Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.559282
Title: Thermoset modelling and simulation analysis, with a focus towards epoxies
Author: Hall, Stephen
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 2012
Availability of Full Text:
Access from EThOS:
Access from Institution:
Abstract:
This work covers a number of aspects central to, and relating to molecular modelling and simulation. Section 1 introduces the diamine, 4,4-diaminodiphenylsulphone (DDS) and the epoxide monomers Bis[4-(glycidyloxy)phenyl]methane (BFDGE) and N,N-Diglycidyl-4- glycidyloxyaniline (TGAP) which are used in this research. The primary and side reactions are explained along with the description and origin of the known impurities. Molecular modelling concepts are explained, covering energy calculations, geometry optimisation and molecular dynamics (MD). The Polymer Consistent Forcefield (PCFF) is used throughout this work, Section 1 includes a comparison of common forecefields, ensembles, thermostats and barostats. Section 2 explains the experimental methodology used for the empirical measurement of glass transition temperatures (T g) using Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Thermal Analysis (DMTA). Also covered are the more technical and specific matters of this research such as how the impurities are modelled and how the molecular ratios are calculated. There are seven primary models built, based on four formulations. Epoxy A is an epoxy rich mixture of BFDGE, TGAP and DDS, Epoxy B is a stoichiometric mix of BFDGE and DDS, Epoxy C is also stoichiometric, but comprised from TGAP and DDS, Epoxy D is epoxy rich, but only uses TGAP and DDS. The Epoxy F, G and H formulations are the second generation models of Epoxy B, C and D respectively, the models differ from the originals slightly on a number of points. Molecular models were used to predict T g for comparison with empirical values. Two programs were written as part of this study, the first will process a molecular model, comprised of epoxy and amine monomer, returning a cured resin model, coded to simulate the epoxy and amine bonding reaction. The second is used to processed density vs. temperature data and determine the T g. The source codes for both programs are available as appendices in Section 6. Materials Studi~ by Accelrys" was used extensively for molecular modelling throughout this work. Section 3 contains the results and discussion from the DSC, DMTA, molecular modelling and lesser experiments. Owing to inter-model similarity, only 4 formulations were subject to thermal analysis. DSC measurements for T g yielded 215 QC for Epoxy II A, 161 QC for Epoxy Band 229 QC for Epoxy C, the DSC analysis of Epoxy D did not establish a value for Tg• The DMTA measurement ofTg gave good agreement for Epoxy A and Epoxy B, about 46 QC higher than DSC for Epoxy C and an average of 280 QC for Epoxy D. The closest simulations to the empirical values were Epoxy B (+3.0%), Epoxy C (+4.3%), Epoxy D (-5.0%) and Epoxy A (-6.0%). It was noticed the simulation of stoichiometric fo~ulations predicted lower, and epoxy rich models predicted higher than empirical measurements. The final sections include the summary (Section 4), discussion on possible further work (Section 5) and the appendices (Section 6).
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.559282  DOI: Not available
Share: