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Chemorhelogical Modeling Of Amine-Cured Multifunctional Epoxy Resin Systems Used As Matrices In Aerospace Composites

Electronic Theses of Indian Institute of Science

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Title Chemorhelogical Modeling Of Amine-Cured Multifunctional Epoxy Resin Systems Used As Matrices In Aerospace Composites
 
Creator Subramaniam, C
 
Subject Chemical Engineering
Composite Materials
Epoxy Resins Systems
Space Frame Structures
Air Frames
Resin Systems
Autocatalytic Model
Dual Arrhenius Model
VISCON Model
Differential Scanning Colorimetry (DSC)
Fourier Transform Infrared (FTIR)
Dyanamic Mechanical Analysis (DMA)
TTT Cure Diagram
 
Description High performance multifunctional epoxy resin systems are becoming increasingly important as matrix materials for the advanced composites used in aerospace, electronics, automotive and other industries. In a composite based on epoxy resin systems, a three-dimensional network of the matrix is formed around the reinforcing fibre as a result of the chemical reaction between the resin and the curing agent. This chemical process, known as curing, is an important event to he considered in the production of composite components made up of these resin systems. Two process parameters namely viscosity and chemical conversion are of paramount significance in the production of composite materials Curing studies of the resin systems based on these two parameters, would therefore assume great importance in deciding the performance reliability of the end product.

The objectives of the present investigation are
1. to study the cure kinetics of three thermoset resin systems, viz.,
i) epoxy novolac (EPIT)/ diamino diphenyl methane{DDM), ii) trigylcidyl para- ammo phenol (TGPAP)/toluene diamine (TDA) and iii) tetraglycidyl diamino diphenyl methane (TGDDM)/pyridine diamine(PDA) using the cure kinetic models based on chemical conversion (α), Theological conversion (β) and viscosity.

2.to develop a correlation between a and viscosity (η) and modify an existing autocatalytic model based on α, to the viscosity domain and

3.to investigate the cure behaviour of these systems in terms of the TTT cure diagram and its associated models.
EPN/DDM, TGPAP/PDA and TGDDM/PDA resin systems were chosen for the studies to represent a range of functionalities, The cure was monitored using differential scanning calorimetry (DSC), fourier transform infrared (FTIR) and dynamic mechanical analysis (DMA) techniques by following the changes in enthalpy, functional groups and rheology, respectively.

The kinetic parameters namely, order of reaction and activation energy were estimated from dynamic DSC data using the methods of Freeman-Carroll and Ellerstein using nth rate expression. Barton, Kissinger and Osawa methods were employed to find out the activation energy from the peak/equal conversion at different heating rates. Isothermal DSC data were also analyzed using nth order model and it was observed that the data could be fitted satisfactorily only for higher temperatures The results obtained from the analysis of both dynamic and isothermal DSC data using nth order model clearly indicate that this model is inadequate for describing the cure behavior. The isothermal DSC data was analyzed by the autocatalytic models of Hone and Kamal Good correlation was observed with Hum and Kamal models up to 60-70%, 25% and 45% conversions for EPN/DDM, TGPAP/TDA and TCDDM/PDA systems respectively. However, the parameters m and n in Kamal model were found to be temperature dependent for EPN/DDM and TCPAP/TDA systems. The limited applicability of the autocatalytic models IK attributed to the counter-effect offered by the intra-molecular bonding taking place.

The primary amine and epoxy groups conversions obtained from FTIR were analyzed using autocatalytic model and the kinetic parameters were calculated. The reactivity ratio of the primary amine and the secondary amine with epoxy was found to be dependent on temperature in agreement with the recent findings reported m the literature.

The existing models that relate the cure kinetics and the rheological changes, are dual Arrhenius nth order model and autocatalytic model The nth order kinetic model was used to evaluate the kinetic parameters using the viscosity data at different cure temperatures under isothermal conditions As the storage modulus, G' is proportional to the chemical cross links and becomes significant only after the g
 
Publisher Indian Institute of Science
 
Contributor Chanda, Manas
Rao, R M V G K
 
Date 2005-07-13T09:19:10Z
2005-07-13T09:19:10Z
2005-07-13T09:19:10Z
1994-10
 
Type Electronic Thesis and Dissertation
 
Format 3000790 bytes
application/pdf
 
Identifier http://etd.iisc.ernet.in/handle/2005/127
null
 
Language en
 
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