Degradation of Mechanical Properties of Conventional and Nanophased Carbon/Epoxy Composites in Seawater

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
M. K. Hossain ◽  
K. A. Imran ◽  
M. V. Hosur ◽  
S. Jeelani
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Flexural Modulus ◽  
Microscopy Study ◽  
Epoxy Composites ◽  
Molding Process ◽  
Bending Tests ◽  
Three Point Bending ◽  
Degradation Of Mechanical Properties ◽  
Marine Applications

Composites used for marine applications are subjected to various environmental effects, such as moisture, temperature, UV radiation, and seawater. In this study, effect of seawater on the degradation of mechanical properties of conventional and nanophased carbon/epoxy composites was investigated. Epoxy resin was modified using 1 wt. %, 2 wt. %, and 3 wt. % nanoclay. Carbon/epoxy composites were fabricated by vacuum assisted resin transfer molding process and compared with neat samples with and without exposure to seawater. Nanoclay was dispersed into matrix by using magnetic stirring. Mechanical characterization performed through three point bending tests showed that 2 wt. % nanoclay loading was optimum. Flexural strength and modulus were increased by 25% and 12.51%, respectively, compared to neat system for samples not exposed to seawater. Flexure samples exposed to the seawater for 30-, 60-, and 180-day periods revealed that samples with nanoclay retained better mechanical properties compared to neat samples. After 30-day exposure to seawater, there was no significant reduction in the strength and modulus. However, flexural strength was reduced by 10.24%, 7.08%, 5.28%, and 7.13% for neat, 1 wt. %, 2 wt. %, and 3 wt. % nanoclay-infused samples, respectively, after the samples were exposed to seawater for 180-day. At the same time flexural modulus was reduced by 12.61%, 7.16%, 4.59%, and 6.11%, respectively. From scanning electron microscopy (SEM) studies, it was found that failure occurred due to delimitation and initiated from the compression side. Nanophased composites exhibited better bonding between fiber and matrix. SEM micrographs also revealed that both unconditioned and conditioned nanophased epoxy, which produce relatively rougher fracture surfaces compared to neat samples. Optical microscopy study revealed no significant physical change in outer surfaces of the samples conditioned up to a 90-day period.

THE INFLUENCE OF SiC COATING PROCESS ON THE PROPERTIES OF C/C COMPOSITES

2007 ◽  
Vol 14 (04) ◽  
pp. 817-820
Author(s):  
MIN HUANG ◽  
KE-ZHI LI ◽  
HE-JUN LI ◽  
QIAN-GANG FU ◽  
GUO-DONG SUN
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Failure Mode ◽  
Flexural Modulus ◽  
Pack Cementation ◽  
Bending Test ◽  
Carbon Composites ◽  
Coating Process ◽  
Three Point Bending ◽  
Coated Carbon

SiC coating for carbon/carbon composites was prepared by pack cementation method. The effects of coating process on the microstructure and the mechanical properties of C / C composites were analyzed by SEM and three-point bending test, respectively. As the infiltrated Si improved the interfaces bonding during the coating process, the flexural strength and flexural modulus of SiC -coated carbon/carbon composites were both increased by about 10% than the naked C / C composites. In addition, the mechanism of the change of failure mode of SiC coated C / C composites and naked C / C composites was addressed.

scholarly journals Influence of a Repeated Preheating Procedure on Mechanical Properties of Three Resin Composites

2015 ◽  
Vol 40 (2) ◽  
pp. 181-189 ◽  
Author(s):  
M D'Amario ◽  
F De Angelis ◽  
M Vadini ◽  
N Marchili ◽  
S Mummolo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Vickers Microhardness ◽  
Flexural Modulus ◽  
Bending Test ◽  
Resin Composites ◽  
Three Point Bending ◽  
Main Effect ◽  
Dependent Variables ◽  
Marginal Means

SUMMARY The aim of this study was to assess the flexural strength, flexural elastic modulus and Vickers microhardness of three resin composites prepared at room temperature or cured after one or repeated preheating cycles to a temperature of 39°C. Three resin composites were evaluated: Enamel Plus HFO (Micerium), Opallis (FGM), and Ceram X Duo (Dentsply DeTrey). For each trial, one group of specimens of each material was fabricated under ambient laboratory conditions, whereas in the other groups, the composites were cured after 1, 10, 20, 30, or 40 preheating cycles to a temperature of 39°C in a preheating device. Ten rectangular prismatic specimens (25 × 2 × 2 mm) were prepared for each group (N=180; n=10) and subjected to a three-point bending test for flexural strength and flexural modulus evaluation. Vickers microhardness was assessed on 10 cylindrical specimens from each group (N=180; n=10). Statistical analysis showed that, regardless of the material, the number of heating cycles was not a significant factor and was unable to influence the three mechanical properties tested. However, a significant main effect of the employed material on the marginal means of the three dependent variables was detected.

scholarly journals Mechanical Characterization of Epoxy Filled with Seed Shells as Reinforcement

2019 ◽  
Vol 8 (4) ◽  
pp. 6972-6977
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Sodium Hydroxide ◽  
Natural Fiber ◽  
Fiber Composite ◽  
Flexural Modulus ◽  
Natural Fibers ◽  
Epoxy Composites ◽  
The Matrix ◽  
Sunflower Seed Shells

The use of natural fiber composite has been widely promoted in many industries such as construction, automotive and even aerospace. Natural fibers can be extracted from plants that are abundantly available in the form of waste such as sunflower seed shells (SSS) and groundnut shells (GNS). These fibers were chosen as the reinforcement in epoxy to form composites. The performance of composites was evaluated following the ASTM D3039 and ASTM D790 for tensile and flexural tests respectively. Eight types of composites were prepared using SSS and GNS fibers as reinforcement and epoxy as the matrix with the fiber content of 20wt %. The fibers were untreated and treated with Sodium Hydroxide (NaOH) at various concentrations (6%, 10%, 15%, and 20%) and soaking time (24, 48 and 72 hours). The treatment has successfully enhanced the mechanical properties of both composites, namely SSS/epoxy and GNS/epoxy composites. The SSS/epoxy composite has the best mechanical properties when the fibers were treated for 48 hours using 6% of NaOH that produced 22 MPa and 13 MPa of tensile and flexural strength respectively. Meanwhile, the treatment on groundnut shells with 10% sodium Hydroxide for 24 hours has increased the Flexural strength tremendously (53%), however no significant effect on the tensile strength. The same trend was also observed on the tensile and flexural modulus. The increase of 41% in flexural modulus after treatment with 10% NaOH for 24 hours was also the evidence of mechanical properties enhancement. The evidence of improved fiber and matrix bonding after fiber treatment was also observed using a scanning electron microscope (SEM). The SSS/epoxy composites performed better in tensile application, meanwhile the GNS/epoxy composites are good in flexural application.

scholarly journals Rapid 3 s Curing: What Happens in Deep Layers of New Bulk-Fill Composites?

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 515
Author(s):  
Danijela Marovic ◽  
Matej Par ◽  
Ana Crnadak ◽  
Andjelina Sekelja ◽  
Visnja Negovetic Mandic ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Raman Spectroscopy ◽  
Flexural Strength ◽  
Flexural Modulus ◽  
Degree Of Conversion ◽  
Resin Composites ◽  
Three Point Bending ◽  
Deep Layers ◽  
Light Curing ◽  
New Generation

This study assessed the influence of rapid 3 s light curing on the new generation of bulk-fill resin composites under the simulated aging challenge and depths up to 4 mm. Four bulk-fill materials were tested: two materials designed for rapid curing (Tetric PowerFill—PFILL; Tetric PowerFlow—PFLW) and two regular materials (Filtek One Bulk Fill Restorative—FIL; SDR Plus Bulk Fill Flowable—SDR). Three-point bending (n = 10) was used to measure flexural strength (FS) and flexural modulus (FM). In the 3 s group, two 2 mm thick specimens were stacked to obtain 4 mm thickness, while 2 mm-thick specimens were used for ISO group. Specimens were aged for 1, 30, or 30 + 3 days in ethanol. The degree of conversion (DC) up to 4 mm was measured by Raman spectroscopy. There was no difference between curing protocols in FS after 1 day for all materials except PFLW. FM was higher for all materials for ISO curing protocol. Mechanical properties deteriorated by increasing depth (2–4 mm) and aging. ISO curing induced higher DC for PFLW and FIL, while 3 s curing was sufficient for PFILL and SDR. The 3 s curing negatively affected FM of all tested materials, whereas its influence on FS and DC was highly material-specific.

scholarly journals Evaluation of New Hollow Sleeve Composites for Direct Post-Core Construction

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7397
Author(s):  
Shinji Yoshii ◽  
Sufyan Garoushi ◽  
Chiaki Kitamura ◽  
Pekka K. Vallittu ◽  
Lippo V. Lassila
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Resin Composite ◽  
Flexural Modulus ◽  
Accelerated Aging ◽  
Fracture Analysis ◽  
Bending Test ◽  
Outer Diameter ◽  
Fiber Post ◽  
Three Point Bending

The preset shape and diameter of a prefabricated FRC post rarely follows the anatomy of the root canal. To solve this problem, a new hollow sleeve composite (HSC) system for post-core construction was developed and characterized. A woven fiber was impregnated with two types of resins: Bis-GMA or PMMA, and rolled into cylinders with outer diameter of 2 mm and two different inner diameters, namely 1.2 or 1.5 mm. The commercial i-TFC system was used as a control. Dual-cure resin composite was injected into these sleeves. Additionally, conventional solid fiber post was used as the inner part of the sleeve. The three-point bending test was used to measure the mechanical properties of the specimens and the fracture surface was examined using an electron microscope (SEM). The HSC (1.5 mm, Bis-GMA) revealed a statistically similar flexural modulus but higher flexural strength (437 MPa) compared to i-TFC (239 MPa; ANOVA, p < 0.05). When a fiber post was added inside, all values had a tendency to increase. After hydrothermal accelerated aging, the majority of specimens showed a significant (p < 0.05) decrease in flexural strength and modulus. SEM fracture analysis confirmed that the delamination occurred at the interface between the outer and inner materials. The HSC system provided flexibility but still high mechanical values compared to the commercial system. Thus, this system might offer an alternative practical option for direct post-core construction.

scholarly journals Halloysite reinforced epoxy composites with improved mechanical properties

2016 ◽  
Vol 18 (1) ◽  
pp. 133-135 ◽  
Author(s):  
Muhammad Jawwad Saif ◽  
Muhammad Asif ◽  
Muhammad Naveed ◽  
Khalid Mahmood Zia ◽  
Waheed -uz- Zaman ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Flexural Modulus ◽  
Halloysite Nanotubes ◽  
Epoxy Composites ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
Interfacial Coupling ◽  
Uniform Dispersion

Abstract Halloysite nanotubes (HNTs) reinforced epoxy composites with improved mechanical properties were prepared. The prepared HNTs reinforced epoxy composites demonstrated improved mechanical properties especially the fracture toughness and flexural strength. The flexural modulus of nanocomposite with 6% mHNTs loading was 11.8% higher than that of neat epoxy resin. In addition, the nanocomposites showed improved dimensional stability. The prepared halloysite reinforced epoxy composites were characterized by thermal gravimetric analysis (TGA). The improved properties are attributed to the unique characteristics of HNTs, uniform dispersion of reinforcement and interfacial coupling.

scholarly journals Reliability and Mechanical Properties of Materials Recycled from Multilayer Flexible Packages

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 3992 ◽  
Author(s):  
Natividad Antón ◽  
Álvaro González-Fernández ◽  
Alberto Villarino
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Flexural Modulus ◽  
Point Of View ◽  
Good Reliability ◽  
Simultaneous Application ◽  
Bending Tests ◽  
Food Packages ◽  
Pressure Time ◽  
Before And After

Present work proposes a recycling form of multilayer food packages to avoid their incineration, landfill of wastes or re-using of their individual components. The manufacturing process of the material consists of binding several sheets by the non-simultaneous application of temperature and pressure, these being bound by the fusion of the polyethylene, without any other adhesives. The influence of elected variables (temperature, pressure, time and number of sheets) on the mechanical properties is determined. Bending tests in three points were carried out, with the purpose of obtaining flexural strength and flexural modulus. Finally, the reliability was determined through the method of Weibull using different failure estimators for the most appropriate materials (relative to flexural strength and porosity values). Light microscopy to obtain information about defectology before and after tests was used. The results obtained by this type of material are very similar to those presented by wood-based materials and present good reliability from the strength point of view.

scholarly journals Mycocomposites: looking for a viable alternative to EPS

2021 ◽  
Author(s):  
Vithoria Réggia Gomes Pessanha ◽  
Maria das Graças Machado Freire ◽  
Michel Picanço Oliveira ◽  
Bárbara Ferreira de Oliveira
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Compression Tests ◽  
Bending Tests ◽  
Three Point Bending ◽  
Synthetic Materials ◽  
Significant Difference ◽  
The Mean ◽  
Compressive Resistance ◽  
Base Substrate

Mycocomposites have received special attention from both academic and commercial environments. These materials give a new purpose to agricultural residues, bringing benefits to companies, society and the environment. Currently, they have been studied to replace synthetic materials such as polyester. However, its field of application is still very limited, making it necessary for more research to be carried out. In this work, mycocomposites were produced in two configurations: without jute and with two jute arranged at 1/3 of the thickness in relation to the surfaces perpendicular to loading plains during bending and compression tests. The base substrate used consisted of coconut mesocarp, white wood sawdust and wheat grain pre-myceliated by the fungus Pycnopurus sanguineus. Analysis by confocal microscopy showed that the fungus produced a network of mycelial hyphae capable of uniting substrate components and incorporated jute. Composites’ mechanical properties were evaluated from three-point bending tests and compression tests. The Shapiro-Wilk tests showed that all determined mechanical properties are normally distributed. The highest compressive resistance (10% deformation) was found in the mycocomposite without jute. The analysis of variance showed that the mean flexural strength of the two configurations analyzed did not present any statistically significant difference; despite this, the composite without jute proved to be more rigid. It was verified that the flexural strength of the produced mycocomposites is located between the values found for the expanded polystyrenes EPS 100 and EPS 150, but that their compressive strength was lower. At first, the materials produced in this work exhibited the necessary properties to be applied in simple pieces such as lampshades, packaging, and plant vases. However, it is still necessary that new studies are carried out to verify the feasibility of its application in the field of engineering, such as in civil construction panels, where EPS are used.

scholarly journals Resin Composite Materials for Chairside CAD/CAM Restorations: A Comparison of Selected Mechanical Properties

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Wojciech Grzebieluch ◽  
Marcin Mikulewicz ◽  
Urszula Kaczmarek
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Weibull Modulus ◽  
Resin Composite ◽  
Flexural Modulus ◽  
Bending Test ◽  
Weibull Analysis ◽  
Three Point Bending ◽  
Characteristic Strength ◽  
Cad Cam

Objective. The aim was to evaluate the flexural strength, flexural modulus, microhardness, Weibull modulus, and characteristic strength of six resin composite blocks (Grandio Blocs-GR, Tetric CAD-TE, Brilliant Crios-CR, Katana Avencia-AV, Cerasmart-CS, and Shofu Block HC-HC). Methods. Flexural strength and flexural modulus were measured using a three-point bending test and microhardness using the Vickers method. Weibull analysis was also performed. Results. The materials showed flexural strength ranging from 120.38 (HC) to 186.02 MPa (GR), flexural modulus from 8.26 (HC) to 16.95 GPa (GR), and microhardness from 70.85 (AV) to 140.43 (GR). Weibull modulus and characteristic strength ranged from 16.35 (CS) to 34.98 (TE) and from 123.45 MPa (HC) to 190.3 MPa (GR), respectively. Conclusions. GR, TE, and CR presented significantly higher flexural strength, modulus, Weibull modulus, and characteristic strength than the others.

scholarly journals Enhanced flexural properties of aramid fiber/epoxy composites by graphene oxide

2019 ◽  
Vol 8 (1) ◽  
pp. 484-492 ◽  
Author(s):  
Yinqiu Wu ◽  
Bolin Tang ◽  
Kun Liu ◽  
Xiaoling Zeng ◽  
Jingjing Lu ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Flexural Strength ◽  
Interfacial Shear Strength ◽  
Flexural Modulus ◽  
Weight Fraction ◽  
Interfacial Shear ◽  
Aramid Fiber ◽  
Epoxy Composites ◽  
Flexural Properties ◽  
Pure Epoxy

Abstract The reinforcing effect of graphene oxide (GO) in enhancing the flexural strength and flexural modulus of aramid fiber (AF)/epoxy composites were investigated with GO-AFs at a weight fraction of 0.1-0.7%. The flexural strength and flexural modulus of the composite reached 87.16 MPa and 1054.7 MPa, respectively, which were about 21.19% and 40.86% higher than those of the pure epoxy resin, respectively. In addition, the flexural properties and interfacial shear strength (IFSS) of composite reinforced by GO-AFs were much higher than the composites reinforced by AFs due to GO improved the interfacial bonding between the reinforcement material and matrix.

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