bluuebunny/crossref_metadata_2025 huggingface dataset:
Introduction to a new class of high performance light stabilizers and the influence of light stabilizers structure on the polymer's life time
Authors: Rytz Gerhard , Hilfiker Rolf , Schmidt Erika , Schmitter André
Published: April 2003

The mode of action of two classes of UV absorbers (2‐(hydroxyphenyl)benzotriazoles and 2‐(2′‐hydroxyphenyl)‐1,3,5‐triazines) is discussed. Theoretical explanations for the superior light stability of the latter are given and confirmed by measured half life times in polycarbonate and solution. A mathematical model for the quantitative prediction of light protection factors is proposed.
The effect of the processing steps on the oxidative stability of polyethylene tubing crosslinked by irradiation
Authors: Iring M. , Fodor Zs. , Bödy M. , Baranovics P. , Kelen T. , Tüdös F.
Published: April 2003

Some chemical and mechanical properties of intermediate products obtained in the production of PE heat shrinkable tubes were studied, seeking correlations between the composition and the properties. Different PE granulates were mixed with antioxidant (amine or phenol derivative), flame retardant agent and, for some samples, with elastomer. The compounds were extruded to tubes, which were then crosslinked by electron beam irradiation and subsequently extended to twice the original diameter.

In the course of the production phases, the thermooxidative stability decreased compared to that of compounded granulate. The greatest decrease was caused by the irradiation. The aromatic amine seems to be the more effective antioxidant at similar compositions than the phenol derivative and it shows a better resistance against irradiation. The oxidative stability of the finished shrinkable tubes was not affected by the quality of commercial granulate (initial polyethylene).

Mechanical properties changed slightly upon ageing, and the introduction of the elastomer did not alter the tensile strength and elongation at break. The remaining stability of the end‐product was more than enough to bear the stress of shrinking in use, and the good tensile strength of the material did not decrease upon thermal ageing either.

During extrusion of the granulated compound no significant change took place in the distribution and molar mass averages. Irradiation produced more than 50% insoluble fraction, and the thermooxidative properties of the crosslinked sample changed significantly compared to the original PE and to the compound prepared from it.
Complexity of the hydrolytic degradation of aliphatic polyesters
Authors: Vert M. , Li S. , Garreau H. , Mauduit J. , Boustta M. , Schwach G. , Engel R. , Coudane J.
Published: April 2003

Aliphatic polyesters are more or less hydrolytically degradable, depending on their chemical, configurational and morphological structures. Hydrolysis can be either homogeneous or heterogeneous, depending on many structural and environmental factors. The present understanding of this hydrolytic degradation is recalled. The importance of diffusion‐reaction phenomena is discussed on the basis of the behaviors of polyesters derived from α‐hydroxy acids, namely lactic and glycolic acids and attempts are made to extend the understanding to other members of the aliphatic polyester family. The main results of some recent investigations of the effects on poly(lactic acid) polymers of basic additives and of initiators such as stannous octoate and zinc metal, which are now industrially used, are presented.
Reactions and kinetic modelling of silicone‐carbon resins
Authors: Kasehagen Leo J. , Cheng H. N. , Cowan Patrick J.
Published: April 2003

This paper aims to calculate the average properties of ideal non‐linear stepwise polymerization of comonomers containing multiple reacting sites at the B‐stage prior to gelation. A kinetic model is used to simulate the polymerization process taking into account the mass balances of differently substituted species possible. The molecular weights are obtained either by the use of the Miller‐Macosko method or by solving the differential equations for the polymerization of low‐molecular‐weight species. The approach is applied to the Pt‐catalyzed hydrosilation reaction between methyl‐substituted cyclosiloxane and dicyclopentadiene which produces a high‐performance silicone‐carbon. resin. The approach gives the concentrations of various species present at any given time and the molecular weights. Different modes of monomer addition can also be simulated.
Copolymere aus bifunktionellen Vinylmonomeren: Allylmethacrylat mit Methylmethacrylat und Styrol
Authors: Schmidt‐Naake Gudrun , Bulmahn Birgit , Janke Gudrun , Witt Beata
Published: April 2003

Monomere mit zwei polymerisierbaren olefinischen Gruppen unterschiedlicher Reaktivität sind interessant für Polyreaktionen. Copolymere des Allymethacrylats (AMA) mit Methylmethacrylat (MMA) und Styrol (St) wurden durch radikalische Polymerisation weitgehend ohne Vernetzung während des Polymerisationsprozesses hergestellt. Diese Copolymeren wurden hinsichtlich ihrer r‐Werte, der Molmassenverteilung und der thermischen Vernetzung in Abhängigkeit von der AMA‐Konzentration untersucht.
Permeability of CO2 through chitosan membrane swollen by water vapor in feed gas
Authors: Ito Akira , Sato Makoto , Anma Tomotoshi
Published: April 2003

The permeation and separation of carbon dioxide through a water‐swollen chitosan membrane was studied. A chitosan membrane was swollen by water vapor contained in a feed gas and, thus treated, exhibited a large gas permeability. Carbon dioxide preferentially permeated through the swollen chitosan membrane with a permeability of 2.5·10−8 cm3 (STP) cm(s cm2 cmHg)−1 and a CO2/N2 separation factor of 70 at room temperature. This separation performance for CO2 resulted from the basic properties of the chitosan amino groups. The membrane preparation conditions, such as acetic acid concentration of the casting solution, affected the membrane permeation rate. The effect of the operation temperature was also measured. To increase the separation performance of the membrane, several methods of membrane treatment and operation were evaluated.
Preparation and characterization of copolymers from methyl methacrylate and cardanyl methacrylate
Authors: Agarwal Seema , Choudhary Veena , Varma I. K.
Published: April 2003

Copolymers of methyl methacrylate (MMA) and cardanyl methacrylate (CMA) were synthesized, characterized and their physico‐mechanical properties were investigated. The benzoyl peroxide‐initiated copolymerization was carried out by using different mole fractions of CMA (0.02–0.10) in the initial feed at 80°C. Structural characterization of copolymers was done using FTIR and 1H NMR spectroscopic techniques. The thermal stability of the copolymers was evaluated using dynamic thermogravimetry. Incorporation of CMA in the MMA backbone leads to an improvement in thermal stability.
Preparation and properties of composites of kevlar‐nomex copolymer and boehmite
Authors: Ahmad Z. , Sarwar M. I. , Krug H. , Schmidt H.
Published: April 2003

A new organic‐inorganic hybrid material was prepared by incorporating boehmite into a Kevlar‐Nomex copolymer via a sol‐gel process. Poly(phenylene‐terephthalamide) chains having aminophenyltrimethoxysilane end groups were prepared by reacting a mixture of m‐and p‐phenylenediamine with terephthaloyl chloride, followed by end‐capping with aminophenyltrimethoxysilane. The hydrolysis of the alkoxy groups of an aluminium sec‐butoxide solution in butanol was carried out in the polymer matrix, thus creating an inorganic network structure combined chemically with the aramid chains. Hybrid materials containing different proportions of boehmite in aramid were thus produced and films were cast by solvent evaporation technique. These films with up to 15 wt.‐% of boehmite were yellow and transparent, whereas the films with 20 wt.‐% or more contents of boehmite were opaque. Mechanical properties of these films were analyzed. The values of tensile strength, initial modulus, toughness and maximum strain at rupture were initially found to increase and then decrease with further addition of boehmite. The tensile modulus of the hybrid material was found to be in the range of 3.0–4.5 GPa at 25°C. These ceramers were found to withstand maximum tensile stress of the order of 252 MPa, and the thermal decomposition temperature was around 450°C. The storage modulus as measured using DMTA was in the range of 7.6–18.9 GPa. The tan δ peak which in general became broader with increasing boehmite content showed a shoulder for composites containing large amounts of boehmite. The position of the peaks shifted towards high temperature with the increase in the inorganic contents showing hindrance in motion with increasing boehmite contents.
Crystallization behavior of poly(propylene)/polyamide 1010 blends using poly(propylene)‐graft‐glycidyl methacrylate as compatibilizer
Authors: Zhang Xiaomin , Li Gang , Li Jingshu , Yin Jinghua
Published: April 2003

Polyamide 1010/poly(propylene) (PA1010/PP) blends were investigated with and without the addition of poly(propylene)‐graft‐glycidyl methacrylate (PP‐g‐GMA). The effect of the compatibilizer on the thermal properties and crystallization behavior was determined by differential scanning calorimetry and wide‐angle X‐ray diffraction. From the results it is found that the crystallization of PA 1010 is significantly affected by the presence of PP‐g‐GMA. PP/PA 1010 (75/25) blends containing higher amounts of PP‐g‐GMA show concurrent crystallization at the crystallization temperature of PP. Isothermal crystallization kinetics also were performed in order to investigate the influence of the compatibilized process on the nucleation and growth mechanism. In the PP/PA 1010 (25/75) blends, concurrent crystallization behavior was not observed, even though the amount of PP‐g‐GMA was high.
Carbon fibre oxidation, textural and surface changes
Authors: Ibarra L. , Paños D.
Published: April 2003

This work reports on the variations in specific surface, porosity, surface functionality and dimension of commercial carbon fibre subjected to oxidative treatment with nitric acid. Scanning electron microscopy (SEM) observation did not reveal any topographic changes on the fibres, although crypton adsorption evidences increases in specific surface and microporosity.

Oxidative treatment has an effect on fibre length, although it also slightly reduces the fibre diameter and the fibre strength, as measured in terms of the elastic modulus.

Functional analysis by means of volumetric measurements and X‐ray photoelectron spectroscopy (XPS) reveals an increase in the overall fibre surface acidity through carboxy group increase. Prolonged treatment gradually removes hydroxy groups from the fibre surface.
Mechanical properties‐structure relationships of crosslinked blends based on LDPE/HDPE waste
Authors: Viksne Armanda , Malers Laimonis , Bledzki Andrzej K.
Published: April 2003

Low‐density polyethylene (LDPE) waste was blended with high‐density polyethylene (HDPE) waste of different degrees of degradation. Structural, mechanical and rheological properties of these blends were investigated. It was found that 2 wt.‐% of dicumyl peroxide improves simultaneously the tensile strength and elongation at break without serious decrease of the melt elasticity of separate PE wastes and their binary blends in comparison with unmodified PE. It was shown by DSC analyses that modification of the blends leads to better compatibility between LDPE and HDPE.
Polymerization of butadiene and isoprene with the NdCl3 · 3TBP‐TIBA catalyst system
Authors: Iovu Horia , Hubca Gheorghe , Simionescu Eugenia , Badea Elena Gabriela , Dimonie Mihai
Published: April 2003

The isoprene and butadiene polymerization processes with the NdCl3 · 3TBP‐TIBA catalyst system (TBP: tributylphosphate, TIBA: triisobutylaluminium) are studied in detail using an original and very accurate experimental technique. The influences of the initial monomer concentration, the polymerization temperature and the catalyst and cocatalyst concentrations on the conversion, the average molar masses, the polydispersity and the microstructure of the polymers are discussed and explained considering the allylic complexes formed between the neodymium atom and the last monomer unit in the macromolecular chain. A first‐order reaction with respect to the monomer was obtained. The calculated value of the activation energy (25.58 kJ mol−1) is lower than for classical Ziegler‐Natta catalysts, thus demonstrating the higher catalytic activity of the NdCl3 · 3TBP‐TIBA catalyst system used. Two types of active centers are possible, as confirmed by GPC data. One of them, which includes aluminium, is more stable and favors the transformation from “anti” allylic units to “syn” allylic units. Thus, the 1,4‐cis unit content of the prepared polymers is mainly determined by the TIBA concentration. The catalyst does not react by transfer reactions as TIBA does. The obtained conversions are always higher for butadiene than for isoprene due to a higher tendency of the former to complexate with the neodymium atom and forming allylic complexes.
Polymerization and characterization of ethylene/propylene and ethylene/1‐octene copolymers produced with bridged Zr‐ and Hf‐based metallocenes
Authors: Starck Paul , Lehtinen Christel , Löfgren Barbro
Published: April 2003

Ethylene/propylene (E/P) and ethylene/1‐octene (E/O) copolymers were polymerized with two bridged metallocene catalyst systems, Et(Ind)2ZrCl2/MAO and Et(Ind)2HfCl2/MAO, respectively. The copolymers produced and some commercial reference copolymers were characterized by DSC, SEC, DMA and 13C NMR.

The Hf‐catalysed E/P polymerizations showed much lower activities than the corresponding Zr‐catalysed polymerizations but gave polymers with high molar mass. The Hf‐based copolymers also showed two melting peaks which may be indicative of several active sites of the catalyst. A comparison of E/P copolymers, containing about 20 mol‐% propylene and produced with Zr, Hf and homogeneous V‐catalysts, respectively, indicated that the Hf and V‐catalysts gave material more similar to each other.

The E/O copolymers produced with Zr‐catalysts gave very low molar masses and the reactivity ratios, calculated from the NMR data, indicated that the Hf‐catalyst has a slightly higher reactivity for 1‐octene and the Zr‐catalyst some better reactivity for ethylene. Segregation fractionation studies by DSC indicated that a lower 1‐octene feed gives more heterogeneous copolymers and the DMA measurements reveal the existence of a linear correlation between the 1‐octene content and the intensity of the tan δmax peak.
A study on the structure and properties of polymeric sulfur
Authors: Cataldo Franco
Published: April 2003

The structure of insoluble sulfur prepared by quenching sulfur vapours, a polymeric sulfur allotrope used as non‐blooming vulcanizing agent in the rubber industry, has been studied by X‐ray diffraction of powders. The diffraction pattern has been compared with previous data taken on stretched plastic sulfur and fibrous sulfur prepared at very high pressures (30–60 kbar).

The superstructures of stretched plastic sulfur and fibrous sulfur are shown to be similar to each other but different from that of insoluble sulfur used in the rubber industry. The FT‐IR spectrum of insoluble sulfur has been reported in comparison with that of rhombic sulfur, showing that this technique is very useful for qualitative analysis of sulfur allotropes. The thermal behaviour of insoluble sulfur was studied by DSC and the heat of fusion and the melting point were determined in comparison with rhombic and monoclinic sulfur.
Textures of thermotropic liquid‐crystalline copolymers containing either 2,7‐, 1,5‐ or 1,4‐naphthalenediol or vanillic acid units
Authors: Li Xin‐Gui , Huang Mei‐Rong
Published: April 2003

The melts of the thermotropic liquid‐crystalline copolymers prepared from 2,7‐, 1,5‐ or 1,4‐naphthalenediol (N)/terephthalic acid/4‐hydroxybenzoic acid/poly(ethylene 2,6‐naphthalene dicarboxylate) or vanillic acid (V)/4‐hydroxybenzoic acid/poly(‐ethylene terephthalate) and other five types of 4‐hydroxybenzoic acid/poly(ethylene terephthalate)/comonomer copolymers are turbid and exhibit a thready texture on the basis of visual observation. Strong shear and stir opalescences in the copolymer melts are also observed. The polarized light micrographs of the melts show a marble or threaded schlieren texture which is a typical optical texture of the nematic mesophase. The polarizing microscopy observation indicates that the vanillate unit‐containing copolymer films obtained by drawing the melts are highly oriented and fibrillated. Elliptical light scattering patterns are obtained for the sheared films of the copolymers, suggesting the existence of a preferred orientation of the copolymer chains. The X‐ray fiber diagrams of the extrudates from the 2,7‐N and 1,5‐N, and V units‐containing copolymers, show broad halos centered at 0.436–0.444 nm and diffraction spots centered at 1.2−1.5 nm along the equator that are reminiscent of amorphous polymers with a “frozen” nematic phase, indicative of chain orientation. Additionally, the X‐ray fiber diagram of the V unit‐copolymer film shows strong meridional reflections at spacings 0.208 and 0.328 nm, representing the molecular repeat spacing of the copolymer chains. The X‐ray fiber diagram of 1,4‐N unit‐containing copolymer rods exhibits two diffuse annular rings, the outer at the d‐spacing 0.438 nm and the inner at 1.3 nm, indicating no definite order or amorphous structure.
Simulation of the hydrolytic polymerization of ϵ‐caprolactam with bifunctional regulators
Authors: Tang Zhi‐Lian , Lin Jian , Huang Nan‐Xun , Fantoni R. F.
Published: April 2003

A simulation model dealing with the kinetic behavior of the hydrolytic polymerization of ϵ‐caprolactam with bifunctional regulators has been proposed to analyse such characteristic data of the polymerization as the concentrations of caprolactam. endgroups, ϵ‐aminocaproic acid, cyclic dimer, and as well as conversion, number‐ and weight‐average molecular weights, and polydispersity index. The calculated values based upon the model were found to be quite compatible with the observed values. It is found that the presence of more bifunctional acid leads to a lower equilibrium value of polydispersity index, unlike the case of monofunctional acid where the polydispersity index asymptotically reaches a value of 2, regardless of the amount of monofunctional acid initially added.
Radiation‐induced graft polymerization of styrene onto poly(3‐hydroxybutyrate) and its copolymer with 3‐hydroxyvalerate
Authors: Bahari K. , Mitomo H. , Enjoji T. , Hasegawa S. , Yoshii F. , Makuuchi K.
Published: April 2003

Graft copolymerization of styrene (St) onto poly(3‐hydroxybutyrate) (PHB) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (P(HB‐HV)) was carried out using simultaneous irradiation and pre‐irradiation techniques with 60Co γ‐rays. The degree of grafting (Xg) of styrene onto PHB increased with increasing pre‐irradiation dose and grafting temperature while in the graft reaction of the copolymer, Xg was higher at 50°C than at 70°C. This Xg was lower than that in grafting methyl methacrylate (MMA) onto PHB and its copolymer. In the electron spin resonance (ESR) study, the PHB radical formed by irradiation was converted to a propagating radical by introducing St monomer at room temperature (25°C) for grafting. The propagating radical was observed even at 50°C and 70°C, grafting of St onto PHB occurs actively at such temperatures. The decay of the radical concentration during grafting well corresponded to radical consumption in graft polymerization. The molecular weight (M̄n) depended on the grafting conditions and the increase of the grafting temperature induced the formation of reduced M̄n because of early termination. It was confirmed that the increase of Xg in pre‐irradiation of more than 10 kGy was due to the increment of the graft chain.
Synthesis and properties of poly(ether ether ketone)/4,4′‐dihydroxydiphenyl sulfone multiblock copolymers
Authors: Cao Junkui , Su Wencheng , Wang Junzuo , Wu Zhongwen , Shibata Mitsuhiro , Yosomiya Ryutoku
Published: April 2003

Poly(ether ether ketone) (PEEK)/4,4′‐dihydroxydiphenyl sulfone (DHDPS) multiblock copolymers with a content of the diphenoxysulfone (DPOS) moiety between 4.9 and 36.6wt.‐% were synthesized by the reaction of DHDPS and fluorine‐terminated PEEK oligomers. The number‐average molecular weight of PEEK oligomers (Mn) was varied from 470 to 4900. The effect of the compositional variation on the properties was investigated. Microphase separation was not observed. The copolymers formed a homogeneous system having good compatibility. The copolymers whose DPOS contents are not exceeding 23.1 wt.‐% (Mn of PEEK segment ≥ 865) have crystalline structure.

From the measurements of wide‐ and small‐angle X‐ray scatterings it was revealed that the crystal structure of the copolymers is rhombic, equal to PEEK, and the distribution of the thickness of the crystalline and amorphous regions is very broad. The degree of crystallinity and the melting point of the copolymers decreased and the glass transition temperature (Tg) gradually rose with the increase of the DPOS content (or the decrease of Mn of the PEEK segment).
Products of polycondensation of 4,4′‐biphenyldithiol with some hydrocarbon dihalides
Authors: Tarasiuk Bogdan , Podkoscielny Wawrzyniec , Majewski Władysław
Published: April 2003

Polysulfides were synthesized with high yield by high‐temperature solution polycondensation of 4,4′‐biphenyldithiol with selected aliphatic and aromatic‐aliphatic hydrocarbon dihalides. To determine the optimum polycondensation conditions, the influence of the following factors on reduced viscosity and yield was studied: type of organic solvent, type of hydrogen halide acceptor, concentration of reagents, reaction temperature, and reaction time. A thorough examination was carried out only for the polycondensation of dithiol with bis(4‐chloromethylphenyl)methane chosen as model system. The structures of the polysulfides were confirmed by elemental analysis, X‐ray analysis, and infrared spectroscopy. The temperature of initial decomposition, the percentage of mass loss, and the temperature of the fastest decomposition, process were determined from curves of differential thermal and thermogravimetric analysis. Some physicochemical, mechanical and electrical properties were determined. The highest thermal and chemical resistance has been found for the polysulfide obtained from 4,4′‐biphenyldithiol and 4,4′‐bis(chloromethyl)biphenyl, probably because of the predominantly aromatic structure.
Carbamoylethylation of moghat mucilage
Authors: Ragheb A. A. , Rahman A. A. Abdel , Hebeish A.
Published: April 2003

Mucilage isolated from the grinded roots of Glossostemon bruguieri (Desf.) (moghat) was subjected to carbamoylethylation, which involved the reaction of the moghat mucilage with acrylamide along with sodium hydroxide as a catalyst. The reaction was found to depend on the acrylamide concentration as well as on temperature. While the extent of carbamoylethylation increases by increasing acrylamide concentration from 20 to 100 g/100 g mucilage, it decreases by raising the reaction temperature from 25°C to 75°C. The carbamoylethylated moghat mucilage exhibits non‐Newtonian pseudoplastic behaviour irrespective of the extent of carbamoylethylation. On the other hand, increasing the extent of carbamoylethylation is accompanied by an enhancement in the apparent viscosity. This was evidenced by the direct relation of the apparent viscosity with the increase in acrylamide concentration and its inverse relation with the temperature. A 72 h storage of the pastes under investigation causes a considerable decrement in apparent viscosity only when the extent of carbamoylethylation is low. Higher extents of carbamoylethylation stabilised the molecular structure of the moghat mucilage.
Organic‐inorganic hybrid sol‐gel materials, 1. Preparation and characterization
Authors: Yang Jen Ming , Chen Hao Sheng , Hsu Ying Gev , Wang Winston
Published: April 2003

Three organic‐inorganic hybrid materials have been prepared by incorporating poly(styrene‐co‐methyl methacrylate) (poly(St‐co‐MMA)), poly(methyl methacrylate) (PMMA), and polystyrene (PS) structure units covalently into the SiO2 glass network via the sol‐gel approach. The polymer precursors were synthesized by freeradical copolymerization of styrene and/or methyl methacrylate with 3‐(trimethoxysilyl)propyl methacrylate (MSMA) to obtain the poly(St‐co‐MMA‐co‐MSMA) copolymer (molar ratio St/MMA/MSMA = 30/48/22), poly(MMA‐co‐MSMA) copolymer (molar ratio MMA/MSMA = 76/24), and poly(St‐co‐MSMA) copolymer (molar ratio St/MSMA = 69/31) with glass transition temperatures at about 67°C, 68°C, and 61°C, respectively. The characteristics and properties of the copolymers were characterized by 1H NMR, Fourier‐transform infrared spectroscopy (FTIR), gel‐permeation chromatography (GPC), elemental analysis, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The copolymers were then hydrolysed and co‐condensated with tetraethyl orthosilicate (TEOS) in tetrahydrofuran at room temperature to afford monolithic poly(St‐co‐MMA)SiO2, PMMASiO2, and PS‐SiO2 hybrid sol‐gel materials having SiO2 contents of 16–84 wt.‐%. The thermal properties of the hybrid materials were characterized by TGA and DSC.
α,ω‐Difunctional oligo(oxyethylene)‐based crosslinked resins as solid‐liquid phase transfer catalysts
Authors: Teodorescu Mircea , Dimonie Mihai , Languri Jean
Published: April 2003

Crosslinked resins were prepared from α,ω‐diglydicyl and α,ω‐dimethacryloyl oligo(ethylene oxide)s by anionic polymerization with triethylenediamine/n‐pentanol initiating system or by free‐radical polymerization, respectively. Their activity as solid‐liquid phase transfer catalysts was proved in the reaction of 1‐bromobutane with potassium phenoxide, and compared with the activity of similar resins synthesized from α,ω‐diglycidyl oligo(ethylene oxide)s and triethylenetetramine (TETA). The catalytic activity of dimethacryloyl resins was higher than that of diglycidyl resins for oligomer chains longer than 6–7 oxyethylene units, whereas the opposite was true for resins of shorter chain lengths. These differences were explained by an unlike graft content of the resins in the former case, and by a different ability to complex the potassium cation into the meshes of the resin lattice, in the latter. In order to improve the catalytic activity of the resins two methods were developed consisting in the increase of the number of grafts either by decreasing the ratio of TETA/epoxy end groups used to the crosslinking of diglycidyl oligomers or by adding 2‐mercaptoethanol as a transfer agent to the free‐radical crosslinking process of dimethacryloyl oligo(ethylene oxide)s.
Structure and properties of poly(vinylamine)‐metal complexes
Authors: Rivas B. L. , Seguel G. V. , Geckeler K. E.
Published: April 2003

Coordination polymers of poly(vinylamine) with copper, nickel, or cobalt have been prepared. Only the polychelate with copper was soluble in water. Elemental analysis, as well as magnetic, spectral, and thermal properties, and electrical conductivities (σ) of the chelates were investigated and probable structures were assigned to the chelates. All the polychelates were found to include water. The highest values of σ0 corresponded to the polychelates with Ni(II) (7.4 Ω 10−5 σ−1 Ω cm−1) and with Cu(II) (8.3 Ω 10−5 Ω−1 Ω. cm−1). The polychelate with Ni(II) shows the highest thermal stability.
Redox copolymer with N‐bromosulfonamide groups for the decomposition of cyanide ions in dilute aqueous solutions
Authors: Kociołek‐Balawejder Elżbieta
Published: April 2003

A redox copolymer, macroporous poly(styrene‐co‐divinylbenzene) (S/DVB) resin having N‐bromosulfonamide groups, was used for removal of cyanide ions from aqueous solutions. This resin contains active bromine in functional groups (1.86 mmol g−1, i. e. 3.72 meq g−1) and shows oxidative properties. It was employed in static and flow system for oxidation of cyanide ions to non‐toxic compounds. The reactions were carried out in aqueous media containing 26–2600 mg L−1 CN− at different pH values. The data showed that the resin having active bromine easily oxidized cyanides, forming cyanates being 1000‐times less toxic than cyanides. In contact with the resin the concentration of cyanides in tested solutions dropped below 0.05 mg L−1 CN−. During the oxidation processes the SO2NBrNa groups transform to SO2NH2 groups. They can be reactivated by use of sodium hypochlorite and bromide solutions. As an alternative to oxidation of cyanides by N‐bromosulfonamide resin, the oxidation of these ions by N‐chlorosulfonamide resin with addition of a small amount of bromides was examined.
Morphology and mechanical properties of poly(propylene)/polystyrene blends compatibilized with polystyrene‐block‐poly(ethylene‐co‐propylene)
Authors: Radonjič Gregor , Musil Vojko
Published: April 2003

Compatibilizing effects of diblock copolymer polystyrene‐block‐poly(ethylene‐co‐propylene) (SEP) on the morphology and mechanical properties of immiscible blends of poly(propylene) (PP) and polystyrene (PS) were investigated. Notched impact strength, yield stress, elongation at yield and Young's modulus were determined as a function of different weight ratios of PP and PS and different amounts of added SEP as well. Scanning electron microscopy revealed a two‐phase morphology of PP/PS blends, which exhibit poor mechanical properties.

Even 2,5 wt.‐% of SEP added to PP/PS blends can improve the notched impact strength and elongation at yield compared to non‐compatibilized PP/PS blends. 10 wt.‐% of SEP compatibilizer converted the brittle PP/PS blend to quite impactresistant polymeric material. Mechanical properties were improved because of the morphological changes and increased interfacial adhesion as a result of SEP localization between PP and PS phases.

An analysis of yield stress data in terms of theoretical models showed that yield stress values of binary PP/PS blends can be predicted with Nielsen's model.
Polymerization of 1,3‐butadiene with neodymium chloride/2‐ethylhexanolate/triethylaluminium catalyst system
Authors: Rao G. S. Srinivasa , Upadhyay V. K. , Jain R. C.
Published: April 2003

Neodymium chloride 2‐ethylhexanolates of the general formula NdCl3 · nL were prepared by ligand exchange reaction between neodymium chloride ispropanolate (I) and 2‐ethylhexanol (EH). These hexanolates, NdCl3 · 1.5 EH (II) and NdCl3 · 2.5 EH (III), were characterized by elemental analysis and gravimetry. The catalytic activity of these hexanolates in combination with triethyl aluminium in the homopolymerization of 1,3‐butadiene was studied, and the activity was found to be higher with III than II. The conversions increased with increasing the catalyst and co‐catalyst concentrations and the temperature, whereas the intrinsic viscosity decreased. The conversions and the intrinsic viscosity decreased. The conversions and the intrinsic viscosity increased with reaction time. The cis‐1,4 structure was influenced by variation in temperature and co‐catalyst concentration, however, the total cis‐1,4 structure was always more than 99% with very low vinyl content (>1%). Addition of an external electron donor decreased the cis‐1,4 content to 87%.
The role of sulfur dioxide and nitrogen dioxide on the degradation of polymers
Authors: Dulog L.
Published: April 2003

The photodegradation of poly(tert‐butyl methacrylate) (PtBMA) and polystyrene (PS) films under 100 ppm sulfur dioxide and 100 ppm nitrogen dioxide in air and mixtures of the gases in air at constant temperature (30 °C) and relative humidity (30 %) was studied. in the presence of sulfur dioxide and nitrogen dioxide, under irradiation the polymers show a rapid degradation, while the thermal degradation is very small as well as the photodegradation in air. Peroxide groups in the polymer have an accelerating effect on the photodegradation in presence of the gases as well as dew and dry cycles (15 min each).

An equation was derived to characterize the degradation by a linear and an autoacceleration factor.
Hydrolytic and thermal stability of novel polyurethane elastomers
Authors: Furukawa Mutsuhisa
Published: April 2003

Novel Polyester glycols with alkyl side groups were used for the improvement of thermal stability and hydrolytic stability of polyester urethane elastomers. The novel polyester glycols used are poly( β ‐methyl‐ δ ‐valerolactone)glycol (PMVL), poly(3‐methyl pentamethylene adipate) glycol (PMPA), poly(nonamethylene‐co‐2‐methyl octamcthylene carbonate) gycol (PNCO). A mixture of PNCO and poly(dimethyl siloxane)gycol (PNCO/PDMS) was also used. Polyurethane network elastomers were prepared from 4,4′‐diphenylmethane diisocyanate (or 2,4‐tolylene diisocyanate), and a mixture of 1,4‐butane diol and trimethylol propane by a prepolymer method. Mechanical properties, Tg, thermal stability, and hydrolytic stability were measured. Morphology were also measured by means of polarizing microscopy, dynamic viscoelastometer, and ESR. The properties of novel polyurethane elastomers have good mechanical properties comparable to those of the general purpose polyester urethanes, and better thermal and hydrolytic stability than PTMG‐based polyurethane. These polyurethane elastomers were exposed in out door during 2 year in Nagasaki, JAPAN. The novel polyurethane clastomers held alomost constant values for gel fraction, swelling ratio, relative modulus during 12 months, while poly(oxytetramethylene oxide)‐based polyurethane as a control decreased the these values. Relationship of degradation behaviors with chemical structure and morphology were discussed.
Aging in nonlinear optical polymer waveguides
Authors: Lindsay Geoffrey A. , Roberts M. Joseph , Nadler M. P. , Yee R. Y.
Published: April 2003

The role that polymers will play as optical waveguides in the photonic communications revolution is described, including examples of polymer photonic devices, physical and optical requirements, aging mechanisms, competing materials, electric‐field poled polymer films, room‐temperature processed polymer films, and analytical methods for studying physical aging. Several important recent aging studies on nonlinear optical polymers, both thermoplastic and thermoset, are reviewed.
Calculated and measured outdoor UV doses
Authors: Pickett James E. , Webb Karen K.
Published: April 2003

The ultraviolet (UV) radiation dose received by a sample is often the determining factor in its outdoor weathering lifetime. However, little relevant data exist for UV doses except for certain standard locations and orientations such as for the commercial test sites in Florida and Arizona. We have modified a computer program by Jokela based on other atmospheric radiation models in the literature to calculate UV doses for any latitude and orientation relative to standard exposure in Florida and have used the fraction of sunshine data for various sites that are readily available from meteorlogical compendia to correct for cloudiness. The usefulness of the calculations have been substantiated by examining the amount of yellowing in unstabilized polycarbonate films exposed at several orientations at six sites in the northern hemisphere. The calculations and doses inferred from the yellowing data are in generally good agreement, although there is increased error in highly cloudy regions and for the northerly exposures.
Chemiluminescence in thermal oxidation of rubbers under stress
Authors: Zlatkevich Lev
Published: April 2003

The thermal oxidative stability of 100 μm sulfur vulcanized latex film stretched to various extent was studied by means of the chemiluminescence technique in 130–160°C temperature interval. In the 130–150°C temperature region the induction period of oxidation increases with deformation, reaches a limiting value at about 60–70% and remains unchanged up to 200%. This effect becomes less pronounced as temperature rises from 130 to 150°C and at 160°C no change in the induction period with the extent of deformation is observed. The oxidation rate constant exhibited different behavior. It was constant in the entire region of deformations studied at 130°C, while a slight increase at extensions exceeding 100% was noticed at higher temperatures. Original sample exhibited a substantially reversible deformation at ambient conditions even when stretched 200% for 1 hour. On the other hand, preliminary 200% stretching for 30 min under nitrogen at 150°C led to 67% residual deformation at room temperature. The latter sample was found to be essentially less stable than the unstretched material. Surprisingly enough, 100% elongation imposed on the sample with residual deformation resulted in the improvement in stability which was primarily due to the rise in the induction period value. The activation energy of oxidation was 62.8 kJ/mol for unstrained and about 12.6 kJ/mol less for all strained samples.
A very effective method for the cationic modification of cellulose
Authors: Petzold Gudrun , Schwarz Simona , Buchhammer Heide‐Marie , Lunkwitz Klaus
Published: April 2003

The interaction between the oppositely charged polymers poly(diallyldimethylammonium chloride) (PDADMAC) and poly(maleic acid‐co‐α‐methylstyrene) (P(MAMS)) in the presence of cellulose can be used for strong surface modification. The dependence of the modification effect on the concentration of polymers and on the method of modification is investigated in detail. Different methods are applied to the characterization of the effect, e.g. polyelectrolyte titration, adsorption of an anionic dye, or measurement of zeta potential (streaming potential). All of these methods can represent the results very well under certain conditions. Polyelectrolyte titration is correlated to the outer layer of the modified material, whereas dye adsorption is sensitive rather to the inner surface region and is very time‐dependent. Another significant value is the isoelectric point, which is shifted to higher pH in dependence on the quantity of surface charges. The stability of modification, tested with different methods, was shown to be very good for water and good for treatment with hydrochloric acid.
Functionalized polyisobutenes by SH‐en addition
Authors: Gorski Ute , Maenz Karsten , Stadermann Dietmar
Published: April 2003

Low molecular weight polyisobutenes can be transformed into macromonomers by means of SH‐en addition, provided that the thiols contain an additional hydroxy group. The product structures formed by free‐radical or electrophilic addition reactions can be determined on model compounds as well as on the polymers by 1H‐ and 13C‐NMR spectroscopy.
Gas separation with organo‐soluble high performance aromatic polyimide films
Authors: Li Baozhong , Fan Guangyu , He Tianbai , Ding Mengxian
Published: April 2003

An organo‐soluble polyimide based on 4,4′‐(1,4‐phenylenedioxy)diphthalic anhydride and 2,2′‐dimethyl‐4,4′‐methylenedianiline was synthesized by two‐step polycondensation accompanied by chemical imidization. Polyimide films were prepared by spray casting onto glass substrates. The study focused on the separation of carbon dioxide (CO2) from natural gas and the enrichment of methane (CH4) from butane (C4H18). The permeability and permselectivity coefficients of these gases were determined.
Synthesis and characterization of polyazomethine conducting polymers and oligomers
Authors: El‐Shekeil Ali G. , Hamid Saad‐Addin M. K. , Ali Dheya A.
Published: April 2003

Conjugated polyazomethine polymers were prepared from the polycondensation of terephthalaldehyde with 4,4′‐thiodianiline, and 4,4‐thiodibenzaldehyde with 4,4′‐thiodianiline, 4,4′‐phenylenediamine and benzidine. The polymers showed good stability in air and were soluble in many organic solvents. The electrical conductivities of the undoped and doped (H2SO4 and I2) polymers were studied. Doping the polymers markedly increased their conductivities from 10−8 − 10−11 S cm−1 (dielectric region) to 10−3 − 10−5 S cm−1 (semiconducting region). The polymers were characterized by IR spectroscopy, elemental analyses, viscosity measurements and X‐ray diffraction.

Furthermore, polyazomethine oligomers were prepared and a comparative study of the physical properties of the oligomers and their corresponding polymers was performed. The electrical behavior of the oligomers was studied. It was found that oligomers with a minimum of eight aromatic (Ar) rings gave almost the same electrical conductivities as long‐chain polymers.
Synthèse d'une résine antistatique par introduction de sites ioniques dans le système Epikote 1001®‐Euredur 423®
Authors: Bonnans‐Plaisance Chantal , Cheradi Karim , Gressier Jean Claude , Greuin Odile , Nakache Evelyne
Published: April 2003

Le but de cette étude est d'apporter des propriétés antistatiques durables à la résine époxy obtenue à partir d'Epikote 1001® et d'Euredur 423®. Deux composés pouvant se lier chimiquement à la résine ont été choisis: le chlorure de (2,3‐époxypropyl)triméthylammonium qui contient un groupe époxy comme l'Epikote 1001® et un groupement chlorure d'ammonium pour les propriétés antistatiques et le 2‐aminoéthanesulfonate de tétrabutylammonium qui contient un groupement amine comme l'Euredur 423® et le groupement sulfonate. Différentes formulations de la résine ont été préparées avec ces deux composés. Leur viscosité et leur résistivité ont été mesurées. Des propriétés antistatiques ont été observées avec des échantillons à taux élevé de composé époxyde. Par contre, le composé à groupement amine n'a montré aucune propriété antistatique. Des tests de dureté et d'adhérence se sont révèlés intéressants pour les formulations présentant des propriétés antistatiques.
The state of water in styrene‐grafted and sulfonated poly(vinylidene fluoride) membranes
Authors: Hietala Sami , Holmberg Svante , Näsman Jan , Ostrovskii Denis , Paronen Mikael , Serimaa Ritva , Sundholm Franciska , Torell Lena , Torkkeli Mika
Published: April 2003

The state of water in proton exchange membranes prepared by pre‐irradiation (electron beam, 100 kGy) grafting of styrene onto poly(vinylidene fluoride) films (PVDF‐g‐PS), followed by sulfonation (PVDF‐g‐PSSA), has been studied with thermal analysis, Raman spectroscopy and small angle X‐ray diffraction (SAXS). Raman spectra show that, in addition to free liquid water in the membranes, single water molecules are weakly bound to the polymer backbone. Thermal analysis shows that there are three types of water molecules in the membrane; non‐freezable water associated with the ionic sites, freezable free water, and freezable bound water. The amount of non‐freezable water is around 10 H2O/SO3H (mol/mol), and is independent of the degree of grafting (d.o.g.). The amount of freezable water is strongly dependent on the d.o.g. as long as the grafting has not penetrated the whole of the film, and reaches a value of around 40 H2O/SO3H (mol/mol) above a d.o.g. of 50%. The conductivity of membranes containing only the non‐freezable water is low, i. e. the ionically bound water alone does not form the domains necessary for proton and water transport. SAXS measurements show that water/sulfonic acid clusters in hydrated PVDF‐g‐PSSA membranes with a Bragg distance of 25 Å are formed; these form the ion conducting channels in the membrane.
Metallization of poly(vinylidene fluoride) by reduction of polymer‐incorporated metal ions
Authors: Shibata Mitsuhiro , Yosomiya Ryutoku , Yosomiya Takatoshi
Published: April 2003

The metallization of poly(vinylidene fluoride) (PVdF) films by reduction of polymer‐incorporated metal chlorides and perchlorates with an aqueous NaBH4 solution was investigated. The conductivity of the metal layers deposited by reduction decreased in the order Cu2+ > Ni2+ > Co2+ > Fe3+ regarding the metal cation, and in the order of Cl− > ClO−4 regarding the counter anion. The high conductivity of the Cu layer deposited from PVdF containing CuCl2 is thought to be attributed to the facts that no side‐reaction occurs during the reduction in contrast to the formation of metal boride in CoCl2 and NiCl2 systems and iron oxides in FeCl3 system, and the surface of the Cu layer is smooth as compared with that obtained with the Cu(ClO4)2 system.
Tensile and flexural behavior of polypropene sheets with different crystallinities of surface layer
Authors: Kawamoto Naoshi , Mori Hideharu , Yui Nobuhiko , Nitta Koh‐hei , Terano Minoru
Published: April 2003

The tensile and flexural moduli of the compression‐molded sheets of polypropene with different surface layer crystallinity were investigated based on a layered composite model. It was found that the tensile stress‐strain curve and flexural deflection depended largely on the surface layer crystallinity, but the ultimate strain‐at‐break values were independent of the surface layer crystallinity. It is suggested that the tensile and flexural behavior can be characterized using a layered composite model in which a bulk plate was sandwiched between two surface layers.
Polymer composition versus low‐temperature characteristics of polysiloxane elastomers
Authors: Polmanteer K. E. , Hunter M. J.
Published: April 2003

Gehman cold‐flex, volume‐temperature, and stress‐temperature studies were used to investigate the low‐temperature characteristics of polysiloxane copolymers with respect to copolymer composition. A complete range of phenyl methyl‐dimethyl siloxane copolymers were examined as elastomeric compounds. Like other copolymers, the stiffening temperature was dependent upon the composition of the copolymer. Stiffening of the elastomers was due to crystallization in some cases and second‐order transition in others. Copolymers having either low or high amounts of PhMeSO stiffened because of crystallization, while copolymers of intermediate composition (7.5 to 15 mole‐% PhMeSiO) stiffened because of nearness to their respective second‐order transition temperatures. Second‐order transition temperature increased with the PhMeSiO content. For those siloxane polymers and copolymers that crystallized, the process was rapid when compared with crystallization behavior of other polymer systems. Only one minimum low‐temperature stiffening point was found in the phenyl methyl‐dimethyl siloxane copolymer system. The unique low‐temperature characteristics of polysiloxane elastomers are explainable on the basis of three factors. These are: (a) very flexible molecules, (b) low temperature coefficient of viscosity over a broad temperature range including low temperatures, and (c) copolymerizability of dimethyl siloxane with other siloxanes containing bulky pendant groups which lower the stiffening temperature.
Anisotropic properties of strained viscoelastic fluids. I. A method for measuring strain birefringence
Authors: Gill Stanley J.
Published: April 2003

A mechanism has been devised for the purpose of introducing a sudden strain of calculable amount into a viscoelastic fluid. The principle of the apparatus relies upon the deformation caused by the rotation of an elliptical sleeve about a flexible tube containing polymer solution. An apparatus has been constructed which can produce a 90° rotation (with consequent deformation) in the period of one millisecond. The detection of the strained state is accomplished by means of strain birefringence. In this way, relaxation can be studied in concentrated solutions for a time range beyond one millisecond.