Modeling and experimentation of multi-layered nanostructured graphene-epoxy nanocomposites for enhanced thermal and mechanical properties

2016 ◽  
Vol 51 (2) ◽  
pp. 209-220 ◽  
Author(s):  
Rasheed Atif ◽  
Islam Shyha ◽  
Fawad Inam
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Strain Energy ◽  
Thermal Flux ◽  
Strain Energy Release ◽  
Dynamic Mechanical Properties ◽  
Thermal And Mechanical Properties ◽  
Graphene Layers ◽  
Relaxation Temperature ◽  
Maximum Improvement

The influence of multi-layered nanostructured graphene as reinforcement on thermal and mechanical properties of epoxy-based nanocomposites has been studied. The maximum improvement in mechanical properties was observed at 0.1 wt%. The Young’s and flexural moduli increased from 610 MPa to 766 MPa (26% increase) and 598.3 MPa to 732.8 MPa (23% increase), respectively. The tensile and flexural strengths increased from 46 MPa to 65 MPa (43% increase) and 74 MPa to 111 MPa (49% increase), respectively. The mode-1 fracture toughness (K1C) and critical strain energy release rate (G1C) increased from 0.85 MPa.m1/2 to 1.2 MPa.m1/2 (41% increase) and from 631 J/m2 to 685 J/m2 (9% increase), respectively. The increase in fracture toughness is attributed to the obstruction of cracks by graphene layers. The reinforcing effect of nanostructured graphene was also manifested in dynamic mechanical properties. The storage modulus and alpha-relaxation temperature values significantly increased indicating the fine integration of NSG in epoxy chains. The thermal properties of nanocomposites were simulated which showed that graphene is very efficient in significantly increasing the scattering and dissipation of thermal flux.

Influence of additive composition on thermal and mechanical properties of β–Si3N4 ceramics

2004 ◽  
Vol 19 (11) ◽  
pp. 3270-3278 ◽  
Author(s):  
Xinwen Zhu ◽  
Hiroyuki Hayashi ◽  
You Zhou ◽  
Kiyoshi Hirao
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Fracture Toughness ◽  
Nitrogen Pressure ◽  
High Fracture Toughness ◽  
Oxygen Impurity ◽  
Thermal And Mechanical Properties ◽  
High Fracture ◽  
Doped Materials ◽  
Gas Pressure Sintering

Dense β–Si3N4 ceramics were fabricated from α–Si3N4 raw powder by gas-pressure sintering at 1900 °C for 12 h under a nitrogen pressure of 1 MPa, using four different kinds of additive compositions: Yb2O3–MgO, Yb2O3–MgSiN2, Y2O3–MgO, and Y2O3–MgSiN2. The effects of additive composition on the microstructure and thermal and mechanical properties of β–Si3N4 ceramics were investigated. It was found that the replacement of Yb2O3 by Y2O3 has no significant effect on the thermal conductivity and fracture toughness, but the replacement of MgO by MgSiN2 leads to an increase in thermal conductivity from 97 to 113 Wm-1K-1and fracture toughness from 8 to 10 MPa m1/2, respectively. The enhanced thermal conductivity of the MgSiN2-doped materials is attributed to the purification of β–Si3N4 grain and increase of Si3N4–Si3N4 contiguity, resulting from the enhanced growth of large elongated grains. The improved fracture toughness of the MgSiN2-doped materials is attributed to the increase of grain size and fraction of large elongated grains. However, the same thermal conductivity between the Yb2O3- and Y2O3-doped materials is related to not only their similar microstructures, but also the similar abilities of removing oxygen impurity in Si3N4 lattice between Yb2O3 and Y2O3. The same fracture toughness between the Yb2O3- and Y2O3-doped materials is consistent with their similar microstructures. This work implies that MgSiN2 is an effective sintering aid for developing not only high thermal conductivity (>110 Wm−1K−1) but also high fracture toughness (>10 MPa m1/2) of Si3N4 ceramics.

Effect of Cellulose Functionalization on Thermal and Mechanical Properties of Epoxy Resin

2017 ◽  
Vol 757 ◽  
pp. 62-67 ◽  
Author(s):  
Kritsanachai Leelachai ◽  
Supissara Ruksanak ◽  
Tarakol Hongkeab ◽  
Supakeat Kambutong ◽  
Raymond A. Pearson ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Diglycidyl Ether ◽  
Cellulose Content ◽  
Thermal And Mechanical Properties ◽  
Chemical Surface ◽  
Pull Out ◽  
Fiber Bridging ◽  
Surface Modified ◽  
Modified Epoxy

In this study, diglycidyl ether of bisphenol A (DGEBA) cured cycloaliphatic polyamine was modified with functionalized celluloses for improved thermal and mechanical properties. Three different types of surface-modified cellulose, polyacrylamide-g-cellulose (PGC), aminopropoxysilane-g-cellulose (SGC), and carboxymethyl cellulose (CMC), were investigated and used as reinforcing agents in epoxy resins. The storage modulus of these modified epoxy systems was found to significantly increase with addition of cellulose fillers (up to 1 wt. % cellulose content). An improved fracture toughness (KIC) was also observed with increasing cellulose loading content with PGC and SGC. Among the surface-modified celluloses, epoxy modified with SGC was found to have the highest fracture toughness followed by PGC and CMC at 1.0 wt.% cellulose addition due to the chemical surface compatibility. The toughening mechanisms of the cellulose/epoxy composites, measured by scanning electron microscopy (SEM), revealed that fiber-debonding, fiber-bridging, and fiber-pull out were responsible for increased toughness.

Effect of Carbon Nanotube on Electrical, Thermal and Mechanical Properties of Epoxy

2007 ◽  
Author(s):  
Yuanxin Zhou ◽  
Peixuan Wu ◽  
Zhongyang Cheng ◽  
Biddut Kanti Dey ◽  
Shaik Jeelani
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Carbon Nanotube ◽  
High Speed ◽  
Mechanical Test ◽  
High Vacuum ◽  
Mechanical Analysis ◽  
Thermal And Mechanical Properties ◽  
Multi Walled Carbon Nanotubes ◽  
Mechanical Agitator

In this study, electrical, thermal and mechanical properties of multi-walled carbon nanotubes (CNTs) reinforced Epon 862 epoxy have been evaluated. Firstly, 0.1 wt%, 0.2 wt%, 0.3 wt%, and 0.4 wt% CNT were infused into epoxy through a high intensity ultrasonic liquid processor and then mixed with EpiCure curing agent W using a high speed mechanical agitator. The trapped air and reaction volatiles were removed from the mixture using a high vacuum. Neat epoxy sample also was made as reference. Electrical conductivity, dynamic mechanical analysis (DMA, three point bending tests and fracture tests were performed on unfilled, CNT-filled epoxy to identify the loading effect on the properties of composites. Experimental results show significant improvement in electric conductivity. The resistivity of epoxy decreased to 15Ωm with 0.4% CNT. DMA studies revealed that filling the carbon nanotube into epoxy can produce a 90% enhancement in storage modulus and a 17° C increase in Tg, but CNT has little effect on decomposing temperature. Mechanical test results showed that modulus increased with higher CNT loading percentages, but the 0.3 wt% CNT-infusion system showed the maximum strength and fracture toughness enhancement. The decrease in strength and fracture toughness in 0.4% CNT/epoxy was attributed to poor dispersions of nanotubes in the composite.

Effects of Crimped Fiber Paths on Mixed Mode Delamination Behaviors in Woven Fabric Composites

2016 ◽  
Author(s):  
Paul V. Cavallaro ◽  
Andrew Hulton ◽  
Mahmoud Salama ◽  
Melvin W. Jee
Keyword(s):  
Fracture Toughness ◽  
Energy Release ◽  
Mixed Mode ◽  
Strain Energy ◽  
Strain Energy Release ◽  
Woven Fabric ◽  
Woven Fabric Composites ◽  
Fabric Composites ◽  
Energy Release Rates ◽  
Strain Energy Release Rates

This research investigated the fracture toughness and crack propagation behaviors of woven fabric reinforced polymer (WFRP) composite laminates subjected to single and mixed mode loadings using numerical models. The objectives were to characterize the fracture behaviors and toughness properties at the fiber/matrix interfaces and to identify mechanisms that can be exploited for increasing delamination resistance. The mode-I and mode-II strain energy release rates GI and GII, the effective critical strain energy release rate, Gc_eff, (also known as the mixed mode fracture toughness) and crack growth stabilities were determined as functions of crimped fiber paths using meso-scale, 2D multi-continuum finite element models. Three variations of a plain-woven fabric architecture were considered; each having different crimped fiber paths. The presence of mixed-mode strain energy release rates at the meso-scale due to the curvilinear fiber paths was shown to influence the interlaminar fracture toughness and was explored for pure single-mode and mixed-mode global loadings. It was concluded that woven fabric composites provided a Fracture Toughness Conversion Mechanism (FTCM) and their toughness properties were dependent upon and varied with positon along the crimped fiber paths. The FTCM was identified as an advanced tailoring mechanism that can be further utilized to improve toughness and damage tolerance thresholds especially when the mode-II fracture toughness GIIc is greater than the mode-I fracture toughness GIc.

Effect of reactive and non-reactive diluents on thermal and mechanical properties of epoxy resin

2017 ◽  
Vol 30 (10) ◽  
pp. 1159-1168 ◽  
Author(s):  
Animesh Sinha ◽  
Nazrul Islam Khan ◽  
Subhankar Das ◽  
Jiawei Zhang ◽  
Sudipta Halder
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Fracture Toughness ◽  
Tensile Strength ◽  
Polyethylene Glycol ◽  
Epoxy Resin ◽  
Mechanical Performance ◽  
Thermal And Mechanical Properties ◽  
Minor Variation ◽  
Reactive Diluents

The effect of reactive (polyethylene glycol) and non-reactive (toluene) diluents on thermal and mechanical properties (tensile strength, hardness and fracture toughness) of diglycidyl ether of bisphenol A epoxy resin (cured by triethylenetetramine) was investigated. The thermal stability and mechanical properties of the epoxy resin modified with reactive and non-reactive diluents at different wt% were investigated using thermo-gravimetric analyser, tensile test, hardness test and single-edge-notched bend test. A minor variation in thermal stability was observed for epoxy resin after addition of polyethylene glycol and toluene at 0.5 wt%; however, further addition of reactive and non-reactive diluents diminished the thermal stability. The addition of 10 wt% of polyethylene glycol in epoxy resin significantly enhances the tensile strength (∼12%), hardness (∼14%) and fracture toughness (∼24%) when compared to that of neat epoxy resin. In contrast, major drop in mechanical performance was observed after addition of toluene in epoxy. Furthermore, fracture surfaces were investigated under field emission scanning electron microscope to elucidate the failure mechanism.

scholarly journals Effect of Carbon Nanofiber Heat Treatment on Physical Properties of Polymeric Nanocomposites—Part I

2007 ◽  
Vol 2007 ◽  
pp. 1-6 ◽  
Author(s):  
Khalid Lafdi ◽  
William Fox ◽  
Matthew Matzek ◽  
Emel Yildiz
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Carbon Nanofiber ◽  
Treatment Temperature ◽  
Polymeric Nanocomposites ◽  
Graphene Layers ◽  
Maximum Improvement ◽  
Definition Of ◽  
The Individual ◽  
Strength Of Adhesion

The definition of a nanocomposite material has broadened significantly to encompass a large variety of systems made of dissimilar components and mixed at the nanometer scale. The properties of nanocomposite materials also depend on the morphology, crystallinity, and interfacial characteristics of the individual constituents. In the current work, vapor-grown carbon nanofibers were subjected to varying heat-treatment temperatures. The strength of adhesion between the nanofiber and an epoxy (thermoset) matrix was characterized by the flexural strength and modulus. Heat treatment to 1800C∘demonstrated maximum improvement in mechanical properties over that of the neat resin, while heat-treatment to higher temperatures demonstrated a slight decrease in mechanical properties likely due to the elimination of potential bonding sites caused by the elimination of the truncated edges of the graphene layers. Both the electrical and thermal properties of the resulting nanocomposites increased in conjunction with the increasing heat-treatment temperature.

Continuous Microindentation and Microscratch Measurements of Metal-Ceramic Adhesive strengths

1991 ◽  
Vol 239 ◽  
Author(s):  
S. Venkataraman ◽  
D. L. Kohlstedt ◽  
W. W. Gerberich
Keyword(s):  
Fracture Toughness ◽  
Strain Energy ◽  
Strain Energy Release Rate ◽  
Strain Energy Release ◽  
Interfacial Fracture ◽  
Interfacial Shear ◽  
Work Of Adhesion ◽  
Interfacial Fracture Toughness ◽  
Heat Treated ◽  
Metal Ceramic

ABSTRACTTo investigate the effect of heat-treatment on the adhesion of Pt thin films to NiO substrates, the strain energy release rate, interfacial fracture toughness and interfacial shear strength were determined from continuous microscratch and continuous microindentation experiments. Samples were prepared by sputtering Pt onto single crystals of NiO, followed by a heat-treatment at temperatures of 300, 500 and 800°C and an oxygen partial pressure of either 0.21 or 10-5 atm. Continuous microscratch tests were performed by driving a conical indenter with either a 1 or 5 μm tip radius simultaneously into and across the Pt film. From the magnitude of the critical load at the point of film delamination and the area of the delaminated piece of the thin film, the strain energy release rate (practical work of adhesion) and interfacial fracture toughness were calculated. The practical work of adhesion and interfacial fracture toughness increased from 0.2 J/m2 and 0.2 MPa√m, respectively, for as-sputtered samples to 4.6 J/m2 and 1 MPa√m for samples heat-treated at 500°C and 10-5 atm. Preliminary analysis of continuous microindentation results for Pt/NiO samples yielded interfacial shear strengths of 270 MPa for as-sputtered samples and 725 MPa for samples heat-treated at 500°C and 10-5 atm. While these values are in good agreement with those determined by other methods for metal-ceramic systems, there are sufficient differences in test method for a single system to require additional analysis of the proposed models.

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