Tensile Values Research Articles

Mechanical properties of platelet-rich fibrin from patients on warfarin

Platelet-rich fibrin (PRF) has been used increasingly in oral and maxillofacial surgery in recent years. The aim of this experimental study was to perform a mechanical evaluation of PRF from patients on warfarin. PRF samples were obtained from 21 patients on warfarin (mean INR 2.30 ± 0.89) and 21 non-anticoagulated patients (control; mean INR 1.08 ± 0.07). For the patients on warfarin, two experimental groups were formed based on the PRF centrifugation time: group A, 10 min (21 samples); group B, 18 min (20 samples). Control group samples (21 samples) were centrifuged for 10 min. Mechanical properties were evaluated by axial tensile test and suture retention test with an Instron 3345 universal testing machine. Mechanical parameters were compared between the groups using the Kruskal–Wallis test and Dunn’s post-hoc test. Axial tensile values were similar in all groups. In the suture retention test, significantly lower values of deformation at maximum force were observed in the experimental group: group A (107.07 ± 25.05%) and group B (104.81 ± 16.79%) versus control (118.01 ± 17.61%) (P = 0.033). Moreover, maximum force was significantly lower in group A (0.17 ± 0.05 N) than in the control group (0.20 ± 0.06 N), while it was significantly higher in group B (0.22 ± 0.07 N) than in group A (P = 0.026). In conclusion, for patients on warfarin, the centrifugation time should be increased to 18 min in order to obtain PRF with superior performance.

Three-Dimensional Printing of Ultrasoft Silicone with a Functional Stiffness Gradient.

A methodology for three-dimensionally printing ultrasoft silicone with a functional stiffness gradient is presented. Ultraviolet-cure silicone was deposited via two independently controlled extruders into a thixotropic, gel-like, silicone oil-based support matrix. Each extruder contained a different liquid silicone formulation. The extrusion rates were independently varied during printing such that the combined selectively deposited material contained different ratios of the two silicones, resulting in localized control of material stiffness. Tests to validate the process are reported, including tensile testing of homogeneous cubic specimens to quantify the range of material stiffness that could be printed, indentation testing of cuboid specimens to characterize printed stiffness gradients, and vibratory testing of synthetic multilayer vocal fold (VF) models to demonstrate that the method may be applied to the fabrication of biomechanical models for voice production research. The cubic specimens exhibited linear stress-strain data with tensile elasticity modulus values between 1.11 and 27.1 kPa, more than a factor of 20 in stiffness variation. The cuboid specimens exhibited material variations that were visually recognizable and quantifiable via indentation testing. The VF models withstood rigorous phonatory flow-induced vibration and exhibited vibratory characteristics comparable to those of previous models. Overall, while process refinements are needed, the results of these tests demonstrate the ability to print ultrasoft silicone with stiffness gradients.

Sustainable, bio-based conductive materials from peanut waste for flexible electronics and tunable piezoresistive strain sensors

Sustainable engineering applications are of great significance in materials science because of limited natural resources. This study presents a sustainable, bio-based approach for the fabrication of flexible electronics and sensors by using peanut shell and skin as the precursors for conductive carbon-based fillers. Carbonized samples showed differences in terms of morphological, structural, and electrical properties. While peanut shell-based carbon showed higher crystallinity and morphology with multiple channels; peanut skin-based carbon showed stacked, layered morphology with smaller particle size. Elastic modulus of the samples increased, tensile strength, and tensile strain values were decreased for both composite sets. The electrical conductivity of the samples prepared by carbon from peanut shell showed lower percolation concentration. Both composites showed piezoresistive response under cycling loading/unloading and tunable piezoresistive sensors were shown to be sensitive to human motions including horizontal and vertical elbow movement and back and forth knee bending and squatting.

Immobilizing imidazolium ionic liquid in flexible proton exchange membranes to modify microstructure fracture

The imidazolium ionic liquid of (Kevlar/bmimCl/SEBS)5 membrane was immobilized in flexible proton exchange membranes (PEMs) with the spin coating technology. In the prepared (Kevlar/bmimCl/SEBS)5 membrane, the imidazolium ionic liquid of 1-butyl-3-methylimidazolium chloride (bmimCl) functioned as glue to modify the microstructure fracture from the stretching operation through occupying the cracks. The proton conduction resistance was reduced with the well-ordered distribution of components in the multilayered microstructure. Although the doped phosphoric acid (PA) molecules charged the proton conductivity, the imidazolium cations of bmim+ could participate in the proton conduction through the formation of continuous proton conduction channels. In this research, the folding and stretching operations exerted the negligible effect on microstructure and property of the prepared PEMs. Besides the modification of bmimCl, the deformation of polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SBES) molecular chains and Kevlar nanofibers in the stretching operation contributed to maintain the stable microstructure. The stretching and folding operations led to slight variation on the membrane property. Specifically, the proton conductivities were respectively 3.21 × 10−2 S/cm and 4.16 × 10−2 S/cm at 160 °C, which were even superior to 2.77 × 10−2 S/cm of the pristine membranes. Furthermore, the tensile stress values of the folding and stretching membranes can reach (18.9 ± 1.19) MPa and (32.6 ± 2.63) MPa.

Experimental investigations on the effect of infill patterns on PLA for structural applications

3D printing is widely employed for a variety of applications due to its numerous advantages. The mechanical properties of a part made using 3D printing are quite important. As a result, it's critical to comprehend how distinct 3D printing process parameter values affect the part's mechanical qualities. However, for some applications, there needs a rigid framework that can tolerate parametric conditions. The mechanical strength of printed objects is influenced by printing parameters such as infill patterns, infill density, and print speed. The infill pattern of 3D printed material for exoskeleton application is examined in this study. In the study performed, it is attempted to find out the best infill pattern for good tensile and bending properties for a particular application. Out of the different patterns which are subjected to study in this investigation, it was found that, the maximum flexural stress value for a honeycomb type infill structure is 65 MPa but their tensile load capacity is less. Cubic type infill structure shows a highest flexural stress value of 64.8 MPa and tensile value of 20.56 MPa. Cubic type infill pattern gave the better result than other type of infill patterns which are subjected to different mechanical property evaluation in this study. According to the mechanical property investigation results obtained for the Cubic type infill pattern, it is found that, this type of infill pattern will be most suitable for exoskeleton applications.

Hydrothermally synthesized 2H-MoS2 under optimized conditions – A structure and morphology analysis

In this study, we obtained the optimized conditions to synthesize pure semiconducting 2H-MoS2 nanomaterial, using a facile and scalable hydrothermal route under the variation of growth parameters such as reaction temperature, reaction time and sulfur precursors. The structural and phase identification of obtained MoS2 powders was analysed using XRD and raman spectroscopy. The reproducible formation of pure 2H-MoS2 phase is reported for the optimized reaction time of 22 h at a temperature of 200 °C using thiourea as sulfur source, with a high yield of 77.4%. FESEM analysis revealed nanoflower-like morphology of average diameter of 300–400 nm with identifiable petals of thickness ∼25 nm for the formed 2H-MoS2 under the optimized conditions. The crystallite size, strain and dislocation density were estimated theoretically using Williamson-Hall plots for the MoS2 formed under the variation of growth temperatures. Tensile strain values were obtained for MoS2 formed using thiourea, which correlated only with phase transitions from mixed 1 T/2H-MoS2 to pure 2H-MoS2. In contrast, only mixed 1 T/2H-MoS2 phase were obtained for MoS2 powders using L-Cysteine, and correspondingly the strain values were extremely small, which may be due to no phase transition observed and presence of nanosheets without curved petal-like features. The results of this study provide optimized condition for the formation of semiconducting 2H-MoS2 nanomaterial by a scalable route. This is useful for low-cost fabrication of flexible nanoelectronic devices such as non-volatile ReRAMs, supercapacitors and sensors based on 2H-MoS2.

Impact of Glass Waste on the Flexural, Compressive, and Direct Tension Bonding Strengths of Masonry Bricks

The waste material problem in today's world has become a major topic affecting all sectors of human life. Researchers are interested in providing solutions for each kind of waste material. Waste glass is one of the waste materials whose amounts increase daily. This article deals with two types of modified cement mortar with glass granular in the masonry wall to find their effect on the wall's property (direct tensile, flexural, and compressive bond strength). Seven different mixes were prepared according to the used glass granular ratio (three mixes contained white glass with 15, 20, and 25% while three of them contained green glass granular 5, 10, and 15%, and the last mix was a controlled mix which contains no glass granular).Based on the obtained result, the used white glass granular provides optimum compression and direct tensile bond strength when 20% of sand is replaced with white glass granular; optimum direct tensile bond value was obtained, which increased by 1.4% and increased compressive strength by 13.08% compared to control mortar. Green glass granular provides optimum compression and direct tensile bond strength when 10% of sand is replaced, direct tensile strength by 1.02%, and increased compressive strength by 3.7% compared to control mortar. The increase of the used waste glass granular in the mortar decreases flexural bond strength, and the amount of decrease depends on the chemical glass compositions.

An investigation on thermo-mechanical characterization of activated carbon/coconut shell powder reinforced natural composites

The main objective of this study is that, to develop the possibility of exploration on the usage of coconut shell (CS) and its derivative of natural activated carbon (AC) filler material, in the motive to fabricate the natural filler reinforced hybrid composite. In this particular study, E-Glass fiber has been chosen as the primary reinforcement and various proportions of CS and AC powder have been selected as the filler components along with the epoxy resin (matrix). Six variants of laminates have been fabricated (GFE, 3% CS, 6% CS, 3% AC, 6% AC and 6% CS/AC) by keeping the E-glass fiber and epoxy as the constant mixture. Besides that, to validate the physical and thermal stability of the composites tests like, Fourier infrared spectroscopy, thermogravimetric analysis (TGA), Scanning Electron Microscope, Tensile, Flexural, Impact, Heat Deflection Test (HDT), Thermal conductivity and Moisture absorption tests have been conducted on all combinations. During the tests, it has been observed that tensile (3% AC—384 MPa), flexural (3% AC—435 MPa), impact (3% AC—19.5 kJ/m2), HDT and moisture values (0% Particulate—0.475%) have shown a significant surge in hybrid composites by slightly compromising the fall of value in moisture absorption on AC composites. Simultaneously, thermal conductivity (6% AC—2.67 W/mK), and TGA (of 6% AC—440°C) values have been found higher in AC epoxy compounds out of all combinations.

Development of Thermoplastic Cassava Starch Composites with Banana Leaf Fibre

Growing environmental concerns have heightened interest in the development of environmentally friendly materials. The purpose of this study is to evaluate how the mechanical and thermal properties of thermoplastic cassava starch (TPCS) are affected by the presence of banana leaf fibre (BLF). By incorporating between 10% and 80% by weight of banana leaf fibre into the TPCS matrix, the biocomposites were created. The thermal and mechanical parameters of the samples were determined. The results revealed that the material’s flexural and tensile characteristics improved significantly, with 50% BLF content in the matrix achieving the highest strength of 20.86 MPa, a flexural strength of 32 MPa, and tensile modulus values. Thermogravimetric examination observed that the addition of BLF improved the material’s thermal stability. The Scanning Electron Microscopy (SEM) morphological tests demonstrated an even spread of banana leaf fibre and a matrix with strong adhesion, which improved the mechanical properties of the biocomposites. The Fourier Transform Infrared Spectroscopy (FT-IR) testing, which confirmed the biocomposite presence of O-H bonds, also confirmed the strong intermolecular hydrogen bonding between TPCS and banana leaf fibre.

Effect of Volume Fraction hybrid composite duck feathers (Anas Plathycus Borneo) - Rat Purun Fiber (Eleocharis Dulcis) With Matrix Polyester On Tensile And Bending Strength

Alabio ducks (Anas Plathycus Borneo) developed in the Alabio area of Hulu Sungai Utara Regency, South Kalimantan with a duck population in 2006 recorded at 3,487,002 heads. So far, alabio ducks have only been used for meat and eggs, even though the feather part of this one poultry can also be used as a composite raw material because of its relatively strong and elastic nature. To improve the quality of the composite, duck feathers are combined with rat purun fibers (eleocharis dulcis) so that they become Hybrid composites. Fraksi volume Hybrid composite Duck Feathers and Rat Purun Fiber are as follows 10% : 90 %, 20% : 80%, 30% : 70%, 40% : 60%, 50% : 50%, 60% : 40%, 70% : 30%, 80% : 20%, 90% : 10%. This study used experimental methods. From the results of the study, it is known that the value of tensile and tensile strength stress and bending strength decreased as the percentage of rat purun fibers decreased compared to the percentage of duck feathers

A rolled Mg−8Al−0.5Zn−0.8Ce alloy with high strength-ductility synergy via engineering high-density low angle boundaries

Developing low-cost rolled Mg alloys with both high strength and ductility is desirable, while the improved strength is generally accompanied with decreased ductility. Here, by using rotated hard-plate rolling (RHPR) with a total thickness reduction of ∼85%, we obtained a Mg−8Al−0.5Zn−0.8Ce (wt.%, AZ80−0.8Ce) alloy with a high strength-ductility synergy, i.e., the yield strength (YS), ultimate tensile strength (UTS) and elongation-to-failure (EF) are ∼308 MPa, ∼360 MPa and ∼13.8%, respectively. It reveals that the high YS is mainly originated from grain boundary strengthening (∼212 MPa), followed by dislocation strengthening (∼43 MPa) and precipitation hardening (∼25 MPa). It is found that a relatively homogeneous fine grain structure containing a large fraction (∼62%) of low angle boundaries (LABs) is achieved in the RHPRed alloy, which is benefit for the high tensile EF value. It demonstrates that LABs have important contributions to strengthening and homogenizing tensile deformation process, leading to the simultaneous high strength and high EF. Our work provides a new insight for fabrication of low-cost high performance Mg alloys with an excellent strength-ductility synergy.

Microstructure and Texture of 2205 Duplex Stainless Steel Additive Parts Fabricated by the Cold Metal Transfer (CMT) Wire and Arc Additive Manufacturing (WAAM)

Additive parts made of 2205 duplex stainless steel were fabricated by cold metal transfer (CMT) wire and arc additive manufacturing (WAAM), and their microstructure and properties were systematically studied. The X-ray diffraction results show that austenite phase and ferrite phase were formed in the additive parts. Due to the low heat input characteristics of CMT-WAAM, no σ phase was observed. The microstructure in the additive parts was different from the bottom to the top, with the content of austenite phase gradually increasing and that of ferrite gradually decreasing. The EBSD results indicate that the ferrite phase in the bottom part grew parallel to the normal direction of {100}. However, the ferrite phase in the middle part grew parallel to the plane composed of the build direction and normal direction, and along {100} and {111}. The effect of the ferrite and austenite contents on the mechanical performance of the additive parts was simulated using the LAMMPS software. The simulation results exhibit a common characteristic in that the dislocations move mainly along the 1/6<112> crystallographic direction families. The simulated maximum tensile stress values of the bottom, middle, and top parts were 23.3 GPa, 22.3 Gpa, and 22.5 Gpa, respectively. The data from the bottom tensile strength simulation were consistent with the actual data, and the bottom tensile strength was the largest in the actual tensile process.

Investigation of the Effect of Yarn Waste Fibers and Cocamide Diethanolamide Chemical on the Strength of Hot Mix Asphalt

In this study, conventional bitumen test were performed on bituminous binder modified with Cocamide Diethanolamide chemical at different ratios. According to results of tests, the most suitable additive ratio has been determined as 5%. However, it was concluded that indirect tensile strength and resistance to moisture of samples prepared with bituminous binder modified with 5% Cocamide Diethanolamide has been adversely affected. It was desired to investigate that whether these properties could be strengthened by yarn waste fibers. Firstly, the effect of 0.1%, 0.2% and 0.3% yarn waste fibers on samples prepared with reference bituminous binder was investigated. Obtained results showed that both indirect tensile strength and resistance to moisture of samples containing 0.1% yarn waste fiber increased. Therefore, 0.1%, 0.2% and 0.3% yarn waste fibers were added to the aggregate mixture and mixing of them with bituminous binder modified with 5% Cocamide Diethanolamide were provided. According to obtained results, different ratios of yarn waste fibers added to aggregate mixture did not have a positive effect on moisture sensitivity. Tensile strength ratio values of samples containing bituminous binder modified with 5% Cocamide Diethanolamide and yarn waste fibers added to the aggregate mixture did not provide specification limit.

Analysis of tensile strength and microstructure on GTAW- Aluminum 6061 welding results

The process of joining aluminum metal requires a special welding method. The use of GTAW welding is a suitable method for joining aluminum plates. This research is intended to analyze the tensile strength and microstructure of the GTAW Aluminum 6061 welding with various currents. The research method used in this research is experimental research. Welding current variations used in this study were 100A, 115A, and 130A, then tested using a destructive test, tensile test. The data analysis used in this study is descriptive analysis, where the data obtained are averaged and then described and concluded. The results of microstructure research on GTAW welding show that changes in the microstructure are very visible in the HAZ area and the weld metal, the greater the heat input, the more spread the Mg2Si grains will be. Good structural dispersion only occurs at 130A current. This is different from the base metal which does not change the material structure at all. Based on the tensile test, the tensile stress value is 80.9 MPa at 100 A current, 84.9 MPa at 115A current variation, and the highest tensile strength is 86.7 MPa at 130A current. So, it can be concluded that the higher the current used, the better the microstructure and tensile strength produced.

Material Properties of Traditional Handmade Paper Samples Fabricated from Cellulosic Fiber of Lokta Bushes.

Handmade papers (HPs) are fabricated from fibrous biomass of Lokta bushes and other plant species following traditional eco-friendly method in Nepal. Although HP fabricated from Lokta bushes is believed to be durable and resistant to bugs and molds, material properties of this paper are not reported in literature. In this study, we measured several material properties of 10 handmade Lokta paper samples collected from local enterprises and paper industries. The mean caliper, grammage, apparent density, equilibrium moisture content, Cobb 60, brightness, opacity, tensile strength, and tensile index values in the paper samples ranged from ∼90 to 700 μm, 50 to 150 g/m2, 0.2 to 0.4 g/cm3, 4 to 7%, 50 to 400 g/m2, 56 to 67%, 83 to 98%, 30 to 2900 N/m, and 1 to 27 Nm/g, respectively. These properties suggested that the HPs are lightweight papers with intermediate to high strength. The tensile strength was found to be significantly higher along the length direction (p < 0.05). Characteristic features of cellulose, hemicellulose, and lignin were observed in FTIR spectra. The crystalline and amorphous phases were also identified in X-ray diffraction (XRD) data. Electron microscopy images revealed a nicely cross-linked network of intact fibers having almost parallel arrangement of microfibrils. These features could provide strength and durability to the paper samples. Understanding the material properties of HPs down to the sub-microscopic level may help improve the paper quality and find novel applications in the future.

Discussion on the Causes of Cracking and Failure of Anticorrosion Layer of a Pipeline

The cause of a rare cracking failure accident of the polyethylene (PE) anti-corrosion layers of a pipeline is analyzed and determined. The properties of the PE raw materials and the anti-corrosion layers were detected and analyzed according to the standard, and the micro-morphology of the anti-corrosion layers was characterized by the scanning electron microscope (SEM). The storage modulus and loss of the anti-corrosion layers at the range of -100~40 °C were tested by the dynamic mechanical analysis (DMA), and the stress of the anti-corrosion layers at low temperature (-40 °C) was calculated. The average thermal expansion coefficient of the anti-corrosion layers in the range of -40~60 °C was tested by the thermomechanical analysis (TMA), and the value at room temperature was obtained, which was compared with the value of the steel materials. The failure accidents caused by raw materials and anti-corrosion layers due to the quality problems, as well as aging and damage of anti-corrosion layers are excluded. The SEM results confirmed that the anti-corrosion layers with no obvious large-scale defects, there were microscopic defects less than 1 μm. At the low temperature (-40 °C), the storage modulus of the anti-corrosion layers is 2.58 GPa, and the corresponding stress is 23.99 MPa, which is higher than the tensile strength test value (22.21 MPa). The average thermal expansion coefficient of the anti-corrosion layers is 14.3×10-5/°C, which is higher than that of the steel material (1.2×10-5/°C). The high stress at low temperature (-40 °C) is one of the reasons for induced defects to cause cracks, and the huge difference in thermal expansion coefficient between the anti-corrosion layers and the steel material is another reason for that.

RETRACTED: Effect of Silane Coupling Agent on the Mechanical Properties of Oil Palm Frond Fiber Composite

Retracted article: In this study, the influence of silane coupling agent on the matrix/ fiber interface bonding and its effect to the mechanical properties of oil palm frond fiber reinforced polyester composites were investigated. Tensile and flexural properties of the composites were studied at 0 - 10.2 volume fraction (% fiber content). Results showed an increasing trend in tensile modulus while tensile strength and flexural strength reduced as the fiber content increased. Higher tensile modulus values were observed in silane treated fiber composites due to additional fiber/ matrix interaction and increment in polyester molecular chain mobility constraint. Reduction in tensile strength is caused by decrease in the matrix crystallinity and formation of stress concentration spots emerging from interface discontinuity. These obstructions, however, were reduced by fiber surface modification, which improved the tensile strength. Enhanced fiber dispersion upon surface modification was unveiled through scanning electron micrograph images.

POLYACRYLONITRILE (PAN) ELECTROSPUN NANOFIBERS COATED 3D PRINTED PLA MATERIALS WITH DIFFERENT INFILL PATTERNS AND THEIR TENSILE PROPERTIES

In this study, the mechanical properties of 3D printed polylactic acid (PLA) samples produced with fused deposition modeling (FDM) technology with five different infill patterns; trihexagon, triangle, line, gyroid, and grid, and these patterns were compared for their mechanical properties. In the second part of the study, PLA specimens with different infill patterns were covered with polyacrylonitrile (PAN) nanofibers synthesized by the electrospinning method to enhance their PLA poor mechanical properties. In the tensile tests, among the infill patterns, gyroid showed the highest Young Modulus with 1108 MPa. SEM results showed that PAN electrospun nanofibers were beadless and ordered nanofibers with an average diameter of 165.7±33 nm. The results showed that after PAN nanofibers coating on PLA specimens, the mechanical properties of the samples for all infill patterns improved, and tensile strain values and therefore, ductile behaviour of all specimens increased. PAN nanofibers could significantly enhance the stiffness of 3D printed PLA materials.

CONSTRUCTION OF CURVED LIMIT DEFORMATIONS OF MATERIALS

The analysis of construction of curves of limiting deformations of metals is carried out in the work. It is established that traditional test methods, such as deposition and stretching of cylindrical specimens, do not ensure the constancy of the stress state, and therefore contribute to the history of deformation in the construction of curves. During deposition, there is an increase in the stress state due to the curvature of the lateral surface of the sample (barrel formation), which is caused by friction at the ends. And when stretched, the stress index also increases, as a result of the formation of the neck due to the loss of resistance to deformation. Therefore, measures were considered to ensure reliable results in the construction of curves of boundary deformations, excluding the influence of the history of deformation. When settling, such measures include the use of plastic, softer than the sample material, foil at the ends of the samples and the gradual removal of the edges of the hole at their ends by grinding or deposition without foil. In addition, the experimental-calculation method was considered, which involves the construction of ways of deformation and correction of the limit deformation using the criterion of deformability. When stretching, in the case of neck formation, the increase in deformation linearly depends on the ratio of the radius of curvature of the neck to its diameter. The equation by which the experimental-calculation method can take into account the influence of the neck on the increase of ultimate deformations is given. To experimentally determine the ultimate tensile deformation, a method of rolling cylindrical specimens on a wedge with rolls whose radii increase during rolling is proposed, which eliminates the appearance of the neck. Boundary strain curves can be constructed with sufficient accuracy for torsion and deposition test specimens, and tensile strain values are obtained using approximated dependences tested for different metals.

Evaluation of structural performances of metakaolin based geopolymer concrete

Last few decades, there has been a substantial advancement of geopolymer (GP) as a Portland cement substitute. It is vital to investigate potential building uses for geopolymer concrete (GPC). Six different mixes were cast for an alkaline to binder (A/B) ratio of 0.25–0.50 with an interval of 0.05. Metakaolin-based geopolymer were cured at ambient temperature and tested for 7, 14, 28, and 90 days. Metakaolin-Marble (MM00) mix was observed to have a maximum slump. For an A/B ratio of 0.35, maximum compressive, split tensile, flexural strength and modulus of elasticity was achieved. For elevated temperature resistance, geopolymer concrete cubes were exposed to temperatures (T) of 200, 400, to 600 C. As the temperature increased, compressive strength (CS) reduced. As the increase of the alkaline to binder (A/B) ratio, the strength of geopolymer concrete increases up to a specific limit beyond the limit strength decline. An empirical formula for split tensile (STS) value prediction using compressive strength values is proposed, valid for determining split tensile strength value. The correlation between compressive strength, split tensile strength, flexural strength, and bulk density varies linearly for a quadratic polynomial.