Retention of mechanical performance of polymer matrix composites above the glass transition temperature by vascular cooling

The mechanical response of polymer matrix composites exhibits a temperature dependency even if the service temperature range is lower than the glass transition temperature of the polymer matrix. This dependency is mainly due to the temperature effect on the mechanical behaviour of the polymer matrix. However, the micro- and meso-structures driving the composite anisotropy and local stress distribution play an essential role regarding the effect of temperature on damage mechanisms specific to reinforced polymers. There are few data in the literature on the sensitivity to temperature of damage mechanisms and scenarios of polymer matrix composites regardless of loading type. In this paper, after a synthetic literature review of the effect of temperature on polymers and polymer composites, several complementary tests are proposed to analyse the temperature effect on damage mechanisms undergone by laminated composites under in-plane quasi static loadings. These tests are applied to an acrylic-thermoplastic composite reinforced by glass fibres in its service temperature range of –20℃ to 60℃. The results show that the testing temperature has a significant impact on the mechanical response and damage mechanisms of the composite material in the selected temperature range, which is markedly lower than the glass transition temperature (around 100℃). While the temperature rise generates a gradual decrease in matrix stiffness and strength, the increase in matrix ductility associated to the stress heterogeneity in the composite microstructure produces a rise in the transverse cracking threshold and removes this damage mode during quasi-static tensile tests when the temperature shifts from 15℃ to 40℃.

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Study of the effect of the reinforcement direction on the identification of relaxation transitions of moisture-saturated carbon fiber VKU-25

Industrial laboratory Diagnostics of materials ◽

10.26896/1028-6861-2021-87-9-38-43 ◽

2021 ◽

Vol 87 (9) ◽

pp. 38-43

Author(s):

O. G. Ospennikova ◽

P. S. Marakhovsky ◽

N. N. Vorobyov ◽

E. V. Nikolaev ◽

A. I. Gulyaev ◽

...

Keyword(s):

Glass Transition ◽

Transition Temperature ◽

Glass Transition Temperature ◽

Carbon Fiber ◽

Polymer Matrix ◽

Structural Parameters ◽

Polymer Materials ◽

Thermal Coefficient ◽

Initial State ◽

Relaxation Transitions

Thermodilatometric methods of analysis are used to study the structural parameters of polymer materials, however, when studying moisture-saturated compositions certain difficulties arise in their identification. The results of thermophysical tests of VKU-25 carbon fiber samples in the initial state and after moisture saturation are presented. It is shown that heat treatment of materials affects the recorded values of the glass transition temperature of the epoxy matrix. When the samples are exposed in water or above the water surface, the sorbate penetrates into the polymer at the same rate, which is confirmed by almost identical values of water absorption at the same exposure time. The estimates of the thermal coefficient of linear expansion (TCLE) of the samples in the range of 20 - 250°C are given. Moreover, it is shown that the glass transition temperature of the plasticized polymer matrix depends on the direction of fiber reinforcement. In the case of moisture-saturated carbon fiber (CF)heated to 210°C, the formation of main cracks occurs mainly at the fiber-matrix interface. The glass transition temperature (GTT) of the material in the dry state (176 - 177°C), appeared almost independent on the heating rate, whereas for water-saturated samples, GTT changes significantly and can be described by a polynomial of the 2nd order. After exposure of the carbon fiber under conditions of high temperature and humidity, two relaxation transitions corresponding to the systems occur in the polymer matrix: epoxidian oligomer— amine hardener and polyfunctional resin— amine hardener. The glass transition temperature is 132 and 159°C in the first and in the second, respectively. The results obtained can be used in the development of new polymer composite materials.

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Polymer matrix–filler interaction mechanism for modified ion transport and glass transition temperature in the polymer electrolyte composites

Solid State Ionics ◽

10.1016/j.ssi.2010.06.055 ◽

2010 ◽

Vol 181 (27-28) ◽

pp. 1270-1278 ◽

Cited By ~ 20

Author(s):

Awalendra K. Thakur ◽

S.A. Hashmi

Keyword(s):

Glass Transition ◽

Transition Temperature ◽

Glass Transition Temperature ◽

Ion Transport ◽

Polymer Electrolyte ◽

Polymer Matrix ◽

Interaction Mechanism

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Fabrication of Laminated Nanocomposites by Vacuum-Assisted Deposition of Clay Onto Glass/Epoxy Prepregs

Multifunctional Nanocomposites ◽

10.1115/mn2006-17081 ◽

2006 ◽

Author(s):

Levent Aktas ◽

M. Cengiz Altan

Keyword(s):

Mechanical Properties ◽

Glass Transition ◽

Transition Temperature ◽

Glass Transition Temperature ◽

Flexural Strength ◽

Microstructural Characterization ◽

Flexural Stiffness ◽

Matrix Composites ◽

Deposition Chamber ◽

Nanoclay Content

In this study we are presenting a novel method for introducing nanoclay in epoxy matrix composites. The method involves vacuum-assisted deposition of fine clay particles directly onto the surface of commercially available prepregs. A deposition chamber is developed that is capable of breaking down nanoclay particles by subjecting them to shear and depositing them uniformly onto prepregs at room temperature. By using the deposition chamber, a thin layer of nanoclay is deposited on 101.6mm×101.6mm woven glass/epoxy prepregs. Twelve of these prepregs are stacked and cured by an autoclave at a temperature of 121°C under a constant pressure of 0.2MPa (30psi) for 1 hour. After the curing is complete, the laminates are cut into 10.8mm×31.7mm samples for three-point bending tests, glass transition temperature measurements and microstructural characterization. The improvements in mechanical properties such as flexural strength, flexural stiffness, and glass transition temperature by the addition of nanoclay are presented. Nanocomposite morphology is studied by light microscopy and scanning electron microscopy. Marginal improvements in mechanical properties are observed with only 0.6% nanoclay content. The flexural stiffness improved by 4% while maintaining the flexural strength constant at around 400Wa. Glass transition temperature is measured as 128°C for samples with and without nanoclay. However, significant differences in microstructure are observed. Although both samples contain micro-voids, these voids are observed to be more extensive in samples involving nanoclay.

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The influence of additives on polymer matrix mobility and the glass transition

Soft Matter ◽

10.1039/d0sm01634a ◽

2021 ◽

Author(s):

Jeffrey DeFelice ◽

Jane E. G. Lipson

Keyword(s):

Glass Transition ◽

Transition Temperature ◽

Glass Transition Temperature ◽

Polymer Matrix ◽

Interfacial Effects ◽

Local Mobility ◽

Additive Particles

In this work, we probe how the interfacial effects of additive particles dispersed in a matrix can influence the local mobility of the material and its glass transition temperature, Tg.

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Design of Nanomodified Intumescent Polymer Matrix Coatings: Theory, Modeling, Experiments

MATEC Web of Conferences ◽

10.1051/matecconf/201825101033 ◽

2018 ◽

Vol 251 ◽

pp. 01033 ◽

Cited By ~ 3

Author(s):

Alexandr Evstigneev ◽

Vladimir Smirnov ◽

Evgenij Korolev

Keyword(s):

Glass Transition ◽

Polymer Matrix ◽

Numerical Experiments ◽

Polymer Matrix Composites ◽

Protective Coatings ◽

Steel Substrate ◽

Matrix Composites ◽

The Novel ◽

Char Residue ◽

Novel Design

Thermoset-based polymer matrix composites are widely used for production of intumescent fire protective coatings; many operational properties of such coatings can be further enhanced by means of nanoscale layers between matrix and disperse phases. The dependence between temperature of processing and temperature of glass transition of thermosetting matrix allows to produce gradient of glass transition temperature along the depth of the coating and lower exfoilation of char residue from steel substrate. In the present article we have offered the novel design scheme for such coating. Several results of laboratory and numerical experiments that are within the framework of the offered scheme are also presented. Application of the offered scheme allows to develop efficient fire protective coatings in purposely and precisely controlled manner.

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