bluuebunny/crossref_metadata_2025 huggingface dataset:
Material characterization in liquid composite molding
Authors: Lee L. James
Published: March 2011

This article reviewed the current knowledge of material characterization in liquid composite molding. Kinetic analysis and modeling of resins, rheological changes and modeling of resins, and the methods to determine permeabilities of fabric reinforcement are presented.
A flexible simulation code for microwave curing of polymers
Authors: Acierno D. , Masi P. , Pierro V. , Pinto I. M.
Published: March 2011

We describe a modular simulation code for microwave curing of polymers. The exposed item geometry can be either 3D or 2D (extruded draw pieces), the item can be multi‐component and contain metal insertions as well. The applied microwave field can be either resonant or traveling wave, with or without mode‐stirring. The output of the code is in the form of cross‐linking degree and temperature maps. Utilities are included to input the problem's geometry and to display the outputs.
Prediction of rheological properties in polymer colloids
Authors: Mewis J. , Haene P. D'
Published: March 2011

The rheological properties of concentrated suspensions, containing sterically stabilized polymer colloids, are reviewed. It is shown that the various rheological characteristics are strongly interrelated in such systems. They deviate from Brownian hard sphere behaviour, but these deviations are closely related to the interparticle potential and other colloidal characteristics like particle diffusivity. As a result the rheological properties can be predicted from the colloidal characteristics and vice versa. This is demonstrated by means of available data on well characterized model dispersions. In the experiments volume fraction, particle size, suspending medium and temperature have been changed. Data reduction schemes and scaling laws for these parameters are discussed.
Crystallization kinetics in relation to polymer processing
Authors: Brucato V. , Piccarolo S. , Titomanlio G.
Published: March 2011

Phase distribution of quenched samples has been determined by a deconvolution procedure of WAXS spectra in a wide range of cooling rates. The informations collected together with isothermal and DSC results provide a very wide set of data on the crystallization kinetics of polymers relevant which covers conditions encountered in most polymer processing operations. They have been compared with predictions of a non‐isothermal crystallization model assuming two independent and parallel crystallization processes competing during solidification.
Morphology‐rheology relationships in incompatible blends based on thermotropic liquid crystalline polymers
Authors: Incarnato L. , Nobile M. R. , Acierno D.
Published: March 2011

In this paper the effect of the inclusion of two different thermotropic liquid crystal polymers (TLCP) on the processing of a polyetherimide (ULTEM 1000) is studied.
Chiral liquid crystalline polymers: Recent issues and perspectives
Authors: Chiellini Emo , Galli Giancarlo , Cioni Fabio , Dossi Eleftheria
Published: March 2011

The syntheses and structures of chiral liquid crystalline polymers (LCPs) are briefly reviewed with emphasis on the established structure‐property correlations. The most recent advances and future trends in their potential applications in optics and electrooptics are also outlined, with particular reference to the ferroelectric, electroclinic, piezoelectric, and nonlinear optical properties of chiral LCPs.
Orientation of crystalline polymers by non‐classical means
Authors: Lotz Bernard , Wittmann Jean‐Claude
Published: March 2011

Crystalline polymers can be oriented by epitaxy on various substrates, including low molecular weight, usually aromatic compounds and polymers oriented by epitaxy and by mechanical means (strain induced polyolefin films and friction‐deposited PTFE layers). The resulting oriented films are thin, but display unusual morphologies with lamellae standing edge‐on and, often, single crystal structure. They are adequate investigation materials for structure determination, show enhanced or maximized orientation‐dependent properties, and may contribute to mechanical strengthening in composite polymer films.
Molecular modelling of melt rheology
Authors: Marrucci G.
Published: March 2011

The main assumptions and concepts used in molecular modelling of melt rheology are briefly reviewed. Because rheological phenomena take place over time scales which correspond to motions of large segments of the chains, models need only account for the long‐range structural aspects of the chain, while the local details of the chemical structure get lumped into a few adjustable parameters. The structural aspects which must be accounted for in a direct way are discussed, and a concise overview of the corresponding modelling is made.
Kinetics of network formation via free‐radical mechanisms — Polymerization and polymer modification
Authors: Zhu S. , Hamielec A.E.
Published: March 2011

The study of polymeric networks synthesized via free‐radical polymerization and/or prepolymer modification have become an attractive research area of both fundamental and commercial interest. Recently, a research/development program was initiated to investigate the fundamentals and applications of polymer networks. The following aspects are being emphasized: the elucidation of crosslinking mechanisms and kinetics, the characterization of network microstructures, and the development of kinetic gelation models. This paper reports recent activities towards these goals.
Linear‐temperature programmed pyrolysis of thermoresistant polymers ‐ mass and FTIR spectrometries I. Experimental; aromatic polyethers and polyetherketones
Authors: Hummel Dieter O. , Neuhoff Ulrich , Bretz Anke , Düssel Heinz‐Jürgen
Published: March 2011

During thermal decomposition, most of the thermo‐resistant polymers leave a considerable fraction of the original mass behind, consisting mainly of a carbonaceous material. The gases evolved are, to the largest part, low‐molecular (H2O, CO2, CO, NH3, HCN, hydrocarbons); they are formed during polycondensation processes. The rate of heating strongly influences the degradation mechanism and thus the composition of the gaseous pyrolyzate. Rapid heating i.v. to the maximum temperature chosen frequently favors the formation of heavy fragments. These can be identified by field‐ionization or low‐voltage mass spectrometry; they usually allow conclusions on the composition of the original polymer.

Slow, temperature‐controlled heating allows rearrangement and polycondensation reactions in the polymer. A study of the processes going on in the residue during temperature‐controlled heating is important with regard to the behavior of thermoresistant polymers under real conditions.

An elegant method of continuous residue analysis is FTIR spectrometry. A heatable IR cell designed in our institute allows the study of both gaseous pyrolyzate and solid residue in separate experiments. The time needed for the measurement of one spectrum (from 20 scans) was 36 s. This, with a heating rate of 5 K/min, corresponds to a temperature resolution of 3 K/spectrum.

Results are given for aromatic polyethers and polyetherketones.
Submolecular dynamics of amorphous polymers probed by two‐dimensional infrared (2D IR) spectroscopy
Authors: Noda Isao , Dowrey A. E. , Marcott C.
Published: March 2011

Two‐dimensional infrared (2D IR) spectroscopy was used to probe the submolecular dynamics of atactic polystyrene. 2D IR is a powerful analytical technique especially suited for the elucidation of localized motions of polymer segments. In 2D IR, a polymer sample is excited by a small‐amplitude oscillatory strain at a frequency in the acoustic range. The fluctuation of IR dichroism signals resulting from the strain‐induced reorientation of electric dipole‐transition moments is monitored with a time‐resolved spectrometer. Spectra defined by two independent wavenumber axes are constructed by applying a correlation analysis to such signals. The 2D spectra provide detailed information about the local dynamics of submolecular constituents of the system. From the sign of cross peaks in the synchronous 2D IR spectrum of glassy polystyrene, it is shown that the main‐chain backbone of polystyrene reorients in the direction of applied strain. Cross peaks in an asynchronous 2D IR spectrum reveal highly localized reorientational motions of phenyl side groups occurring more or less independently of the main‐chain realignment. In the glassy state, the phenyl ring tends to fold back along the main‐chain, indicating that there exists a highly constrained local distortion of side groups during deformation.
Micro‐Raman study of the transition front in uniaxially stretched semicrystalline polymers
Authors: Pastor J. M. , Jawhari T. , Merino J. C. , Fraile J.
Published: March 2011

The transition front of the neck between the isotropic and oriented region in uniaxially stretched polyvinylidene fluoride (PVDF) and polypropylene (PP) is analyzed with a high spatial resolution by micro‐Raman spectroscopy. The variation of the microstructure, i.e. change in the degree of crystalline modification in the case of PVDF and in the orientation of the PP chains in function of the strain rate, is correlated with other parameters associated with the drawing response of these polymers and the temperature rise during deformation. The results here described can be understood through the clear increase of temperature that was detected in the neck due to the heat generated by the deformation work of the drawing process.
NMR spectroscopy and relaxation studies on liquid‐crystalline side‐chain polysiloxanes
Authors: Hempel Günter , Wobst Matthias , Israel Gunter , Schneider Horst
Published: March 2011

Two polysiloxanes with mesogenic side chains were investigated with polarization microscopy, DSC, 1H and 13C NMR. From proton NMR the global order parameter of one sample (the other does not orient itself in the magnetic field of 2.1 T) and some information about phase transitions was obtained. 13C NMR yielded selective order parameters with respect to different atomic positions. The order parameter varies slightly also within the mesogenic unit, but much stronger within the spacer (odd‐even effect). With the help of T1ρ experiments some molecular motions had been detected and characterized (main‐chain motion, over‐head rotation of the mesogenic unit, methyl rotation, side‐chain rotation).
Rheo‐optical fourier‐transform infrared spectroscopy of polymers 16 orientation and strain‐induced conformational regularity of poly(dimethylsiloxane) networks during cyclic elongation and recovery
Authors: Besbes S. , Bokobza L. , Siesler H. W.
Published: March 2011

Two SiO2‐filled poly(dimethylsiloxane) networks with different molar masses Mc (22000 g/mol and 33000 g/mol) between the junctions have been investigated by simultaneous mechanical and Fourier‐transform infrared (FTIR) spectroscopic (rheo‐optical) measurements to monitor the structural changes in cyclic elongation‐recovery procedures. Higher polymer chain orientation was observed at corresponding elongations for the low‐Mc network, but due to the higher extensibility appreciable strain‐induced conformational regularity occurred only in the high‐Mc material. Differences with reference to unfilled model networks are pointed out.
Ring‐opening polymerization and copolymerization of cyclic carbonates with a variety of initiating systems
Authors: Höcker H. , Keul H. , Kühling S. , Hovestadt W. , Müller A. , Wurm B.
Published: March 2011

The ring‐opening polymerization of cyclic monomers is a field of long tradition. More recently, however, under the pressure to recycle polymers the generally undesired capability of ring‐closing depolymerization has gained a new aspect. As an example, the anionic ring‐opening polymerization of six‐membered cyclic carbonates is discussed, the alcoholate being the active species. The latter is also able to initiate the ring‐opening polymerization of lactones such as ϵ‐caprolactone and pivalolactone. On the other hand, monofunctional and bifunctional alcoholates of polytetrahydrofuran can be used as initiators for the anionic ring‐opening polymerization of cyclic carbonates to produce AB‐ and ABA‐block copolymers. The use of other initiators than alcoholates on the basis of Al, Zn, and Sn is discussed for both the polymerization and the depolymerization reaction.
High‐speed living ring‐opening polymerization by a new catalyst based on metalloporphyrin
Authors: Inoue Shohei , Aida Takuzo
Published: March 2011

Polymerization of ϵ‐caprolactone and δ‐valerolactone initiated with aluminum porphyrin (1) was much accelerated by the addition of methylaluminum diphenoxide with bulky substituents 2, to give polymers with narrow molecular weight distribution. The polymerization of β‐butyrolactone was also accelerated by 2, to different extents depending on the mode of ring scission. 2 also accelerated the living polymerization of propylene sulfide initiated with zinc porphyrin (3). The effect of 2 is due to the coordinative activation of monomer.
Some linear and branched macromolecules by ring‐opening polymerization
Authors: Schulz Rolf C.
Published: March 2011

In the first part the ring‐opening polymerization of some macrocyclic ether‐acetals is briefly described. Of special interest are acetal polymers with functional groups, for instance C=C‐double bonds. Appropriate unsaturated monomers and their polymerizability are discussed. The second part deals with the polymerization of oxazolines, substituted in 2‐ and/or 4‐position. Branched polymers are obtained by copolymerization of 2‐ethyl‐2‐oxazoline with 2‐hexyl‐2‐oxazoline or 2‐undecyl‐2‐oxazoline. The properties of the random copolymers and corresponding block copolymers are compared. By a “mixed mechanism technique” a block copolymer composed of a poly(tert ‐butyl methacrylate) block and a poly(phenyloxazoline) block was prepared.

A new initiator system for the polymerization of oxazolines using alkyl chloroformates is introduced. The chloroformate of a trifunctional alcohol led to a three‐arm star polymer. Telechelics with two chloroformate endgroups form ABA type block copolymers.

Finally four chiral oxazolines are described and the influence of substitution in dioxolanes and oxazolines on the polymerizability is discussed.
Synthesis and ionic polymerization of 1,2‐epoxy‐3‐nitropropane
Authors: Lagarde F. , Durand C. , Reibel L. , Franta E.
Published: March 2011

The synthesis of 1,2‐epoxy‐3‐nitropropane (ENP) was improved so that this monomer could be obtained in a pure, stable form with an acceptable yield.

Anionic polymerization even using milder conditions causes isomerization of ENP into nitroallylic alcohol.

Cationic polymerization using a classical initiator produces a mixture of compounds of low molecular weight.

We have studied in detail the cationic polymerization of ENP in the presence of a diol such as ethylene glycol (“Activated Monomer Mechanism”): only the first two steps follow this latter, but a competitive mechanism takes over rapidly which limits severely the molecular weight of the products: this mechanism was analyzed.
Synthesis of degradable copolymers by ring‐opening polymerization
Authors: Albertsson Ann‐Christine , Löfgren Anders , Sjöling Maria
Published: March 2011

Hydrolysable copolymers made from different cyclic monomers have been studied. The monomers involved are 1,5‐dioxepan‐2‐one (DXO), L‐dilactide, 1,3‐dioxan‐2‐one (TMC), oxepan‐2,7‐dione (AA) and oxepan‐2‐one (ϵ‐CL). The hydrolysis of the DXO/L‐dilactide copolymer showed great differences in degradation rate depending on composition. A statistical copolymer made from TMC and ϵ‐CL was amorphous with a glass transition temperature of −48°C. TMC and AA could form a blockcopolymer with n‐BuLi as initiator in toluene, 0°C.
Ring‐opening polymerization of strained cyclotetrasilanes as a new route towards well defined polysilylenes
Authors: Cypryk M. , Chrusciel J. , Fossum E. , Matyjaszewski K.
Published: March 2011

Ring‐opening polymerization of cyclic silanes is described as a new synthetic route to well defined high molecular weight polysilylenes (polysilanes). Strained cyclotetrasilanes with phenyl and methyl substituents at each Si atom in the four‐membered ring are prepared by partial dephenylation of octaphenylcyclotetrasilane with triflic acid and the subsequent treatment with methylmagnesium bromide. Chemoselectivity, regioselectivity and stereoselectivity of monomer synthesis is discussed in detail. In addition to classic anionic initiators for the ring‐opening process, new catalysts and initiators based on transition metals (Cu, Pd, Pt) are described. They provide much better control of the microstructure than systems with Li+ counterion.
Molecular conformation of optically active polyesters and their stereocomplexes
Authors: Prud'Homme Robert E. , Ritcey Anna M.
Published: March 2011

Crystal lattices for various polymorphs of poly(α‐methly‐α‐ethyl‐β‐propiolactone) (PMEPL) are proposed on the basis of combined electron and x‐ray diffraction data. Single crystal‐like electron diffraction is observed from melt crystallized thin films of isotactic PMEPL and stereocomplex. Melt‐crystallized isotactic PMEPL exhibits a monoclinic, pseudo orthorhombic lattice with the unit cell parameter c (4.75 Å) equivalent to the periodicity of the planar zigzag conformation typically obtained by sample elongation. The stereocomplex crystallizes in a distinctly different orthorhombic lattice with c = 7.1 Å, implying a 21 helical conformation. In addition, melt‐crystallized mixtures of isotactic PMEPL and isotactic poly(α‐methyl‐α‐n‐propyl‐β‐propiolactone) (PMPPL) are examined by solid state 13C nuclear magnetic resonance spectroscopy and x‐ray diffraction. These techniques reveal that, in such blends, the conformation and crystal structure found for isotactic PMEPL of a given chirality depends on the absolute configuration of the PMPPL present. In samples containing PMEPL and PMPPL of opposite absolute configuration, isotactic PMEPL crystallizes from the melt as a helix, in contrast to its behavior in the pure state, whereas PMPPL adopt the same helical conformation in the blend as when crystallized alone.
Characterisation of fire retardant poly(phenylene ether) high impact polystyrene in the UL‐94 test
Authors: Boscoletto A. B. , Checchin M. , Milan L. , Camino G. , Costa L. , Luda M. P.
Published: March 2011

The distribution of the temperature and the morphology of the charred material formed in the combustion of blends of poly(phenylene ether) (PPE) with high impact polystyrene (HIPS), carried out in the UL94 test, were examined. The effect of the fire retardant triphenyl phosphate is shown to be the decrease of time of burning, of temperature of the specimen and of zone involved in combustion, without apparent modification of the char structure. Hypothesis on gas and condensed phase fire retardant mechanisms are discussed.
Invariant values of kinetic parameters — Evaluation of fire retardancy application to the PP‐APP/PER system
Authors: Édelobel Ren , Bourbigot Serge , Le Bras Michel , Schmidt Yannick , ‐Marie Leroy Jean
Published: March 2011

A method allowing the determination of the formulation leading to the best fire retardancy properties is presented in the case of intumescent systems. The method consists in the determination of invariant physicochemical parameters deduced from TG analysis: invariant activation energy and invariant preexponentiel factor. The relation between the values given by an evaluation test (LOI) and the invariant activation energy is then discussed.
The potential applications of x‐ray photoelectron spectroscopy (XPS) to the flame retardance mechanism of polymers
Authors: Wang Jianqi
Published: March 2011

In recent years X‐ray photoelectron spectroscopy (XPS) has rapidly matured and used routinely now in industries / universities providing a wealth of information including elemental composition, chemical bonding and depth profiles of both aspects in the surface of solids. However, few has been reported so far in the flame retardance areas. An attempt has been made in the present paper aiming at introducing and exemplifying examples of XPS applied to the fields relevant to the flame retardance of polymers, such as:degradation of polymers upon heating, synergisms, smoke suppression and structural investigation. All of which were achieved recently in the laboratory.
Flame retardant polymers current status and future trends
Authors: Troitzsch J.
Published: March 2011

High demands in fire safety have increased the consumption of flame retardant polymers. Environmental issues, raised particularly in Germany, could affect the use of certain halogenated flame retardants in the future. Therefore, equivalent halogenated and non‐halogenated substitutes are currently studied and developed. An overview of the main systems of flame retardants acting in the gas phase and the condensed phase is given. The future belongs to halogenated and non‐halogenated systems with minimal environmental impact and optimal flame retardancy. To this end, enhanced basic research on polymer degradation and on the combustion process is necessary.
Synthesis and fire retardant properties of vinylic polymers bearing phosphonated groups
Authors: Catala J.‐M. , Brossas J.
Published: March 2011

To overcome the use of halogenated compounds, which are usually incorporated in plastics as flame retardant additives, the authors investigated the synthesis possibilities, to introduce with covalent bonds, the flame retarder groups at different positions of the polymer chains. They established correlations between the topology of the phosphonated groups and the flame retardant properties. They attempt to determine the origin of the flame resistance obtained in several cases. Their goal is to extend their interesting results obtained from oligomers, to polymer of high molecular weight.
Flame retarding materials for advanced composites
Authors: Kunz Dieter H.E.
Published: March 2011

Mechanical properties of advanced composites are often impaired by flame retardants. The least adverse effect is found with synergistic combination of antimony oxides and brominated epoxies. Where low smoke generation is absolutely necessary phenolic resins are used. The new development of combining epoxy and phenolic resin layers in structural applications with high flame retardancy is introduced.
New fire retardant halogenfree polymers
Authors: Schreiber H. , Saur W.
Published: March 2011

Todays fire retardant plastics for high strength FRP (fibre‐reinforced polymers) or electronic devices (printed circuit boards, PCB) are based on brominated epoxy resins (EP resins). The smoke gases of this resins are highly toxic and corrosive. A new class of fire retardant duroplastics, based on dihydrobenzoxazines, doesn't contain halogen, sulfur or phosphor. Processibility is equal to that of thermosetting epoxy resins. Mechanical and electrical properties are equal to brominated epoxy resin, heat resistance is considerably enhanced (glass temperature 180 ‐ 280 °C), while density, toxicity and corrosivity of smoke are very low.
A way to halogenfree, flame‐retardant laminates for electronic applications
Authors: Von Gentzkow W. , Huber J. , Rogler W. , Wilhelm D.
Published: March 2011

Due to legal specifications and standards flame retardant polymers are used as insulating materials for electrical cable and wire, as casing and constructive materials in electrical engineering, as encapsulation materials for electronic components and in laminates for printed circuit boards. The most effective way to achieve flame retardancy is by using halogenated organic materials. Because of ecological reasons a major trend is the development of halogenfree non‐corrosive flame retardant polymer materials. On the laminate side Siemens R&D developed a way to halogenfree laminates meeting the UL 94V‐O specification.
Hydrolytically stable thermoplastic and thermosetting poly(arylene phosphine oxide) material systems
Authors: D. Smith Carrington , Gungor Atilla , A. Wood Paul , C. Liptak Steven , Grubbs Harvey , Ho Yoon Tae , McGrath James E.
Published: March 2011

Several thermoplastic and thermosetting polymeric materials containing the phenyl phosphine oxide group were prepared and characterized by physical methods. High molecular weight poly(arylene ether)s and polyimides containing the hydrolytically stable bulky phosphine oxide unit were synthesized and found to be soluble materials with moderately high glass transition temperatures. The phenyl phosphine oxide moiety was further incorporated into epoxy and bismaleimide type crosslinked systems. Phosphorus promoted char formation in air was displayed by both the linear and crosslinked macromolecules, leading to improved self‐extinguishability relative to the non‐phosphorus containing analogous polymeric systems.
Integral fire tests with oil and cable in a nuclear power plant
Authors: Dobbernack R. , Müller K.
Published: March 2011

Experiments with oil pool and cable fires were performed in a former Nuclear Power Plant during the last years.

The fire room was a closed subcompartment equipped with ventilation ducts, fire dampers, extinguishing lines and connected by a floor to the plant containment to study fires in a real environment under conditions typical for Nuclear Power Plants.

Unsolved issues such as behavior of fire damping components and filters; production of soot; fire fighters entrance to a burning room were evaluated as well as ventilation needs of involved rescue areas.

The fire behavior was calculated by different types of fire codes.
Pur ‐ sandwich panels in the building industry ‐ development of fire regulations in Europe
Authors: Walter R. , Wittbecker F.‐W.
Published: March 2011

The European Community aims to harmonize standards for fire safety of building products. The report starts with an overview of the existing different testing methods for sandwich panels with PUR‐rigid‐foam core and metal facings. For harmonization of the fire standards experts are looking for a robust longtime solution, which shall have a better relation to the end‐use conditions of the building products. First results of proposed ISO‐Room/Corner‐Tests for PUR‐sandwich panels are discussed.
Laboratory systems to evaluate the toxicity of polymers combustion products and hazard assessment
Authors: Jean‐Michel Jouany , Michel Guerbet , Roland Capron , Eric Dittmar
Published: March 2011

Several laboratory systems have been proposed to evaluate the toxicity of combustion products of materials. Generally, the “fire models” were poorly instrumented, excepted the analysis of the major toxicants. Better informations being needed in this respect, a furnace has been made, based on the 2 zones NBS model, and allowing the evaluation of flammability, heat release and weight loss. Moreover, opacity and toxic gases are monitored. The time to incapacitation is probably the more realistic toxicological evaluation. It is worth while to rank materials by an hazard assessment, separating the variables involved in the fire hazard and the variables corresponding to the toxicological hazards and to plot them in a two‐dimensional graphic which looses less information than an index.
The thermal susceptibility of poly(chloroethyl methacrylates)
Authors: G. popović Ivanka , Katsikas Lynne , žana Sne , Rangelov M. , Veličkovič Jovan S. , Schnabel Wolfram
Published: March 2011

The non‐oxidative thermal degradation kinetics and mechanism of poly(2‐monochloro, 2, 2‐dichloro and 2, 2, 2, ‐trichloroethyl methacrylates) were studied. The influence of the antioxidant IRGA‐NOX 1010 on the thermal degradation of the monochloroethyl derivative was also investigated. Initial hydrolysis data on the major degradation products, the corresponding monomers, were obtained.
Flame‐resistance of polyetherimides
Authors: Rusanov A. L. , Serkov B. B. , Kazakova G. V. , Bulycheva E. G. , Kolosova T. N. , Dzhashiashvili T. K. , Matvelashvili G. S.
Published: March 2011

Polyetherimides containing isopropylidene and hexafluoroisopropylidene groupings were obtained by the interaction of m‐phenylenediamine with the dianhydrides of 2, 2‐bis[4‐(3, 4‐dicarboxyphenoxy) phenyl]‐propane and 2, 2‐bis[4‐(3, 4‐dicarboxyphenoxy) phenyl] hexafluoropropane using high‐temperature solution polycyclocondensation in phenolic solvents. The same procedure was used for the preparation of the isopropylidene‐ and hexafluoroisopropylidene‐containing polyetherimides on the basis of 3, 3′ 4, 4′‐tetracarboxy(diphenyl ether) dianhydride and 2, 2‐bis[4‐(3‐aminopheno‐xy)phenyl] hexafluoropropane. Investigation of the polymers obtained has demonstrated that the replacement of isopropylidene groupings for hexafluoroisopropylidene fragments in polyetherimides leads to the increasing of the polymers flame‐resistance.
Mechanism of fire retardance in poly(2,6‐dimethyl‐1,4‐phenylene ether)‐high impact polystyrene
Authors: Checchin M. , Boscoletto A. B. , Camino G. , Luda M. P. , Costa L.
Published: March 2011

Preliminary results are presented of a study concerning the mechanism of action of triphenyl phosphate (TPP) added to blends of poly(phenylene ether) (PPE) and high impact polystyrene (HIPS), 65/35 w/w. Comparison of effectiveness of TPP in increasing either the oxygen index or the nitrous oxide index of the polymeric blend, indicates that the fire retardant may act by a mixed gas‐condensed phase mechanism. The thermogravimetric behaviour of the fire retarded blend is compatible with this suggestion.
Factors affecting the burning behaviour of combustion modified high resilience polyurethane foams
Authors: Horrocks A. R. , Price D. , C. Edwards N. L.
Published: March 2011

Nine different flexible polyurethane foams of varying density and containing melamine and a phosphorus‐based flame retardant at different concentrations have been assessed for burning behaviours using oxygen index techniques at ambient and elevated temperatures. Major foam variables influencing flammability are density and melamine flame retardant content.
Investigation of the mechanisms underlying the influence of flame retardant on cotton (cellulose) pyrolysis in air
Authors: Price D. , Colemann G. V. , Faroq A. A. , Horrocks A. R.
Published: March 2011

An investigation is being undertaken into the influence of flame retardant type on the pyrolytic degradation of cotton (cellulose) fabrics in air over the temperature range 300–100°C. Thermal analysis techniques (TGA and DSC), detailed evolved gas analysis and extent of char formation measurements have all been utilised. The information obtained is used to develop a detailed model for the pyrolytic degradation of cellulose in air and the influence of flame retardants thereon. This paper reports the use of differential scanning calorimetry to further investigate the proposed CELLULOSE → CELLULOSE* transition.
Flammability of macrocyclic polymers and their complexes with metals
Authors: Aseeva R. M. , Zaikov G. E.
Published: March 2011

The peculiarities of thermal degradation and the flammability of nitrogen‐containing macrocyclic polymers have been investigated. It has been shown that the thermal and thermo‐oxidative stability of these polymers depend on the structure of the macrocycle, the type of organic radicals of the main unit and the metal nature. The effect of the type of n‐conjugated macromolecules, as well as of the planarity and symmetry of macrocycle, on thermal stability as well as flammability of macrocyclic polymers has been studied. Metals (Cu, Co, Ni) in the coordination sphere increase the thermal stability and decrease the thermo‐oxidative degradation of macrocyclic polymers.
Standardized methods of testing flammability of plastics
Authors: Horák O.
Published: March 2011

The paper is giving a survey of the most important standardized methods for testing flammability and relative parameters of plastics. The items described are dealing with the determination of flash point, heat resistance, burning behaviour. Some new drafts and projects of international standards are also mentioned.
Flame retardant polymeric additives for polyolefines. Different role of phosphoric and boric acids as FR agents in their reaction products with triglycidyl isocyanurate
Authors: De Chirico A. , Audisio G. , Provasoli F. , Armanini M. , Franzese R.
Published: March 2011

Two adducts based on triglycidyl isocyanurate and phosphoric or boric acid have been compared by means of thermogravimetric analysis to investigate their activity as flame retardants and thermostabilizing agents respect to polypropylene. Better behaviour of phosphoric acid adducts have been observed.
Vertical burning tests UL 94‐V and IEC 249–1 (4.3.4) theoretical considerations and experimental results
Authors: Schreiber H.
Published: March 2011

Experimental results show, that the UL 94 classifications V0 or V1 are not in accordance with the real inflammability properties. For ignition times up to 20 s the classification is very erratic and accidental. More flammable materials may yield a better classification and vice versa. These results are explainable and confirmed by theoretical considerations.
The application of composites in aerospace
Authors: Bolding G.
Published: March 2011

After the introduction of the advanced composite materials, i.e. carbon‐ and aramidfibre reinforced thermosets, in the late 60's, for a long time the application of these materials used to be considered a panacea for many problems in civil aircraft structures. After many years of trial and error, it is becoming clear that these materials most certainly contribute to better aircraft, but are not a miracle cure. And if there is a key role for composite materials, there is still a long way to go to the all composite (commercial) aircraft.

The applications in the aerospace market started with components that used to be designed in glassfibre reinforced thermosets. Although the manufacturing technology was well known, the approach to designing in advanced composites changed in the sense, that the designs had to be optimized for minimum weight (to obtain lower DOC). Also the materials had to be recognized by the designer as being anisotropic (high allowable stresses in the fibre direction). Soon it became evident that also the material‐ and process technology had to be optimized for the advanced composites.

Due to the cost involved in the manufacturing of highly loaded composite components, the design philosophy changed from design for minimum weight to (more or less) design for minimum cost. Also the service experience and resulting remarks from the operators, changed the design approach. The maturity of automated manufacturing will enable further cost reduction and after sufficient service experience with the components that are flying at this moment, the aircraft industry will be ready for the next step: the application of the advanced composite materials in primary, flight‐critical aircraft components. The close cooperation between the aerospace industry and the material suppliers will be an essential condition for success in the quest for a “better” aircraft.
Stimulating innovative research (on special polymers) in The Netherlands
Authors: van Der Torren Hendrik‐Jan , van Mechelen Tony
Published: March 2011

Innovation is considered one of the keys to a successful and competitive industry. The Dutch Ministry of Economic Affairs therefore stimulates research and development in strategic subject areas of potentially significant importance for the industry. It has created several national stimulating instruments, such as IOP (Innovation Oriented Research Programme), PBTS (Programmatic Business Oriented Technology Stimulation) and TOK (Technical Development Loan). At an European level it stimulates participation in the Eureka programme.

The precompetitive IOP is meant to generate new technology, to add value to promising research activities, to establish new and strenghten existing skill pools and to cluster existing and newly established research groups. It enhances the orientation of university groups towards the needs of industry.

The IOP “Polymer Composites and Special Polymers” is a.o. concerned with topics on special (functional) polymers like non‐linear optically active polymers, electrically active polymers and liquid crystalline polymers. In this presentation the current status is reviewed of research on special (functional) polymers in the Netherlands. Insight is given in policies and rational of selecting specific IOP‐programmes in this area. In addition attention is paid to a post‐IOP perspective and a possible participation of dutch companies in Eureka projects.
Product design for productivity and innovation with engineering thermoplastics and their blends in the nineties
Authors: Bailly C. , Sederel W. L.
Published: March 2011

Companies must constantly improve their technologies to survive the competitive battle in the nineteen nineties and beyond. This now holds more than ever for producers of engineering thermoplastics, who traditionally have enjoyed significantly higher margins than the commodity plastic producers. In today's competitive environment it is vital to be the high quality, low cost producer. At the same time products and processes need to become “greener”. The drivers call for specific R&D approaches focused at cost and ecological improvements of processes and products. Examples are:

(i) novel catalysis with fewer process steps, higher yields and selectivity for the production of monomers and polymers.

(ii) solvent‐free polymerisation processes, resulting in lower investment cost, lower operating cost and the lack of solvent traces in the final product

(iii) design of polymer modifications, e.g. higher flow and/or higher heat co‐polymers such that products can be produced in existing equipment resulting in acceptable Return‐on‐Investment (ROI).

Higher flow products are specifically needed for thin‐wall designs to allow optimum use of the high mechanical properties of engineering thermoplastics, making shorter processing cycles possible during moulding and bringing less material in the environment.

This paper reviews various routes to high flow technology, such as improving processing window, molecular engineering and blends. The pull for these technology developments come from optical data storage, thin wall bumper and super thin note bloc computer applications. The need for greener products is addressed through improved flame and fire retardant product design.
Interfaces in polymer matrix composites from micromechanical tests to macromechanical properties
Authors: Verpoest Ignaas , Desaeger Muriel , Ivens Jan , Wevers Martine
Published: March 2011

The properties of a composite material are gouverned by the fibre, the matrix and the interface properties. However, in a test, used to determine a composite property, the influence of the interface is often muffled by other influences (fibre volume fraction, inhomogeneity, voids, defects,). To understand the relation between the composite performance and the fibre‐matrix interface properties, it is necessary to work in several steps. In a first step, a thorough understanding of the fibre‐matrix interface behaviour is needed. This not only involves the determination of the interface properties using micromechanical test methods, but also the fundamental study of the stresses at the interface and of the failure events occuring during the test. In this paper, the fragmentation, the pull‐out and the micro‐indentation test will be elaborated. The former test is used to explain the importance of an accurate data reduction model. In a second step, the influence of these interface properties on the composite performance is investigated. It is well known that an improved interface quality is beneficial for the transverse tensile and the interlaminar shear strength. However, a strong fibre‐matrix interface is not favourable for all composite properties. This is illustrated by an overview of micromechanical models, developed to understand the macromechanical behaviour of composites. Three properties are addressed: the longitudinal tensile strength, the interlaminar fracture toughness, and the damage development in cross‐ply laminates.
Ultimate toughness of amorphous polymers
Authors: van Der Sanden M.C.M. , Meijer H.E.H.
Published: March 2011

The deformation and toughness of amorphous glassy polymers is discussed in terms of both the molecular network structure and the microscopic structure at length scales of 50–300 nm. Two model systems were used: polystyrene‐poly(2,6‐dimethyl‐1,4‐phenylene ether) blends (PS‐PPE; where PS possesses a low entanglement density and PPE a relatively high entanglement density) and epoxides based on diglycidyl ether of bisphenol A (DGEBA) with crosslink densities comparable with up to values much higher than the thermoplastic model system. The microscopic structure was controlled by the addition of different amounts of non‐adhering core‐shell‐rubber particles. Toughness is mainly determined by the maximum macroscopic draw ratio since the yield stress of most polymers approximately is identical (50–80 MPa). It is shown that the theoretical maximum draw ratio, derived from the maximum (entanglement or crosslink) network deformation, is obtained macroscopically when the characteristic length scale of the microstructure of the material is below a certain dimension; i.e. the critical matrix ligament thickness between added non‐adhering rubbery particles (‘holes’). The value of the critical matrix ligament thickness (IDc) uniquely depends on the molecular structure: at an increasing network density, IDc increases independent of the nature of the network structure (entanglements or crosslinks). A simple model is presented based on an energy criterion to account for the phenomenon of a critical ligament thickness and to describe its strain‐rate and temperature dependency.
From incompatible poly(aryl ether sulfone)/polyamide 4.6. blends to new impact resistant alloys by a synergistic combination of a block copolymer emulsifier and an impact modifier
Authors: Koning C. E. , Fayt R. , Bruls W. , Vondervoort L.v.D. , Rauch T. , Teyssié PH.
Published: March 2011

The compatibilization and impact modification of blends of a relatively new engineering plastic polyamide 4.6 (PA 4.6) and a poly(aryl ether sulfone) (PSU) are investigated. PSU‐b‐PA6 block copolymers, which can be easily synthesized by ring opening polymerization of ϵ‐caprolactam in the presence of a commercial PSU, were found to be very efficient emulsifiers for these incompatible blends. Small amounts (1–4%) of copolymer are sufficient to significantly reduce the particle size and to improve the tensile and impact properties. Combinations of the copolymer and an impact modifier (ethylene‐propylene rubber grafted with maleic anhydride) are synergistic and high impact PSU/PA 4.6 alloys are obtained in that way.
1,3‐Dipolar cycloaddition: A new approach to telechelics
Authors: Maier Gerhard , Nuyken Oskar , Losert Klaus
Published: March 2011

The ability of the cycloaddition reaction between aromatic aldazines and diisocyanates to form polymers was studied. Reaction conditions were found which allow the direct synthesis of telechelics by this reaction. These telechelics have two isocyanate end groups due to the nature of the cycloaddition reaction. Functionality of a telechelic oligomer was confirmed to be f = 1.95 by end goup titration. Chain extension experiments were successful with this material.
Reaction and diffusion on amberlyst‐15 ion‐exchange polymer
Authors: Velo E. , Recasens F.
Published: March 2011

In this work, the effects of liquid polarity on the intrapolymer diffusion rates of iso‐Butene, using the heterogeneously catalysed hydration of i‐Butene to tert‐Butyl alcohol, are studied. Values for the effective diffusivity are correlated as a function of tert‐Butanol concentration and temperature. The tortuosity factor of the solid polymer matrix is seen to decrease with temperature and increase with alcohol content. Tentative conclusions regarding the shrinkage of the macroporous matrix, are drawn.
A development of Ahmad‐Stepto gelation theory
Authors: Rolfes H. , Stepto R. F. T.
Published: March 2011

The Ahmad‐Stepto (A‐S) theory of gelation in RA2+ RBf polymerisations has been improved and developed to include general polymerisations of A‐ and B‐bearing reactants, namely, \documentclass{article}\pagestyle{empty}\begin{document}$$ {\sum\limits_{\rm i}}{\rm RA}{_{{\rm fai}}} + {\sum\limits_{{\rm i}}}{\rm RB}{_{{\rm fbi}}} $$\end{document} polymerisations and \documentclass{article}\pagestyle{empty}\begin{document}$$ {\sum\limits_{\rm i}}{\rm RA}{_{{\rm fai}}} $$\end{document} self‐polymerisations. It is found that the values of the ring‐forming parameter needed to fit experimental data on polyester‐forming RA2+ RB3 polymerisations are much nearer to those expected from solution properties than the values required by A‐S theory. The present theory is proposed as a useful basis for the prediction of unknown gel points from reactant structures and reaction conditions.
Mechanistic discussion on deviation from ideal network formation in radical polymerization of multivinyl monomers
Authors: Matsumoto Akira
Published: March 2011

The network formation in the radical polymerization of multivinyl monomers, especially including diallyl esters and dimethacrylates, is dealt by focusing our attention on the mechanistic discussion on deviation from ideal network formation. Thus, in the bulk polymerization of diallyl phthalate, the actual gel point was obtained to be 6.9 times higher compared with the theoretical one. In common multivinyl polymerization systems, the discrepancy was more than 10 times and sometimes, more than 102. Moreover, the extent of deviation was enhanced with increasing primary chain length, the content of pendant vinyl groups in the prepolymer, and dilution. In order to interpret reasonably the greatly delayed gelation different structural factors were considered. The primary factor concerns the significance of the thermodynamic excluded volume effect on the intermolecular crosslinking reaction between growing radical and prepolymer, especially at high molecular weight. Beyond the theoretical gel point, a secondary factor is related to the intramolecular crosslinking which becomes progressively important with conversion. The latter leads to the restriction of segmental motion of prepolymer and, moreover, imposes the steric hindrance, inducing the significance of the reduced reactivity of prepolymer as a tertiary factor. Solvent effect was observed as much delayed gelation in a good solvent as opposed to Walling's results, although this is expected by considering the significance of excluded volume effect.
Gelation process of amylose‐DMSO‐water system
Authors: Takeyama Hidenobu , Kobayashi Masatoshi , Yajima Hirofumi , Endo Ryuichi , Kohyama Kaoru , Nishinari Katsuyoshi
Published: March 2011

Amylose gel is obtained by cooling amylose aqueous solution at a certain cooling rate. In order to clarify the gelation process of amylose in the mixed solvent of water and DMSO, the characteristics of turbidity and dynamic viscoelasticity of the solution as a function of temperature have been studied by optical and rheological methods, respectively. Accordingly, cloud temperature (Tc) at which the aggregation of amylose occurs, and gelation temperature (Tgel) at which the elasticity began to appear were obtained. Tc and Tgel were strongly dependent on cooling rate, and these values shifted to higher temperatures with decreasing cooling rate. However, there was difference between Tc and Tgel, and Tc was higher than Tgel, indicating the gelation process occurs in two stages.
Dynamics of shearing in flocculating fine sediment suspensions
Authors: Aijaz Saima , Jenkins Scott A.
Published: March 2011

The variability of rheological properties in cohesive sediment suspensions are studied and related to the flocculation process. It was found that the steady state shear stress increases exponentially with increasing sediment concentration and increases logarithmically by increasing the salinity of the suspension. The salinity dependence of the shear stress was correlated with changes in the floc‐size. These results reflect the dominant influence of fluid‐sediment interactions on the flocculation behavior of the suspension. An analytic model predicting shear stress as a function of the physical and electrochemical properties of the fine sediment suspension is developed.