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Papers by Jonathan Cail

Research paper thumbnail of Polymer networks: principles of formation, structure and properties

Research paper thumbnail of The gel point and network formation including poly(dimethylsiloxane) polymerizations : Theory and experiment

Acs Symposium Series, 2007

Research paper thumbnail of Atomistic Modeling of the Formation of Radical Pairs in Irradiated Amorphous Poly(propylene)

Macromolecules, Nov 12, 1999

ABSTRACT

Research paper thumbnail of Molecular Modelling of the Conformational Flexibility and Elastic Behaviour of Short Poly(ethylene terephthalate) Chains

Journal of Inorganic and Organometallic Polymers and Materials, 2011

The Monte-Carlo (MC) rotational-isomeric-state (RIS) method developed previously to model the str... more The Monte-Carlo (MC) rotational-isomeric-state (RIS) method developed previously to model the stress-strain behaviour of poly(ethylene terephthalate) (PET) is now applied to short PET chains of between 42 and 84 skeletal bonds. The effects on the radial and probability density distribution functions of the long, flexible virtual bond used to represent the terephthaloyl unit are investigated. The distribution functions generated, based on finite samples of chains, are found to be discontinuous with subsidiary maxima in their tails. The discontinuities lead to uncertainties in the simulated network elasticity properties and, in order to reduce the uncertainty, it is necessary to truncate the distributions at the values of r where they first become discontinuous. The stressstrain properties calculated from the truncated distributions are shown to be consistent with those presented previously for longer PET chains, for which discontinuities in the sampled functions are not apparent.

Research paper thumbnail of The stress optical behavior of PET fibers and films

Polymer Engineering & Science, 1999

... POLYMER ENGINEERING AND SCIENCE, DECEMBER 1999, Vol. 39, No. 12 ... (Drawn films at 80°C) (Un... more ... POLYMER ENGINEERING AND SCIENCE, DECEMBER 1999, Vol. 39, No. 12 ... (Drawn films at 80°C) (Uniaxial and biaxial films at 85'C) Matthews et al (Ball et al modeling at 85°C) (Drawn fibers at 90°C) ... Bleackley et al 1.2 1.73 molecular network formed is similar in all cases. ...

Research paper thumbnail of The gel point and network formation – theory and experiment

Polymer Bulletin, 2007

Summary Gel points, accounting for intramolecular reaction, are predicted using Ahmed-Rolfes-Ste... more Summary Gel points, accounting for intramolecular reaction, are predicted using Ahmed-Rolfes-Stepto (ARS) theory. They are compared with experimental gel points for polyester (PES)-forming, polyurethane (PU)-forming and poly(dimethylsiloxane) (PDMS) polymerisations. The PES and PU polymerisations were from stoichiometric reaction mixtures at different initial dilutions and the PDMS ones were from critical-ratio experiments at different fixed dilutions of one reactant. The ARS predictions

Research paper thumbnail of Molecular modelling of the elastic behaviour of poly(ethylene terephthalate) network chains

Polymer, 2003

The Monte-Carlo (MC) method developed to model the elastomeric stress-strain behaviour of polyeth... more The Monte-Carlo (MC) method developed to model the elastomeric stress-strain behaviour of polyethylene (PE) and poly(dimethyl siloxane) (PDMS) networks and the stress-optical behaviour of PE networks is now applied to the stress-strain behaviour of poly(ethylene terephthalate) (PET) networks. In keeping with the previous results for PE and PDMS networks, increases in the proportions of fully extended chains with macroscopic deformation are found to give rise to steady decreases in the rates of Helmholtz energy changes, causing reductions in moduli at moderate macroscopic deformations. There is no need to invoke a transition from affine to phantom chain behaviour as deformation increases. By using rotational-isomeric-state (RIS) models of the network chains and the MC method, stress-strain behaviour can be related to chemical structure. In this respect, the greater conformational flexibility of the PET chain leads to lower network moduli and smaller deviations from Gaussian network behaviour than for PE networks. In addition, the stiff, aromatic section of the PET repeat unit structure is seen to endow particular characteristics on the end-to-end distribution functions of PET chains. These characteristics are taken fully into account in evaluating the elastomeric properties of the PET networks. Subsequent publications will apply the present results to interpreting the measured stress-strain and the stress-optical properties of entangled PET melts.

Research paper thumbnail of Molecular modelling of the stress–strain behaviour of elastomers in pure shear

Polymer, 2005

It is demonstrated that experimental stress–strain data for several types of polymer network unde... more It is demonstrated that experimental stress–strain data for several types of polymer network under pure shear display an approximately universal behaviour. The Monte–Carlo network-modelling method of Stepto, Taylor and Cail is extended to treat stress–strain behaviour in pure shear and its predictions are in good agreement with the experimental data. The predictions of Gaussian network theory are shown to be

Research paper thumbnail of Rescaling Approach to Molecular Orientation for NMR and Optical Properties of Polymer Networks

Macromolecules, 2002

ABSTRACT

Research paper thumbnail of Formation, structure and properties of polymer networks: gel-point prediction in endlinking polymerisations

Macromolecular Symposia, 2001

Gel points, predicted using Ahmed-Rolfes-Stepto (ARS) theory and a Monte-Carlo (MC) simulation me... more Gel points, predicted using Ahmed-Rolfes-Stepto (ARS) theory and a Monte-Carlo (MC) simulation method accounting for intramolecular reaction, are compared with experimental data for polyester (PES)-, polyurethane (PU)- and poly(dimethyhl siloxane) (PDMS)-forming ...

Research paper thumbnail of Developments in understanding the formation, structure and properties of polymer networks

Macromolecular Symposia, 2003

ABSTRACT

Research paper thumbnail of Predicting the modulus of end-linked networks from formation conditions

Macromolecular Symposia, 2003

Research paper thumbnail of Quantitative Modeling of the Stress‐Optical Properties of Polyethene Networks

Journal of Macromolecular Science, Part B: Physics, 2005

The Monte‐Carlo (MC) modeling of the deformation‐related properties of polymer networks due to St... more The Monte‐Carlo (MC) modeling of the deformation‐related properties of polymer networks due to Stepto and Taylor (1995a; 1995b) is applied to the stress‐optical behavior of polyethene (PE) networks published by Saunders (1954). Quantitative modeling is achieved on the bases of the realistic rotational‐isomeric‐state model of the PE chain, due to Abe, Jernigan, and Flory (1966), and the C–C and C–H

Research paper thumbnail of Experimental studies and molecular modelling of catalytic steam gasification of brown coal containing iron species

Fuel, 2012

The paper presents experimental data of catalytic steam gasification of brown coal containing aqu... more The paper presents experimental data of catalytic steam gasification of brown coal containing aqua-iron species, and the chemical mechanism(s) at a molecular level. Experimental techniques provided weight loss from catalysed reaction of char with steam of 17 wt% at 800°C and 40 wt% at 900°C, over 15 min, on a dry ash free basis (daf). Inorganic and organic oxygen, identified using XPS in the char samples, was derived from reactions with steam. High yields of H 2 resulted from catalysed reactions between char and steam. Semi-empirical (SE) quantum molecular modelling using MOPAC, of reaction routes for high temperature pyrolysis and steam gasification, provided results consistent with experimental data for weight loss, iron species, and the distribution of inorganic and organic oxygen in char samples after reaction with steam. The catalysis mechanism(s) that have been examined are considered to be a hybrid of organometallic and heterogeneous chemistry, involving iron hydride species that precede H 2 formation; oxygen insertion into [Fe-C-] to form [Fe-O-C-] followed by elimination of CO, creating another [Fe-C] site to continue the catalytic cycle. SE modelling indicates concerted reactions were more energetically favoured. Initial results from molecular dynamics (MD) show a higher concentration of H 2 O molecules about the active site [Fe-C].

Research paper thumbnail of Further computer simulation studies of the orientational behaviour of poly ( …

Physical Chemistry …, 2000

Further computer simulation studies of the orientational behaviour of poly(ethylene terephthalate... more Further computer simulation studies of the orientational behaviour of poly(ethylene terephthalate) chains ... Jonathan I. Cail,a Robert FT Stepto,*a David JR Taylor,a Richard A. Jonesb and Ian M. Wardb ... Received 22nd May 2000, Accepted 11th August 2000 First ...

Research paper thumbnail of Polymer networks: principles of formation, structure and properties

Research paper thumbnail of The gel point and network formation including poly(dimethylsiloxane) polymerizations : Theory and experiment

Acs Symposium Series, 2007

Research paper thumbnail of Atomistic Modeling of the Formation of Radical Pairs in Irradiated Amorphous Poly(propylene)

Macromolecules, Nov 12, 1999

ABSTRACT

Research paper thumbnail of Molecular Modelling of the Conformational Flexibility and Elastic Behaviour of Short Poly(ethylene terephthalate) Chains

Journal of Inorganic and Organometallic Polymers and Materials, 2011

The Monte-Carlo (MC) rotational-isomeric-state (RIS) method developed previously to model the str... more The Monte-Carlo (MC) rotational-isomeric-state (RIS) method developed previously to model the stress-strain behaviour of poly(ethylene terephthalate) (PET) is now applied to short PET chains of between 42 and 84 skeletal bonds. The effects on the radial and probability density distribution functions of the long, flexible virtual bond used to represent the terephthaloyl unit are investigated. The distribution functions generated, based on finite samples of chains, are found to be discontinuous with subsidiary maxima in their tails. The discontinuities lead to uncertainties in the simulated network elasticity properties and, in order to reduce the uncertainty, it is necessary to truncate the distributions at the values of r where they first become discontinuous. The stressstrain properties calculated from the truncated distributions are shown to be consistent with those presented previously for longer PET chains, for which discontinuities in the sampled functions are not apparent.

Research paper thumbnail of The stress optical behavior of PET fibers and films

Polymer Engineering & Science, 1999

... POLYMER ENGINEERING AND SCIENCE, DECEMBER 1999, Vol. 39, No. 12 ... (Drawn films at 80°C) (Un... more ... POLYMER ENGINEERING AND SCIENCE, DECEMBER 1999, Vol. 39, No. 12 ... (Drawn films at 80°C) (Uniaxial and biaxial films at 85'C) Matthews et al (Ball et al modeling at 85°C) (Drawn fibers at 90°C) ... Bleackley et al 1.2 1.73 molecular network formed is similar in all cases. ...

Research paper thumbnail of The gel point and network formation – theory and experiment

Polymer Bulletin, 2007

Summary Gel points, accounting for intramolecular reaction, are predicted using Ahmed-Rolfes-Ste... more Summary Gel points, accounting for intramolecular reaction, are predicted using Ahmed-Rolfes-Stepto (ARS) theory. They are compared with experimental gel points for polyester (PES)-forming, polyurethane (PU)-forming and poly(dimethylsiloxane) (PDMS) polymerisations. The PES and PU polymerisations were from stoichiometric reaction mixtures at different initial dilutions and the PDMS ones were from critical-ratio experiments at different fixed dilutions of one reactant. The ARS predictions

Research paper thumbnail of Molecular modelling of the elastic behaviour of poly(ethylene terephthalate) network chains

Polymer, 2003

The Monte-Carlo (MC) method developed to model the elastomeric stress-strain behaviour of polyeth... more The Monte-Carlo (MC) method developed to model the elastomeric stress-strain behaviour of polyethylene (PE) and poly(dimethyl siloxane) (PDMS) networks and the stress-optical behaviour of PE networks is now applied to the stress-strain behaviour of poly(ethylene terephthalate) (PET) networks. In keeping with the previous results for PE and PDMS networks, increases in the proportions of fully extended chains with macroscopic deformation are found to give rise to steady decreases in the rates of Helmholtz energy changes, causing reductions in moduli at moderate macroscopic deformations. There is no need to invoke a transition from affine to phantom chain behaviour as deformation increases. By using rotational-isomeric-state (RIS) models of the network chains and the MC method, stress-strain behaviour can be related to chemical structure. In this respect, the greater conformational flexibility of the PET chain leads to lower network moduli and smaller deviations from Gaussian network behaviour than for PE networks. In addition, the stiff, aromatic section of the PET repeat unit structure is seen to endow particular characteristics on the end-to-end distribution functions of PET chains. These characteristics are taken fully into account in evaluating the elastomeric properties of the PET networks. Subsequent publications will apply the present results to interpreting the measured stress-strain and the stress-optical properties of entangled PET melts.

Research paper thumbnail of Molecular modelling of the stress–strain behaviour of elastomers in pure shear

Polymer, 2005

It is demonstrated that experimental stress–strain data for several types of polymer network unde... more It is demonstrated that experimental stress–strain data for several types of polymer network under pure shear display an approximately universal behaviour. The Monte–Carlo network-modelling method of Stepto, Taylor and Cail is extended to treat stress–strain behaviour in pure shear and its predictions are in good agreement with the experimental data. The predictions of Gaussian network theory are shown to be

Research paper thumbnail of Rescaling Approach to Molecular Orientation for NMR and Optical Properties of Polymer Networks

Macromolecules, 2002

ABSTRACT

Research paper thumbnail of Formation, structure and properties of polymer networks: gel-point prediction in endlinking polymerisations

Macromolecular Symposia, 2001

Gel points, predicted using Ahmed-Rolfes-Stepto (ARS) theory and a Monte-Carlo (MC) simulation me... more Gel points, predicted using Ahmed-Rolfes-Stepto (ARS) theory and a Monte-Carlo (MC) simulation method accounting for intramolecular reaction, are compared with experimental data for polyester (PES)-, polyurethane (PU)- and poly(dimethyhl siloxane) (PDMS)-forming ...

Research paper thumbnail of Developments in understanding the formation, structure and properties of polymer networks

Macromolecular Symposia, 2003

ABSTRACT

Research paper thumbnail of Predicting the modulus of end-linked networks from formation conditions

Macromolecular Symposia, 2003

Research paper thumbnail of Quantitative Modeling of the Stress‐Optical Properties of Polyethene Networks

Journal of Macromolecular Science, Part B: Physics, 2005

The Monte‐Carlo (MC) modeling of the deformation‐related properties of polymer networks due to St... more The Monte‐Carlo (MC) modeling of the deformation‐related properties of polymer networks due to Stepto and Taylor (1995a; 1995b) is applied to the stress‐optical behavior of polyethene (PE) networks published by Saunders (1954). Quantitative modeling is achieved on the bases of the realistic rotational‐isomeric‐state model of the PE chain, due to Abe, Jernigan, and Flory (1966), and the C–C and C–H

Research paper thumbnail of Experimental studies and molecular modelling of catalytic steam gasification of brown coal containing iron species

Fuel, 2012

The paper presents experimental data of catalytic steam gasification of brown coal containing aqu... more The paper presents experimental data of catalytic steam gasification of brown coal containing aqua-iron species, and the chemical mechanism(s) at a molecular level. Experimental techniques provided weight loss from catalysed reaction of char with steam of 17 wt% at 800°C and 40 wt% at 900°C, over 15 min, on a dry ash free basis (daf). Inorganic and organic oxygen, identified using XPS in the char samples, was derived from reactions with steam. High yields of H 2 resulted from catalysed reactions between char and steam. Semi-empirical (SE) quantum molecular modelling using MOPAC, of reaction routes for high temperature pyrolysis and steam gasification, provided results consistent with experimental data for weight loss, iron species, and the distribution of inorganic and organic oxygen in char samples after reaction with steam. The catalysis mechanism(s) that have been examined are considered to be a hybrid of organometallic and heterogeneous chemistry, involving iron hydride species that precede H 2 formation; oxygen insertion into [Fe-C-] to form [Fe-O-C-] followed by elimination of CO, creating another [Fe-C] site to continue the catalytic cycle. SE modelling indicates concerted reactions were more energetically favoured. Initial results from molecular dynamics (MD) show a higher concentration of H 2 O molecules about the active site [Fe-C].

Research paper thumbnail of Further computer simulation studies of the orientational behaviour of poly ( …

Physical Chemistry …, 2000

Further computer simulation studies of the orientational behaviour of poly(ethylene terephthalate... more Further computer simulation studies of the orientational behaviour of poly(ethylene terephthalate) chains ... Jonathan I. Cail,a Robert FT Stepto,*a David JR Taylor,a Richard A. Jonesb and Ian M. Wardb ... Received 22nd May 2000, Accepted 11th August 2000 First ...