scholarly journals Development of Epoxy-Polyester Composite with Improved Thermophysical Properties for Restoration of Details of Sea and River Transport

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
A. Buketov ◽  
M. Brailo ◽  
S. Yakushchenko ◽  
A. Sapronova
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Thermal Resistance ◽  
Thermophysical Properties ◽  
Polyester Resin ◽  
Linear Shrinkage ◽  
Nonlinear Dependence ◽  
Thermal Coefficient ◽  
Polyester Matrix

The results of the experimental investigations of the optimization of the content of the polyester resin in the epoxy binder are shown in the work. It was determined that composite with concentration of the polyester (q = 10 mas.fr.) was characterized by the maximal values of the thermophysical properties. The Martens thermal resistance temperature, the linear shrinkage, the thermal coefficient of linear expansion, and the glass transition temperature of the epoxy-polyester matrix were investigated. It was found that introducing the polyester resin into the epoxy oligomer in quantity of q = 10 mas.fr. leads to improving the Martens thermal resistance of the material to the T = 352 K and decreasing the linear shrinkage to the Δl = 0.06%. The nonlinear dependence of the TCLE on the temperature was confirmed, and the tendency of changes in their values, depending on the content of polyester resin, was defined. The dilatometric curves were analyzed, and the glass transition temperature of developed epoxy-polyester matrix was determined at the level Tс = 318 K.

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

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.

scholarly journals Preparation and Properties of Polyester-Based Nanocomposite Gel Coat System

2006 ◽  
Vol 2006 ◽  
pp. 1-7 ◽  
Author(s):  
P. Jawahar ◽  
M. Balasubramanian
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Polyester Resin ◽  
Unsaturated Polyester ◽  
Flexural Modulus ◽  
Tensile Modulus ◽  
Barrier Properties ◽  
Mechanical Analysis ◽  
Water Barrier

Nanocomposite gel coat system is prepared using unsaturated polyester resin with aerosil powder,CaCO3, and organoclay. The influence of organoclay addition on mechanical and water barrier properties of gel coat system is studied for different amount (1, 2, and 3 wt%) of organoclay. The nanolevel incorporation of organoclay improves the mechanical and water barrier properties of nanocomposite gel coat system. The nanocomposite gel coat system exhibits 55%improvement in tensile modulus and 25%improvement in flexural modulus. There is a 30%improvement in impact property of nanocomposite gel coat system. The dynamic mechanical analysis shows a slight increase in glass transition temperature for nanocomposite gel coat system.

scholarly journals Viscoelastic properties of hydroxyl-terminated poly(butadiene) based composite rocket propellants

2014 ◽  
Vol 68 (4) ◽  
pp. 435-443 ◽  
Author(s):  
Sasa Brzic ◽  
Ljiljana Jelisavac ◽  
Jela Galovic ◽  
Danica Simic ◽  
Jelena Petkovic
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Free Volume ◽  
Loss Modulus ◽  
Mechanical Analysis ◽  
Thermal Coefficient ◽  
Fractional Free Volume ◽  
Rocket Propellants ◽  
Wide Range

In the present study, the viscoelastic response of three composite solid propellants based on hydroxyl-terminated poly(butadiene), ammonium perchlorate and aluminum has been investigated. The investigation was surveyed by dynamic mechanical analysis over a wide range of temperatures and frequencies. The mechanical properties of these materials are related to the macromolecular structure of the binder as well as to the content and nature of solid fillers. The storage modulus, loss modulus, loss factor and glass transition temperature for each propellant sample have been evaluated. The master curves of storage (log G' vs log ?) and loss modulus (log G'' vs log ?) were generated for each propellant. A comparison of logaT vs temperature curves for all propellants indicate conformance to Williams-Landel-Ferry equation. Choosing the glass transition as the reference temperature, WLF equation constants are determined. Fractional free volume at the glass transition temperature and thermal coefficient of free volume expansion values are in accordance with the consideration that Al is reinforcing filler.

Effect of cladding layer glass transition temperature on thermal resistance of graded-index plastic optical fibers

2014 ◽  
Vol 46 (11) ◽  
pp. 823-826 ◽  
Author(s):  
Hirotsugu Yoshida ◽  
Ryosuke Nakao ◽  
Yuki Masabe ◽  
Kotaro Koike ◽  
Yasuhiro Koike
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Thermal Resistance ◽  
Optical Fibers ◽  
Graded Index ◽  
Cladding Layer ◽  
Plastic Optical Fibers

Nonlinear thermal expansion and contraction of asphalt concrete

1999 ◽  
Vol 26 (1) ◽  
pp. 26-34 ◽  
Author(s):  
Menglan Zeng ◽  
Donald H Shields
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Thermal Stress ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Viscoelastic Material ◽  
Asphalt Concrete ◽  
Nonlinear Function ◽  
Single Type ◽  
Thermal Coefficient

Asphalt concrete for paving roads is a viscoelastic material. In the prediction of thermal stress in asphalt pavements, the thermal expansion-contraction property of the material is required. In current practice, thermal expansion-contraction is assumed to be a linear function of temperature, and a constant thermal coefficient is used. The fact that a viscoelastic material may have a glass transition temperature and the thermal property may have a discontinuity at the glass transition temperature has not been considered. This study investigates the thermal nonlinearity of asphalt concrete. In this research, the thermal expansion-contraction was continuously measured on a single type of asphalt concrete in the temperature range from +40°C to -40°C. It was found that the thermal expansion-contraction was a continuous nonlinear function of temperature, resulting in a variable thermal coefficient. Evaluations of the effect of the nonlinearity indicated that the assumption of thermal linearity can result in moderate errors in stress prediction in asphalt pavements.Key words: asphalt concrete, thermal expansion-contraction, thermal coefficient, nonlinear thermal behaviour, asphalt pavement, thermal stress.

scholarly journals Structure, thermophysical properties and electrical conductivity of nanocomposites based on epoxy polymer and carbon tubes

2021 ◽  
pp. 7-13
Author(s):  
V.V. Korskanov ◽  
O.M. Fesenko ◽  
V.B. Dolgoshey
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Percolation Threshold ◽  
Thermophysical Properties ◽  
Epoxy Polymer ◽  
Transition Range ◽  
Epoxy Polymers

The aim of this work was to find the optimal conditions for the formation of nanocomposites, study their structure and properties and conditions for the formation of multicomponent materials based on epoxy polymers and carbon nanotubes with predetermined performance properties. The basis for the formation of epoxy polymers was an epoxydian oligomer (EDO) based on bisphenol A. Polypox H354 was used as a hardener for EDO. Carbon nanotubes (CNT) were used as a nanofiller for the preparation of nanocomposites. The research methods were a diffractometer for measuring the intensity of X-ray scattering in the region of small angles and a differential scanning calorimeter for obtaining heating thermograms. The electrical conductivity of the samples at a temperature of 293 K was measured at direct current according to the two-electrode scheme. In this work the structure, thermophysical properties and electrical conductivity of nanocomposites based epoxy polymers and carbon  nanotubes have been studied. It was found that at low CNT content the formation of nanocomposites occurs by the mechanism of epoxy network growth, which is accompanied by the displacement of CNT particles to the periphery of the epoxy matrix. This process is accompanied by an increase in the scattering intensity of the SAXS, a rapid increase in the glass transition temperature and the degree of crosslinking of the epoxy polymer. When the critical concentration is reached, CNT particles form a continuous cluster, which leads to occurrence percolation threshold, reducing the glass transition temperature, expanding the glass transition range, occurrence of pores and reducing the degree of completion of the crosslinking reaction in nanocomposites relative to the epoxy polymer. It is established that the improvement of nanocomposite properties and the occurrence of the percolation threshold is due to the maximum specific energy of ER-CNT interaction and is achieved at a critical mass concentration of nanofiller from 0,1% to 0,4%.

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.

Sign in / Sign up

Export Citation Format

Share Document