Publications - DryAdd

The following papers describe work that was done using various versions of DryAdd. These are given in date order, with the oldest first.

Prediction of the Rheological Properties of Reactive Polymer Systems, D Hayward, R A Pethrick, B Eling and E Colbourn, Polym. Int. 44 248-254 (1997)

A polymerization reaction may lead to either a thermoplastic or thermoset system depending upon the chemical structure of the monomers, and is usually accompanied by a marked increase in viscosity, which is directly related to the extent of reaction. As the molecular weight increases and branch chain structure develops, so a characteristic frequency dependence is observed in the rheology of the system. This paper describes the development of theoretical models which are capable of describing the behaviour of a system in which a condensation polymerization reaction is taking place. Polymerization of difunctional monomers leads to linear polymers, whereas higher functional monomers will ultimately form a three-dimensional network structure. Validation of the models used is achieved by comparing the prediction with experimental data for well defined stable polymer systems. Two sets of materials are studied: firstly, a series of narrow molecular weight linear polystyrenes and secondly, a series of polyisoprene star branched materials. The results of the simulations of the growth of a linear and a branched polymer system are presented, and the implications in relation to the form of the equations used are discussed.

Computer modelling and chemical kinetics of the cure of aerospace resin systems, I Hamerton and B J Howlin, Aircraft Engineering and Aerospace Technology 71 470-478 (1999)

Abstract

The authors are experienced researchers in the selection, evaluation and simulation of polymeric matrix resins for advanced composites. This article reviews the current state-of-the-art in cure monitoring techniques and the application of modern computational methods to determine the kinetics of cure in commonly used aerospace systems. Extensive reference is made to primary sources and conclusions drawn about the possible future developments that may evolve in this area of interest.

Comparison of the structure of step-growth networks obtained by Monte Carlo simulation and branching theory, Erich Hädicke *, Herbert Stutz, J Appl Polym Sci 85 929-935 (2002)

Abstract

To facilitate the characterization of polymer networks, a comparison was made between branching theory and Monte Carlo simulations using an amine-cured epoxy as an example for step-growth polymer networks. The primary objective was the validation of the simulation results with the existing statistical theories by a cross-check, to ensure that simulations can also be used for the characterization of real, highly complicated multicomponent systems, which are intractable by theories. Commercially available software was used for simulation; the theoretical calculations were performed using the approach of Macosko and Miller. In general, the results of both methods are consistent; the simulation revealed some uncertainties only in the vicinity of the gel point. Since the statistical theories have been validated experimentally, it may be concluded that the simulation can also successfully be used for the treatment of real, highly complicated multicomponent systems, which for practical purposes are intractable by statistical theories. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 929-935, 2002

Mechanical property changes and degradation during accelerated weathering of polyester-urethane coatings, S Croll, JCT Research, 1 January 2006

Abstract

Chemical changes, measured using spectroscopy, and crosslink density, measured by mechanical thermal analysis, were determined during accelerated weathering on a model polyester-urethane coating of known composition. The tensile modulus, measured above the glass transition temperature, and thus the cross-link density, decreased with exposure, as expected from the chemical changes. However, the tensile modulus, measured at room temperature, increased with exposure. Physical aging of the polymer network was found to occur concurrently with photodegradation and accounts for much of the increase in room temperature modulus. Increased hydrogen bonding in the increasingly oxidized polyester-urethane may also contribute to the increase in modulus at room temperature. Both physical and chemical changes must be determined if changes, and rates of change, in performance due to weathering are to be understood.

Surface microtopography in siloxane-polyurethane thermosets: the influence of siloxane and extent of reaction, P Majumdar and D C Webster, Polymer 48 7499-7509 (2007)

Abstract

The effect of polydimethylsiloxane (PDMS) content, PDMS molecular weight, and the extent of prepolymerization reactions between hydroxyl functional PDMS and polyisocyanate were explored in order to understand the influence of these variables on the formation of surface microtopography in a siloxaneepolyurethane thermoset. The system is based on a difunctional hydroxyalkyl terminated PDMS, trifunctional poly(caprolactone) polyol, and a polyisocyanate. The effect of PDMS content was studied with PDMS of MW 1000 and 2000. PDMS of MW 1000 was varied from 5% to 15% and with PDMS of MW 2000 the level was varied from 5% to 12%. Tapping mode AFM images of the surface topography were used to characterize the system. The extent of reaction prior to film formation was studied by FTIR and correlated with microdomain formation in the final polymer film. Two different mixing strategies were explored: one where all of the ingredients were mixed together and a second approach where PDMS and polyisocyanate were mixed first, followed by the addition of the trifunctional polyol. Monte Carlo simulation of the polymerization with 10% PDMS of MW 1000 in the formulation revealed that there was a window of conversion for both PDMS and isocyanate at which the system spontaneously phase separates to form a microtopographical surface.

Novel water-dispersible glycidyl carbamate (GC) resins and waterborne amine-cured coatings, Umesh D. Harkal, Andrew J. Muehlberg, Peter A. Edwards and Dean C. Webster, J Coat. Technol. Res. DOI 10.1007/s11998-011-9356-8 (2011)

Water-dispersible glycidyl carbamate (GC) functional resins were synthesized and crosslinked using a water-dispersible amine to form coatings. GC functional resins are synthesized by the reaction of an isocyanate functional compound with glycidol to yield a carbamate (urethane) linkage (–NHCO–) and reactive epoxy group. The combination of both functionalities
in a single resin structure imparts excellent mechanical and chemical properties to the coatings. Previous studies on the development of GC coatings have focused on solvent-borne coating systems. In this study, GC resins were modified by incorporating nonionic hydrophilic groups to produce water-dispersible resins. To determine the influence of the content
of hydrophilic groups on dispersion stability, aqueous dispersions were made from a series of hydrophilically modified GC resins and characterized for particle size and dispersion stability. The composition of a typical, dispersed GC resin particle was predicted using Monte Carlo simulations. Stable GC dispersions were used to prepare amine-cured coatings. The coatings were characterized for solvent resistance, water resistance, hardness, flexibility, adhesion, and surface morphology.
It was observed that GC resins were able to be dispersed in water without using any surfactant and by minimal mixing force (hand mixing) and produced coating films with good properties when crosslinked with a compatible waterborne amine crosslinker.

DryAdd has also been used in patent applications from Huntsman.

Title: Foamed Supramolecular Polymers

Publication Date: 14 July 2005

Document Type and Number: United States Patent 20050151291

Title: Supramolecular Polymer Forming Polymer

Publication Date. 13 June 2002, International Filing Date 3 December 2001

Document type and number: International Application Number PCT/EP2001/014082