Impact Strength Values Research Articles

Tropik ağaç türü olan dahoma (Piptadeniastrum africanum) odununun odun plastik kompozit üretiminde kullanımı

Bu çalışma kapsamında profil çekme makinesinden çıkan atık dahoma odun ununun polipropilen (PP) bazlı odun plastik kompozit üretiminde dolgu maddesi olarak kullanımının kompozit malzemelerin mekanik ve morfolojik özellikleri üzerine etkileri incelenmiştir. Atık odun unları fabrikadan alındığı gibi ve dört farklı oranda (%0, %15, %30 ve %45) kullanılmıştır. Atık odun unlarının boyut analizi gerçekleştirilmiştir. Uyumlaştırıcı olarak %3 oranında maleik anhidrit polipropilen (MAPP) ve yağlayıcı olarak %3 parafin wax kullanılmıştır. Elde edilen sonuçlar neticesinde odun ununun eklenmesi ile çekme ve darbe direnci değerlerinde hafif dalgalanmalar gözlemlense de genel olarak mekanik değerlerde iyileşmeler belirlenmiştir. Odun ununun katılım oranının artması ile çekmede elastikiyet modülü, eğilme direnci ve eğilmede elastikiyet modülü özellikleri iyileşmiştir. Kopmada uzama değerlerinde ise keskin bir düşüş gözlemlenmiştir. Morfolojik özellikleri incelendiğinde odun ununun homojen bir şekilde polimer matris içerisinde dağılım gösterdiği ve polimer matrisin dolgu maddelerinin etrafını iyice sardığı ve iyi bir arayüz etkileşiminin olduğu gözlemlenmiştir. Sonuç olarak, atık dahoma odun unlarının odun plastik kompozit üretiminde değerlendirilebileceği kanaatine varılmıştır.

Polivinil klorür (PVC)’ün geri dönüştürülmesi: PVC köpük üretimi ve Karakterizasyonu

Plastikler hayatımızın birçok alanında yıllardır kullanılmakta olup kullanım ömrü sonunda önemli miktarda atık oluşturmaktadır. Doğada uzun yıllar bozunmadan kalan ve çevreye zarar veren bu malzemelerin geri dönüştürülüp tekrar kullanıma kazandırılması önem taşımaktadır. Termoplastik köpük malzemeler düşük yoğunluk, yüksek spesifik mukavemet, yüksek enerji absorblama özellikleri ve üstün yalıtım özelliklerinden dolayı ısı yalıtımı, otomotiv koltukları, ambalaj malzemeleri ve enerji absorblayıcı (soğurucu) malzemeler olarak yaygın bir şekilde kullanılmaktadır. Bu çalışmada, en çok kullanılan plastiklerden biri olan ve önemli miktarda atık oluşturan polivinil klorür (PVC)’ün geri dönüşüm yoluyla termoplastik köpük malzemelerin üretiminde kullanımı amaçlanmıştır. Bu amaçla kapı ve pencere profil atıklarından elde edilen atık PVC kullanılarak termoplastik köpük malzemeler üretilmiştir. PVC köpük malzemelerin bazı fiziksel, mekanik ve morfolojik özellikleri üzerine kimyasal köpük oluşturucu miktarının etkisi incelenmiştir. Üretilen PVC köpük malzemelerde kimyasal köpük oluşturucu malzeme miktarının artması ile PVC köpüklerin yoğunluk değerlerinde %40’lara kadar bir azalma sağlanmıştır. PVC köpüklerin spesifik darbe direnci değerleri kimyasal köpük oluşturucu miktarı ile doğrusal bir şekilde artış göstermiştir. Köpüklerin hücre yapısı incelendiğinde ise kimyasal köpük oluşturucu miktarının artması ile hücre birleşmelerinin meydana geldiği ve daha büyük hücrelerin oluştuğu gözlemlenmiştir.

Development of material extrusion 3D printable ABS/PC polymer blends: influence of styrene–isoprene–styrene copolymer on printability and mechanical properties

ABSTRACT In this work, a series of 3D printable ABS/PC blends were successfully prepared via filament extrusion and fused deposition fabrication. Influence of styrene–isoprene–styrene (SIS) copolymer on printability and mechanical properties were examined. It was revealed that SIS not only enhances the compatibility of the two blend phases, but also enhances the 3D printability of the resulting materials. The effect of print temperature, bed temperature, print speed, layer thickness, number of shell and infill density on mechanical properties of the printed parts were investigated using the Taguchi experimental design method, and the samples were printed using optimized process parameters according to the Taguchi method. It was revealed that the optimization of extrusion multiplier was an efficient method to overcome voids in the printed parts. Interestingly, incorporation of SIS considerably improved the adhesion and distribution of the blend phases. In addition, with an increase in SIS content, tensile strength, yield strength, elastic modulus, and hardness were found to decrease, whereas Izod impact strength and percentage elongation values of the 3D-printable blend increased. Finally, an efficient post-processing technique was successfully employed to improve the aesthetics of additive manufactured specimens. This work provides a facile strategy to prepare new 3D-printable polymer blends with improved adhesion between phases and minimized voids in the printed parts.

Potency of Banana (<i>Musa acuminata Linn.</i>) Stem Fiber as a Reinforcement Material for Heat Cured Acrylic Resin

Denture base made of heat-cured acrylic resin can be sometimes fractured easily during impact such as falling while cleaning it. This study aimed to evaluate the impact strength of heat-cured acrylic resin added with banana (Musa acuminata Linn.) stem fiber of 0.5%, 1%, 1.5% by weight. A total of 32 plate-shaped specimens of heat-cured acrylic resin measuring 65 x 10 x 2.5 mm were divided into 4 groups, group I as control (without addition of banana stem fiber), group II (with addition of 0.5% banana stem fiber), group III (with addition of 1% banana stem fiber), and group IV (with addition of 1.5% banana stem fiber), then the impact strength test was performed using a Charpy Impact Tester. The result shows that the impact strength were increased from group I to group IV and the data obtained were analyzed statistically using One Way ANOVA and post hoc LSD test (p <0.05). The data showed significantly results of the impact strength value with group IV as the highest among all groups, and an increase in impact strength occurred along with increase in the percentage of fiber added to the heat-cured acrylic resin. Based on the results, banana stem fiber has the potential as heat cured acrylic resin reinforcement materials.

Assessment of Mechanical Properties of Aluminium Metal Matrix Composite Reinforced with Carbonized Eggshell Ash (CESA)

A useful alloying agent for aluminium-based composites is eggshell powder, which has a well-deserved reputation for hardness. Aluminium cans and eggshells are regarded as waste and a pollutant because they are no longer needed. Conversion of wastes into useful products will be of economic boost for a nation and make the environment clean. Eggshell particles were studied for their reinforcing properties in a waste aluminium alloy in this study. An eggshell particle of 150 µm in size and a weight fraction of 2%, 4.4%; 6.6%; 8.8%; and 10% was incorporated into aluminium produced from recycled aluminium wastes during casting. A Light Emission Polyvac Spectrometer was used to determine the alloy's constituent makeup. The required experimental procedures and tools were used to measure the tensile strength, hardness, and impact strength. Using a weight fraction of reinforcement of 2, 4, 6, 8, and 10%, tensile strength was found to be 78.07098MPa; 81.09587MPa; 83.04546MPa; 86.12769MPa; and 89.12769MPa respectively. Hardness values of 75.25Hv, 77.03Hv, 78.27Hv, 80.15Hv, and 85.72Hv were obtained at the same specified% weight fraction. Impact strength values of 12.64J, 10.08J, 7.39J, 7.12J, and 7.39J were obtained at the same composition. It may be inferred that the mechanical characteristics of the aluminium alloy reinforced with eggshell particles improved considerably with the number of eggshell particles used and the study, therefore, converted waste to worth.

Investigation of Mechanical Strength and Weight Fraction of Date Palm Fibre Hybrid Composites Reinforced with Polyethylene

Polyethylene, elastomer, and date palm fibre are all readily available, it have an positive impact on growth of new composite materials with desirable features and characteristics. There are many different types of composites, but they all have the same goal: to create a new material with greater qualities than the constituent materials. Date palm fibre was employed to reinforce a composite matrix made of polyethylene (PE) plastic and elastomer. To find out the tensile, impact, and bending strength values of composites by weight fractions of 25% (75:25), 35% (65:35), and 45% (55:45), this research set out to find (55:45). Composites with a weight percentage of 25% (75:25) had less Tensile strength (TS) 1.213 MPa, though mixtures with weightage proportion of 45% (55:45) had the maximum TS of 2.613 MPa. The minimum tensile strain value was discovered in composites with a weight fraction of 25% (75:25), while the maximum tensile strain value was identified in composites with weight fraction of 45 percent (0.0067). (55:45). 45 % (45-55) weight ratio mixture had the minimum impact strength of 45321 kJ/mm2, while the 25 percent (75-25) weight ratio mixture had the maximum impact strength of 17721.41 kJ/mm2. A 25 percent weight fraction (75:25) composite had the lowest bending strength measurement result (1.816 MPa), whereas a 35 percent weight fraction (65:35) composite had the highest measurement result (4.9 MPA) in this category. At 75:25 (75:25), the bending strain of the composite was at its highest, with a value of 0.0216

Features of formation of the structure of thin slabs cast at different speeds, their influence on the structure and properties of hot-rolled steel

For the first time, a complete comprehensive study of the internal quality of metal products with a carbon content of 0.3 % produced in a combined process of thin-slab casting and rolling was carried out. A feature of the combined process is the absence of a cooling and heating cycle before rolling and the small thickness of the initial slab. The zonal chemical heterogeneity of continuously cast "thin" slabs poured at different speeds has been studied. The research methods were metallographic analysis of the macrostructure and spectral method for determining the content of elements by the thickness of slabs. The results of calculations of the segregation coefficients of basic and impurity chemical elements in slabs poured at different speeds are presented. As a result of the study, it was found that an increase in the casting rate by ~ 1.2 times does not lead to a significant increase in the zonal chemical heterogeneity of the continuously cast metal produced in the process of thin-slab casting. Of particular interest was the measurement of quantitative parameters of the initial dendritic structure of "thin" slabs depending on the casting speed. The segregations formed as a result of dendritic liquation were measured. It is shown that with an increase in the casting rate, the dispersion of the dendritic structure increases and the dendritic segregation decreases by 20 %. In the course of simulation rolling, the regularity in changing the parameters of the dendritic structure during deformation of "thin" slabs into the final microstructure of rolled products is considered. When the slabs are compressed by 65 %, the distance between the primary dendrite arm spacing decreases by an average of 65 %. The comparison of the microstructure and mechanical characteristics of rolled products produced in industrial conditions from slabs poured at different speeds using thin-slab casting technology is carried out. The results of the study indicate that an increase in the casting rate increases the dispersion of the initial dendritic structure and, as a result, favorably affects the formation of the final microstructure. It is shown that hot-rolled products made from a slab with a 1.2-fold increased casting speed have a homogeneous microstructure and demonstrate an increase in the values of impact strength by an average of 30 J/cm2.

EFFECT OF MACHINING ON IMPACT TOUGHNESS VALUE OF RAIL SAMPLES DT350 FROM STEEL GRADE 76ХФ

It is known that the value of impact toughness is sensitive to the geometric accuracy of manufacturing, the quality of the surface and concentrator of samples for impact bending. These parameters have a particularly strong influence on samples made of high-carbon materials. At present, the main regulatory document for the manufacture of samples for impact bending is GOST 9454‒78, which does not regulate the method of applying concentrators. Currently, methods of drawing, milling and electroerosion processing are used to apply the concentrator. The issue of the influence of processing methods on the magnitude of impact strength, in particular rail steel, has not been fully studied. To study the effect of electroerosion processing on impact toughness value we made specimens of P65 rail of DT350 category from 76ХФ steel of current EVRAZ ZSMK production using CNC milling machine and electroerosion processing. It has been established that the decrease in the values of impact strength of samples made using electroerosive machining was due to martensite released during local melting of the metal and non-ferrous metals (Cu and Zn) released during processing. During the operation of the electroerosion processing machine, an uneven surface was formed when the arc locally knocked out “holes”, which serve as additional stress concentrators during impact bending tests. The application of the concentrator by a milling machine leads to the formation of a deformed layer up to 80 µm deep, which is not a stress concentrator and does not reduce the impact strength of the rail steel. As part of a further study, it is planned to investigate the effect of the application of the concentrator by the pulling method on the value of the impact toughness.

A comparative study on the effect of nano seashell, multiwall carbon nanotubes and nano alumina on mechanical and impact properties of bidirectional Kevlar/epoxy composite

The use of composite materials is becoming more widespread by the day. Composite materials are used in a variety of vital applications including aerospace, defense and marine. As a result, it is critical to investigate the mechanical and impact properties of these material-based components. Testing of these materials can provide information such as Ultimate Tensile Strength, Impact Strength, and modulus of elastic allowing their application to be better understood. It has been observed that symmetric laminates produce better results. Because of the presence of stiff filler material, the infusion of nanofillers changed the material failure behavior from ductile to brittle. In this comparative study, an attempt has been made in investigating the improvements in the material behavior of neat Kevlar along with the infusion of nano additives like alumina, seashell and MWCNT in varying proportions. Based on the obtained experimental values, graphs were plotted to demonstrate the variation of properties when these infusions were made. There is a significant improvement in the modulus values of the material, Ultimate tensile strength and Impact strength after the incorporation of the nano additives. The Ultimate Tensile Strength was improved by 0.32% in Alumina 1% + 0.25% wt. MWCNT, 21% improvement was found in Alumina 3% + 0.25% wt. MWCNT and 28.86% improvement in alumina 6 % + 0.25% wt. MWCNT compared to neat aramid fiber composite specimen. For the combination of seashell + MWCNT, it is also found that Ultimate Tensile Strength is considerably improved. It was observed that, that there is a 15.96% improvement in Seashell 1% + 0.25% wt. MWCN, 21% improvement in Seashell 3% + 0.25% wt. MWCNT and 29.78% improvement in Seashell 7% + 0.25% wt. MWCNT compared to neat aramid fiber composite specimen. The impact strength was evaluated by performing Charpy Impact Test (ASTMD 256). It was found that there is a 12% improvement in Seashell 1% + 0.25% wt. MWCNT, for Seashell 2% + 0.25% wt. MWCNT, there is a 50% increment in the Impact Strength value. It is also seen that impact properties have significantly improved when the combination of Alumina + MWCNT was infused. There is a 23.072% rise in Alumina 1% + 0.25% wt. MWCNT and 56.83% improvement in Alumina 3% + 0.25% wt. MWCNT compared to its neat aramid fiber composite specimen.

Study of Polymeric Composite Reinforced with Natural Particles: Measurement and Evaluation

Natural particles and their composites are important in materials science, where a significant attentiveness is being displayed in the usage of natural particles as reinforcement in polymer composites. The purpose of this research is to investigate the effect of the walnut shell particles as reinforcing fillers in a matrix composite. So, the amount composite examples were advanced through varying the percentage by weight of filler (3, 5, 7, and 9%) in an epoxy and unsaturated polyester polymer. Composite samples were mechanically characterized by tensile tests, flexural tests, hardness tests, and the Izod impact test. The tensile strength and impact strength of epoxy resin were increased after adding organic waste filler. The highest values of tensile strength and impact strength happened at 7% wt. The flexural strength and hardness of shore D increased with the percentage of walnut shell particles. The highest values of flexural strength and hardness were found at 9% wt. The results show that the mechanical properties of epoxy composite are better than the mechanical properties of unsaturated polyester composite when walnut shell particles are added.

Analysis of Volume Fraction and Fiber Orientation on Tensile Strength and Impact Strength of Cannabis Sativa-Polyester Fiber Composites

The development of composite materials in the engineering field is increasingly being used. This is due to its superior properties compared to conventional materials, such as the ratio between strength and density is quite high, rigid, the manufacturing process is very simple and resistant to corrosion and fatigue loads. The article determines the composition of the volume fraction and orientation of the fibers that have the most optimal tensile strength and impact on Sativa-Polyester Cannabis fibers. In this study, the fiber volume fraction was varied into 10%, 15%, 20% and the orientations were 0o , 30o, 45o, 60o and 90o .The method of making specimens in this study used a hand lay up with the ASTM tensile and impact test standards. The result indicates that the fiber volume fraction of 20% with the fiber orientation of 90o has the highest average tensile strength value of 30.56 MPa, compared to other variations. And the fiber volume fraction of 20% with a fiber orientation of 90o has the highest average value of impact strength, namely 493.6 Joules

The effect of woven oil palm empty fruit bunches (OPEFB) filler fiber on the mechanical properties of natural and synthetic rubber

Oil palm empty fruit bunches (OPEFB) are biomass from palm oil (CPO) processing which can be produced into long lignocellulose and made of yarn as raw material for woven textiles for sandwich biocomposite applications. The purpose of this study was to obtain a biocomposite sandwich variation of natural rubber, butyl, and silicone reinforced with OPEFB woven fibers at optimum filler concentration by studying mechanical properties. The biocomposite of rubber sandwiches with OPEFB fiber reinforced with concentrations of 14, 20, and 28 sheets with a size of 10 x 10 x 1 cm. The methodology used was layered printing with constant pressure and heat using a hot press. The best fiber concentration based on mechanical properties was a composite with a fiber concentration of 28 sheets on 70 shore A hardness natural rubber. This was because the fibers in the composite functioned as load bearers, where this containment was carried out by the distribution of stress. The more fiber concentration, the more effective and uniform distribution of stresses will be, so that an increase in the mechanical properties of the composite occurs. The mechanical properties of rubber have been shown to increase with the addition of fiber as a reinforcing material, the ratio of the impact strength of rubber (control) and fiber-reinforced rubber was lower than that of fiber-reinforced rubber. The natural rubber had an impact strength of 48 kJ/m2, while natural rubber with fiber reinforcement had a higher impact strength value of 321.40 kJ/m2.

The Utility of Recycled Rice Husk-Reinforced PVC Composite Profiles for Façade Cladding.

The production process of construction profiles from natural fibre-reinforced polymer composites, as well as their assembly, generates considerable amounts of waste. The study analysed the possibility of utilising the said waste to produce profiles with the same intended use as products made from the primary material. The analysis involved the recycling of rice husk-reinforced PVC profiles. As a result of the applied post-processing, a composite of higher homogeneity and better filler dispersion than the product made of primary material was obtained. A slight improvement in thermal properties was observed. From the DSC test, Tg values of 78 °C and nearly 80 °C were obtained, while from the TGA test, mass loss values of 0.6% and 0.4% and the decomposition temperatures of 211 °C and 217 °C were noted for profiles of primary and secondary material, respectively. A softening temperature of 75 °C was obtained for primary material profiles, while nearly 77 °C was obtained for secondary. The more favourable mechanical properties of recycled profiles were also maintained. The higher value of flexural strength, flexural modulus, impact strength and hardness by 31%, 24%, 48% and 40% were obtained, respectively. After hydrothermal cycling, the same properties were higher for secondary material profiles by 35%, 20%, 68%, and 67%, respectively. The recorded level of performance properties of recycled products, better than those of primary material standard construction products’, allows us to conclude that profiles made of waste are useful for façade claddings.

Biocomposites from Thermoplastic Postindustrial Waste Starches Filled with Mineral Fillers for Single‐Use Flexible Packaging

AbstractPlasticized starch (PS) materials hold a fundamental role in the design of novel biodegradable and compostable plastics aimed to reduce global single‐use plastic wastes. This work exemplifies the plasticization of postindustrial waste wheat starch (pWWS) and postindustrial corn starch (pWCS) with a comparison to food‐grade corn starch (pCS) by introducing technical waste glycerol (25%) along with urea (5%) and water. The PS (30%) is blended with 70% poly(butylene adipate‐co‐terephthalate) (PBAT) to design a matrix with optimized mechanical properties. As a result, the inclusion of pWCS and pCS shows similar impact strength and melt flow index (MFI) values. Further, the mineral fillers, i.e., talc and calcium carbonate (CaCO3) (25%), are introduced into the PBAT/PS (70%/30%) matrix to explore the effect on MFI, mechanical, thermal, and morphological properties. Scanning electron microscopy analysis reveals good dispersion of PS particles and mineral fillers into the PBAT. Adding talc into the PBAT/pWWS and PBAT/pCS blends shows significantly higher modulus (≈134% and ≈105%, respectively) and heat deflection temperature (HDT) (7.8% and 9.3%, respectively). The addition of 25% CaCO3 results in the impact strength of PBAT/pWWS being improved by ≈20%. Due to talc's lamellar platelet structure and better dispersion, the inclusion of talc into the PBAT/PS blends shows improved rheological properties compared to that of CaCO3.

Градієнтність структури і характеристики руйнування сталевих виливків

The effect of melt overheating over the equilibrium liquidus to temperatures of 1570 ºС, 1620 ºС and 1670 ºС and heat removal conditions (normal and rapid cooling) on the formation of a gradient structure and fracture characteristics over the cross section of castings of 25L and 30HGSL steels was investigated. The differentiated phase-structural state of rectangular castings (60x60x100 mm) was provided by the predominant one-sided heat removal in foundry molds with different heat removal capacity and average cooling rate 2 – 5 ºС/s and 300 – 350 ºС/s. Regular changes in the length of the main macrostructural zones in castings are established depending on the crystallization conditions, in particular, an increase in the zone of near-surface small crystals and the transcrystallization zone during rapid cooling of the melt. It is shown that depending on the temperature conditions of melt preparation and cooling during crystallization, the grain size in the cross section of castings varies by 4-5 numbers (steel 25L) and by 6-8 numbers (steel 30HGSL). The rapid cooling of the melt causes a significant increase in the impact strength of the cross section of the castings in the range of 50-35 J/cm2 (steel 25L) and 40-20 J/cm2 (steel 30HGSL), even under conditions of significant overheating of the melt. Under normal cooling conditions, there is a significant decrease in the values of impact strength in the cross section of the castings from 30 to 15 J/cm2. According to the results of determining the toughness in castings with differentiated structure depending on the crystallization conditions and test temperature (+20 ºС… -60 ºС) the regression equation for changing its values in the range of viscous-brittle transition temperatures and brittleness temperature (Tbrtl50) of steels in the volume of castings. The obtained results create preconditions for the development of technological principles of engineering of cast steel products to ensure the specified properties in accordance with the requirements of their operation. Keywords: steel, crystallization, gradient structure, toughness.

Evaluation of the effect of heat treatment on the structure parameters and cold resistance of metals produced by additive electric arc growth

In this work, we studied the influence of the type and mode of heat treatment on the structure and parameters of cold resistance of 09Mn2Si and 07Cr25Ni13 steels obtained by additive electric arc growth. It is shown that, under optimal printing conditions, a relatively uniform and fine-grained material structure is observed in 09Mn2Si steel, while a dendritic structure is observed in the 07Cr25Ni13 alloy. Heat treatment of the investigated alloys leads to a more uniform distribution of structural components in metals, and in steel 07Cr25Ni13 the dendrites are destroyed, which leads to a decrease in the anisotropy of material properties. Also, heat treatment leads to a significant reduction in internal residual stresses in the material. The results of the study of impact strength in a wide range of low temperatures show that in the initial state after surfacing, the investigated alloys have a significant anisotropy of impact strength (up to 8 and 25% for alloy 09Mn2Si and 07Cr25Ni13, respectively). Heat treatment significantly reduces the anisotropy of the properties of the studied alloys and increases the values ​​of impact strength. So for steel 09Mn2Si after heat treatment, an increase in impact strength by more than 1.5 times is observed over the entire temperature range. The studies carried out made it possible to identify the temperature range of the ductile-brittle transition and the impact strength of 09Mn2Si and 07Cr25Ni13 alloys, which is of great practical importance in the manufacture of parts and structural elements of the Northern version.

Processing and Mechanical Properties of Basalt Fibre-Reinforced Thermoplastic Composites.

Basalt fibre is derived from volcanic rocks and has similar mechanical properties as glass fibre. However, poor fibre-matrix compatibility and processing issues are the main factors that have restricted the mechanical performance of basalt fibre-reinforced thermoplastic composites (BFRTP). In this work, basalt continuous fibre composites with polypropylene (PP) and polycarbonate (PC) matrices were studied. The composites were processed by compression moulding, and a processing study was conducted to achieve good quality composites. For the BF-PC composites, the optimisation of material preparation and processing steps allowed the polymer to impregnate the fibres with minimal fibre movements, hence improving impregnation and mechanical properties. For BF-PP composites, a compatibiliser was required to improve fibre-matrix compatibility. The compatibiliser significantly improved the tensile and impact strength values for short BF-PP composites and continued to increase at 40 wt%. Furthermore, the analytical modelling of the Young’s moduli indicated that the induced fibre orientation during processing for short BF-PP composites and unidirectional (UD) BF-PC composites had better stress transfer than that of UD BF-PP composites.

The Effect of Zirconium Dioxide (ZrO2) Nanoparticles Addition on the Mechanical Parameters of Polymethyl Methacrylate (PMMA): A Systematic Review and Meta-Analysis of Experimental Studies.

The number of studies on the subject of effects of zirconium dioxide (ZrO2) nanoparticles addition on the mechanical parameters of polymethyl methacrylate (PMMA) is still very limited. Therefore, in this research, the authors wanted to assess PMMA modified with the nano-ZrO2 additive in terms of changes in flexural, impact and tensile strength values in relation to PMMA without such component. A systematic review and meta-analysis were performed to evaluate the effect of incorporating nano-ZrO2 into PMMA on individual types of material strength. The obtained numerical data were tabulated and analyzed in the search for percentage changes in those parameters. It was then calculated for each set and the procured model was examined using residual sum of squares (RSS) to assess the discrepancy between the data and the estimation model whilst mean absolute deviation (MAD) was employed to determine robustness. The results of the systematic review were composed of data obtained from individual studies presented in eight independent articles. Overall, the addition of nano-ZrO2 increases the flexural strength of the composite with the PMMA matrix depending on the size of the ZrO2 grains administered. Unfortunately, these conclusions are based on a very limited amount of research and require further verification, especially regarding tensile strength.

Effect of T6, RRA and nano chromium carbide content on microstructure and mechanical properties of AA7075-Cr3C2 nanocomposite

In the present study, AA7075 nanocomposites reinforced with varying weight percentage of Cr3C2 nano particles were successfully synthesized by stir casting technique. The pre-milled powder of Cr3C2 nano particles and aluminum powder was incorporated into molten AA7075 during stir casting for uniform dispersion of nano particles. Thereafter, the nanocomposite samples were aged at T6 and RRA (Retrogression and Reaging). The microstructural characterization examined by SEM and optical microscopy revealed uniform distribution of nano particles up to 1.5 wt.% content, above which the agglomeration occurred. The grain refinement was observed with increase in reinforcement content. The T6 and RRA aging treatment led to reduction in the amount of eutectic phases and grains were further more refined. The combined effect of reinforcement addition and aging, significantly improved the strength and hardness, but deteriorated the ductility. The hardness increased from 110.1 BHN for as cast alloy to 159.3 BHN for T6 treated 1.5 wt.% Cr3C2 nano particles reinforced nanocomposite. Similarly, the maximum value of ultimate tensile strength (308.77 MPa) and impact strength (9.3 J) were obtained for T6 treated 1.5 wt.% Cr3C2 nano particles reinforced nanocomposite. Also, T6 treated nanocomposite showed better strength and hardness whereas RRA treated nanocomposites possessed better ductility.

Effect of Chemical Solutions on Some Mechanical Properties of (Fe + Cu/UPE)

This research includes the preparation of polymeric composites by (Hand lay-up method) of unsaturated polyester resin as a matrix material and (iron, copper) particles as strengthening materials with different weight ratios (5%, 10%, 15%, 20%). The hardness and impact strength properties are studied before and after immersion in (NaOH) solution and (HCl) solution at a normality of (0.3N) and for a period of one immersion (30 days). The results showed that the hardness and impact values increased with the increase in the percentage of iron and copper before immersion, after immersion, that hardness and impact strength values increased with increasing the iron and copper ratio of the compounds For all samples, but their value was lower than in normal conditions. And also these values in the (HCL) solution were lower than the (NaOH) solution.