium phytate (APA). The introduction of the coating significantly improved the flame retardant, anti‐dripping, and antibacterial properties of PET fabrics. The PET fabric that has been treated exhibits a limiting oxygen index of 34.6%. During the vertical flame test, it forms an expanded char layer, reduces the damage length to 3.4 cm, and produces no molten drops. The cone calorimeter test results revealed that the peak heat release rate of the treated PET fabric decreased by 62.0%. Additionally, the finished PET fabric has significant antibacterial properties against Escherichia coli, a slight increase in tensile breaking strength, and a slight decrease in whiteness index. This study presents a fully bio‐based, simple, and effective method for flame retardant, anti‐dripping, and antibacterial finishing of PET fabrics.

Failure mechanisms and acoustic responses of cylindrical lithium-ion batteries under compression loadings

To understand the crashworthiness safety of lithium-ion battery (LIB) comprehensively, acoustic emission (AE) testing technology is introduced to explore the mechanical response and failure mechanism. In this paper, the compression process and failure behavior of 18650 LIBs under plane compression, local indentation and three-point bending are experimentally investigated. The effects of indenter diameter, state of charge (SOC) and capacity of the battery on the force-voltage-temperature responses are discussed in detail. The relation between the failure behavior and acoustic response of LIB is studied in combination with AE detection technique. The results show that the deformation of the battery can be divided into three stages before the failure, including the stress on the shell, compression on the internal gap and electrolyte, and stress on the whole. The failure inside the battery is caused by fold, shear fracture, local buckling and tensile break under different loading forms. The smaller the diameter of the indenter is, the lower bearing capacity at the point of failure is. High-SOC batteries experience higher forces and displacements at the failure point. High-capacity batteries have poor bearing capacity and are more prone to thermal runaway. AE signal can be detected at special points during the compression. Combined with the acoustic response of the battery, the whole deformation process is divided into five stages. The researches will provide a guidance for the failure detection and safety evaluation of LIBs.

Particle size effects on silyl‐chromate/VOx/silica bimetallic catalyst for UHMWPE/HDPE in‐reactor blends

AbstractIn this work, four kinds of silica with similar textural properties but different particle size (PS) from 6 to 60 μm were selected as support to prepare silyl‐chromate/VOx/silica bimetallic catalysts for ethylene polymerization, thus making it possible to conduct convincing investigation on the effects of catalyst PS over catalytic behaviors and polymer properties. It is found, owing to mass‐ and heat‐transfer limitations, the catalysts with smaller PS showed higher initial activity, while the deactivation in the later stage was more remarkable. Meanwhile, catalysts with smaller PS synthesized bimodal ultrahigh molecular weight polyethylene/high‐density polyethylene in‐reactor blends (UHMWPE/HDPE IRBs) with higher molecular weight (MW) and narrower molecular weight distribution (MWD). Four PE sample couples with MW increasing from 5 × 105 to 10 × 105 g mol−1 and PS from 40 to 460 μm were selected for tensile and rheological tests. For each couple with similar MW and MWD, the sample with smaller PS always had larger tensile strength and breaking elongation. The cryogenically fractured surface of the samples made by smaller PE particles showed fewer delamination defects and unfused small particles. The rheological results indicate that higher homogeneity was achieved for the sample with smaller PS, which was reflected by the unexpected higher viscosity and storage modulus.

Local delivery of methotrexate/glycyrrhizin-loaded hyaluronic acid nanofiber for the management of oral cancer

The challenges in treating oral cancer include the limited effectiveness and systemic side effects of conventional chemotherapy and radiation therapy. Hyaluronic acid (HA) based Glycyrrhizin (GL) and Methotrexate (MT) loaded localized delivery systems, specifically nanofiber (NF) based platforms, were developed to address these challenges. The electrospinning method was used for the successful fabrication of a homogenous NF membrane and characterized for morphology, drug entrapment efficiency, tensile strength, and ex-vivo mucoadhesive study. Also, it was evaluated for in-vitro drug release profile, ex-vivo drug permeability, in-vitro anti-inflammatory, apoptosis assay by MTT and flow, and against specific cell lines in order to determine their potential for therapeutic use. Superior tensile breaking force (50 g), mucoadhesive strength of 153 gm/cm2, drug permeability, and releasing properties of designed NF, making them perfect requirements for oral cavity delivery. The anticancer potential of MT in the MTT assay and flow cytometry analysis was significantly increased in oral epidermal carcinoma cell (KB cell) for drug-loaded NF with 63.97 ± 1.99 % apoptosis, at 24 h. With these incorporated, GL with MT in NF had an anti-inflammatory potential, also demonstrated in-vitro and in-vivo. In the Ehrlich Ascites Carcinoma (EAC) induced mice model, the optimal formulation’s shows better potential for tumor regression when comparing the developed NF formulation to the drugs. Experimental results show that by lowering mucositis-related inflammation and enhancing the effectiveness of oral cancer treatment, a developed nanofiber-based local drug delivery system offers a feasible strategy for managing oral cancer.