Entity

Time filter

Source Type

Everberg, Belgium

Shimizu K.,University of Surrey | Abel M.-L.,University of Surrey | Phanopoulos C.,Huntsman PU | Holvoet S.,Huntsman PU | Watts J.F.,University of Surrey
RSC Advances | Year: 2013

Polymeric methylene diphenyl diisocyanate (PMDI) is the major component of polyurethane formulations and as a result the adhesion, or indeed abhesion, of polyurethanes, in a variety of forms (foams, coatings and adhesives), to metal substrates will be a function of the interactions between PMDI and metal surfaces. In this paper the adsorption of PMDI on oxidised metal (aluminium and iron) substrates has been investigated. The thermodynamics of adsorption has been examined by the construction of adsorption isotherms derived from ToF-SIMS data. At low solution concentration, the adsorption isotherms of PMDI are not of the Langmuir type, but are shown to conform to Langmuir adsorption at higher solution concentrations (>1 g L-1). The interaction between the PMDI and iron is probably an acid-base interaction, and thus the adsorption of small PMDI molecules is displaced by larger PMDI molecules on the iron surface above a critical solution concentration. By contrast, such displacement is small on the aluminium surface as a result of the dominance of covalent bond formation between PMDI and the metal substrate. © The Royal Society of Chemistry 2013. Source


Tardio S.,University of Surrey | Abel M.-L.,University of Surrey | Carr R.H.,Huntsman PU | Castle J.E.,University of Surrey | Watts J.F.,University of Surrey
Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films | Year: 2015

The very thin native oxide film on stainless steel, of the order of 2nm, is known to be readily modified by immersion in aqueous media. In this paper, X-ray photoelectron spectroscopy (XPS) and time of flight secondary ions mass spectrometry are employed to investigate the nature of the air-formed film and modification after water emersion. The film is described in terms of oxide, hydroxide, and water content. The preferential dissolution of iron is shown to occur on immersion. It is shown that a water absorbed layer and a hydroxide layer are present above the oxide-like passive film. The concentrations of water and hydroxide appear to be higher in the case of exposure to water. A secure method for the peak fitting of Fe2p and Cr2p XPS spectra of such films on their metallic substrates is described. The importance of XPS survey spectra is underlined and the feasibility of C60+ SIMS depth profiling of a thin oxide layer is shown. © 2015 American Vacuum Society. Source


Maryska M.,ISP UMET ENSCL | Bourbigot S.,ISP UMET ENSCL | Duquesne S.,ISP UMET ENSCL | Lindsay C.,Huntsman PU | And 2 more authors.
23rd Annual Conference on Recent Advances in Flame Retardancy of Polymeric Materials 2012 | Year: 2012

Polyurethanes are unique polymeric materials with a wide range of physical and chemical properties. With well-designed combinations of monomeric materials, polyurethane can be tailored to meet diversified demands of various applications such as coatings, adhesives, fibers, thermoplastic elastomers, and foams. Ammonium polyphosphate has been added to a polyurethane coating model leading to a very efficient intumescent system. Intumescence describes the ability of a material to swell when exposed to a temperature increase leading to the formation of an expanded insulating layer. The addition of synergists considerably enhanced the fire performance of the intumescent polyurethane by a combination of chemical and physical effects. The purpose of the talk is to present the systematic approach to draw general rules associated to well defined governing parameters for designing polyurethanes with enhanced flame retardancy. © (2012) by BCC Research All rights reserved. Source


Muller M.,ISP UMET ENSCL | Bourbigot S.,ISP UMET ENSCL | Duquesne S.,ISP UMET ENSCL | Klein R.,Huntsman PU | And 3 more authors.
Polymer Degradation and Stability | Year: 2013

The morphology of carbonized materials resulting from an intumescence phenomenon was studied. The investigated material is a polyurethane matrix filled either by 30 wt.-% of ammonium polyphosphate or by a combination of 28 wt.-% of ammonium polyphosphate and 2 wt.-% of nano-magnesium oxide. These fillers were incorporated in the polyurethane directly during the synthesis step. The carbonized materials or char, are obtained in a specific fire scenario. Characterization of their morphology is carried out using X-ray computed tomography. The heat conductivity of the systems is additionally measured as a function of temperature in order to correlate structure and properties of the intumescent residues. The formation of different char structures with incorporation of magnesium oxide (in particular formation of bubbles of different size) is first evidenced. These observations are consistent with the heat conductivity data. Tomography images demonstrate that the intumescence process is a dynamic process since non degraded polymer is left at the beginning of the fire test, which is not the case for longer time. The dispersion of fillers has finally been investigated in the chars and it is evidenced different steps of intumescence's development in the material. © 2013 Elsevier Ltd. All rights reserved. Source


Muller M.,Ecole Nationale Superieure de Chimie de Lille | Bourbigot S.,Ecole Nationale Superieure de Chimie de Lille | Duquesne S.,Ecole Nationale Superieure de Chimie de Lille | Klein R.A.,Huntsman PU | And 2 more authors.
Journal of Fire Sciences | Year: 2013

This work investigates the parameters influencing the mechanical resistance of intumescent chars. A polyurethane matrix containing 30 wt% of ammonium polyphosphate was used in this study as intumescent model system. Three heating devices (rheometer furnace, mass loss calorimeter, and tubular oven) were used as heat treatment scenarios to obtain a charred structure. This char is then analyzed by measuring its compression resistance using a protocol involving a plate-plate rheometer (estimation of the char strength). The study of the char strength reveals that the presence of a flame, the heating type (convective or radiative heating), and the quenching temperature do not modify the mechanical properties of the resulting intumescent char. On the contrary, it was found that the critical parameters involved in the formation of a resistant char are the heating temperature and the heating rate. The strongest charred structure is reached after a heat treatment at 10 C/min until 500 C. Additionally, the modification of the temperature at which the mechanical test is performed (linked to the experimental protocol) leads also to different mechanical resistance of the tested materials. © The Author(s) 2013. Source

Discover hidden collaborations