Interactions between chlorinated paraffins and melamine in intumescent paint—investing a way to suppress chlorinated paraffins from the formulations

It is known that acid source, carbon source and blowing agent are the main ingredients of an intumescent paint. Melamine and halogenated additives, such as polychlorinated alkanes (PCAs) are used as blowing agents, however, the legislation tends to prohibit the use of halogenated coumpounds for environmental reasons. The aim of our study is to investigate the mode of action of melamine and PCAs in an intumescent formulation. Their interactions are also studied. It is found that the combination of PCAs and melamine leads to more efficient systems. Spectroscopic analyses (FTIR and solid state ¹³C NMR) led us to conclude that when the intumescent paint was heated melamine condensed to create melem via Diels-Alder-type reaction. Melem could then react with PCAs leading to the stabilisation of the PCA-melamine mixture. The proposed mechanism of action led us to propose a method for the substitution of PCAs.     

Mineral Fillers in Intumescent Fire Retardant Formulations — Criteria for the Choice of a Natural Clay Filler for the Ammonium Polyphosphate/Pentaerythritol/Polypropylene System

Addition of natural clay materials in intumescent polypropylene-based formulations (additive: ammonium polyphosphate and pentaerythritol) leads either to a decrease or to an increase of their fire retardant performances versus the chemical or the physical characteristics of the clay materials. A study of the factors affecting these performances has been carried out using linear and principal components analysis. This analysis shows that the results of the evaluation tests (LOI and UL 94) are affected in different ways by the adduct of the different clay material and that an increase in the LOI is not necessarily related to an increase in the UL 94 classification. LOI values are improved by the presence of the montmorillonite and of illite clay minerals which may react with acidic phosphate to form active carbonization catelysts, in addition, the results of the LOI test are improved by the presence of quartz and other foreign minerals in the clay materials. This study discusses the part played by the different constitutive minerals in the formation of defects in the polymer chain during the mixing process. It is proposed that the presence of these defects leads to a change in fire retardant performance.     

High throughput methods for polymer nanocomposites research: Extrusion, NMR characterization and flammability property screening

A large number of parameters influence polymer-nanocomposite performance and developing a detailed understanding of these materials involves investigation of a large volume of the associated multi-dimensional property space. This multi-dimensional parameter space for polymer-nanocomposites consists of the obvious list of different material types under consideration, such as polymer and nano-additive, but also includes interphase surface chemistry, and processing conditions. This article presents combinatorial library design and high-throughput screening methods for polymer nanocomposites intended as flame-resistant materials. Here, we present the results of using a twin-screwn extruder to create composition-gradient library strips of polymer nanocomposites that are screened with a solid-state NMR method to rapidly evaluate the optimal processing conditions for achieving nanocomposite dispersion. In addition, we present a comparison of a new rapid Cone calorimetry method to conventional Cone calorimetry and to the gradient heat-flux flame spread method.     

Characterisation and reaction to fire of “M5” rigid rod polymer fibres

In this work, the flammability properties of a new rigid rod polymer fibre are examined. This new fibre was called M5 and is formally poly[2,6-diimidazo[4,5-b:4,5-e]- pyridinylene–1,4(2,5-dihydroxy)phenylene or PIPD. In a first step, characterisation of PIPD (M5) by solid state NMR confirms the chemical composition of the fibre. The investigation of the fire performance of M5 fibers using the cone calorimeter has shown the excellent behaviour of M5 in comparison with poly-p-phenylenediamine-terephtalamide (PPTA). M5 fibre does not burn even in very severe conditions (flashover conditions). It can then be used where high level of safety is required. The investigation of its heat resistance shows that M5 degrades via exothermic reactions of 30% lower energy than PPTA and have a strong pyrolysis resistance which can explain, in part, its unique fire properties.     

Membranes as pretreatment to desalination in wastewater reuse

This article looks at the benefits of wastewater reuse for industrial and municipal applications. It demonstrates how continuous microfiltration pretreatment to reverse osmosis can reduce capital and operating costs of reverse osmosis systems, improve their efficiency and enable reliable operation on a wider variety of water sources. This information is supported by operational data from a number of continuous microfiltration/reverse osmosis installations worldwide on difficult-to-treat feed waters.     

Salt wastage, plasma volume contraction and hypokalemic paralysis in self-induced water intoxication

Eleven episodes of severe hyponatremia secondary to hiccup-induced potomania were recorded in 3 years in a man who had essential hypertension, a low protein intake and a normal diluting ability. Paradoxical increase in hematocrit and plasma protein with acute extensive natriuresis was associated as well as urine potassium loss and hypokalemia producing paralysis in 1 episode. During a chronic water loading test, the defect in water excretion was related to a low urine solute delivery which was partially reverted by the natriuretic response to plasma volume expansion, promoting water diuresis. In acute water intoxication, this natriuretic response was exaggerated, producing a brisk water diuresis. Plasma volume was rapidly normalized but without any improvement in plasma sodium due to the concomitant negative sodium balance. Thus, water diuresis persisted until plasma volume was significantly contracted. Potassium loss appeared to be related to sodium excretion. Metabolic disturbances have not reoccurred despite persistent hiccup and potomania during 2 years of urea therapy.     

Thermal degradation of poly(p‐phenylenebenzobisoxazole) and poly(p‐phenylenediamine terephthalamide) fibres

This study investigates the thermal stability of poly(p‐phenylenediamine‐terephtalamide) (PPT) and poly(p‐phenylenebenzobisoxazole) (PBO) fibres. Excellent behaviour of PBO is shown in comparison to that of PPT. The thermal stability (under pyrolytic or thermo‐oxidative conditions) of PBO is 150 °C higher than that of PPT. Moreover, the strong influence of oxygen, which plays the role of an initiator of degradation, on the degradation of fibres is shown. Using the invariant kinetic parameter (IKP) method, it is shown that the degradation rate of PBO is strongly reduced in comparison with that of PPT. It provides a simulation of the ‘fuel flow’ able to feed the flames, which can explain the high fire performance of PBO compared to PPT. © 2001 Society of Chemical Industry     

Chitosan-grafted nonwoven geotextile for heavy metals sorption in sediments

Functionalized polypropylene nonwoven (PP) geotextiles can be used as a new eco-friendly way to trap heavy metals in sediments. Chitosan was chosen as sorbent because of its ability to trap heavy metals, its natural origin (from shells) and its low cost. PP was first functionalized with acrylic acid using a low pressure cold plasma process, in order to bring reactive carboxylic functions onto the surface. Chitosan was then covalently grafted on the acrylic acid modified PP. The functionalized surfaces were characterized by Fourier Transform Infrared Spectroscopy–Attenuated Total Reflectance (FTIR–ATR) and X-ray Photoelectron Spectroscopy (XPS) and evidence of chitosan grafting was given. The ability of the functionalized geotextile to trap heavy metals was then investigated. Copper was chosen as a model heavy metal, and artificial solutions of CuSO₄ were prepared for the experiments. Sorption studies were carried out at 20 °C with Polypropylene-grafted-Acrylic acid-Chitosan (PP-g-AA-chitosan) varying the concentration of copper in polluted solutions to evaluate the maximum of adsorption of the surface: the textile can chelate copper increasingly as a function of the initial copper concentration until 830 ppm. At this concentration, it reaches a plateau at about 30 mg of trapped copper per gram of geotextile. The effects of pH and of the ionic strength (adsorption in a NaCl containing solution) were finally investigated. The trapping of Cu²⁺ decreases slowly when the ionic strength increases. When there are 30 g/L NaCl in the artificial polluted solution (like in seawater), only 20 mg of Cu²⁺ can be trapped per g of geotextile. Finally, the optimum pH to trap the maximum amount of copper was determined to be 4.8, which corresponds to the optimum pH for the chitosan solubility.     

Nonwoven as heat barrier: Modeling of the efficiency of Carbtex fibers

In this work, we examine the use of nonwoven (NW) as heat barrier to protect a metallic substrate. Carbtex fibers consisting in a thermoplastic core inside an oxidized outer shell (polyacrylonitrile or PAN fibers) are selected to make the NW. Measuring temperature profiles in a heat radiator test; it is revealed that Carbtex NW is an efficient heat barrier. A macroscopic model is then developed to simulate heat transfer in NW (considered as a porous medium) used as a protective heat barrier on aluminum plate. The model is validated comparing experimental results obtained by the heat radiator test and predicted values. The efficiency of NW layer is simulated varying different parameters characteristic of the NW (porosity and heat conductivity) and of the design (thickness of the layer). It is revealed to get good efficiency of the NW heat barrier that heat conductivity of the fibers is crucial to get superior performance as well as high porosity (higher than 0.5) associated with a reasonable thickness of NW (5–7 mm). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008