Tensile Strength Test Results Research Articles

Stability of kangaroo rat burrows in the Sonoran Desert: Evidence of biocementation

Kangaroo rats (Dipodomys deserti) construct complex burrow systems in loose desert sand that survive temperature and relative humidity fluctuations and storms. Animals that burrow in desert sand typically burrow in compacted sand, near plant roots, or when the soil is unsaturated. However, these processes are insufficient to explain tunnel stability of kangaroo rats. Our goal is to understand how kangaroo rat burrows remain stable in loose desert sand, intending to translate this knowledge to geotechnical engineering. A kangaroo rat habitat in the dunes of The Sonoran Desert, AZ, was selected for the study. Dynamic cone penetrometer tests performed at active, abandoned, and no-burrow sites demonstrated that the animals prefer loose sand for burrow construction. Soil samples collected from the burrows' ceilings, subsurface, and surface were characterized. Brazilian tensile strength test results showed that burrow soil has approximately 3 times greater tensile strength than the rest at dry state, which indicates increased interparticle attractive stress in burrow ceilings due to biocementation. Laboratory experiments, scanning electron microscopy, and confocal microscopy images showed that fungal and microbial biofilms provided 17 kPa increase in interparticle attractive stress at less than 1% biomass concentration, indicating potential to be used in soil improvement applications.

PENGARUH VARIASI KUAT ARUS SMAW TERHADAP SIFAT MEKANIK BAJA AISI 1045

This study discusses the effect of variations in the parameters of the welding process on the tensile strength and Vickers hardness tests. In general, it is widely known that in the fabrication process, welding is a very important process that is used to join two or more materials. The welding process is carried out with variations in the strength of the welding current, namely 75, 85, and 95 A. The experimental method used in this research is AISI 1045 steel material with a thickness of 6.0 mm. The results of the tensile strength test have the highest value at a current strength of 75 A which is equal to 756.642 MPa. The lowest tensile strength test results were obtained with a tensile strength of 687.608 MPa at a current strength of 95 A. specimens with variations in current strength of 95 A have the highest value in the Vickers hardness test, with a hardness value of 281.25 HV. From the research conducted it is known that as the welding current increases there is a decrease in the value of the tensile strength. The hardness value in the heat affected zone (HAZ) area of all test specimens has the highest value, while the hardness value of weld metal (WM) and base metal (BM) has almost the same hardness value.

Advancing Sustainability and Performance with Crushed Bottom Ash as Filler in Polymer-Modified Asphalt Concrete Mixtures.

Amid the growing demand for sustainable pavement solutions and the need to incorporate recycled materials into construction practices, this study explored the viability of using crushed thermal power plant bottom ash as a filler in polymer-modified asphalt concrete mixtures. Conventional lime filler was replaced with bottom ash at varying levels (0%, 25%, 50%, and 75%), and the resulting mixtures were evaluated using several performance tests. The optimal replacement level was determined to be 25%, based on the results of the indirect tensile strength (ITS) test. Comparisons between the control mixture and the 25% bottom ash-modified mixture were conducted using the dynamic modulus test, Cantabro test, Hamburg wheel tracking (HWT) test, and tensile strength ratio (TSR) test. The findings indicate that the 25% bottom ash-modified mixture demonstrated improved performance across multiple parameters. The HWT test showed enhanced rut durability, with a recorded depth of 7.56 mm compared to 8.9 mm for the control mixture. The Cantabro test results revealed lower weight loss percentages for the modified mixture, indicating better abrasion resistance. The dynamic modulus test indicated higher resilience and stiffness in both high- and low-frequency stages. The TSR test highlighted improved moisture resistance, with higher TSR values after 10 wet-drying cycles. These improvements are attributed to the fine particle size and beneficial chemical composition of bottom ash, which enhance the asphalt mixture's density, binder-aggregate adhesion, and overall durability. The results suggest that incorporating 25% crushed bottom ash as a filler in polymer-modified asphalt concrete mixtures is a viable and sustainable approach to improving pavement performance and longevity.

Modelling the mechanical properties of concrete produced with polycarbonate waste ash by machine learning

India’s cement industry is the second largest in the world, generating 6.9% of the global cement output. Polycarbonate waste ash is a major problem in India and around the globe. Approximately 370,000 tons of scientific waste are generated annually from fitness care facilities in India. Polycarbonate waste helps reduce the environmental burden associated with disposal and decreases the need for new raw materials. The primary variable in this study is the quantity of polycarbonate waste ash (5, 10, 15, 20 and 25% of the weight of cement), partial replacement of cement, water-cement ratio and aggregates. The mechanical properties, such as compressive strength, split tensile strength and flexural test results, of the mixtures with the polycarbonate waste ash were superior at 7, 14 and 28 days compared to those of the control mix. The water absorption rate is less than that of standard concrete. Compared with those of conventional concrete, polycarbonate waste concrete mixtures undergo minimal weight loss under acid curing conditions. Polycarbonate waste is utilized in the construction industry to reduce pollution and improve the economy. This study further simulated the strength characteristics of concrete made with waste polycarbonate ash using least absolute shrinkage and selection operator regression and decision trees. Cement, polycarbonate waste, slump, water absorption, and the ratio of water to cement were the main components that were considered input variables. The suggested decision tree model was successful with unparalleled predictive accuracy across important metrics. Its outstanding predictive ability for split tensile strength (R2 = 0.879403), flexural strength (R2 = 0.91197), and compressive strength (R2 = 0.853683) confirmed that this method was the preferred choice for these strength predictions.

Analysis of the Influence of Velocity Effect on the Indirect Tensile Strength Test Results of Asphalt Concrete

The asphalt mixture AC-20C was compacted by standard method, and the physical and mechanical properties of asphalt concrete specimens were tested. In the test process, the difference of indirect tensile strength is investigated by using different loading rates, so as to evaluate the correlation between the test process and the test results of asphalt mix-ture. The test results show that: when the appropriate loading speed is adopted, the asphalt mixture test can achieve more ideal test results, and different test conditions will produce completely different results, so that the test data are completely distorted. Under the condition of excluding other factors, more real test data can be obtained, so the test should be carried out in strict accordance with the requirements of the specification.

Characterization of the spin arc welding technique for dissimilar materials Hastelloy C-2000 and C-276

Hastelloy C-2000 and C-276 are primarily employed in the petrochemical and pharmaceutical industries. Finding an effective way to combine these alloys is still a complex task in industry. The main focus of this study is to investigate the potential efficacy of the spin arc welding process on Hastelloy C-2000 and C-276. The welding process was carried out under various conditions, such as weld current, spinning speed, and spin diameter. ERNiCrMo-4, with a diameter of 1.2 mm, was employed as a filler. Optical microscopy, XRD and FESEM were used for microstructural examination. The mechanical properties of the welded samples were critically analyzed. The results of the ultimate tensile strength (UTS), hardness value (HV), and impact tests of spin arc welding were compared with those of the multipass pulsed current gas tungsten arc welding process (MPCGTAW). In spin arc welding, Hastelloy C-2000 and C-276 exhibited higher UTS, HV, and toughness compared to MPCGTAW because there was no secondary TCP phase formation in the weld centre and hot cracking in spin arc weldments. Additionally, compared to MPCGTAW, the elongation with spin arc welding was noted to be lower. Moreover, microstructural analysis revealed no evidence of grain segregation, which may have contributed to the improved UTS and HV of the materials during spin arc welding. Thus, spin arc welding proves to be superior for dissimilar Hastelloy joints of C-2000 and C-276.

BIOPLASTIC FROM TAPIOCA STARCH WASTE AND RICE WASTE

Bioplastic is a plastic that is easily decomposed naturally by the activity of microorganisms without leaving toxic residues because of its that can return to nature. Aim: This study aim to examine the quality of bioplastics from variations of tapioca starch and rice waste raw materials for optimal composition. Methodology and Results: The method used is by mixing the raw material of tapioca starch waste and rice waste with variations in the composition of the material; 100% rice waste, 100% tapioca starch waste, 30% tapioca starch waste: 70% rice waste, 50% tapioca starch waste: 50% rice waste, 70% tapioca starch waste: 30% rice waste. Add 10 mL of glycerol, 30 mL of distilled water, 40 mL of acetate solvent, and 40 ml of 96% ethanol. The product will be tested on a laboratory scale for tensile strength, elongation at break, FTIR tests, and biodegradation according to SNI 7188.7:2016 for the bioplastic category that is easily biodegradable. The result shows that the optimal composition was found in the composition of 100% rice waste raw material with the quality of the tensile strength test results of 3,45 MPa, the value of elongation at break 3,8%, and the value of biodegradation 100%. The resulting bioplastics contain functional groups O-H (hydroxyl) bonded to hydrogen, C-H (alkanes), C≡C (alkynes), esters, simple aromatic compounds, C-O (carboxyl), C=C (alkenes), and hydrocarbons -(CH2)n. Conclusion, significance, and impact of study: The use of starch to produce biodegradable materials is because it is environmentally friendly, easily degraded, available in large quantities, and affordable, moreover, the bioplastics derived from these waste sources are typically biodegradable, meaning they can break down into natural compounds under certain conditions, reducing environmental pollution.

Performance evaluation of grouted porous asphalt concrete

Abstract Semiflexible pavement (SFP) is considered a composite mixture, as it consists mainly of a porous asphalt mixture with high air voids grouted with highly flowed cementitious grout. Numerous benefits have been attributed to this technology, including exceptional slip resistance, a high static bearing capacity, and rutting resistance. In this study, two different types of semiflexible paving mix were produced by using two different types of grouting materials (GMs). There is a discrepancy between the compressive strengths of the two GMs used, as the compressive strength of the first mixture, which consisted of 96% cement and 4% silica fume (SF), was approximately twice the compressive strength of the second mixture, which consisted of 75% cement and 25% sand. The mechanical and durable properties of the two SFPs were studied, in addition to the effect of variation in the compressive strengths of the two GMs and their effect on the final performance of the pavement. The results of Marshall and rutting tests show that the SFP material exhibits good high-temperature stability. The effect of the variation in the compressive strength of the two mixtures was evident in the results of the tests compared with the sand mixture at a strength of 20.8 MPa, the SF at a strength of 48.1 MPa witnessed a 39.54% increase in the Marshall stability at 28-day curing age. Also, the composite material (CM) showed better rutting performance than traditional asphalt mixtures, which did not exceed 2 mm. The results of the indirect tensile strength (ITS) test showed a discrepancy between the two types of CM, as the ITS value of the grouting material of SF (GMSF) mixture increased by 14.91% compared with the grouting material of sand (GMSN) for the curing age of 28 days for unconditioned samples and by 20.22% for the conditioned samples for the same curing age, while the durability of two types of CM was measured by Cantabro abrasion loss and tensile strength ratio. The results were acceptable and within the specification limits. With a variation for the two types of CM, the GMSF mixture showed an increase in the value of Cantabro loss by 11.52% over the GMSN mixture for ageing samples and 6.59% for non-aging samples of 28 days of curing age.

Cymbopogon nardus Leaf Ash as an Alternative Material for Enhancing Concrete Strength

Numerous waste materials containing calcium and silica have been adopted as partial cement substitutes. This practice is intended to reduce the environmental impact of cement production, specifically in terms of carbon dioxide (CO2) emissions. However, plantation waste, specifically waste from Cymbopogon nardus leaf, has not been completely exploited. The presence of silica in C. nardus leaf ash (CNLA) presents an opportunity to partially replace cement in concrete. The purpose of this study is to determine the effect of substituting CNLA at 0%, 5%, 10%, and 15% as a partial replacement for cement on the compressive and tensile strengths of concrete after 28 days of curing. For testing purposes, 15 cm × 30 cm cylindrical concrete specimens were formed. The investigation was conducted following ACI 211.1-91 (American Concrete Institute) and ASTM (American Society for Testing and Materials) standards. The required compressive strength for the concrete was 17.00 MPa. The results of the study indicate that the addition of CNLA to cement at concentrations of 0%, 5%, 10%, and 15% resulted in compressive strengths of 21.56, 21.12, 22.58, and 17.88 MPa, respectively. The results of the split tensile strength test were 2.43, 2.72, 2.87, and 3.18 MPa, respectively. According to the findings of this study, increasing the amount of CNLA in cement by 10% can increase the compressive and tensile strengths of concrete. In addition, as the percentage of CNLA exceeds 10%, the workability of the concrete decreases, posing challenges in attaining the targeted strength of the concrete.

Полимерный композит для распылителей сельскохозяйственных опрыскивателей: испытания

The long service life of a farm sprayer depends on the material, the nozzles are made of. To increase the wear resistance of polymer nozzles, dispersed fillers are incorporated into the composite. Composites for agricultural sprayer atomizers should have high chemical resistance to agrochemicals and mechanical strength, as well as low hydro-abrasive wear. In order to select the optimal polymer composite for farm sprayer atomizers, three composites based on polyoxymethylene of MASCON POM 27 brand were produced, in which glass fiber, graphite and silicon carbide with the degree of volume filling 10, 15 and 20% were used as disperse fillers. The polymer composites were tested for 14 weeks for chemical resistance to agrochemicals (herbicide “Lazurit”, fungicide “Rakurs”, insecticide “Borei-Neo”), mechanical strength and hydro-abrasive wear. MASCON POM 27 polyoxymethylene samples served as a reference. The results of mechanical tensile strength tests showed the greatest increase in the strength index at 15% filler content regardless of its type. The strength of the composite with silicon carbide increased by 30.2%, with glass fiber - by 26.8%, with graphite - by 27.4%. It was found that the chemical resistance of composites does not depend on the concentration of agrochemical solution. The experiments on hydro-abrasive wear revealed that graphite and silicon carbide are effective as fillers and can reduce wear up to 7.5 times. It is recommended to use polyoxymethylene with 15% content of silicon carbide for manufacturing farm sprayer atomizers.

Fracture behavior of concrete made with sintered fly ash lightweight coarse aggregate in comparison to normal weight concrete

Sintered fly ash lightweight aggregate based concrete has been reported to give mechanical and durability properties similar to conventional concrete. But concrete made up of lightweight aggregate possesses lower stiffness and shear strength resulting into a brittle mode of failure due to crack propagating directly inside aggregate which is weak in nature. The study presents findings from the experimental investigation of fracture behavior of concrete made with sintered fly ash lightweight coarse aggregate in comparison to normal weight concrete (NWC) at w/b ratio of 0.5, 0.4 and 0.3. The mixes have been tested for compressive and split tensile strength for both concrete types. On notched beams of size 100x 100 x 500 mm, a three-point bend test has been carried out for both lightweight and normal weight concrete to evaluate fracture parameters. The results of split tensile strength test indicated that the split tensile to compressive strength ratio lies in the range of 5-8% for lightweight concrete and this ratio lies between 5-10% for normal weight concrete. The study indicates comparable fracture behavior for both lightweight and normal weight concrete. The non-linear ascending and descending branches in load vs deflection curve of concrete with sintered fly ash lightweight coarse aggregate can be linked with the non-linearity in tensile type stress-strain behavior and formation of the fracture zone in front of the initial notch. The modulus of elasticity of lightweight concrete is significantly lower than normal concrete. The modulus of elasticity, area under the load deflection curve, tensile strength, fracture behavior etc. needs to be considered appropriately in the non-linear analysis of lightweight concrete.

In vivo study on the repair of rat Achilles tendon injury treated with non-thermal atmospheric-pressure helium microplasma jet.

Non-thermal atmospheric-pressure plasma (NTAPP) has been widely studied for clinical applications, e.g., disinfection, wound healing, cancer therapy, hemostasis, and bone regeneration. It is being revealed that the physical and chemical actions of plasma have enabled these clinical applications. Based on our previous report regarding plasma-stimulated bone regeneration, this study focused on Achilles tendon repair by NTAPP. This is the first study to reveal that exposure to NTAPP can accelerate Achilles tendon repair using a well-established Achilles tendon injury rat model. Histological evaluation using the Stoll's and histological scores showed a significant improvement at 2 and 4 weeks, with type I collagen content being substantial at the early time point of 2 weeks post-surgery. Notably, the replacement of type III collagen with type I collagen occurred more frequently in the plasma-treated groups at the early stage of repair. Tensile strength test results showed that the maximum breaking strength in the plasma-treated group at two weeks was significantly higher than that in the untreated group. Overall, our results indicate that a single event of NTAPP treatment during the surgery can contribute to an early recovery of an injured tendon.

Polydopamine-modified cellulose-based composite separator for inhibiting dendritic growth of lithium metal batteries

The inhomogeneous pore structure and lack of polar groups in lithium metal battery separators lead to uneven transport of Li+ through the separator, the uneven flux of Li+, and eventually the formation of lithium dendrites. Therefore, to provide uniform Li+ transport and inhibit the growth of lithium dendrites, a polydopamine-modified cellulose membrane (PDA-CM) was created by oxidative self-polymerizing dopamine and binding it to the surface and interface of the cellulose membrane through hydrogen bonds. The successful preparation of the PDA-CM separator by PDA-modified cellulose membrane by hydrogen bonds was proved by the FT-IR test. TGA, thermal shrinkage test, tensile strength test, FESEM, and porosity test results indicated that neither the PDA-CM nor the CM separators shrank at 160 °C, the PDA-CM separator also had better tensile strength (Stress = 31.1 MPa), and uniform pores (Porosity = 54.95 %) with homogeneous Li+ flux. The polar functional groups (-NH- and -OH) in PDA improved the electrolyte uptake rate (Electrolyte uptake rate = 469.77 %), the electrolyte retention (Electrolyte retention = 409.04 %), and electrolyte wettability (Contact angle = 18.35°) of the separator and promoted the uniform distribution of Li+ through the PDA-CM separator. In addition, the PDA-CM separator had better ionic conductivity (1.54 × 10−3 S·cm−1) and lower impedance (849 Ω). The catechol on the PDA molecule created strong adhesion between the separator and the lithium metal, reduced the local tension on the surface of the lithium metal and inhibited dendrite growth. The lithium metal anode remained smooth after cycling. The lithium metal battery prepared by the PDA-CM separator showed decent cycle performance and remained a high capacity retention rate (90.48 %) after 100 cycles. This study provides a new solution for the modification of cellulose-based lithium metal battery separators, which can achieve uniform transmission of Li+, inhibit the growth of lithium dendrites, and improve battery performance.

Pavement design using bituminous surface course with recycled aggregates

The utilization of Recycled Aggregates (RA) in the construction of pavement structure is one of the inventive and eco-friendly construction techniques. This scale down the construction cost without negotiates the strength and the durability of the pavement structures. However, RA is rigid in nature because it is obtained from aged bituminous mixtures to enhance a rejuvenator is usually added in order to lower the stiffness. Rejuvenator surges the utility of the bituminous mixtures and makes them be smoothly paved and compacted. The objective of this study is to design a flexible pavement structure using Stone Matrix Asphalt (SMA) as a surface course in order with RA. In SMA mixture major component is occupied by coarse aggregates, mineral filler, bitumen and a minor component of fine aggregates helps to fill the voids present in coarse aggregate which gives stone-on-stone contact. The bitumen binder and mineral filler form mastic, providing durability to the mixture. In this study, the performance of SMA mixtures with different RA proportions and a rejuvenator will be compared with conventional SMA mixture with zero percentage RA. Marshall Mix design is outlined to find the Marshall and volumetric properties of SMA mixtures and to regulate the Optimum Binder Content (OBC). The mixtures will be compared based on the drain down, stripping, Indirect Tensile strength (ITS) and Semi circular bend (SCB) test results. The analysis and design of flexible pavement structure using the prepared SMA mixtures with different RA contents as surface courses also will be carried out as a component of the study.SMA mixture of 40% replacing RA with 3% of palm sludge oil as rejuvenator exhibits optimum bitumen content where vertical stress, strain and displacement obtain reduction with compared to IRC 37 conventional SMA mixture.

About Dynamics of Improving the Foam Concrete Technological and Operational Properties upon Disperse Reinforcement with Polypropylene Fibers

Introduction. The efficiency of the foam concrete products manufacture and application in construction is briefly overviewed. The reasons constraining the nomenclature of the manufactured products are listed. The information about evolvement of the foam concrete disperse fiber-reinforcement technology is provided. The need for scientific research aimed at studying the dynamics of the foam concrete technological and operational properties upon disperse reinforcement with polypropylene fibers is formulated.Materials and Methods. The composition and properties of the materials used for manufacturing the foam concrete mixtures are listed. The methods used for assessing the technological and mechanical properties of the materials under study are indicated.Results. The results of the experimental assessment of the polypropylene fiber length and amount influence on the dynamics of the plastic strengthening growth of the equally dense foam and fiber-reinforced concrete mixtures are presented. The scope of the polypropylene fiber influence on the dynamics of the studied mixtures plastic strengthening is analysed. The scientific substantiation of the reasons accelerating the mass transfer processes during the disperse reinforcement of mixtures with fibers is given. The results of the bending tensile strength tests of the large-size D600 concrete specimens are presented.Discussion and Conclusion. The efficient positive influence of the polypropylene fiber, in correlation with its length, on the following foam concrete properties has been distinguished:speed of phase transfer;ultimate extensibility;elasticity and strength modulus of D600 concrete.

Pengembangan Uji Eksperimental Penuaan Dipercepat Sistem Isolasi Kertas Terendam Minyak Transformator

A transformer is a static electric device that is used to change the alternating voltage to a higher or lower level and is used to transfer energy from one electric circuit to another without changing the frequency. When the transformer is working, there is a temperature rise in the transformer which affects the degradation of the insulating paper and transformer oil. This accelerated aging tester applies the drying and vacuuming process as well as the arrangement of paper insulation racks to achieve maximum test results. The research method refers to IEC 60216-3 2006 for aging time, IEC TS 62332-1 2014 and IEC TS 62332-1 2011 as a reference for the Development of Accelerated Aging Experimental Test Cells for Transformer Oil-immersed Paper Insulation Systems. After achieving the existing goals, the addition of the drying process resulted in quite good Breakdown Voltage test results, not only that after the addition of vacuum it produced a good oil color according to ASTM D1500 as well as after the presence of paper placement racks the results of good tensile strength testing were proven by a graph which relatively decreased from sample 1 to sample 3.

Investigating the Impact of Polymer and Portland Cement on the Crack Resistance of Half-Warm Bituminous Emulsion Mixtures

Cold mix asphalt (CMA) is emerging as an environmentally friendly alternative to traditional hot mix asphalt (HMA). It offers advantages such as lower costs, reduced energy demands, decreased environmental impacts, and improved safety aspects. Among the various types of CMA, the cold bitumen emulsion mixture (CBEM) stands out. The CBEM involves diluting bitumen through emulsification, resulting in lower bitumen viscosity. However, this process has certain drawbacks, including extended setting (curing) times, lower early strength, increased porosity, and susceptibility to moisture. This study focuses on enhancing CBEM properties through the utilization of low-energy heat techniques, such as microwave technology, and the incorporation of a polymeric additive, specifically acrylic. These innovations led to the development of a novel paving technology known as a half-warm bitumen emulsion mixture (HWBEM). The research was conducted in two phases. First, the study assessed the impact of low-energy heating on the CBEM. Subsequently, it explored the combined effects of low-energy heating and the addition of an acrylic polymer. CBEM samples containing ordinary Portland cement (OPC) as an active filler were utilized in the sample manufacturing process. The effectiveness of these techniques in enhancing crack resistance was evaluated by analysing the results of the indirect tensile strength test. Notably, CBEM samples containing an amount of 2.5% of acrylic polymer and OPC exhibited the highest resistance to cracking. Furthermore, significant improvements were observed in their volumetric and mechanical properties, comparable to those of HMA.

Effect of Sorbitol and Chitosan Addition on Tensile Strength and Degradation Rate of Biodegradable Plastic from Rice Bran Starch

The increasing use of plastic can cause enviromental pollution because plastic takes a very long time to decompose in the soil. Solutions that can be used to accelerate the process of plastic decomposition in the soil by replacing plastic making materials with natural polymer materials. Natural polymers are polymers produced from organic monomers, one of which is starch. Starch is one of the natural polymer materials used in the manufacture of biodegradable plastics, one of the natural materials containing starch is rice bran waste. From rice bran waste starch, bioderadable plastic can be made by adding chitosan and sorbitol by varying then succesively, namely 5:2:8, 5:3:7, 5:5:5, 5:7:3, 5:10:0, then making samples, then the samples are printed and tensile strength testing and degradation testing are carried out. From the tensile strength test results, the values obtained were 0.69 Mpa, 0.74 Mpa, 1.50 Mpa, 1.98 Mpa and 2.28 Mpa, respectively. The finel weight of the sampel after degradation is 0 gram, 0 gram, 0.0189 gram, 0.0226 gram, 0.1017 gram. It is concluded that biodegardable plastic with good tensile strength is in the variation of starch 5 grams, without sorbitol and chitosan 10 grams and for good degradation test in the variation of starch 5 grams, sorbitol 8 ml, chitosan 2 grams and variation of starch 5 grams, sorbitol 7 ml, chitosan 3 grams.

Mechanical properties of recycled PLA and PETG printed by FDM/FFM method

The aim of this paper is to compare the mechanical properties of selected recycled thermoplastics against their equivalents made from new raw materials manufactured using the FDM/FFF additive method.Two materials were tested: recycled polylactide (R-PLA) and recycled poly(ethylene terephthalate) with the addition of glycol (R-PETG). Reference materials are their equivalents made from new raw materials. Both types of materials are widely available on the market. In order to compare their mechanical properties and to check whether recycled materials do not differ in quality from their equivalents made from new raw materials, tensile strength tests were performed. In addition, the Vickers microhardness was measured, and the structure of printed samples using optical microscopy was observed.The paper presents the results of the static tensile strength test of samples made by the FDM/FFF technology from the tested materials in accordance with the ISO-00527-2-2012 standard. The samples were manufactured at the average temperature recommended by the producer 10C. The results of tensile strength tests indicate that the samples printed at the average temperature show the best tensile strength for both methods of filament deposition.The recycled materials are not significantly different from the reference materials in terms of tensile strength, microhardness and structure. It is reasonable to test other polymeric materials further and check materials from several consecutive recycling cycles.Closing the cycle of plastic used in 3D printing. The ability to quickly transform waste products, e.g. PET bottles, into filaments and reuse them to produce full-value products.The paper presents the results of strength and microhardness tests as well as microscopic investigations of two recycled thermoplastics commonly used in the industry manufactured using the FDM/FFF technology against the background of reference materials made from new raw materials.

EFFECT OF ADDITION RAMIE AND COCONUT COIR FIBERS WITH DIFFERENT CONCENTRATIONS ON TENSILE STRENGTH OF ACRYLIC DENTURE BASE

Background: Acrylic denture base material has advantages such as good aesthetics, ease of repair, and affordable price, but this denture has mechanical properties, one of which is low tensile strength so fractures often occur during use. Utilization of natural fibers such as ramie (Boehmeria Nivea) and coconut coir (Coco Nucifera L) can be used as an alternative reinforcement for acrylic denture bases. Purpose: To determine the effect of adding ramie fiber and coconut coir fiber at different concentrations on the tensile strength of the acrylic denture base. Method: This study used a laboratory experimental method with a flat dumbell-shaped specimen with a size of 75 × 10 × 3 mm based on ISO 527-1 (2019). The specimens consisted of 42 plates which were divided into 7 groups, namely 6 specimens each group without fiber addition (control), with the addition of ramie fiber 1%, 2%, 3%, and the addition of coconut coir fiber 1%, 2%, 3%. Tensile strength testing using Universal Testing Machine (UTM), data were analyzed by One-way ANOVA test and Post Hoc LSD test. Result: The 3% ramie fiber addition group had the highest tensile strength (76.47 MPa), the 1% coconut coir fiber addition group had the lowest tensile strength (58.91 MPa). There was a significant difference in the results of the control group's tensile strength test and the addition of 3% ramie fiber and 1% coconut coir fiber (p-value < 0.05). Conclusion: The greater the concentration of ramie and coconut fiber additions, the higher the tensile strength value, although the tensile strength value in the coconut fiber addition group was lower than the control group and ramie fiber addition.