Structural Effects on the Decomposition Kinetics of EPDM Elastomers by High-Resolution TGA and Modulated TGA

Effects of ethylene content and maleated EPDM content on the thermal stability and degradation kinetics of ethylene propylene diene monomer (EPDM) have been studied using high resolution thermogravimetric analysis (Hi-Res TGA) and Modulated TGA (MTGA). Modulated TGA shows that EPDM degradation is complex, with activation energy of degradation increasing throughout the degradation. Values from both dynamic and constant heating rate experiments are in good agreement with each other and with the literature value. However, the dynamic heating rate experiment shows that if the difference of peak temperature of components in a system is less than 5°C, Hi-Res TGA does not resolve them.This revised version was published online in November 2005 with corrections to the Cover Date.     

Synthesis of dipotassium dimethylsilanediolate monohydrate

Dipotassium dimethylsilanediolate monohydrate has been synthesised for the first time. The compound has been extensively characterised. The utilization of this new compound as an initiator or monomer in the interfacial polymerisation of silicones is discussed.     

Ethynylbenzene monolayers on gold: a metal-molecule binding motif derived from a hydrocarbon

Exposure of a Au(111) surface to ethynylbenzene in solution leads to the formation of a bound monolayer. A chemisorption process occurs to give a stable layer consisting of oxygen-containing hydrocarbon species. Ethynylbenzene itself does not oxidize under the deposition conditions indicating that the gold surface facilitates the oxidation process. Calculations show that ethynylbenzene and its oxidation products phenylacetic acid and phenyloxirane have positive binding energies to the gold surface. 1,4-Diethynylbenzene also binds to Au(111) and anchors gold nanoparticles deposited from solution to form dense, semiregular arrays.     

Solvent effects on the kinetics of gelation and the crosslink density of polysiloxane gels

A wide range of hydrocarbons were rapidly gelled by adding a polysiloxane copolymer in the presence of divinylbenzene and a platinum catalyst. The gel point was measured over a range of concentrations for hydrocarbons/solvents and organogels, using three separate methods: rheology, visual (tilt-tube) and FTIR. As the fraction of solvent was increased, the rate of reaction decreased, leading to an increase in the gelation time. The absolute value of the gel point depends upon the techniques used to measure it. For any particular system the gel point values always followed the order: rheology > visual > FTIR. The crosslink densities of the gel systems were determined using both swelling and thermomechanical analysis. The swelling measurements confirmed that the addition of large quantities of solvent markedly reduced the crosslink density of the obtained chemical gel networks, which helped in designing gels with suitable critical strength for effective field work. Also the effectiveness of gelation with the proposed gelling system for different hydrocarbons/solvents was evaluated, and discussed in relation to their dielectric properties.This paper is dedicated to Mike Owen on occasion of his winning the DeBruyn medal, the first silicon chemist to do so.     

Deposition characteristics of γ-ureidopropyltrimethoxysilane onto E-glass fibres using toluene and carbon tetrachloride as carrier solvents

Industrial grade γ-ureidopropyltrimethoxysilane was adsorbed onto industrial grade E-glass fibres from toluene and carbon tetrachloride at 23 °C. The treated surfaces were characterised using thermogravimetry, diffuse reflectance Fourier transform IR spectroscopy, electron spectroscopy for chemical analysis, scanning electron microscopy and the zeta potential. When ureidosilane was deposited from toluene and CCl₄, both of which have very low hydrogen-bonding ability, a ureido surface was obtained. The ureidosilane deposited from CCl₄ hydrolysed at the surface and condensed to form a solvent-swollen Si–O–Si network. The ureidosilane deposited from toluene also hydrolysed at the E-glass surface. Condensation of the silane deposited from toluene was not apparent. Aluminium dissolved from the E-glass surface was condensed into the network of the silane deposited from CCl₄. Aluminium was not detected at the surface of the samples with ureidosilane deposited from toluene. Received: 10 November 2000 Accepted: 23 March 2001     

The effect of gas environment on rolling oil removal from cold-rolled steel as studied by TG

Summary This study investigates mechanisms of cold rolling oil removal from the surface of low-carbon steel. The removal process has been probed using thermogravimetric analysis techniques. A range of furnace atmospheres, from non-oxidizing through to highly oxidising, have been used to simulate the oil removal conditions in the industrial process. The activation energies of oil removal under each gas atmosphere have been determined by MTG and the Flynn-Wall-Ozawa method. The results show that a reducing atmosphere is the optimal environment for effective oil removal. Steel-oil surface interactions have also been investigated to show that the steel substrate catalyses oil removal.     

Adsorption of an Isocyanurate Silane on E-Glass Fibers from Ethanol and Toluene

Isocyanurate silane was adsorbed onto E-glass fibers from toluene and ethanol in order to gain a better understanding of the surface processes at the silane-glass interface of composite materials. Use of DRIFT (diffuse reflectance infrared Fourier transform spectroscopy), XPS (X-ray photoelectron spectroscopy), and TGA (thermogravimetric analysis) techniques allowed for the qualitative and quantitative determination of such surface processes. The degree of chemisorption of the silane to the glass surface was investigated by using a sequential washing procedure with solvents characterized by solubility parameters differing from each other. All the analyzing techniques indicated that coupling between the glass and the silane occurred. However, the structure of the silane film depends considerably on the solvent and on the subsequent washing procedure. Copyright 2000 Academic Press.     

Polymer brushes on multiwalled carbon nanotubes by activators regenerated by electron transfer for atom transfer radical polymerization

The synthesis and characterization of multiwalled carbon nanotube (MWCNT) polymer brushes produced by activators regenerated by electron transfer (ARGET) in atom‐transfer radical polymerization (ATRP) was discussed. The polymer brushes were synthesized by esterification of the MWCNT carboxylic acid groups with hydroxyethyl‐2‐bromoisobutyrate and subsequently used in ARGET ATRP. This created a well defined living polymer brush carbon nanotube of comparatively low polydispersity and a polymer layer 10 nm thick. As, ARGET ATRP uses only minute concentrations of copper (II) catalyst, and is less sensitive to air compared to other living polymerization techniques, this process is a more industry‐compatible route for the commercialization of such materials. The structural and chemical properties were explored by a range of techniques including high resolution transmission electron microscopy, gel permeation chromatography, elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. In addition, the polymer brush nanotubes were explored for their potential use in films and as fillers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Matching Cure Characteristics of Automotive Rubber Compound and Polyurethane Coating

The present investigation focuses on matching cure characteristics of EPDM rubber compound and polyurethane (PU) coating using temperature modulated and pressure differential scanning calorimetry (TMDSC, PDSC). TMDSC provides a detailed and better understanding of the curing process of model rubber system as well as complex automotive rubber compounds. The low level of unsaturation present in EPDM, results in the small heat of vulcanization (2–5 J g^–1), which is difficult to accurately measure using conventional differential scanning calorimetry (DSC). Thus, curing of highly filled EPDM compound was investigated using TMDSC. The kinetics of PU curing was monitored using pressure DSC (PDSC), and heat of curing was determined as 4.2 J g^–1 at 10°C min^–1 heating rate. It is found that complex automotive compounds and the PU coating are curing simultaneously. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis and characterization of an isocyanate functionalized polyhedral oligosilsesquioxane and the subsequent formation of an organic-inorganic hybrid polyurethane

Organic-inorganic hybrids are an important class of new materials that offer improved thermal and mechanical properties over normal polymers. They may be produced by either the sol-gel route or through the use of inorganic compounds possessing reactive functional groups. Polyhedral oligosilsesquioxanes (POSS) are completely defined molecules of nanoscale dimensions that may be functionalized with reactive groups suitable for the synthesis of new organic-inorganic hybrids. Here we report the synthesis and characterization of a novel POSS possessing eight isocyanate groups via the hydrosilylation of octakis(hydridodimethylsiloxy)octasilsesquioxane (Q8M8H) and m-isopropenyl-alpha,alpha'-dimethylbenzyl isocyanate (m-TMI). The suitability of this new macromer to the synthesis of a organic-hybrids has been explored by forming a new type of highly cross-linked polyurethane elastomer via reaction of the macromer with poly(ethylene glycol) using dibutyltin dilaurate catalyst.