Effect of layering pattern and fiber hybridization on viscoelastic properties of PALF/COIR hybrid epoxy composites

2021 ◽  
Vol 15 (1) ◽  
pp. 7894-7906
Author(s):  
Mohit Mittal ◽  
Rajiv Chaudhary
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Viscoelastic Properties ◽  
Volume Fraction ◽  
Interfacial Region ◽  
Damping Factor ◽  
Structural Applications ◽  
Fiber Matrix ◽  
Hybrid Biocomposite

To design and develop a hybrid biocomposite material for structural applications, it becomes necessary to determine the optimum fibers layering pattern. Therefore, in this research work, the different layered hybrid biocomposite boards i.e. bilayer pineapple/coir (P/C), trilayer (PCP, CPC), and intimately mixed (IM) were developed and characterized for viscoelastic properties. The composites were made by hand lay-up method, keeping the volume ratio of PALF and COIR 1:1 and the total fiber volume fraction is 0.40 volume of composite. Dynamic mechanical thermal analysis test was employed to characterize the viscoelastic behavior in terms of storage modulus, loss modulus, loss damping factor, and the glass transition temperature. Amongst all the different layered hybrid composites, the trilayer CPC has lowest value (0.635) of effectiveness coefficient with highest stiffness and activation energy (40.54 kJ/mole). It confirms the better fiber-matrix interaction at the interfacial region. The glass transition temperature of CF-EP and PF-EP was increased by 8.74% and 13.15% respectively by the synergistic hybridization of cellulosic fibers. The PCP layered composite possesses lowest value of phase transition energy (9.17 kJ/mole) and this was because of the poor fiber-matrix interfacial adhesion.

scholarly journals The effective complex permittivity stability in filled polymer nanocomposites studied above the glass transition temperature

2018 ◽  
Vol 149 ◽  
pp. 01080 ◽  
Author(s):  
F. Elhaouzi ◽  
A. Mdarhri ◽  
M. Zaghrioui ◽  
C. Honstettre ◽  
I. El Aboudi ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Complex Permittivity ◽  
Dielectric Response ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Mechanical Analysis ◽  
Low Frequencies ◽  
Neat Polymer

The temperature effecton the dielectric response of nanocomposite at low frequencies range is reported. The investigated samples are formed by a semi-crystalline ethylene-co-butyl acrylate (EBA) polymer filled with three concentrations of the dispersed conducting carbon black (CB) nanoparticles. The temperature dependence of the complex permittivity has been analyzedabove the glass transition temperature of the neat polymer matrix Tg=-75°C. For all CB concentrations, the dielectric spectra follow a same trend in frequency range 100-106Hz. More interestingly, the stability of the effective complex permittivity ɛ=ɛ' -iɛ'' with the temperature range of 10-70°C is explored. While the imaginary part of the complex permittivity ɛ'' exhibits a slight decreasewith temperature, the real part ɛ' shows a significant reduction especially for high loading samples. The observed dielectric response may be related to the breakup of the three-dimensional structurenetwork formed by the aggregation of CB particles causing change at the interfaceEBA-CB.This interface is estimated bythe volume fraction of constrained polymer chain according to loss tangent data of dynamic mechanical analysis.

scholarly journals Evaluation of viscoelastic properties, hardness, and glass transition temperature of soft denture liners and tissue conditioner

Odontology ◽  
2019 ◽  
Vol 108 (3) ◽  
pp. 366-375 ◽  
Author(s):  
Yukiro Kitagawa ◽  
Kazuhiro Yoshida ◽  
Kazuma Takase ◽  
Alireza Valanezhad ◽  
Ikuya Watanabe ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Viscoelastic Properties ◽  
Denture Liners ◽  
Tissue Conditioner

A Model for Irradiation-Induced Amorphization

1997 ◽  
Vol 504 ◽  
Author(s):  
S. X. Wang ◽  
L. M. Wang ◽  
R. C. Ewing
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Temperature Dependence ◽  
Dose Rate ◽  
Volume Fraction ◽  
Ion Irradiation ◽  
Crystallization Rate ◽  
Single Equation ◽  
Sigmoidal Functions

ABSTRACTA model based on cascade melting and recrystallization is derived to describe ion irradiation-induced amorphization. The accumulation of amorphous volume fraction during irradiation is represented in a single equation. Depending on the extent of recrystallization of a subcascade, the amorphous volume accumulation can be described by a set of curves that change from exponential to sigmoidal functions. The parameters (including temperature, cascade size, crystallization rate, glass transition temperature, dose rate) that affect the extent of recrystallization are included in the model. The model also describes the temperature dependence of critical dose for amorphization.

scholarly journals Epoxy-Anhydride Vitrimers from Aminoglycidyl Resins with High Glass Transition Temperature and Efficient Stress Relaxation

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1148 ◽  
Author(s):  
Michael Giebler ◽  
Clemens Sperling ◽  
Simon Kaiser ◽  
Ivica Duretek ◽  
Sandra Schlögl
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Elevated Temperature ◽  
Glass Transition Temperature ◽  
Stress Relaxation ◽  
Covalent Bond ◽  
Service Temperature ◽  
Exchange Reactions ◽  
Structural Applications ◽  
Relaxation Measurements

Epoxy-anhydride vitrimers are covalent adaptable networks, which undergo associative bond exchange reactions at elevated temperature. Their service temperature is influenced by the glass transition temperature (Tg) as well as the topology freezing transition temperature (Tv), at which the covalent bond exchange reactions become significantly fast. The present work highlights the design of high-Tg epoxy-anhydride vitrimers that comprise an efficient stress relaxation at elevated temperature. Networks are prepared by thermally curing aminoglycidyl monomers with glutaric anhydride in different stoichiometric ratios. The tertiary amine groups present in the structure of the aminoglycidyl derivatives not only accelerate the curing reaction but also catalyse the transesterification reaction above Tv, as shown in stress relaxation measurements. The topology rearrangements render the networks recyclable, which is demonstrated by reprocessing a grinded powder of the cured materials in a hot press. The epoxy-anhydride vitrimers are characterised by a high Tg (up to 140 °C) and an adequate storage modulus at 25 °C (~2.5 GPa), which makes them interesting candidates for structural applications operating at high service temperature.

Characterizing and Modeling the Free Recovery and Constrained Recovery Behavior of a Polyurethane Shape Memory Polymer

2010 ◽  
Author(s):  
Brent L. Volk ◽  
Dimitris C. Lagoudas ◽  
Duncan J. Maitland
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Shape Memory ◽  
Volume Fraction ◽  
Shape Memory Polymer ◽  
Tensile Tests ◽  
Stress Recovery ◽  
Shear Moduli ◽  
Recovery Experiment

In this work, tensile tests are performed on a polyurethane shape memory polymer for both free recovery (extension recovery at zero load) and constrained recovery (stress recovery at constant extension) conditions. The experimental characterization is conducted on an electromechanical screw driven test frame, and a laser extensometer is used in conjunction with the electromechanical frame to provide a non-contact technique for measuring the deformation of the material. The specimens are deformed, above the glass transition temperature, to 10% extension. The SMP is then cooled, at a constant value of extension, to below the glass transition temperature to ‘lock’ the temporary shape. The extension recovery at zero load as well as the stress recovery at a constant value of extension is measured during the first shape memory cycle as the SMP is heated to above its glass transition temperature. The material is observed to recover 93% of the applied deformation when heated at zero load. In addition, a stress recovery of 1.5 MPa is observed when heated while holding a constant value of deformation (10% extension). After performing the experiments, the Chen and Lagoudas model, implemented in 1-D by Volk, et al., is used to simulate and predict the experimental results. The material properties used in the model — namely the coefficients of thermal expansion, shear moduli, and frozen volume fraction — are calibrated from a single free recovery experiment. The calibrated model is then used to simulate the material response for the free recovery tests as well as predict the response for the constrained recovery condition. The model simulations agree well with the free recovery experimental data but predict a larger compressive stress than what is observed during the constrained recovery experiment.

Viscoelastic Properties Assessment of Syntactic Foams by Dynamic Mechanical Analysis

2010 ◽  
Vol 636-637 ◽  
pp. 280-286 ◽  
Author(s):  
Carlos Capela ◽  
José A. Martins Ferreira ◽  
José Domingos M. Costa
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Dynamic Mechanical Analysis ◽  
Glass Fibre ◽  
Volume Fraction ◽  
Mechanical Analysis ◽  
Fibre Reinforcement ◽  
Dynamic Mechanical ◽  
Filler Volume Fraction

Low-density sheet moulding compounds incorporating hollow glass micro-spheres are being increasing used namely in automotive industry, boats and deep-water submarines and core materials. This paper presents the results obtained in a current study of the viscous properties on hybrid short fibre/hollow glass microspheres composites fabricated with epoxy binder. Dynamic mechanical analysis (DMA) was used to study the effect of the filler volume fraction and of the addition of glass fibre reinforcement on the dynamic stiffness modulus, damping coefficient and glass transition temperature in tensile mode. The specimens were cut from plates produced by resin transfer moulding in vacuum with microspheres weight contents up to 13%. Elastic modulus decreases significantly with the increasing of filler volume fraction. In contrary, it increases significantly with the glass fibre reinforcement content. Glass transition temperature apparently tends to decrease with microspheres and of glass fibre reinforcement’s content. Tmax temperatures tend to increase slightly with the addition of fibre reinforcements and the microsphere filler. Maximum damping coefficient is much lower for the foams when compared with net resin.

Thermal Viscoelastic Analysis of 3D Fabric Nanocomposites

2008 ◽  
Vol 47-50 ◽  
pp. 1133-1136 ◽  
Author(s):  
Nan Jia Zhou ◽  
Andrey Beyle ◽  
Christopher C. Ibeh
Keyword(s):  
Thermal Analysis ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Loss Tangent ◽  
Viscoelastic Properties ◽  
Vinyl Ester ◽  
Loss Modulus ◽  
Viscoelastic Analysis ◽  
Storage And Loss Moduli

Viscoelastic properties of 3D fabric reinforced Vinyl Ester composites were studied in different directions using Dynamic Mechanical Thermal Analysis (DMTA). Such materials filled by nanoparticles (silicon carbide) with different concentrations were also investigated. The increases of storage and loss moduli with addition of nanoparticles and with increase of their concentrations were observed. The maximal tangent of the angle of mechanical losses was especially compared at below and over glass transition temperature. Below glass transition temperature the presence of nanoparticles increases storage and loss moduli and loss tangent. These effects achieved maximum at glass transition temperature. Over glass transition, the loss modulus and loss tangent are decreased with increase of the concentration of nanoparticles.

The damping properties of dealloyed porous copper and its PMMA composite

1994 ◽  
Vol 9 (11) ◽  
pp. 2884-2890
Author(s):  
Un-Sig Min ◽  
James C.M. Li
Keyword(s):  
Activation Energy ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Apparent Activation Energy ◽  
Volume Fraction ◽  
Pure Copper ◽  
Damping Properties ◽  
Young’S Moduli ◽  
Porous Copper

Incramute Cu-Mn alloys were dealloyed to remove Mn by selective electrolytic separation. The porous dealloyed specimens were compressed at 0.17-14 GPa, resulting in densities of 55-88% of the density of pure copper. Some porous copper specimens before compression were soaked in a mixture of monomer (MMA) and the initiator (AIBN), compressed, and then polymerized by heating. Young's moduli of both the dealloyed porous copper and its PMMA composite were found to decrease exponentially with porosity and volume fraction of PMMA, respectively. The apparent activation energy for damping of Cu-PMMA composite near the glass transition temperature of PMMA was found to increase with decreasing volume fraction of PMMA.

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