Uncovering the glass-transition temperature and temperature-dependent storage modulus of graphene-polymer nanocomposites through irreversible thermodynamic processes

2021 ◽  
Vol 158 ◽  
pp. 103411 ◽  
Author(s):  
Xiaodong Xia ◽  
Jackie Li ◽  
Juanjuan Zhang ◽  
George J. Weng
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Storage Modulus ◽  
Polymer Nanocomposites ◽  
Irreversible Thermodynamic ◽  
Temperature Dependent ◽  
Thermodynamic Processes

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.

The Effects of Chemical Resistance for Nanocomposite Materials via Nano-Silica Addition into Glass Fiber/Epoxy

2013 ◽  
Vol 853 ◽  
pp. 28-33
Author(s):  
Huey Ling Chang ◽  
Chih Ming Chen ◽  
Kung Liang Lin ◽  
Bor Kae Chang
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Glass Fiber ◽  
Epoxy Resin ◽  
Storage Modulus ◽  
Chemical Resistance ◽  
Dynamic Mechanical Properties ◽  
Silica Nanopowder

Nanocomposite samples containing epoxy resin, glass fiber and 0~2 wt.% SiO2 nanopowder are prepared. The effects of SiO2 addition on the chemical resistance, glass transition temperature (Tg) and dynamic mechanical properties of the various samples are then observed. The chemical resistance of the nanocomposite specimens is compared with that of pure glass fiber/epoxy composite specimens when tested in acetone. The results show that the addition of 2 wt.% SiO2 increases the value of storage modulus by 1646MPa compared to that of the sample containing no silica nanopowder. Following immersion in acetone, all the nanocomposite specimen storage modulus decreased, but the addition of SiO2 reduced the decline, where the 2 wt. % samples decrease from 11.76% reduction to 0.84% and no significant change in the Tg compared to that of the sample with no silica nanopowder. Therefore, the experimental results indicate that 2 wt.% SiO2 addition is beneficial in improving chemical resistance, glass transition temperature, and dynamic mechanical properties of epoxy resin / glass fiber nanocomposites.

scholarly journals Determination of glass transition temperature using temperature dependent signal from a cryogenic photopyroelectric instrument

2019 ◽  
Vol 676 ◽  
pp. 7-12 ◽  
Author(s):  
Allen Mathew ◽  
Fabrice Goutier ◽  
Benoit Escorne ◽  
Abdelaziz Elass ◽  
Gérard Louis ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Temperature Dependent ◽  
Dependent Signal

The Dynamic Viscoelastic Behavior of Wood-Plastic Composites

2013 ◽  
Vol 815 ◽  
pp. 639-644 ◽  
Author(s):  
Pei Ying Liu ◽  
Zhi Hong Jiang
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Storage Modulus ◽  
Loss Modulus ◽  
Viscoelastic Behavior ◽  
Peak Frequency ◽  
Wood Plastic Composite ◽  
Plastic Composite ◽  
Positive Effect

Wood-plastic composite is a kind of viscoelastic materials. This paper presents the dynamic viscoelastic behavior of WPCs at different temperature, frequency and bamboo flours levels. The storage modulus decreased with the rise of temperature, the loss modulus and tanδ increased as temperature increased but decreased after reaching the peak. Frequency had a little influence on storage modulus and loss modulus, but the glass transition temperature increased with the increase of frequency, while the tanδ decreased. The glass transition temperature of this kind WPCs is about 85°C. The addition of bamboo flours had a positive effect on the dynamic viscoelastic behavior. From the results above, the activation energy of the WPCs was measured using an Arrhenius relationship to investigate the interphase between the wood and plastic.

Thermo-mechanical properties and thermal conductivity of CdS-trans-polyisoprene, polymer nanocomposite

2011 ◽  
Vol 31 (2-3) ◽  
Author(s):  
Mahesh Baboo ◽  
Manasvi Dixit ◽  
Dinesh Patidar ◽  
Kananbala Sharma ◽  
Narendra Sahai Saxena
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Storage Modulus ◽  
Structural Changes ◽  
Polymer Nanocomposite ◽  
Cds Nanoparticles ◽  
Chemical Route

Abstract This paper focuses on the comparative evaluation of the glass transition temperature (Tg), storage modulus and thermal conductivity of trans-polyisoprene (TPI) and CdS-TPI nanocomposite. The CdS nanoparticles synthesized by chemical route are dispersed into TPI using ultrasonic vibrations. Particle size of nanocrystals is obtained from X-ray diffraction and found to be 1.84 nm. Thermo-mechanical properties (Tg and storage modulus) are measured by dynamic mechanical analyzer (DMA), while thermal conductivity is a measured using the transient plane source (TPS) technique. It is observed that glass transition temperature and thermal conductivity are higher while storage modulus and mechanical properties are lower for CdS-TPI nanocomposites than for pure TPI. This has been explained on the basis of structural changes occurring due to introduction of CdS as filler into the TPI.

scholarly journals Review of Recent Developments of Glass Transition in PVC Nanocomposites

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4336
Author(s):  
Jolanta Tomaszewska ◽  
Tomasz Sterzyński ◽  
Aneta Woźniak-Braszak ◽  
Michał Banaszak
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Thermomechanical Analysis ◽  
Mechanical Analysis ◽  
Temperature Dependent ◽  
Scanning Calorimetry ◽  
Recent Developments ◽  
Dielectric Thermal Analysis ◽  
The Impact

This review addresses the impact of different nanoadditives on the glass transition temperature (Tg) of polyvinyl chloride (PVC), which is a widely used industrial polymer. The relatively high Tg limits its temperature-dependent applications. The objective of the review is to present the state-of-the-art knowledge on the influence of nanofillers of various origins and dimensions on the Tg of the PVC. The Tg variations induced by added nanofillers can be probed mostly by such experimental techniques as thermomechanical analysis (TMA), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and dielectric thermal analysis (DETA). The increase in Tg is commonly associated with the use of mineral and carbonaceous nanofillers. In this case, a rise in the concentration of nanoadditives leads to an increase in the Tg due to a restraint of the PVC macromolecular chain’s mobility. The lowering of Tg may be attributed to the well-known plasticizing effect, which is a consequence of the incorporation of oligomeric silsesquioxanes to the polymeric matrix. It has been well established that the variation in the Tg value depends also on the chemical modification of nanofillers and their incorporation into the PVC matrix. This review may be an inspiration for further investigation of nanofillers’ effect on the PVC glass transition temperature.

Cure Kinetics of Nanocomposites Prepared From Aqueous Dispersion of Nanoclay

2006 ◽  
Author(s):  
Levent Aktas ◽  
M. Cengiz Altan
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Storage Modulus ◽  
Glass Fibers ◽  
Aqueous Dispersion ◽  
Cure Kinetics ◽  
Temperature Cycle ◽  
Waterborne Epoxy ◽  
Kinetics Of

The effect of nanoclay on the cure kinetics of glass/waterborne epoxy nanocomposites is investigated. First step in sample preparation involves dispersing Cloisite® Na+, a natural montmorillonite, in distilled water at 70°C with the aid of a sonicator. Then, desired amounts of dicyandiamide and 2-methyl imidazole, serving as cross-linkers, are mixed to the aqueous nanoclay solution. As the mixing continues, Epi-Rez 3522-W-60 waterborne epoxy resin is introduced to the solution and the compound is mixed for an additional 30 minutes. The nanoclay content of this batch is adjusted to be at 2wt%. An identical second batch, which does not comprise nanoclay, is also prepared to serve as the baseline data. Glass/waterborne epoxy prepregs containing 30% glass fibers are prepared from these batches and used to characterize the effects of nanoclay. The evolution of viscoelastic properties during curing are characterized by the APA2000 rheometer. Using the storage and loss moduli profiles during curing, gel time and maximum storage modulus are characterized. Effect of nanoclay on the glass transition temperature is determined by applying an additional temperature cycle following the cure cycle. In addition, mechanical performances of the samples are characterized by three point bending tests. Nanoclay is observed to yield 2-fold higher storage modulus during curing. Rate of curing is measured to be substantially slower for the samples comprising nanoclay. In addition, glass transition temperature improved by 5% to 99°C with the addition of nanoclay compared to 94.5°C for the samples without nanoclay. Flexural stiffness of the samples containing nanoclay is measured to be 20% higher than the samples without nanoclay while the strength remained virtually unaffected.

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