Decrease In Tensile Strength Research Articles

Unsaturated polyester resin based composites: A case study of lignin valorisation

Materials from green resources boast a low carbon footprint, forming the foundation of the circular economy approach in materials science. Thus, in this study, waste poly(ethylene terephthalate) (PET) was subjected to depolymerization using propylene glycol (PG), and subsequent polycondensation with bio-based maleic anhydride (MA) produced unsaturated polyester resin (b-UPR). Bio-derived acryloyl-modified Kraft lignin (KfL-A) served as a vinyl reactive filler in the b-UPR matrix to create b-UPR/KfL-A composites. The structural characterization of KfL-A and b-UPR involved the use of FTIR and NMR techniques. The mechanical properties of the newly fabricated composites were assessed through tensile strength, Vickers microhardness, and dynamic mechanical tests. The addition of KfL-A to the rigid b-UPR matrix enhanced material flexibility, resulting in less stiff and hard materials while preserving composite toughness. For instance, incorporating 10 wt% of KfL-A in b-UPR led to a 17% reduction in hardness, a 48% decrease in tensile strength, and a 20% reduction in toughness. Positive environmental impact was achieved by incorporation of 64 wt% of renewable and recycled raw material. Analogously prepared b-UPR/KfL composites showed structural inhomogeneity and somewhat better mechanical properties. Transmission (TEM) and scanning (SEM) electron microscopies revealed a suitable relationship between mechanical and structural properties of composites in relation to the extent of KfL-A addition. The UL94V flammability rating confirmed that flame resistance increased proportionally with the KfL-A addition. Once deposited in a landfill, these composites are expected to disintegrate more easily than PET, causing less harm to the environment and contributing to sustainability in the plastics cycle.

The synthesis of a novel polymer‐type antistatic agent and its effect on the properties of polypropylene

AbstractIn this paper, a novel polymeric antistatic agent, TMQ, with excellent antistatic properties, low cost, and good compatibility with polypropylene (PP), was prepared from isopentenyl polyoxyethylene ether (TPEG), maleic anhydride (MAH) and homemade quaternary ammonium salt (QAS). The structure is characterized using FTIR and 1H NMR. How the addition of TMQ and the molar ratio of TPEG, QAS, and MAH affect the antistatic, mechanical, and crystalline properties of PP are investigated. The results show that as the feed ratio of TPEG, MAH and QAS is TPEG:MAH:QAS = 1:8:8, the modified PP displays the best overall performances. Further exploring finds out when TMQ is added at 15 wt%, the surface resistivity of PP reduces to 6.78 × 109 Ω/sq and the volume resistivity of PP reduces to 7.9 × 109 Ω cm−1, the notched impact strength and melt index improve by 357% and 991%, respectively, while the tensile strength decreases by 38.6% compared with that of pure PP. Besides, the crystal study shows after TMQ is added, the crystallinity of PP reduces, the melt peak temperature remains essentially unchanged, and the crystallization peak temperature increases slightly. The material has excellent antistatic resistance to washing and durability, and the changes in relative humidity have little effect on its antistatic properties.

Effect of hydrophobic nano-silica content on the surface properties of corn-starch films

Starch-based films can be used for applications such as single-use packaging for food with a short shelf life. Hence, starch-based films could be a green alternative to some plastic packaging. This study analyzes the influence of hydrophobic silica content on mechanical properties, surface free energy, surface roughness, and morphology of corn starch-based films. For this purpose, commercially available amorphous hydrophobic nano-silica, Aerosil® R972, was used. The lowest value of surface free energy was observed for the starch films with the lowest glycerol and silica content (57 ± 1 mJ·m–2 for CG40S2.5), while the highest value was with the highest glycerol and silica content (73 ± 2 mJ·m–2 for CG80S5.0). The influence of silica content on the tensile strength decreases and elongation at break was investigated. The results showed that the surface roughness increases when the silica content increases. The SEM and EDS observation confirmed the homogeneity of the developed materials. This study shows that the commercially available Areosil® type of silica can be successfully used to change the performance of starch films.

Performance assessment of blended self-compacting concrete with ferrochrome slag as fine aggregate using functional ANOVA

The current study explored the feasibility of re-use of ferrochrome slag (FS), a waste byproduct from the ferrochrome industry as a replacement to fine aggregate in self-compacting concrete (SCC) with cement and fly ash as binders. The study investigated the mechanical and durability characteristics of SCC of M25 grade, incorporating FS in lieu of fine aggregate, up to 60 % replacement levels. Albeit workability of fresh concrete decreased with the increase of FS content, they were within the recommended limits of EFNARC for SCC. Considerable decreases in compressive, tensile and flexural strengths were observed in the mixtures with FS contents above 40 %. Slightly better performances in terms of water absorption, sorptivity, chloride ion permeability and sulphate attack were found in the concretes partially blended with FS. Leaching of chromium (Cr) from FS-incorporated self-compacting concrete samples were within the Indian discharge limits. Microstructural studies were conducted to decipher the arrangement of components in the concrete as well as determine the elemental composition of ferrochrome slag. Functional analysis of variance (ANOVA) was conducted to determine the significance of functional components in explaining the variability of the mechanical properties expressed as continuous functions. The test findings indicate that there is no statistical difference in the compressive strength and split tensile strength as a result of substituting a portion of sand with FS. Nevertheless, a rise in flexural strength is noticed after surpassing a 5 % substitution.

Experimental Study on Salt-Bearing Sandstone Samples Under the Change of Temperature and Humidity Cycle

ABSTRACT Salt crystallization is a common type of disease in grottoes. Due to the change in temperature and humidity, the soluble salt originally existing in sandstone will have a negative impact on the protection of rock relics. In this study, sandstone samples containing Na2SO4 solution and distilled water were used to study the difference in sample damage under the condition of temperature and humidity cycle changes. It was found that the damage degree of samples containing soluble salts was much higher than that of salt-free samples, especially under the influence of freeze-thaw cycles. With the increase of freeze-thaw cycles, the internal friction angle and wave velocity of sandstone decrease linearly, while the surface hardness, tensile strength, and cohesion decrease exponentially. In addition, the damage caused by freeze-thaw cycles and dry-wet cycles develops from the inside to the outside of the rock sample, which is manifested by the increase in the number of macropores and the emergence of new pores. The different combinations of several effects lead to different changes in pore structure and mineral composition of the samples under the four conditions. The research results are helpful in providing a scientific basis for the disease control of stone cultural relics.

Modulating hierarchical microstructural components to enhance strength-ductility synergy of a high-entropy alloy containing brittle sigma phase

Although brittle intermetallic phases are usually unwanted in the design of strong and ductile alloys, high strength and good ductility can be achievable in high-entropy alloys (HEAs) containing brittle phases. Here, we present an investigation on modulating the hierarchical microstructural components in a prototype metastable HEA (Fe30Cr25Co25Mn10Ni10, at. %) containing sigma (σ) phase to optimize the mechanical properties. An excellent combination of tensile strength (999.3 MPa) and ductility (57.7 %) is achieved in alloy sample containing recrystallized grains of various sizes, which is mainly attributed to the continuous transformation-induced plasticity (TRIP) effect and the back stress effect caused by the pile-up of geometrically necessary dislocations at various interfaces in the hierarchical microstructures. The decrease in fraction of hard domains (σ particles, non-recrystallized and small-sized grains) can lead to the decrease of tensile strength due to the weakened back stress effect. However, an excessively high fraction of hard domains (particularly with small-sized grains and σ particles) suppresses the TRIP effect, facilitating crack propagation and reducing ductility. The back stress effect can be rationally controlled through tuning the fraction and size of small-sized grains (accompanied with fine σ particles) by thermo-mechanical treatments, which can also enable the activation of TRIP effect in grains of various sizes to render high strain-hardening rate and good strength-ductility synergy. This provides a strategy for achieving an optimum combination of strength and ductility for metastable HEAs containing fine brittle phases via alleviating the embrittling effect of brittle phases and retaining the precipitation strengthening effect.

Recycled Household Plastic and Oil Palm Filler Reinforced Epoxy Composite for Lightweight Construction Applications

Polypropylene is extensively used in aerospace, automotive and construction applications due to its versatile properties. This project aims to reduce plastic and oil palm waste and promote the development of strong, sustainable and eco-friendly construction materials. The objective of this project is to develop a sustainable yet high-performance construction material by incorporating polypropylene particles, oil palm empty fruit bunch (OPEFB) fibres and oil palm shell (OPS) particles into epoxy composites through the hand lay-up method. The composite specimens undergo ASTM D638 tensile test to determine the tensile properties. The addition of PP particles in varying weights shows decrease in tensile strength, likely due to poor dispersion and compatibility with the epoxy matrix. Incorporating 3 wt% OPEFB fibres with fibre length from 2mm to 4mm improves tensile strength by 2.32% and 23.36% respectively at higher PP particle loadings which are 15 wt% and 25 wt%. Adding 1 wt% and 3 wt% OPS particles improves the tensile strength by 2.96% and 4.68% respectively, in composites with 10 wt% PP particles and 3 wt% OPEFB fibres. The tensile performance may be improved by treating PP particles with compatibilizers such as silane or maleic anhydride grafted polypropylene.

Gelatine Blends Modified with Polysaccharides: A Potential Alternative to Non-Degradable Plastics.

Non-degradable plastics of petrochemical origin are a contemporary problem of society. Due to the large amount of plastic waste, there are problems with their disposal or storage, where the most common types of plastic waste are disposable tableware, bags, packaging, bottles, and containers, and not all of them can be recycled. Due to growing ecological awareness, interest in the topics of biodegradable materials suitable for disposable items has begun to reduce the consumption of non-degradable plastics. An example of such materials are biodegradable biopolymers and their derivatives, which can be used to create the so-called bioplastics and biopolymer blends. In this article, gelatine blends modified with polysaccharides (e.g., agarose or carrageenan) were created and tested in order to obtain a stable biopolymer coating. Various techniques were used to characterize the resulting bioplastics, including Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA)/differential scanning calorimetry (DSC), contact angle measurements, and surface energy characterization. The influence of thermal and microbiological degradation on the properties of the blends was also investigated. From the analysis, it can be observed that the addition of agarose increased the hardness of the mixture by 27% compared to the control sample without the addition of polysaccharides. In addition, there was an increase in the surface energy (24%), softening point (15%), and glass transition temperature (14%) compared to the control sample. The addition of starch to the gelatine matrix increased the softening point by 15% and the glass transition temperature by 6%. After aging, both compounds showed an increase in hardness of 26% and a decrease in tensile strength of 60%. This offers an opportunity as application materials in the form of biopolymer coatings, dietary supplements, skin care products, short-term and single-contact decorative elements, food, medical, floriculture, and decorative industries.

Material recycling of acrylonitrile butadiene styrene (ABS) from wiring devices using mechanical recycling

Plastics play a significant role in various sectors by offering advantages such as durability, cost-effectiveness, and lightweight properties. However, the extensive production and consumption of plastics create significant environmental threats, leading to high carbon footprints, global warming, and the accumulation of hard-to-recycle waste. This study explores innovative recycling technologies, focusing on the circular economy and zero waste strategies. In line with this scope, the study aims to conduct research on the reuse of coated plastic materials in production, specifically selecting ABS materials that are difficult to recycle. In the study, wiring devices were prepared using 70% raw ABS (Acrylonitrile Butadiene Styrene) material and 30% recycled ABS (rABS) material, with this cycle being repeated three times. Experiments have been conducted to evaluate the suitability and performance of recycled ABS material for mass production. The results have revealed a slight decrease in tensile strength and impact strength compared to raw ABS material, yet significant mechanical performance has been maintained, thus demonstrating the viability of rABS in preserving product quality throughout successive recycling processes.

Polylactic acid/epoxidized linseed oil/polypropylene grafted maleic anhydride: A promising combination of toughness and rigidity

AbstractIncreasing toughness of brittle polymer without losing modulus of elasticity and tensile strength is highly important for enlarging the range of applications. In this study, polylactic acid (PLA) modified with epoxidized linseed oil (ELO) and polypropylene‐grafted maleic anhydride (PPgMA) with a good balance of toughness and rigidity was successfully prepared by melt mixing procedure. The addition of PPgMA/ELO with appropriate proportions (3:1, 5:1, and 5:5 wt%) resulted in PLA modified samples with significant ductility improvement (around 2200% of elongation at break and 1800% of tensile toughness compared to the neat PLA) with low decrease in Young modulus and tensile strength. This feature was attributed to improved interfacial interactions and the formation of crosslinked structures at the interface that also increased viscosity of the melting system and cold crystallization temperature of PLA. The scanning electron microscopy revealed the presence of small domains of modified systems. The effectiveness of reactive compatibilization among the components was also suggested by Fourier transform infrared (FTIR) spectroscopy and thermal degradation analysis. The combination of toughness, modulus of elasticity and good thermal properties make this low‐cost and scalable eco‐friendly material a promising candidate for use as biodegradable plastic in several fields including medical applications and packaging.

The Influence of Friction and Twisting Angle on the Tensile Strength of Polypropylene Baling Twine

Polypropylene is a widely used linear hydrocarbon polymer with diverse applications due to its exceptional physicochemical characteristics and minimal changes during the recycling process. Numerous studies have focused on factors influencing the mechanical properties of polypropylene and its application in composites. However, despite their significance in the agricultural industry, there is limited research on polypropylene baling twines. This study analyses the behaviour of polypropylene baling twine under tensile loading, exploring the influence of fibre friction and twisting angle on the material’s tensile strength. Experimental investigation indicated that tensile strength increases with twisting angle, but only until the angle reaches a critical value. Further increase in the twist angle led to a decrease in tensile strength. The increase in tensile strength is attributed to the rise in the coefficient of friction between fibres in the twine. An experimental approach was employed to evaluate the mechanical characteristics of the twine, including the effect of prestressing by twisting. Understanding these characteristics is crucial for enhancing the quality of polypropylene baling twines and optimising their application in the agricultural industry.

Thermo-mechanical characterizations and erosion wear studies of fumed silica-reinforced jute/epoxy composites

This study investigates the influence of nano-fumed silica content on thermo-mechanical properties of jute/epoxy composites. The results reveal that jute composites without filler (JJJJ-0) exhibited highest tensile strength (33.01 MPa) and percentage elongation (1.9522%), while composites with 1.5% and 2.5% filler demonstrated the highest tensile modulus (1967 MPa) and flexural modulus (2432.9 MPa), respectively. The observation demonstrates that as the filler content increases in jute composites, tensile strength decreases but flexural strength increases. However, an exception is noted for sample containing excess filler (3.5%), which exhibited the lowest flexural strength (44.36 MPa). The composite with 2.5% filler exhibited the highest flexural strength (53.5 MPa). Thermal analysis indicated that the addition of nanofiller enhanced both the activation energy (Ea) and thermal stability of the jute composites. A four-layer carbon composite without filler (CCCC-0) was also fabricated in order to compare wear and thermal stability performance with jute composites. The wear study was performed at different temperatures and found that JJJJ-3.5 composite exhibited superior wear resistance at ambient temperature, while CCCC-0 composite had better wear resistance at high temperatures. Also, the surface morphology of the eroded surface was examined using a scanning electron microscope (SEM) to study the failure mechanism of composites.

Investigation on the Correlation between Biaxial Stretching Process and Macroscopic Properties of BOPA6 Film.

Biaxially oriented polyamide 6 (BOPA6) films were prepared by extrusion casting and biaxial stretching with polyamide 6. The effects of different biaxially oriented on the macroscopic properties of BOPA6 were investigated by characterizing the rheological, crystallization, optical, barrier and mechanical properties. The results show that the increase of stretching temperature leads to the diffusion and regular stacking rate of BOPA6 chain segments towards crystal nuclei increases, the relative crystallinity increases, reaching 27.87% at 180 °C, and the mechanical strength and optical performance decrease. Heat-induced crystallization promotes the transformation of β-crystals to α-crystals in BOPA6, resulting in a more perfect crystalline structure and enhancing oxygen barrier properties. BOPA6 chains are oriented, and strain-induced crystallization (SIC) occurs during the biaxial stretching. Further increasing the stretch ratio, the relative crystallinity increased to 30.34%. The machine direction (MD) and transverse direction (TD) tensile strength of BOPA6 (B-33) are nearly two times higher than the unstretched film, reaching 134.33 MPa and 155.28 MPa, respectively. In addition, the permeation decreases to 57.61 cc·mil/(m2 day), and the oxygen barrier performance has improved by nearly 30% compared to the sample B-22. BOPA6 has a high storage modulus at a high stretching rate (300%/s). Rapid chain relaxation would promote the molecular chain disorientation, destroy the entangled network of the molecular chain, and lead to a decrease in tensile strength, reducing to about 110 MPa.

Experimental Studies for the Creation of Composite Materials with Increased Static Mechanical Characteristics

The aim of the study was to experimentally verify the enhancement of certain mechanical properties of a composite material consisting of unsaturated polyester matrix reinforced with fiberglass, by incorporating specific proportions of sodium aluminosilicate (SAS) powders and talc as fillers for the fabrication of large wind turbine blades. Samples composed of these materials, with varying combinations of the added components, underwent testing for tensile and bending strength, and experiments were conducted to determine their modulus of elasticity. The findings indicate that the inclusion of SAS in the matrix material resulted in increased values of tensile strength and modulus of elasticity up to certain proportions. Solely adding talc to the matrix material led to a rise in bending strength. Increasing the talc percentage in the matrix material reinforced with 20% fiberglass resulted in decreased tensile strength and elastic modulus of the samples, while incorporating a blend of SAS and talc into the matrix material reinforced with 20% fiberglass significantly boosted the elastic modulus and tensile strength of the samples under tensile conditions.

Effect of conductive surface-coated polyethylene fiber on the electrical and mechanical properties of high-performance fiber-reinforced cementitious composites

This study investigated the electrical conductivity and mechanical properties of high-performance fiber-reinforced cementitious composites (HPFRCC) with conductive coated ultra-high-molecular-weight (UHMW) polyethylene (PE) fibers. The silver nanoparticles with spherical shape were coated most evenly. Despite some parts of the fiber surface being less coated with carbon nanotube (CNT) and graphite nanofiber (GNF) compared to the silver nanoparticles, they effectively increased electrical conductivity of the plain PE fiber. Both the coating degree and conductivity of the coating material affect the conductivity of PE fiber. The compressive strength of HPFRCC was not affected by conductive coating. The electrical conductivity of HPFRCC improved by 18.7%–45.1% than the control specimen, and the highest electrical conductivity was achieved when coated with silver nanoparticles. Incorporating conductive coating fibers had a negative effect on tensile strengths (18.9–23.5% decreases) but a positive effect on the ductility. The GNF-coated PE fibers led to the strain capacity and energy absorption capacity improved by 69.4 and 44.8%, respectively. Therefore, given the increase in deformation performance outweighs the decrease in tensile strength, engineered, conductive coating fibers can be used as novel reinforcement in HPFRCC to attain additional functionalities related to electrical capabilities.

Effect of preheating temperature on the microscopic structure and mechanical performance of pulsed laser welding in sheet AZ31 alloy

To achieve high quality welding of an AZ31 magnesium alloy sheet, butt experiments are conducted using an Nd:YAG pulsed laser welder to weld the AZ31 magnesium alloy (1 mm). The influence of preheating temperature on the microscopic structure and mechanical performance of AZ31 magnesium alloy pulsed laser welding is studied. Experimental results show that with the rising of preheating temperature, the grain size of an equiaxed crystal in the weld center and columnar crystal at the fusion boundary (FB) first decreases and then increases and reaches the minimum values of 18.89 ± 0.45 and 32.09 ± 1.52 μm, respectively, when preheated at 200 °C. The maximum force and tensile strength increase first and decrease and reach the maximum of 2.32 kN and 193.3 MPa, respectively, when the preheating temperature is 300 °C. Above all, the welds with excellent mechanical performance can be obtained at the preheating temperature of 300 °C.

Construction of core–shell‐structured halloysite nanotubes with TiO2 nanoparticles for ultra‐high‐molecular‐weight polyethylene (UHMWPE) nanocomposites with improved wear resistance

AbstractA hybrid of halloysite nanotubes decorated with titanium dioxide nanoparticles (HNTs@TiO2) was synthesized by the sol–gel method and then mixed with ultra‐high molecular polyethylene (UHMWPE) by melt compounding to enhance its wear resistance properties. The incorporation of HNTs@TiO2 increased the crystallinity as well as the hardness of UHMWPE nanocomposites, which benefited less prone to plastic deformation during the friction process. In addition, the UHMWPE/HNTs@TiO2 maintained a high ductility character with a slight decrease in tensile strength compared to pure UHMWPE. With the addition of 3 wt% HNTs@TiO2, the UHMWPE nanocomposite achieved a remarkably low friction coefficient of 0.073 and a reduced wear rate of 6.67 × 10−6 mm3/N·m. These values represented a 32.4% decrease in friction coefficient and a 43.9% decrease in wear rate compared to pure UHMWPE. The improvement in wear resistance was due to the dislodged TiO2 and HNTs had good synergistic rolling effects at the counterface. Furthermore, the wear scan morphology observation revealed that the transferred HNTs@TiO2‐based materials could help to improve the quality of the tribofilms, which alleviated the abrasive wear from the metallic counterpart. This work offers a feasible way to enhance the wear resistance of UHMWPE nanocomposite without sacrificing the high ductility for expanding its engineering applications.Highlights TiO2‐decorated halloysite nanotubes were synthesized by the sol–gel method. The addition of HNTs@TiO2 maintained the high ductility character of UHMWPE. The UHMWPE composite with 3 wt% HNTs@TiO2 had the best wear resistance.

Minimizing porosity and optimizing microstructure of hot-wire arc additive manufactured Al-Cu-Mg-Ag alloy for strength increment

Here, wire arc additive manufacturing (WAAM) is employed for the fabrication of Al-Cu-Mg-Ag alloy, focusing on improving mechanical property via eliminating porosity and tuning microstructures. Via optimizing the hot-wire current and pulse frequency of WAAM, the volume fraction of porosity reduces from 3.13 % to 1.77 %, along with grain refinement. Overhigh pulse frequency leads to lower sphericity of pores and larger grain size. Finite element analysis performed by Abaqus software reveals that both ultimate tensile strength (UTS) and elongation decrease with higher volume fraction of porosity, and large pores are the preferential sites of strain concentration, crack initialization and final fracture. Based on the optimization of WAAM processing parameters, a WAAM-customized T6 temper is proposed for the Al-Cu-Mg-Ag alloy, to enable the formation of strengthening Ω precipitates. Resultantly, UTS and yield strength (YS) reach 425.2 ± 6.0 MPa and 400.3 ± 4.6 MPa, respectively, which increased by 42.6 % and 111.2 % compared with as-deposited alloy.

The effect of fullerene soot on polymer-metal adhesion in thermoplastic fiber metal laminates

The paper investigated the effect of fullerene soot (FS) additions into amorphous polysulfone (PSU) on its mechanical properties, adhesion to the pretreated surface of an aluminum alloy, and on the flexural properties of a PSU-based fiber metal laminate (FML). It was shown that even small additions of FS have a negative effect on polymer mechanical properties: a decrease in tensile strength and elongation to break; and the addition of more than 1% of FS led to the brittle fracture of PSU. At the same time, the addition of 0.5–1.0% FS increased adhesion between Al and PSU by 60–70%. Finally, it was shown that the use of PSU films filled with fullerene soot as an adhesive layer in an FML increases its flexural strength by 12% and elastic modulus by 20%.

Hydrogen diffusion and hydrogen embrittlement of a 1500 MPa hot-stamped steel 22MnB5 in different austenitizing conditions

We investigated the influence of hydrogen on a 1500 MPa hot-stamped steel 22MnB5 with different prior austenite grain size (PAGS, ranging from 14.0 μm to 22.2 μm), which were produced by precise control of the austenitizing temperature and time. All steel specimen exhibited a significant reduction of ductility (e.g., by 70%) and a small decrease in ultimate tensile strength (≤15%), measured using the linearly increasing stress test. The effect of PAGS on hydrogen embrittlement of the hot-stamped steel was not significant for these test conditions. Martensite with smaller PAGS exhibited a slightly lower hydrogen diffusion coefficient. Fracture for all steel variants after yielding occurred for hydrogen contents greater than those that actually occur during service.