Increase In Impact Strength Research Articles

Influence of epoxy resin species on the curing behavior and adhesive properties of cyanate Ester/Poly(aryl ether nitrile) blends

In this study, four different bisphenol A glycidyl ether epoxy resins (E06, E12, E20, and E44) with varying epoxide equivalents were utilized to investigate their effect on the curing behavior, mechanical, thermal, and adhesive properties of bisphenol A cyanate ester (ACE)/fluorinated poly(aryl ether nitrile) (PFPEN) blends. The differential scanning calorimetry (DSC) results revealed that the use of epoxy resin reduced the curing temperature and activation energy of the modified resin system. The hydroxyl and epoxy groups in the EP resin respectively facilitated the polymerization of cyanate group and the formation of oxazoline and oxazolidone structures, instead of rigid triazine rings. This, in turn, improves the toughness of the cross-linked network structure. Rheological analysis showed that the EP resin could reduce crystallinity in the modified resin and improve low-temperature processing performance. Comparatively, E20/PFPEN/ACE showcased a significant increase in both tensile and impact strength, reaching 74.6 MPa and 19.35 kJ/m2, respectively. Likewise, shear strength and peel strength at room temperature showed an improvement by 18.7% and 20.7%, respectively, when compared to the pure PFPEN/ACE system. Overall, this modified resin exhibits relatively good comprehensive properties and could be used for high-performance adhesives and resin matrix composites.

Mechanical, Morphological, and Fire Behaviors of Sugar Palm/Glass Fiber Reinforced Epoxy Hybrid Composites

This research aims to investigate using sugar palm fiber (SPF) and glass fiber (GF) in an epoxy matrix to develop composite materials with improved mechanical, morphological, and flammability properties. The mechanical and flammability properties are examined per ASTM standards, while the morphological study examines the fractured surfaces of the samples. Using the hand lay-up technique, the hybrid composite comprises 15% SPF, 15% GF, and 70% epoxy resin. Three treatments are applied to the SPF: untreated, alkaline treated, and benzoyl chloride treated, which enables research into the effect of fiber treatment on mechanical properties and flammability. The morphological investigation reveals that both treated SPF/GF/EP composites exhibit lower tensile strength than the untreated SPF/GF/EP composite due to inadequate mechanical interlocking at the fiber-matrix interface. However, the alkaline-treated SPF/GF/EP composite demonstrates a 24.8% improvement in flexural strength, a 1.52% increase in impact strength, and a 9.76% enhancement in flammability. Similarly, the benzoyl chloride-treated SPF/GF/EP composite improves flexural strength, impact strength, and flammability by 24.6%, 0.51%, and 5.66%, respectively. These results highlight the potential of fiber treatment to improve composite materials’ mechanical and flammability properties.

A new approach to prepare flame retardant epoxy resin with excellent transmittance, mechanical properties, and anti-aging performance by the incorporation of DOPO derivative

Aiming to develop high performance flame-retardant epoxy resin (EP), a novel phosphorus-containing flame retardant named 6-(3-(2-hydroxyphenyl)propyl)dibenzo-[1,2]oxaphosphinine 6-oxide (HP-DOPO) was synthesized and employed as a multi-functional additive for EP with simultaneously excellent flame retardancy, transmittance, mechanical enhancement and anti-aging. With 5 wt.% loading of HP-DOPO, EP composites showed outstanding flame retardancy with a high limiting oxygen index of 35.6 % and V-0 rating in UL-94 test, while the cone calorimetric test results demonstrated that HP-DOPO could efficiently restrain the heat and smoke release. Compared with pure EP, the resultant EP/5 %HP-DOPO exhibited superior mechanical properties with 27.9 % and 56.2 % increase in tensile and impact strengths, respectively. Furthermore, HP-DOPO accelerated the curing procedure and did not sacrifice the transparency of cured EP, while anti-aging performance was obtained at the same time. The exploration of this novel multi-functional additive provided a powerful basis for the technologies and potential industrial applications of epoxy materials.

Investigation of the Properties of Polyethylene and Ethylene-Vinyl Acetate Copolymer Blends for 3D Printing Applications.

3D printing of polyolefins, such as polyethylene (PE) and polypropylene (PP), is of great practical interest due to the combination of high properties of these materials. However, the use of these materials in 3D printing is associated with many problems due to their high rate of crystallization, which causes shrinkage and warpage of the printed object. In this regard, blends of PE and ethylene-vinyl acetate copolymer (EVA) of various compositions were investigated for 3D printing. It was found that with an increase in the concentration of EVA, an increase in the pseudoplastic effect and amorphization of PE occurs. It has been shown that with an increase in the EVA content, the degree of crystallinity of PE decreases slightly (by 11% at a content of 80% EVA); however, a significant decrease in the rate of crystallization of PE is observed (by 87.5% at the same EVA concentration). It was found that PE and EVA are completely compatible in the amorphous phase and partially compatible in the crystalline phase, which leads to a slight decrease in the melting point of PE. The introduction of EVA also leads to a significant increase in impact strength: the maximum value is achieved at a 50/50 ratio, which is five times the value of the initial PE and two times the value of the initial EVA. At the same time, it was revealed that EVA leads to a gradual decrease in the elastic modulus and strength of PE, the change of which generally obeys the additivity rule. The resulting printing filaments are characterized by a certain ovality due to their shrinkage, which decreases with increasing EVA content and reaches a minimum value at a PE/EVA ratio of 30/70. This composition also demonstrates the lowest shrinkage of the printed sample and higher processability during printing.

Characterization of mechanical and wear properties of Prosopis juliflora thorn powder-filled epoxy nanocomposites

The mechanical and wear behavior of agro waste thorn ( Prosopis juliflora [PJ]) derived as a nanoparticle with different weight compositions (0, 2.5, 5, 7.5 and 10 wt.%) reinforced in an epoxy matrix is investigated in this study. First, the effect of thorn nano epoxy composite is studied under ASTM standards. The results indicated that the nanocomposites with 2.5 wt.% filler have the maximum tensile strength, flexural strength and hardness of the epoxy composite, while those with 10 wt.% filler exhibit a noticeable increase in impact strength and compressive strength. Furthermore, the incorporation of thorn nanoparticles improved the wear resistance. 2.5 wt.% nano PJ thorn composites improved wear resistance by 9.03%. Additionally, the size of the nanoparticles, the fracture surfaces, the crystalline nature, the elements and the compounds in the thorn nanofillers are examined using transmission electron microscope, field emission scanning electron microscope, X-ray diffraction, energy dispersive X-ray and Fourier transform infrared spectroscopy.

Enhancing Stiffness, Toughness, and Creep in a 3D-Printed Bio-Based Photopolymer Using Ultra-Low Contents of Nanofibrillated Cellulose

UV-light-assisted additive manufacturing (AM) technologies require bio-based resins that can compete with commercial petroleum-based ones to enable a more sustainable future. This research proposes a significantly improved vegetable oil-based resin reinforced with nanofibrillated cellulose (NFC). The incorporation of ultra-low concentrations (0.1–0.5 wt%) of NFC produced disproportionate enhancements in mechanical performance. Noteworthy, a 2.3-fold increase in strain at the break and a 1.5-fold increase in impact strength were observed with only 0.1 wt% of NFC, while at 0.5 wt%, a 2.7-fold increase in tensile modulus and a 6.2-fold increase in toughness were measured. This is in spite of NFC agglomeration at even the lowest loadings, as observed via examination of fracture surfaces and dynamic mechanical analysis (DMA) Cole–Cole plot analysis. The addition of 0.1 wt% NFC also increased creep resistance by 32% and reduced residual strain by 34% following creep recovery. The Burgers model satisfactorily described the composites’ viscoelastic–viscoplastic behavior within the applied stress levels of 1–3 MPa. The successful development of novel NFC/bio-resin composites with enhanced mechanical performance and long-term stability highlights the potential of these composites to substitute petroleum-based resins in the context of AM resins.

Experimental study on the mechanical behavior of natural fibers reinforced with epoxy-based hybrid composites

Natural fiber composite is the most preferable research area in the modern situation due to its availability, applications, and ecofriendly quality. This study investigates the properties of bamboo, banana, and hemp composite samples, focusing on thermal conductivity, water absorption behavior, tensile strength, flexural strength, and impact strength. Thermal conductivity, a crucial property, was measured using ASTM standards and revealed that composite sample C exhibited lower thermal conductivity (2.42 W/m-K) than samples A and B (2.71 W/m-K and 3.29 W/m-K). Additionally, sample C demonstrated excellent water absorption resistance, absorbing only 11.67 % water after 24 h of immersion, while sample A absorbed 20.25 %, and sample B absorbed 16.98 %. In tensile tests, increasing palm fiber content from 5 % to 15 % resulted in a 12 % increase in tensile strength, with sample C outperforming samples A and B. Flexural strength improved by 55 % with a shift from 5 % to 15 % bamboo weight percentage and a decrease in banana fiber content. Sample C exhibited a 36.24 % and 20 % higher flexural strength than samples A and B, respectively. Impact tests demonstrated that higher palm fiber content increased impact strength by 57 %, with sample C showing a 36.59 % improvement over sample A.

An In Vitro Study Comparing the Impact and Flexural Strength of Leucitone 199 Denture Base Resin and Conventional Denture Base Resin Enhanced With Glass Fibre Mesh and Polyethylene Fibre Mesh.

Purpose The purpose of this in vitro study was to compare and evaluate the impact and flexural strength of conventional denture base resin reinforced with glass fiber mesh and polyethylene fiber mesh with Leucitone 199 denture base resin (Dentsply Sirona, Charlotte, USA). Leucitone is an expensive denture base material. To come up with a cheaper solution for reinforced denture base resin with superior impactand flexural strength was the goal of this study Material and methods The specimens (maxillary denture bases) were fabricated using a standard polyvinylsiloxane mold with conventional heat-cured polymethyl methacrylate resin (ISO 1567:1999). The specimens were divided into three groups (n = 10). Group I specimens, or the control group, were pre-reinforced Leucitone 199. Group II and Group IIIspecimens were reinforced with 3% by weight of glass fibers and polyethylene fibers in weave form, respectively. All the specimens were immersed in water for 1 week before testing. The impact strength was measured with a falling weight impact testing machine. One-way analysis of variance and Tukey's post hoc test were used for statistical analysis. The flexural strength was measured with the three-point bending test in a universal testing machine. Results The highest impact strength values were exhibited by the Leucitone 199 group, followed by the polyethylene fiber mesh group, followed by the glass fibers mesh group. The highest flexural strength was seen in the Leucitone 199 group, followed by the glass fiber mesh group. The least flexural strength was seen in the polyethylene fiber mesh-reinforced group. Conclusion Reinforcement of maxillary complete dentures showed a significant increase in impact strength and flexural strength, but not in comparison to pre-reinforced Leucitone 199 dentures. By using pre-impregnated glass and polyethylene fibers in woven form (prepregs), the impact strength of the denture bases can be increased effectively.

Biochar reinforced PLA composite for fused deposition modelling (FDM): A parametric study on mechanical performance

Rice husk biochar was added to polylactic acid (PLA) to create a biocomposite filament suitable for the extrusion-based 3D printing process of fused deposition modelling (FDM). Taguchi L16 was used for experiment design, and the significance of process parameters was determined using variance analysis (ANOVA). For a 0.3-mm layer thickness, the addition of 5 wt.% biochar resulted in ultimate tensile strength and a modulus of elasticity of 36 MPa and 1103 MPa, respectively. The addition of biochar had a negative influence on flexural strength. The maximum flexural modulus was obtained with 3 % biochar, 100 % infill density, and 0.1 mm layer thickness. Particularly, 1 % biochar resulted in a considerable increase in impact strength, while a subsequent rise in biochar resulted in a decrease, probably due to the agglomeration effect. For 3D printed neat PLA, the average tensile strength, tensile modulus, flexural strength, flexural modulus, and impact strength observed were 19 MPa, 550 MPa, 54 MPa, 1981 MPa, and 25 KJ/m2, respectively. Additionally, considering the output of each test, a multicriteria decision-making model, namely, TOPSIS, has been utilized for ranking the mechanical performance. In order to optimise the mechanical properties of three-dimensional printed objects, the study suggests a layer thickness of 0.2 mm, an infill density of 100 %, and raster angle of 0° as the FDM process parameters.

Construction of hierarchical SiO2 microcapsule towards flame retardation, low toxicity and mechanical enhancement of epoxy resins

A novel approach for improving the flame retardancy, smoke suppression and mechanical properties of epoxy resins (EPs) has been proposed by incorporating functionalized hollow mesoporous silica microcapsules (SHP) loaded with phosphorous silane flame retardants (SCA) and coated with polydopamine (PDA) and transition metals. The proposed approach involves a multi-level structure that combines several mechanisms to enhance the flame-retardant properties of EP. The physical barrier provided by silica serves to impede heat and mass transfer during combustion, while the catalytic carbonization effect of phosphorus and transition metals promotes the formation of a protective char layer, which acts as a barrier to further flame propagation. Incorporating a low loading amount of 3 wt% SHP into the epoxy matrix resulted in EP/SHP-3 composites with significantly improved flame retardancy, as evidenced by a limiting oxygen index of 31.5% and a V-1 rating, in contrast to the values obtained for unmodified EP, which were 23.8% and no rating, respectively. In addition, cone calorimeter test (CCT) results indicated that the total heat release, peak heat release rate and total smoke production of EP/SHP-3 decreased by 18.2%, 25.2% and 18.4%, respectively. Moreover, the improved interfacial compatibility facilitated by polydopamine assists in the dispersion and compatibility of the SHP with the epoxy matrix, leading to better mechanical properties. Herein, the addition of 1 wt% SHP to EP significantly improved its mechanical performance, with a 16.7% increase in tensile strength and a 19.2% increase in impact strength. The design of the multi-level structural approach has the potential to provide new ideas for the simultaneous improvement of fire safety as well as mechanical properties of polymers.

The effect of funcionalized ethylene-n-octene copolymer on mechanical properties of bioPET with organic waste fillers

The effect of compatibilizer - ethylene-n-octene copolymer grafted with maleic anhydride(EOC-g-MAH) used in the amount of 3 wt% on tensile and flexural properties and impact strengthof bioPET with the addition of 10 wt% filler derived from organic waste (egg and mollusc shells, coffeegrounds) was investigated. EOC-g-MAH slightly decreased tensile strength, flexural strength, andmodulus of elasticity, while significantly increasing impact strength (up to 426%). Moreover, ability ofbioPET-based composites to dissipate mechanical energy was improved.

Effect of angle interlocking/plain weave compound fabric system on mechanical properties of aramid epoxy resin composites

Preform is one of the important factors affecting the mechanical properties of textile composites. To further reflect the influence of the preform structure on the mechanical properties of composite materials, the angle interlocking and plain weave structures are configured in a certain proportion to form a composite fabric with both structures. The results show that the compound fabric preform has a positive effect on the improvement of the mechanical properties of AERC. An increase in the proportion of angle interlocking organization configuration in the compound fabric system is beneficial to the increase in tensile strength of AERC. In this experiment, when the ratio of angle interlocking structure and plain weave structure in the compound fabric system is 3:1, the tensile strength of AERC increases significantly, which is 80.98% higher than that of AERC with angle interlocking preformed structure. When the preform is made of compound fabric, the bending properties of AERC are greatly improved, and the bending strength is also increased 1.20 times compared to the AERC with angle interlock structure as the preform. When the ratio of angle interlock weave and plain weave in the compound fabric system is 1:3, the bending strength of AERC increases 1.81 times the maximum. The proportion of two fabric structures in the compound fabric system has a significant impact on the impact properties of AERC. The increase in the proportion of plain weave in the compound fabric system is not conducive to the increase in impact strength of AERC, and the large proportion of corner interlock configuration is conducive to the increase in bending strength of AERC. When the ratio of angle interlocking structure to plain weave structure is 2:1, the AERC has the maximum impact strength of 33.14 KJ/m2, which is increased by 26.28%.

Thermo-mechanical analysis of bhimal fiber (Grewia optiva)-CaCO3/flyash/TiO2 reinforced epoxy bio-composites

The Bhimal fiber, derived from agro-waste and found in abundant Himalayan forest is having no commercial utilization and economical contribution to the state yet while it possess superior mechanical properties. This study explores the novel idea of utilizing bhimal fiber, and the interaction of agro-industrial wastes, resulting in will improve the economy of the farmers and the state. The bio composites were created by incorporating different types of industrial-waste particulates, including CaCO3, Flyash, and TiO2, at varying weight percentages with 15% and 20% by weight of Bhimal fiber. NaOH-treated Bhimal fiber was cast-off for improving to surface structure of native cellulose and resulting in enhancement of the mechanical properties of the biocomposites. The study found that the incorporation of CaCO3/Flyash/TiO2 at 5, 10, and 15 Weight (wt.)% with 20 and 15 wt% of Bhimal-fiber enhanced the properties of developed biocomposites. Incorporation of TiO2 at 5 wt% leads to a significant improvement in tensile and compressive strength along with hardness, by 122.26%, 103.02%, and 73.54%, respectively. The flexural strength decreased with increasing percentages of CaCO3/TiO2 (from 5 to 15 wt%), while fly-ash incorporation at 5, 10, and 15 wt% led to an increase in flexural strength, with a maximum increase of 135.06% at 15 wt% fly-ash, and an increase in impact strength of 295.51% at 10 wt% of fly-ash. The incorporation of nano-TiO2 resulted in lowest porosity by 13.22% and higher thermal stability. The study concluded that Nano-TiO2 is the most effective filler for reinforcing the bio composite.

Flexural strength and impact properties of UHMWPE bio-composite as bone plate fixation

ABSTRACT Ultra-high molecular weight polyethylene (UHMWPE) is utilised for several purposes, including as a biomedical material for artificial joint replacement. This study looks at the effects of adding nanosized hydroxyapatite (HAP), nanosized titanium dioxide (TiO2), carbon fibre (CF), and Kevlar fibre (KF) to bone plate fixation in the femur bone prosthesis. Because of the ease with which they could be processed, their low cost, remarkable mechanical properties, good cell interaction, different amounts of n-HAP and n-TiO2 (1.5, 2.5, 3.5, and 4.5 wt%), and a fixed amount of CF and KF (5 wt%) were dispersed in UHMWPE-based biocomposites. The UHMWPE/n-HAP and UHMWPE/n-TiO2 particulate biocomposites were prepared by using the dispersing technique followed by hot pressing moulding, then mechanical testing was performed, including flexural, maximum shear stress, and impact tests. Scanning electron microscopy (SEM) is used to observe reinforcement and matrix fractures. Biocomposites with n-HA/Carbon fibre hybrid biocomposites showed better results concerning specific mechanical strength, as well as flexural strength, max. shear and impact energy. The composites show an increase in flexural strength, flexural modulus, impact strength, and max. shear stress by 44%, 32.49%, 120.7%, and 182.6% respectively concerning neat UHMWPE. This review focuses on the benefits of UHMWPE particulate biocomposites in a variety of weight proportions and hybrid biocomposites, which have not yet been tested as a superior alternative for the creation of bone plate fixation.

Effects of Irradiation Dose of Sheet-Like Electron Beam and its Cathode Voltage on Impact Strength of Carbon Fiber Reinforced Thermoplastic Polyamide just before Shipping

Achieving a strong bond between carbon fiber (CF) and recyclable thermoplastic polymer (TP) has always been highly sought after. So far, applying electron beam (EB) irradiation with optimal dose and cathode potential (Vc) has shown success in increasing mechanical properties of interlayered CFRTPs. However, with concern for durability and safety, higher strength is desired. Therefore, EB setting applying electron beam (EB) irradiation with cathode potential (Vc) to 170, 210, 225 or 250 kV was applied to CFRTPA (carbon fiber reinforced thermoplastic polyamide) articles just before shipping. Specimens were 9 CF plies alternating between 10 PA (polyamide) sheets, designated [TPA]10[CF]9. When optimal EB dose of 43.2 kGy is applied to both finished specimen surfaces after fabrication, experimental results show higher Vc setting of 250 kV can increase impact strength of the [TPA]10[CF]9 over that at 170 kV. In summary, the 250 kV-EB (250 kV) strengthens [TPA]10[CF]9 significantly, about 25 to 27% larger than that of 170 kV and zero (untreated). Based on Christenhusz and Reimer equation to calculate penetration depth, Dth of EBI into polymers, increasing Vc to 250 kV increased Dth to more than 2 times that at 170 kV.

Enhanced mechanical properties, thermal behavior and foaming ability of PP‐g‐MAH modified PP/BF composites

AbstractThe mechanical properties of fiber‐reinforced polymer composites strongly depend on its interfacial bond strength and fiber content, and their further lightweight is the current urgent demands for industry. Basalt fiber (BF), as an emerging natural and environmental‐friendly material, possess a broad application prospect as it can replace glass fiber. Herein, strong PP/BF composites with excellent heat deflection temperature and enhanced impact performance were successfully prepared, which augmented with the increase of BF content. The effect of PP grafted with maleic anhydride (PP‐g‐MAH) on the interfacial bonding properties between BF and PP was investigated based on the PP/20BF composite system, which was significantly improved due to the reaction of maleic anhydride polar groups with the hydroxyl groups on the BF surface. The incorporation of PP‐g‐MAH led to 24.7%, 46.9%, and 77.2% increase in tensile strength, flexural strength and impact strength of PP/20BF composites, respectively. Moreover, the crystallization properties, rheological behavior and thermal stability of the composites were significantly enhanced, which all contributed to the refinement and densification of cellular structure. The cell size was reduced from 36.38 to 13.41 μm after the addition of PP‐g‐MAH with an opening distance of 2 mm, and the cell density was enhanced by nearly one order of magnitude to 6.43 × 107 cells/cm3. The cellular structure further lightens the weight of product and promotes the lightweight development of PP/BF composites.

Structural, thermal, and mechanical characterisation of PEEK-based composites in cryogenic temperature

Thermal, thermo-mechanical and mechanical properties of four different commercially available polyetheretherketones (PEEK) based materials were investigated. PEEK matrix was either modified and/or reinforced with carbon fibres, graphite and/or PTFE. Impact strength was measured at three different temperatures: 25 °C, −100 °C, and −195 °C. At 25 °C, thermal stability and mechanical properties, including the elastic modulus, compression, and impact strength, were enhanced with the addition of carbon fibres. Matrix modification had a minor impact on thermal stability, while the mechanical properties decreased, except for impact strength. At −100 °C, the mechanical properties of the neat polymers were improved, including increased impact strength by 20% compared to values at 25 °C. Addition of fillers hindered the rise of impact strength due to complex mechanisms caused by different coefficients of thermal expansion of reinforcements and matrix. At −195 °C, the significant increase of impact strength was revealed for unmodified PEEK reaching 30 times higher values than at 25 °C, while matrix modification suppressed the rise of impact strength. The scratch test indicated the superior behaviour of unfilled PEEK during the tested load range (up to 15 N), while the effect of the fillers was observed at much lower load threshold of 7 N.

Investigation of Mechanical, Corrosion and Microstructural Behaviour of Heat Treated Cr-Modified Al-Mg-Si Alloy

Despite the choice of Al-Mg-Si alloy as a material for innumerable industrial and structural applications, challenges such as undesired scratch resistance, formability and mechanical properties deterioration in saline environment hinders the extent of its application for automotive and aerospace components. Nevertheless, with the growing interest in the application of Al-Mg-Si alloy in automotive and aerospace industries, there is need for cautious control of thermal treatments and inclusion of alloying elements with requisite potentials for enhancing the microstructure and mechanical properties of the alloy. Chromium is known to improve strength and corrosion resistance in several applications. Therefore, this study focuses on the investigation of the effect of Cr particles inclusion in Al-Mg-Si alloy. The effect of ageing heat treatment on selected properties of Al-Mg-Si-Cr alloy was also studied in this work. The Al-Mg-Si and Al-Mg-Si-Cr alloys were developed using a two-step stir casting technique. Chromium was added to Al-Mg-Si alloy at varying percentages of 0, 0.5, 1.0, 1.5, 2.0 and 2.5. All the samples were solution treated in an electric furnace at 500 oC for 30 minutes and water quenched. Then the samples were artificially aged at 210 oC for 3 hours and quenched in natural air. The hardness test revealed that the inclusion of Cr particles in Al-Mg-Si alloy samples increased hardness from 35.03 Kgf/mm2 (hardness of Al-Mg-Si-0%Cr alloy sample) to a maximum value of 126.54 Kgf/mm2 (hardness of Al-Mg-Si-1.5%Cr alloy sample). After heat treatment, the hardness of Al-Mg-Si-0%Cr alloy sample increased to 80.84 Kgf/mm2, while that of Al-Mg-Si-1.5%Cr alloy sample decreased slightly to 120.88 Kgf/mm2. The impact strength test also showed that the inclusion of Cr in Al-Mg-Si alloy increased impact strength from 9.52 J/mm2 (impact strength of Al-Mg-Si-0%Cr alloy sample) to a maximum value of 19.04 J/mm2 (impact strength of Al-Mg-Si-2.0%Cr alloy sample). After heat treatment, the impact strength of Al-Mg-Si-0%Cr alloy sample increased marginally to 10.09 J/mm2, while that of Al-Mg-Si-2.0%Cr alloy sample decreased slightly to 17.57 J/mm2. The tensile and electrochemical tests revealed that the heat-treated Al-Mg-Si-1.0%Cr alloy sample exhibited the highest tensile strength and lowest corrosion rate of 152 MPa and 0.0014 mm/year, respectively. The microstructural examination further revealed that the inclusion of Cr particles in Al-Mg-Si alloy improved its surface morphology. Al-Mg-Si-1.0%Cr alloy sample was adjudged to possess the best microstructural properties. Therefore, this sample is recommended as a potential material for machine tools and other structural or advanced manufacturing applications.

Features of the Heat Treatment of High Speed Steel

The aim of the study was to determine the optimal heat treatment for cast steel P6M5F3 to ensure an increase in impact strength, under conditions of impact loads (planing cutters), minimize carbide liquation and compare with the impact strength of powder steel P6M5F3-MP. For the study, the issue of quenching P6M5F3 steel by simultaneous tempering was considered in order to select optimal values of impact strength, since the reliability of the tool is provided along with high hardness and high impact strength, especially with intermittent turning. Intensive separation of alloying elements and carbon from the residual austenite during its recrystallization makes it possible to apply the proposed method for the efficient and rational use of high-speed steels operating under conditions of increased dynamic loads, which require increased toughness. An increase in the temperature of the martensitic transformation interval as a result of heating indicates a significant depletion of residual austenite with carbon and alloying components during the holding of samples at these temperatures. The proposed heat treatment of high-speed steel allows, unlike the known methods, to completely avoid the martensitic transformation of high-temperature austenite into lamellar martensite, which causes a noticeable decrease in the strength and viscosity of the steel.

Development of an Engineering Material with Increased Impact Strength and Heat Resistance from Recycled PET

The goal of the research was the concurrent enhancement of the impact strength and the heat resistance of recycled poly(ethylene terephthalate) (RPET). The morphology and the dynamic mechanical properties were examined at 0-5-10-15% ethylene-butyl-acrylate-glycidyl methacrylate (PTW) elastomer contents. The blends were crystallized for different time periods (0-20-40-60-180 s) at 150 °C and the morphology change during crystallization and its effect on impact resistance, stiffness, and thermal resistance were examined taking the three-phase model: crystalline fraction/mobile amorphous fraction/rigid amorphous fraction (CRF/MAF/RAF) into consideration. Based on DSC analyses it is proposed that before crystallization, the polymer chains covalently linked to PTW molecules contribute to the rigid amorphous phase (RAF). During thermal annealing, the relaxation of segments (which increases mobility) and ordering into crystals (which decreases mobility) have a complex effect and their resultant determines the ratio of the three phases and thereby also the macroscopic properties of the blends. After annealing the 15% PTW containing RPET blend at 150 °C for 180 s, a fivefold increase in notched impact resistance and a 50-fold increase in thermal resistance (expressed as E90’ value) were achieved compared to the neat RPET reference.