scholarly journals EXPERIMENTAL STUDY ON MECHANICAL PROPERTIES OF POLYURETHANE POWDER COMPOSITES

2021 ◽  
Vol 30 (4) ◽  
Author(s):  
Kexin Zhang
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Quartz Sand ◽  
Strain Curve ◽  
Test Block ◽  
Control Group ◽  
Flexural Test ◽  
Polyester Polyol ◽  
Polyurethane Composite ◽  
Powder Composites

In this paper, the effects of emery, lime, quartz sand and cement on the mechanical properties of polyurethane powder composites were studied by three-point flexural test, and the stress-strain curve was drawn. In the flexural test, the polyurethane cement composite formed a control group by changing the content of polyester polyol. When polyester polyol: isocyanate: cement =1:1:2, the average flexural strength of polyurethane cement was 37.1 MPa, and the strain was 10854 με.When polyester polyol: isocyanate: cement =1.15:1:2, the average flexural strength is 38.9 MPa and the strain is 23520 με.When polyester polyol: isocyanate: cement =1.3:1:2, the average flexural strength is 42.5 MPa and the strain is 32942 με. The flexural strength and ductility are improved to a certain extent due to the addition of polyester polyol.The average flexural strength of other polyurethane powder composites such as polyurethane emery test block is 45.1 MPa and the strain is 6203 με, the average flexural strength of polyurethane lime test block is 33.4 MPa and the strain is 6470 με, the average flexural strength of polyurethane quartz sand test block is 49.23 MPa and the strain is 7521 με. The results show that the flexural strength of polyurethane emery material and polyurethane quartz sand material is higher than that of polyurethane cement, which can be used to replace cement to a certain extent to reduce the cost of polyurethane composite material.

scholarly journals Effect of bleaching agents on mechanical properties of bulk fill resin and conventional composites

2020 ◽  
Vol 9 (9) ◽  
pp. e918998279
Author(s):  
Hellen Caroliny de Carvalho ◽  
Omar Geha ◽  
Gabriela Torres Zanin ◽  
Maria Fernanda Braga Reis ◽  
Ricardo Danil Guiraldo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Hydrogen Peroxide ◽  
Flexural Strength ◽  
Control Group ◽  
Resin Composites ◽  
Flexural Test ◽  
Carbamide Peroxide ◽  
Tooth Whitening ◽  
Home Office ◽  
Bleaching Treatment

This study evaluated the effect of tooth whitening on resin composites (RC) on roughness, microhardness and flexural strength. There were three RC: one Bulk Fill type resin (Filtek Bulk Fill) and two conventional, Filtek Z350 (Z350) and Z250 (Z250). Twenty-four bar-shaped specimens were made for each RC. First, the initial roughness and microhardness were evaluated; thus, the RC were subdivided into 3 other groups, according to treatments: control group (C), this did not receive bleaching treatment; home bleaching with 10% carbamide peroxide (10%CP) (Opalescence PF),  8h/14 days; home-office bleaching with 40% hydrogen peroxide (40%HP) (Opalescence Boost PF) 3 ´ 15 minutes for 3 days at 48 hour intervals. After treatments, roughness and microhardness were again evaluated and then the samples submitted to the three-point flexural test. Data were tabulated, normality assessed, then submitted to ANOVA followed Tukey’s test (p <0.05). The results showed that the bleaching change the roughness of RC, but 10%CP had a significant increase. The gel concentration does not influence microhardness and flexural strength. After bleaching, Z350 has a lower elastic modulus. Based in the results obtained, could be concluded that the different bleachings did not promote significant changes on the RC studied.

Effects of Hydrothermal Treatment on the Phase Transformation, Surface Roughness, and Mechanical Properties of Monolithic Translucent Zirconia

2022 ◽  
Author(s):  
CY Zhang ◽  
C Agingu ◽  
H Yang ◽  
H Cheng ◽  
H Yu
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Phase Transformation ◽  
Flexural Strength ◽  
Hydrothermal Treatment ◽  
Cross Sections ◽  
Monoclinic Phase ◽  
Control Group ◽  
Hydrothermal Aging ◽  
Characteristic Strength

SUMMARY Objectives: This study aimed to investigate the effects of hydrothermal treatment on four types of monolithic, translucent, yttria-stabilized, tetragonal zirconia polycrystals (Y-TZPs). Methods and Materials: Two commercially available Y-TZP brands—SuperfectZir High Translucency (Aidite Technology Co, China) and Katana HT (Kuraray Noritake Dental, Japan) were assessed. For each brand of Y-TZP, materials of four coloring types, including noncolored (NC), colored by staining (CS), precolored (PC), and multilayered (ML) specimens were investigated after hydrothermal aging in an autoclave at 134°C/0.2 MPa for 0 (control group), 5, 10, and 20 hours. The tetragonal-to-monoclinic phase transformation, surface roughness, flexural strength, and structural reliability (Weibull analysis) were measured and statistically analyzed (α=0.05). The subsurface microstructure was analyzed with scanning electron microscopy. Results: The group ML exhibited the lowest flexural strength and Weibull characteristic strength among the four coloring types (p&lt;0.05). Slight increases in the monoclinic phase volume, flexural strength, and Weibull characteristic strength were observed after hydrothermal aging (pall&lt;0.05). Regardless of coloring type, no significant effects of aging on the Weibull modulus or surface roughness were found for the tested materials. Compared with the Katana HT cross-sections, the SuperfectZir High Translucency cross-sections exhibited a similar but thicker transformation zone. Conclusions: The coloring procedure and material type were found to affect the mechanical properties and aging resistance of translucent monolithic Y-TZP ceramics. Regardless of the aging time, the surface roughness of the tested Y-TZP ceramics remained unchanged.

Influence of Fiber’s Surface State on Mechanical Properties and Fiber-Matrix Interaction of CFRP

2013 ◽  
Vol 690-693 ◽  
pp. 323-328
Author(s):  
J. J. Sha ◽  
Y.X. Zhang ◽  
J. Li ◽  
J. X. Dai ◽  
Z. Q. Wei ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Functional Groups ◽  
Carbon Fibers ◽  
Surface State ◽  
Elevated Temperatures ◽  
Fiber Surface ◽  
Flexural Test ◽  
Matrix Interaction ◽  
Fiber Matrix

In order to investigate the influence of carbon fiber’s surface state on the mechanical properties and the fiber-matrix interaction of CFRP, the change of surface state was achieved by thermal treatment of carbon fibers at elevated temperatures, and the surface state was characterized by XPS. The mechanical properties were measured from the flexural test. The CFRP reinforced with 600 °C treated fabrics containing the highest reactive functional groups, showed the highest flexural strength and modulus. But in the case of CFRP reinforced with 1500 °C treated fabrics containing the lowest reactive functional groups, exhibited the lowest flexural strength and modulus. Combining the mechanical properties with the microstructure analysis, the results indicated that the fiber-matrix interaction (strong or weak) depends on the relative percentage of reactive functional groups present on the carbon fiber surface.

scholarly journals Mechanical Properties of Lightweight Concrete Using Recycled Cement-Sand Brick as Coarse Aggregates Replacement

2018 ◽  
Vol 34 ◽  
pp. 01029
Author(s):  
Ilya Joohari ◽  
Nor Farhani Ishak ◽  
Norliyati Mohd Amin
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Mechanical Testing ◽  
Lightweight Concrete ◽  
Control Sample ◽  
Density Measurement ◽  
Flexural Test ◽  
Coarse Aggregates ◽  
Optimum Proportion ◽  
Natural Aggregates

This paper presents the result of replacing natural course aggregate with recycled cement-sand brick (CSB) towards the mechanical properties of concrete. Natural aggregates were used in this study as a control sample to compare with recycled coarse aggregates. This study was also carried to determine the optimum proportion of coarse aggregates replacement to produce lightweight concrete. Besides, this study was conducted to observe the crack and its behaviour development during the mechanical testing. Through this study, four types of concrete mixed were prepared, which were the control sample, 25%, 50% and 75% replacement of CSB. The test conducted to determine the effectiveness of recycled CSB as coarse aggregates replacement in this study were slump test, density measurement, compression test, and flexural test and. The strength of concrete was tested at 7 days and 28 days of curing. From the results obtained, the optimum proportion which produced the highest strength is 25% replacement of recycled CSB. The compressive and flexural strength has decreased by 10%-12% and 4%-34% respectively compared to the control sample. The presence of recycled coarse aggregates in sample has decreased the density of concrete by 0.8%-3% compared to the control sample.

scholarly journals Effect of 5% Calcium Hypochlorite on Mechanical Properties of Root Dentin: An in vitro Study

2016 ◽  
Vol 1 (2) ◽  
pp. 56-59
Author(s):  
Natanasabapathy Velmurugan ◽  
Poornima Reddy ◽  
Suma Balla ◽  
Sandhya S Raghu ◽  
Garlapati T Gupta ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Modulus Of Elasticity ◽  
In Vitro Study ◽  
Chlorine Concentration ◽  
Control Group ◽  
Calcium Hypochlorite ◽  
Significant Difference ◽  
Root Dentin

ABSTRACT Introduction The aim of this study was to compare in vitro the effect of 5% calcium hypochlorite [Ca(OCl)2] and 5% sodium hypochlorite (NaOCl) on flexural strength and modulus of elasticity of root dentin. Materials and methods The available chlorine concentration of each solution was determined using iodometric titration. Standardized planoparallel dentin bars (n= 20) were divided into two test groups and one control group. The control, group 1, consisted of dentin bars stored in normal saline. The dentin bars in the two test groups were treated by exposure to following solutions: Group 2 to 5% Ca(OCl)2; and group 3 to 5% NaOCl. All the three test solutions were changed once in 15 minutes for 30 minutes. The dentin bars were then loaded to failure using three-point bend test. Results Available chlorine concentration was 64% in both the test solutions. There was a significant reduction in the flexural strength of 5% NaOCl group compared to 5% Ca(OCl)2-treated ones. A significant difference in modulus of elasticity was observed between the test groups and the control groups and also between the 5% Ca(OCl)2 and 5% NaOCl groups. Conclusion Within the limitations of this study, 5% NaOCl reduced the flexural strength and modulus of elasticity of root dentin bars more when compared to 5% Ca(OCl)2. How to cite this article Reddy P, Balla S, Raghu SS, Velmurugan N, Gupta GT, Sahoo HS. Effect of 5% Calcium Hypochlorite on Mechanical Properties of Root Dentin: An in vitro Study. J Oper Dent Endod 2016;1(2):56-59.

scholarly journals Effects of Different Storage Conditions on Mechanical Properties of CAD/CAM Restorative Materials

2019 ◽  
pp. 161-174
Author(s):  
Ayşe Atay DDS, PhD ◽  
Elçin Sağirkaya DDS, PhD
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Vickers Hardness ◽  
Flexural Modulus ◽  
Water Storage ◽  
Storage Conditions ◽  
Flexural Test ◽  
Cad Cam ◽  
Provisional Restoration ◽  
Hardness Values

The aim of this study was to evaluate mechanical properties of six new-generation all-ceramic materials for CAD/CAM (Lava Ultimate [LU], VITA Mark II [VM], InCoris TZI [IC], IPS e.max CAD [EM], VITA Suprinity [VS], IPS Empress CAD [EC]) and two different provisional restoration CAD/CAM materials (Telio CAD [TC], Vita CAD-Temp [VC]) after different storage conditions. 36 bar-shaped samples of 4 mm in width and 14 mm in length with 1.2 mm thicknesses were prepared from each material group (N=288). The specimens from each material were kept under three different storage conditions (n=12): under dry conditions at room temperature; 37°C distilled water for 7 days; and 37°C distilled water for 7 days followed by 10,000 thermal cycles. All specimens were subjected to a 3-point flexural test with a crosshead speed of 1.0 mm/min. The specimens were loaded until failure. Twelve fractured specimens after the flexural test from each group were used for the Vickers hardness test (under 300 gf of loading in 15 seconds). The flexural modulus, flexural strength and Vickers hardness values were separately analyzed with two-way analysis of variance, Tukey’s multiple comparison tests at a significance level of p<0.05. There were statistically significant differences between materials and storage conditions according to flexural modulus, flexural strength and Vickers hardness values (p<0.05).  The flexural strength, flexural modulus and Vickers hardness values of LU, VC, TC, VS and IC decreased after water storage followed by thermal cycling (p<0.05). The mechanical properties of provisional restoration CAD/CAM materials had showed a significantly decrease after water storage followed by thermal cycles but their mechanical properties were acceptable for fabrication of provisional restorations. The mechanical properties of VM, EC and EM were not affected by different storage conditions whereas IC and VS were affected.

The Effect of Blending Ratio on Mechanical Properties of Polylactic Acid (PLA) / Ethylene Vinyl Acetate (EVA)

2014 ◽  
Vol 554 ◽  
pp. 194-198
Author(s):  
Abdul Manan Siti Najihah ◽  
Zurina Mohamad
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Polylactic Acid ◽  
Vinyl Acetate ◽  
Flexural Modulus ◽  
Ethylene Vinyl Acetate ◽  
Flexural Test ◽  
Screw Extruder ◽  
Blend Ratio ◽  
Twin Screw

The objective of the study is to improve the mechanical properties of Polylactic acid (PLA)/Ethylene Vinyl Acetate (EVA) blend. The blend was prepared via twin screw extruder and compression molding with different composition. The effect of different blend ratio on the mechanical properties was investigated by Tensile and Flexural test. The mechanical properties of PLA shown an improvement compared to the pure PLA with the incorporation of EVA. The flexural modulus increased with the increased of EVA content, while the tensile and flexural strength also increased when EVA increased. The optimum tensile and flexural strength was at 90PLA/10EVA of blends ratio.

Improvement of Mechanical Properties of Polycaprolactone (PCL) by Addition of Nano-Montmorillonite (MMT) and Hydroxyapatite (HA)

2013 ◽  
Vol 315 ◽  
pp. 815-819 ◽  
Author(s):  
Reazul Haq Abdul Haq ◽  
Wahab Saidin ◽  
Uzir Wahit Mat
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Injection Molding ◽  
Human Body ◽  
Testing Machine ◽  
Tensile Modulus ◽  
Flexural Test ◽  
Molding Machine ◽  
Weight Percentage ◽  
Flexural Analysis

For many years, researcher have focused on developing a medical part of human body from polymer as to replace metal. This report described the mechanical characteristic of biodegradable Polycaprolactone (PCL) blend with nanoMontmorillonite (MMT) and Hydroxyapatite (HA). The amount of nanoMMT is varies from 2 to 4 by weight % meanwhile the amount of HA is fixed to 10 by weight percentage (wt %). The addition of nanoMMT and HA filler is to tune and indirectly improve the mechanical properties of PCL. These are proven by carrying out the tensile, and also flexural test for samples which is injected from injection molding machine. Both the tensile and flexural test are conducted using Shimadzu AG-I Unversal Testing Machine with 10kN capacity. From the analysis it is found that overall PCL/MMT/HA composites gives better result in both tensile and flexural analysis compare to PCL/MMT composite. PCL/MMT/HA composite with 2 wt% of MMT and 10 wt% of HA have indicated the highest tensile modulus, meanwhile PCL/MMT/HA composite with 4 wt% MMT and 10 wt% HA have plotted the highest flexural strength and modulus value.

scholarly journals Investigating the Mechanical Properties of ZrO2-Impregnated PMMA Nanocomposite for Denture-Based Applications

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1344 ◽  
Author(s):  
Saleh Zidan ◽  
Nikolaos Silikas ◽  
Abdulaziz Alhotan ◽  
Julfikar Haider ◽  
Julian Yates
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Impact Strength ◽  
Flexural Strength ◽  
Flexural Modulus ◽  
Surface Hardness ◽  
Bending Test ◽  
Zro2 Nanoparticles ◽  
Control Group ◽  
The Mean

Acrylic resin PMMA (poly-methyl methacrylate) is used in the manufacture of denture bases but its mechanical properties can be deficient in this role. This study investigated the mechanical properties (flexural strength, fracture toughness, impact strength, and hardness) and fracture behavior of a commercial, high impact (HI), heat-cured denture base acrylic resin impregnated with different concentrations of yttria-stabilized zirconia (ZrO2) nanoparticles. Six groups were prepared having different wt% concentrations of ZrO2 nanoparticles: 0% (control), 1.5%, 3%, 5%, 7%, and 10%, respectively. Flexural strength and flexural modulus were measured using a three-point bending test and surface hardness was evaluated using the Vickers hardness test. Fracture toughness and impact strength were evaluated using a single edge bending test and Charpy impact instrument. The fractured surfaces of impact test specimens were also observed using a scanning electron microscope (SEM). Statistical analyses were conducted on the data obtained from the experiments. The mean flexural strength of ZrO2/PMMA nanocomposites (84 ± 6 MPa) at 3 wt% zirconia was significantly greater than that of the control group (72 ± 9 MPa) (p < 0.05). The mean flexural modulus was also significantly improved with different concentrations of zirconia when compared to the control group, with 5 wt% zirconia demonstrating the largest (23%) improvement. The mean fracture toughness increased in the group containing 5 wt% zirconia compared to the control group, but it was not significant. However, the median impact strength for all groups containing zirconia generally decreased when compared to the control group. Vickers hardness (HV) values significantly increased with an increase in ZrO2 content, with the highest values obtained at 10 wt%, at 0 day (22.9 HV0.05) in dry conditions when compared to the values obtained after immersing the specimens for seven days (18.4 HV0.05) and 45 days (16.3 HV0.05) in distilled water. Incorporation of ZrO2 nanoparticles into high impact PMMA resin significantly improved flexural strength, flexural modulus, fracture toughness and surface hardness, with an optimum concentration of 3–5 wt% zirconia. However, the impact strength of the nanocomposites decreased, apart from the 5 wt% zirconia group.

Effect of Coupling Agent on Mechanical Properties of Composite from Microcrystalline Cellulose and Recycled Polypropylene

2012 ◽  
Vol 576 ◽  
pp. 390-393 ◽  
Author(s):  
J. Awanis ◽  
S. Anis Sofia ◽  
Noorasikin Samat
Keyword(s):  
Mechanical Properties ◽  
Maleic Anhydride ◽  
Impact Strength ◽  
Flexural Strength ◽  
Microcrystalline Cellulose ◽  
Coupling Agent ◽  
Impact Test ◽  
Flexural Test ◽  
Recycled Polypropylene ◽  
The Impact

This study shows the effect of using 3-aminopropyltriethoxysilane (APS) and maleic anhydride-grafted polypropylene (MAPP) as coupling agent on composite of RPP/MCC fiber. The compositions of MCC were varied from 0, 2, 4, 8 and 12 wt%. The compounded samples were prepared into test specimens by using injection moulding. The RPP/MCC composites with and without the coupling agent were characterized through mechanical testing of flexural and impact test. The incorporation of the modified MCC was found to increase the modulus and flexural strength. The flexural test indicates that the addition of 4 wt% MCC-APS and 8 wt% MCC-MAPP significantly increased the flexural strength of the RPP composite compared to the unmodified MCC. The impact test shows higher impact strength at 4 wt% of RPP/MCC-APS and 2 wt% of RPP/MCC-MAPP, respectively.

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