bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some aspects of polymer pyrolysis
Authors: Zaikov G. E. , Aseeva R. M. 
Published: March 2011

AbstractPyrolysis is the important stage of polymer combustion. This process depends on molecular and submolecular structure of polymer as well as conditions of heat affect. It may be realized through the formation of nonvolatile carbonized product. The basic conception of the present work consists in the transformation of macromolecules into carbonized structure which realises by means of formation of the thermodynamically‐advantageous intermediate compounds with a system of π‐conjugated unsaturated carbon bonds (acyclic or aromatic nature) and by their following conversion into condensed aromatic structures.It has been examined the correlation between the structure and properties of carbonized products and the flammability of polymers.
Flame retardant chemical mechanisms of flame retardant viscose fibres and blends with polyester
Authors: Nousiainen Pertti , Heidari Shahram 
Published: March 2011

AbstractA systematic investigation of structurally identical flame retardant viscose, modal and polyester blended fabrics and fibres was carried out in order to develop a chemical basis for more effective products based on organic and inorganic flame retardants. The oxygen indices and chemical compositions of phosphorus‐nitrogen flame retardants (P‐N) were used in efficiency and synergy evaluations. A new flame retardant viscose fibre containing silicid acid was included in the comparative evaluation procedure. Thermal gravimetry and X‐ray diffractometry were used for determine physical factors during pyrolyzing of fibres. Charred residues were analyzed by applying elementary and solid 13‐C NMR (CPMAS) spectrometry. The pyrolysis gas‐liquid chromatographer connected with a gas phase FT infrared spectrometer was applied to identify the decomposition products of P‐N‐containing fabrics.
Mechanistic aspects of intumescent fire retardant systems
Authors: Camino G. , Costa L. , Luda M. P. 
Published: March 2011

AbstractThe mechanism of intumescence is studied in mixtures of ammonium polyphosphate (APP) with several polycondensates as a part of a systematic study of intumescent fire retardants. It is shown that APP reacts on heating with the polycondensate to form a precursor of the intumescent char which is obtained on further heating. The introduction of the intumescent system in polypropylene does not modify the structure of the char formed on heating. However, the polymer modifies the foaming behaviour of the system. The thermal decomposition of the char occurs with volatilisation of phosphorus moieties and formation of a relatively thermally stable residue. Effects of the thermal behaviour of the char, on fire retardance, are discussed.
Thermoanalytical studies of intumescent systems
Authors: P. Taylor Andrew , R. Sale Frank 
Published: March 2011

AbstractFire retardant intumescent coatings which produce a swollen char on heating are being frequently used to protect buildings containing structural steel from the effects of exposure to high temperatures caused by fire. This paper contains details of a study carried out using thermal analysis techniques to elucidate the mechanisms of the development of intumescent chars during the heating of an intumescent coating system based on ammonium polyphosphate, pentaerythritol and melamine. In particular, the role of melamine as the spumific agent has been studied. The melamine is shown to react chemically with the ammonium polyphosphate in addition to carrying out its role as the spumific, or blowing agent.
The use of thermographic technique in the evaluation of polymers combustion and fire retardants performance
Authors: Bertelli G. , Benassi R. , Marchini R. , Camino G. , Costa L. , Luda M. P. 
Published: March 2011

AbstractThe combustion behaviour of polymeric materials either fire retarded or not, burning in the Glow Wire and UL 94 tests, was characterised by means of thermography. It is shown that the distribution of temperatures in the gas and condensed phase of the burning specimen thus recorded, supplies fundamental complementary information for the characterisation of the combustion process.
The chemistry of smoke suppression in polyurethane foams using thermogravimetry‐infrared residue analysis
Authors: Anthony Geoffrey M. 
Published: March 2011

AbstractThe analysis of TG residues using FT‐IR has shown that at 270°C. pyromellitate esters can react with aromatic amines formed from polyurethane foam degradation to form a pyromellitimide structure. This stabilises the main smoke and toxic gas precursors formed during combustion.
Practical aspects of modeling ignition and burning of organic polymers 1. The case of PE loaded with mixtures of Al (OH)3 and Hg(OH)2 or MgCO3
Authors: Rychlý Jozef , Búcsi Alexander , Csomorová Katar ína , Rychlá Lyda , Šimúnková Dagmar 
Published: March 2011

AbstractA correlation has been found between limiting oxygen index and tendency towards decomposition into volatiles as determined from nonisothermal thermogravimetry for polyethylene charged with the mixtures of Al(OH)3 and Mg(OH)2 or MgCO3. An interpretation based on the model of ignition and burning of polymers has been put forward and a dependence of heat transfer coefficient on temperature of ignition and initial mass of sample was found.
Fire retardants and fire safety how can tests reflect reality?
Authors: Becker Wolfram 
Published: March 2011

AbstractIn the standard test methods, the thermal action proceeds even today in most cases under the conditions of the well ventilated fire. The intensity of the thermal action varies widely, however, depending on the designed safety level. In the last few years, the outstanding purpose was to test the behaviour of products under the action of fire, in particular the time to the flash‐over. The intensity of the fire action rises accordingly, despite the possibility of further free ventilation, to such a degree that the test conditions in laboratory processes can reflect reality only under certain conditions.This philosophy is drawn from the results of statistical investigations in the U.S. is that the time to the flash‐over in a room is equal to the time to untenability, because most of the victims of the fire were not present in the room where the fire broke out. Test methods on a real scale that serve this designed safety level will therefore have to work with the high fire action on the products to be tested.In contrast, however, in some European countries the philosophy underlying the adoption of designed safety levels is that the main purpose is to protect human beings who are present in the room where the fire breaks out. According to this philosophy, a fire development that threatens to become dangerous must always be prevented. Consequently, interest is focused mainly on restricting the spread of fire and thus preventing a flash‐over. The test methods to be designed with this purpose in view should, therefore, simulate the conditions of the starting fire or the developing fire. The efficiency of a fire retardant can then be evaluated according to whether the fire spread is restricted or not. Under these conditions, the question of the time to be flash‐over is of no significance.With standard tests, it is impossible to make a statement as to how far the fire safety of products can be improved by the use of fire retardants unless the safety‐relevant range of application for the test method has been defined.
Thermal and flammability behaviour of copolymers of N‐(2, 4, 6‐tribromophenyl)maleimide with some acrylates
Authors: Janović Zvonimir , Malavašić Tatjana , Sarić Karla 
Published: March 2011

AbstractThe copolymers of N‐(2, 4, 6‐tribromophenyl)maleimide (TBPMI) with methyl acrylate, methyl methacrylate and acrylonitrile of different composition were prepared by free radical polymerization at low conversion. Their thermal behaviour was established by TGA measurements in helium atmosphere and flammability properties were determined by limiting oxygen index method. The higher TBPMI content in the copolymer led to a higher thermal stability and lower flammability particularly when Sb2O3 was used as a synergist.
The use of fluorinated additives in fire retardance of polymers
Authors: Roma P. , Luda M. P. , Camino G. 
Published: March 2011

AbstractPolytetrafluoroethylene (PTFE) is shown to improve fire retardance characteristics of brominated compounds/antimony trioxide systems added to polymers burning with or without dripping, as for example high‐impact polystyrene or acrylonitrilebutadiene‐styrene terpolymer, respectively. The action of PTFE seems to be the reduction of intrinsic flammability of the material as shown by parallel improvement of Underwriters Laboratories (UL94) tests and oxygen index parameters. A mechanistic interpretation is tentatively proposed which takes into account the very high effectiveness of PTFE.
Mechanisms of fire retardance in glass fibre polymer composites
Authors: Casu A. , Camino G. , Luda M. P. , De Giorgi M. 
Published: March 2011

AbstractIt is shown that the introduction of glass fibres in the poly(butylene terephthalate) (PBT) matrix, increases its flammability. The mechanism of action of a typical fire retardant for PBT which is a mixture of a brominated organic compound and antimony trioxide, seems to involve both the condensed and the gas phase.
Opportunities and threats in polymer based materials science and technology
Authors: Clark David T. 
Published: March 2011

AbstractDespite the fact that materials research has completed an innovative and exciting decade from a fundamental science perspective, the fact remains that at the exploitation stage commercial returns on the R&T Investment made by large companies has been poor. In this article we look at one such company's experience; at the general challenge of maintaining a strategic research capability in the face of drastic business reorganisation and address some of the interesting challenges and threats for the polymer community (in academe and industry) over the next decade.
Surface phenomena at polymers
Authors: Jacobasch Hans‐Jörg 
Published: March 2011

AbstractPolymers with advanced properties can be achieved among other measures by reinforcing with fibrous materials, by polymer blending and surface modification. Using the surface treatment of PP‐EPDM injection moulding specimens (washing, flaming, plasma‐treatment) an overview on progress in surface analytics is given. It is shown that XPS, contact angle and zeta‐potential measurements give corresponding results concerning the composition of the surface region.Additional to the kind of interaction forces at interfaces the mechanical properties of reinforced polymers are governed by sorption layers and electrical phenomena at interfaces. Corresponding results were obtained at chalk filled PE‐HD and glass fibre reinforced polyamide.
Specialty and advanced polymers by carbocationic macromolecular engineering
Authors: Iván Béla 
Published: March 2011

AbstractThis study briefly surveys a variety of new advanced polymeric materials and controlled synthetic processes available by carbocationic macromolecular engineering techniques and having potential commercial interest. These recent developments, mainly by living carbocationic polymerization, have led to new opportunities in polymerization process control, and in designing microstructure, functionality, molecular weight and molecular weight distribution (MWD) and thus properties of a wide variety of unique polymer systems. The fundamentals of these new emerging technologies and the novel materials offered by them, such as macromonomers, telechelics, polymers with pendant functional groups (liquid crystalline homo‐ and co‐polymers, non‐linear optical materials etc.), star‐shaped macromolecules, block and graft copolymers, high temperature polymers, and specialty networks (amphiphilic networks and rubber toughened bone cements) as potential biomaterials will be overviewed.
Synthesis of copolyesters via interchange reactions with polypivalolactone
Authors: Tijsma Edze Jan , van Der Does Leen , Bantjes Adriaan , Vulić Ivan , Buning Gerard Hidde Werumeus 
Published: March 2011

AbstractThe synthesis of copolyesters via interchange reactions of polypivalolactone (PPVL) with bisphenol‐A polycarbonate (PC) and dimethyl terephthalate (DMT) was studied. Random copolyesters with high thermal stability were obtained by heating PPVL with PC and DMT in the melt at 280 °C in the presence of tetrabutylorthotitanate (TnBT) as a catalyst. Results from SEC measurements showed that the values for Mn of these copolyesters ranged from 7,000 to 16,000. The process for preparing these copolyesters was studied in detail and based on the results of these studies, the reactions occurring during copolyester synthesis were discussed. It was found that in the early stages of the process mainly interchange reactions occurred between PPVL and PC chains, whereas the amount of terephthalate units increased only after longer reaction times.
Reactive blending of polypivalolactone with polycarbonate
Authors: Tijsma Edze Jan , van Der Does Leen , Bantjes Adriaan , Vulić Ivan , Buning Gerard Hidde Werumeus 
Published: March 2011

AbstractBlends of polypivalolactone (PPVL) with bisphenol‐A polycarbonate (PC) were studied. Physical PPVL/PC blends showed one Tg close to the Tg of 145 °C for PC, indicating immiscibility. Reactive blending of PPVL and PC with 0.5 wt.‐% tetrabutylorthotitanate was performed in diphenyl ether (260 °C) and in a twin screw extruder (TSE) at 280 °C. Based on the results from NMR, FT‐IR and thermal analysis, it was concluded that interchange reactions had occurred. The thermal properties indicated that, due to these interchange reactions, PPVL/PC blends had become more miscible. Although blending in a TSE was more efficient with respect to interchange reactions compared with blending in diphenyl ether, complete randomization was not observed.
Polyacrylamide–graft–poly(ethylene oxide)
Authors: De Vos S. C. , Möller M. 
Published: March 2011

AbstractWater‐soluble graft copolymers were synthesized by copolymerization of acrylamide with mono‐methoxy‐poly(ethylene oxide)‐methacrylates (Me‐PEO‐MA). The Me‐PEO‐MA macromers were synthesized by a catalytic esterification of methacrylic acid with mono‐methoxy‐poly(ethylene glycol)s with different molecular weights. The graft copolymers obtained were characterized by 1H‐NMR spectroscopy, gel permeation chromatography (GPC) and Ubbelohde viscosimetry. The rheological behaviour of aqueous polymer solutions, which are expected to show hydrophobic association at elevated temperatures, was studied with a cone and plate‐rheometer.
A program generator for describing copolymerization and network formation in step reactions
Authors: Tiemersma‐Thoone G.P.J.M. , Scholtens B. J. R. , Braam A. W. M. 
Published: March 2011

AbstractA multi‐purpose computer program has been developed for describing copolymerization and network formation in step reactions. It operates at two hierarchical levels: a generation level and an application level. At the generation level, the class of problems is defined and prepared, and this information is used to generate automatically a problem‐specific program based on generalized concepts of the branching theory. At the application level, the problem‐specific program can be used for model calculations with all possible variations in recipes and kinetic parameters within the boundaries of the specific class of processes concerned.
Mechanical and stress‐optical properties of strongly swollen hydrogels
Authors: Schröder U. P. , Oppermann W. 
Published: March 2011

AbstractCrosslinked polyelectrolytes exhibit extreme swelling in aqueous systems; fluid uptake usually amounts to 100 to 1000 times of their dry volume. The mechanical and stress‐optical properties of such highly swollen gels show some peculiarities because the network chains are stretched far beyond the Gaussian limit. The shear modulus increases markedly at high degrees of swelling, and the stress‐optical coefficient decreases.A quantitative treatment has to be based on non‐Gaussian chain statistics. In order to provide experimental data, stress‐optical and modulus measurements were carried out on hydrogels made from partially hydrolyzed poly‐(acrylamide) and other polyelectrolytes. The degree of swelling was adjusted by using aqueous NaCl‐solutions of different concentration as the swelling medium. Using a description based on the inverse Langevin function, the course of the shear modulus on the degree of swelling can be fitted to the experimental data. The optical modulus, n/(λ2‐λ−1), is predicted with somewhat less agreement. However, a different set of parameters has to be used for the mechanical and optical properties. This shows that the treatment is not fully consistent.
The viscoelastic behaviour of elastin in aqueous ethylene glycol
Authors: Lillie M. A. , Gosline J. M. 
Published: March 2011

AbstractThe viscoelastic behaviour of arterial elastin in aqueous ethylene glycol has been studied to compare the effects of two solvents of differing polarity. The behaviour of elastin in low concentrations of ethylene glycol was similar to that of elastin that had been indirectly dehydrated using polyethylene glycol as an osmotic agent. That is, at low concentrations the dominant effect of ethylene glycol was to reduce the activity of the water molecules. However, at high concentrations, ethylene glycol appeared to interact directly with the elastin, altering both the swelling and the viscoelastic behaviour of the network.
Circular dichroism of aqueous solutions and gels of partial benzyl esters of the polysaccharide gellan
Authors: Crescenzi Vittorio , Dentini Mariella , Maschio Sergio , Segatori Maurizio 
Published: March 2011

AbstractThree partial benzyl esters of gellan have been studied by means of circular dichroism spectroscopy in aqueous tetramethylammonium chloride solution and in the gel state (aqueous NaCl). Thermal stability of the solution ordered chain states as well as of the gels, maximal in the case of gellan, markedly decreases with increasing degree of esterification.
Contribution of entanglements to the modulus of end‐linked poly(ethylene oxide) networks
Authors: Larsson Iben , Kramer Ole 
Published: March 2011

AbstractPoly(ethylene oxide) networks were made at 75 °C by end‐linking of short linear chains with an excess of Tolonate HDT, a tri‐functional aliphatic isocyanate. Molecular weights of poly(ethylene oxide)were 4000, 6000 and 12000. The observed elastic moduli were much higher than predicted from affine theory, indicating a large contribution from entanglements in contrast to the findings of previous studies. With increasing excess of cross‐linker, the contribution from entanglements levels off at a value of approximately 5 MPa which is in good agreement with the rubber plateau modulus of pure poly(ethylene oxide).
Studies on the solution behaviour of self‐assembling polymeric systems
Authors: Stock Jochen , Stadler Reimund 
Published: March 2011

AbstractFunctional groups were attached to styrene‐butadiene copolymers with different polymeric architectures and a low molecular weight compound. These polar stickers form binary, chelate‐like contacts or extended juntion zones depending on their chemical nature. The solution properties of these amphiphilic species in toluene were studied by static light scattering.
Structure of filled rubbers and mechanism of reinforcement
Authors: Strauß Michael , Pieper Thomas , Peng Weiguo , Kilian Hanns‐Georg 
Published: March 2011

AbstractIt will be shown that a consequent modelling of filler‐to‐filler and filler‐to‐matrix contacts and of individual slippage processes allows to describe the mechanical deformation behaviour of rubbers filled with rigid filler particles. The phenomenon of reinforcement turns out to be due to non‐Gaussian rubber elasticity (van der Waals network). Surprisingly, there are universal aspects which characterize the fractal structure in the composite as well as the processes under large strain. Moreover it is possible to deduce the atomic distance distribution in the adhesional layers from WAXS‐measurements. Together with a description of the WAXS‐pattern of pure graphitized and degraphitized carbon blacks some new aspects of the conditions to maximize the filler‐to‐matrix adhesion will be discussed.
Dielectric cure characterization of model elastomers
Authors: Xu Xiaofeng , Galiatsatos Vassilios 
Published: March 2011

AbstractIsothermal dielectric properties of poly(dimethylsiloxane) (PDMS) networks during cure were studied at room temperature with emphasis on the effect of catalyst concentration. The frequency range employed was 10−1 to 105 Hz. The dielectric response is sensitive to a change in catalyst levels as this was evidenced by the change in the values of the logarithm of the loss factor log ϵ”. We attribute these changes to dipolar and ionic contributions. A profile of the cure reaction of model elastomers may readily be obtained by using a combination of microsensors and time‐domain dielectric spectroscopy. The results obtained show that the catalyst concentration affects both crosslinking and chain extension reactions. However, for the typical catalyst concentration at which typical networks are prepared, the crosslinking reaction is the dominant effect.
Quasi‐elastic neutron scattering in gels and solutions
Authors: Geissler Erik , Hecht Anne‐Marie , Guillermo Armel , Horkay Ferenc , Legrand Jean François , Mallam Simon 
Published: March 2011

AbstractMeasurements of swelling pressure, neutron spin‐echo scattering, and dynamic light scattering were made in an end‐linked poly(dimethylsiloxane) (PDMS) gel swollen to equilibrium in a good solvent (toluene) and also in the equivalent solution. The macroscopic osmotic modulus is depressed in the gel. Neutron spin echo observations at intermediate and high values of the scattering vector Q reveal that the mobility of the monomers is unaffected by cross‐linking. Elastic neutron scattering at small Q detects non‐uniformities in the polymer concentration distribution, which are absent from the solution. These non‐uniformities play a major role in the dynamic response of the system at lower Q, and and appear to be the cause of the observed reduction in osmotic pressure.
Chemical pattern formation in gels
Authors: Kárpáti‐Smidróczki éva , Büki András , Zrínyi Miklós 
Published: March 2011

AbstractPrecipitate forming chemical reactions have been studied in chemically crosslinked poly(vinyl alcohol) gel medium. One of the reactive components was incorporated into the gel, the other was allowed to diffuse into the swollen network. This reaction‐diffusion process often results in pattern formation which can occur intermittently in terms of time and space or both. Experiments were carried out in order to investigate the effect of various factors (crosslinking density, swelling degree as well as the concentrations of the outer and inner electrolyte). The following precipitates were intensively studied: Mg(OH)2, Cr(OH)3, PbCl2. Three basically different morphologies (Liesegang band formation, moving bands and tree‐like structure) have been observed and investigated. One‐ and twodimensional computer simulations were carried out in order to establish the influence of various factors on the precipitation.