The glass transition temperature of partially cured polymers as a non-equilibrium parameter and its effect on observed dynamic mechanical behavior

1981 ◽  
Vol 21 (14) ◽  
pp. 951-957 ◽  
Author(s):  
C. Y-C. Lee ◽  
I. J. Goldfarb
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Mechanical Behavior ◽  
Dynamic Mechanical ◽  
Dynamic Mechanical Behavior ◽  
Equilibrium Parameter ◽  
Non Equilibrium

Dynamic-Mechanical Behavior of Malva Fiber Reinforced Polyester Matrix Composites

2014 ◽  
Vol 775-776 ◽  
pp. 278-283 ◽  
Author(s):  
Sergio Neves Monteiro ◽  
Frederico Muylaert Margem ◽  
Jean Igor Margem ◽  
Lucas Barbosa De Souza Martins ◽  
Caroline Gonçalves Oliveira ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Loss Modulus ◽  
Damping Capacity ◽  
Matrix Composites ◽  
Flexural Mode ◽  
Dynamic Mechanical ◽  
Dynamic Mechanical Behavior ◽  
Polyester Matrix

Dynamic-mechanical (DMA) tests have not yet been conducted in malva aligned fiber reinforcing polymeric composites. In this work, the temperature dependence of the DMA parameters in polyester matrix composites reinforced with up to 30% in volume of continuous and aligned malva fibers was investigated. These parameters were the storage and the loss modulus as well as the tangent delta. The investigation was conducted in the temperature interval from-20 to 180°C using a Perking-Elmer DMA equipment operating in flexural mode. The results showed that the incorporation of malva fibers tends to increase the viscoelastic stiffness of the polyester matrix. Sensible modifications in the glass transition temperature and the damping capacity of the structure were found with the amount of fiber in the composite. The molecular mobility of the polyester matrix is affected by its interaction with the malva fibers.

Effect of reduced graphene oxide on mechanical behavior of an epoxy adhesive in glassy and rubbery states

2021 ◽  
pp. 002199832110316
Author(s):  
Ata Khabaz-Aghdam ◽  
Bashir Behjat ◽  
EAS Marques ◽  
RJC Carbas ◽  
Lucas FM da Silva ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Ambient Temperature ◽  
Mechanical Behavior ◽  
Reduced Graphene Oxide ◽  
Epoxy Adhesive ◽  
Ultimate Strain ◽  
Reduced Graphene

The mechanical behavior of an adhesive, in neat state and reinforced with up to 0.5 wt% of reduced graphene oxide (RGO) was investigated here. Tests were done at temperatures between the ambient temperature and the glass transition temperature ( Tg[Formula: see text] of the adhesive. Using a metal mold, cured plates of the neat and RGO reinforced epoxy adhesive were prepared. The adhesive powder and the bulk dumbbell-shaped specimens, obtained from cured adhesive plates, were subjected to differential scanning calorimetry (DSC) and tensile tests, respectively, to obtain the Tg as well as mechanical properties of the adhesives. The results indicated that adding RGO up to 0.5 wt% increased the glass transition temperature, the modulus of elasticity, and the strength of the adhesive. It was found that the presence of RGO reduced the adhesive’s strain at the break at the ambient temperature. However, at high temperatures, near the Tg, the ultimate strain of RGO-reinforced adhesives decreased slightly when compared to the ultimate strain of the neat specimens. This explains the reduction in toughness at ambient temperature obtained by adding RGO and the increase at high temperatures. Finally, the failure morphology of the neat and RGO-reinforced adhesive specimens was investigated using microscopic imaging of the specimens’ failure cross-sections, which supported and justified the experimental observations.

Dynamic mechanical behaviour of kevlar and carbon-kevlar hybrid fibre reinforced polymer composites

2020 ◽  
pp. 095440622097060
Author(s):  
Pragati Priyanka ◽  
Harlal Singh Mali ◽  
Anurag Dixit
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Dynamic Mechanical Analysis ◽  
Storage Modulus ◽  
Composite Laminates ◽  
Mechanical Analysis ◽  
Textile Composites ◽  
Elastic Behaviour ◽  
Dynamic Mechanical

Comprehensive experimental results of dynamic mechanical analysis (DMA) of polymer reinforced textile composites are presented in the current investigation. Plain and 2x2 twill woven multilayer fabrics of monolithic kevlar and hybrid carbon-kevlar (C-K) are reinforced into the thermoset polymer matrix. Kevlar/epoxy and C-K/epoxy composite laminates are fabricated using an in-house facility of the vacuum-assisted resin infusion process. Variation of the visco-elastic behaviour (storage modulus, damping factor and glass transition temperature, Tg) along with time, temperature and frequency is studied for the composites. Dynamic mechanical analysis is performed under temperature sweep with frequency ranging from 1-50 Hz. Results depict the effect of inter yarn hybridisation of carbon with kevlar yarns on the storage modulus, damping performance, and creep behaviour of dry textile composites. Temperature swept dynamic characterisation is also performed to evaluate the degradation and damping performance of the composite laminates soaked in the deionised water at glass transition temperature Tg, ½ Tg, and ¾ Tg. The morphological study has been performed post the dynamic mechanical analysis using field emission scanning electron microscope.

Dynamic Mechanical Analysis of Nanosilica Filled Epoxy Nanocomposites

2014 ◽  
Vol 699 ◽  
pp. 239-244 ◽  
Author(s):  
Nurhidayah R. Zamani ◽  
Aidah Jumahat ◽  
Rosnadiah Bahsan
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Epoxy Polymer ◽  
Loss Modulus ◽  
Matrix Material ◽  
Mechanical Analysis ◽  
Dynamic Mechanical ◽  
Mechanical Stirring ◽  
Tan Δ

In this study, Dynamic Mechanical Analyzer (DMA) was used to study the effect of nanoparticles, which is nanosilica, on glass transition temperature (Tg) of epoxy polymer. A series of epoxy based nanosilica composite with 5-25 wt% nanosilica content was prepared using mechanical stirring method. The weight fractions of nanosilica in epoxy were 5 wt%, 13 wt% and 25 wt%. 30mm x 10mm x 3mm size specimens were tested using DMA machine from room temperature up to 180oC at 2°C/min heating rate. From the analysis of the results, dynamic modulus and glass transition temperature of pure polymer and nanosilica filled polymer were obtained. The glass transition of a polymer composite is a temperature-induced change in the matrix material from the glassy to the rubbery state during heating or cooling. Glass transition temperature Tg was determined using several method: storage modulus onset, loss modulus peak, and tan δ peak. The results showed that the presence of nanosilica reduced Tg of epoxy polymer.

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