bluuebunny/crossref_metadata_2025 huggingface dataset:
PSI3: An open‐source Ab Initio electronic structure package
Authors: Crawford T. Daniel , Sherrill C. David , Valeev Edward F. , Fermann Justin T. , King Rollin A. , Leininger Matthew L. , Brown Shawn T. , Janssen Curtis L. , Seidl Edward T. , Kenny Joseph P. , Allen Wesley D.
Published: April 2007

PSI3 is a program system and development platform for ab initio molecular electronic structure computations. The package includes mature programming interfaces for parsing user input, accessing commonly used data such as basis‐set information or molecular orbital coefficients, and retrieving and storing binary data (with no software limitations on file sizes or file‐system‐sizes), especially multi‐index quantities such as electron repulsion integrals. This platform is useful for the rapid implementation of both standard quantum chemical methods, as well as the development of new models. Features that have already been implemented include Hartree‐Fock, multiconfigurational self‐consistent‐field, second‐order Møller‐Plesset perturbation theory, coupled cluster, and configuration interaction wave functions. Distinctive capabilities include the ability to employ Gaussian basis functions with arbitrary angular momentum levels; linear R12 second‐order perturbation theory; coupled cluster frequency‐dependent response properties, including dipole polarizabilities and optical rotation; and diagonal Born‐Oppenheimer corrections with correlated wave functions. This article describes the programming infrastructure and main features of the package. PSI3 is available free of charge through the open‐source, GNU General Public License. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
Nickel peroxide: A more probable intermediate in the Ni(II)‐catalyzed decomposition of peroxomonosulfate
Authors: Thendral P. , Shailaja S. , Ramachandran M. S.
Published: April 2007

The Ni(II) ion catalyzed thermal decomposition of peroxomonosulfate (PMS) was studied in the pH range 3.42–5.89. The rate is first order in [PMS] and Ni(II) ion concentrations. At pH greater than or equal to 5.23, the reaction becomes zero order in [PMS] and this changeover in the order of the reaction occurs at a higher concentration of nickel ions. The first‐order kinetics in PMS can be explained as a rate‐limiting step and is the transformation of nickel peroxomonosulfate into nickel peroxide. This peroxide intermediate reacts rapidly with another PMS to give oxygen and Ni(II). The formation of nickel peroxide is associated with a small negative or nearly zero entropy of activation. The zero‐order kinetics in [PMS] can be explained by the fact that the hydrolysis of aquated nickel(II) ions into hydroxocompounds is the rate‐limiting step. The turnover number is 2 at pH 3.42 and increases with pH. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 320–237, 2007
Long‐term pulmonary function in survivors of childhood Hodgkin disease and non‐Hodgkin lymphoma
Authors: Oguz Aynur , Tayfun Tayyar , Citak Elvan Caglar , Karadeniz Ceyda , Tatlicioglu Turkan , Boyunaga Oznur , Bora Huseyin
Published: April 2007

Background

The aim of our study was to evaluate the long‐term effects of chemotherapy and/or radiotherapy on lung function in 75 childhood Hodgkin disease (HD) and non‐Hodgkin lymphoma (NHL) survivors several years after treatment.

Patients and Methods

We studied 37 HD and 38 NHL survivors. These patients were divided into two groups according to the treatment protocols applied. Group I consisted of 23 patients who were treated with both chemotherapy and thoracic irradiation and Group II consisted of 52 patients who were treated with chemotherapy and no thoracic irradiation. A detailed history of smoking habits, respiratory symptoms, and diseases was recorded. Complete physical examinations and pulmonary function tests [PFT, including spirometry, lung volume, and diffusion capacity for carbon monoxide (DLCO)] were performed on all subjects.

Results

No patients reported acute or chronic respiratory symptoms or diseases. Pulmonary function abnormality (reduced lung volume and diffusion capacity) was found in 13% of patients at a median 5 years after diagnosis. The percentage of predicted normal value of forced expiratory volume in the 1st sec (FEV1), residual volume (RV), and DLCO were significantly lower in Group I than these values for Group II. There were no significant differences in PFT parameters between patients with HD and NHL (P > 0.05). It appears that the risk of reduced lung function was greater the younger the patient in therapy.

Conclusion

Chemotherapy or chemo‐radiotherapy‐induced pulmonary sequalae in childhood may remain asymptomatic for many years. Pediatr Blood Cancer 2007;49:699–703. © 2007 Wiley‐Liss, Inc.
Effect of epoxidized oils and/or fortifier on glass fibre‐epoxy composites
Authors: Thakkar Jatin R. , Patel Ravji D. , Patel Ranjan G. , Patel Vithal S.
Published: April 2007

This paper deals with the effect of addition of epoxidized mowrah oil (EMO) and epoxidized cashew‐nut‐shell liquid (ECNSL) on the properties of glass fibre reinforced conventional epoxy resin, diglycidyl ether of bisphenol‐A (DGEBA) composites. The chemical resistance, tensile strength and flexural strength of the laminates increased, while impact and hardness were found to decrease on using these diluents with DGEBA. Dielectric properties such as breakdown strength, dielectric constant (ϵ′) dielectric loss (ϵ″) and loss tangent (tan δ) were compared. A significant improvement in the properties was observed on addition of 20 parts per hundred grams (phr) of an epoxy fortifier, a condensation product of phenyl glycidyl ether and 4‐hydroxyacetanilide.
Comparison of the thermal stabilities of some resin matrices for composites
Authors: Knight G. J. , Wright W. W.
Published: April 2007

The thermal stabilities of eleven different epoxy resin formulations, ten different polyimide resin formulations, a triazine resin formulation and two aromatic thermoplastic matrices have been compared by isothermal gravimetry in air. The overall activation energies for degradation as a function of percentage weight loss have been determined by regression analysis of the isothermal data. The values obtained indicate a very complex breakdown mechanism in the majority of cases.
Effects of inorganic electrolytes upon emulsion polymerisation reactions. I. Effects upon kinetics of styrene emulsion homopolymerisation and of styrene‐acrylic acid emulsion copolymerisation
Authors: Blackley David C. , Andries S. , Sebastian R. D.
Published: April 2007

Results are given for the effects of two added inorganic electrolytes, potassium chloride and calcium chloride, upon the kinetics of the emulsion homopolymerisation of styrene and of the emulsion copolymerisation of styrene with a minor amount of acrylic acid, using sodium dodecylbenzenesulphonate as surfactant and potassium persulphate as initiator. Three reaction systems were investigated. Two were for the emulsion homopolymerisation of styrene, one reaction system using a relatively high level of surfactant and the other a relatively low level of surfactant. The third reaction system was for the emulsion copolymerisation of styrene and acrylic acid using an intermediate level of surfactant. The results show that the effects of added electrolytes can be varied and complex: they depend upon several factors such as the nature and amount of the added electrolyte, the level of surfactant, and the presence or absence of the acidic comonomer.
Developments in modelling emulsion polymerisation processes
Authors: Brooks B. W.
Published: April 2007

Developments in models for emulsion polymerisation are considered; various types of model can be used and the choice depends on circumstances. Descriptions of batch processes include radical desorption, gel effects and molecular weight distributions. With flow reactors, allowance is made for variations in particle size and number. Population balances are useful in model formulation. Progress is being made with copolymerisation and the use of semi‐batch reactors.
Further experimental considerations on poly(dihalophenylene oxide)
Authors: Kisakürek Duygu , Türker Lemi
Published: April 2007

The decomposition of copper(II) 2,6‐dibromo‐4‐chlorophenoxide in acetonitrile yields poly(dihalophenylene oxide). 1H NMR study revealed that 1,4‐catenation was favoured over 1,2‐catenation, leading to higher linearity in the structure.
Some thermal studies on polystyrylpyridine resins and related model compounds
Authors: Bloch B. , Wright W. W.
Published: April 2007

Five model compounds representing part of the structure of polystyrylpy‐ridines have been studied using differential scanning calorimetry (DSC) and pyrolysis‐gas chromatography‐mass spectrometry (P‐GC‐MS). Cured resin samples have also been examined by pyrolysis‐gas chromatography‐mass spectrometry and thermogravimetry.

DSC showed that, with one exception, all the model compounds were crystalline as supplied and recrystallisation occurred readily on melting and cooling.

The breakdown products in P‐GC‐MS, with the exception of 1‐methyleneindene (produced from three of the model compounds), could all be explained on the basis of general bond scission followed by H or C6H5 transfer.

Thermogravimetry indicated the minimum cure cycle necessary to give optimum thermal stability on a weight loss basis.
Ionic conductivity of unsaturated polyester resin networks containing LiCIO4
Authors: Hu Chun Pu , Wright Peter V.
Published: April 2007

Poly(ethylene oxide) (PEO) 400‐maleate‐isophthalate resins have been prepared and LiCIO4 dissolved in the resins before crosslinking with 30% of styrene, vinylpyrrolidone or vinylpyridine. The DC conductivities of the resins were measured and found to increase in the order vinylpyridine 〈vinylpyrrolidone〉 styrene for the same [EO]/[Li+] ratio ( = 50). For the styrene system σ = 3 × 10−6Scm−1 at ambient temperatures and for the vinylpyridine system σ = 1 × 10−7 Scm−1. The Tgs of the system were also measured using dynamic mechanical thermal analysis and were found to be very close (257‐260 K). The above sequence was therefore attributed to stronger site‐binding of lithium ions at the more polar comonomers. An interpenetrating network (IPN) consisting of the styrene‐polyester and incorporating 40% PEO 400 was also prepared with[EO]/[Li+]ratios of 20 and 50. These gave ambient temperature conductivities of 1 × 10−5 and 3 × 10−5 Scm−1, respectively.
Studies on the incorporation of trans‐polyoctenylene in polystyrene and PVC blends
Authors: Lau Wayne W. Y. , Swee‐Hin Teoh , Suat‐Hong Goh
Published: April 2007

trans‐Polyoctenylene rubber, TOR, has been melt blended with PVC and with polystyrene, PS, in various proportions. PVC/TOR and PS/TOR blends were rigid, lending support to the claim that TOR improves dimensional stability of polymer and rubber blends. A processability study of PVC/TOR blends using a Brabender Plasti‐corder showed that TOR is a suitable processing aid for PVC.
Effect of culture conditions of acetic acid bacteria on cellulose biosynthesis
Authors: Kamide Kenji , Matsuda Yukiko , Iijima Hideki , Okajima Kunihiko
Published: April 2007

An attempt was made to clarify the effect of culture conditions of an acetic acid bacteria (Acetobacter xylinum) on cellulose biosynthesis using glucose as carbon source in complex medium. Synchronous culture conditions were first realised on cellulose biosynthesis by cooling the system to 4°C for 24 h. Under the synchronous conditions stepwise division of the cell and the stepwise production of cellulose were found. Furthermore, cellulose was proved to be produced when the cell number in the medium was constant.
VIscometric behaviour of Kevlar fibre filled liquid crystalline solutions of ethyl cellulose in m‐cresol
Authors: Suto Shinichi , Hayasaka Shin‐Ichi
Published: April 2007

Liquid crystalline solutions of ethyl cellulose in m‐cresol were mixed with Kevlar® fibres, and the viscometric behaviour with respect to temperature of those filled systems was determined with a cone‐plate type viscometer. The viscosity of the systems exhibited a maximum and a minimum at temperatures denoted by Tmax and Tmin' respectively. The effects of fibre on the critical temperatures (Tmax and Tmin) and critical concentrations (Ca and Cb) and on the viscosity enhancement are discussed.

Tmax and Tmin decreased with fibre concentration for single‐phase anisotropic solutions, whereas they increased for the biphasic solution. The critical concentrations increased with fibre concentration and Cb was more sensitive to the fibre than Ca. The viscosity enhancement due to the fibre depended on the phase of solution. In the single‐phase (isotropic and anisotropic), the viscosity enhanced with fibre; however, in the biphasic solution, the effect was not simple. The viscosity enhancement for the single‐phase anisotropic solutions with fibre was lower than that for the isotropic solutions.
Biomedical aspects of the direct measurement of the forces between adsorbed polymers and proteins
Authors: Luckham P. F. , Ansarifar M. A.
Published: April 2007

The forces between mica surfaces covered with an adsorbed layer of a wide range of polymers, polyelectrolytes and proteins are described as a function of the separation between the surfaces. For polymers in a good solvent at full coverages, repulsive forces are always observed, essentially due to osmotic forces. The range of the force increases as the molecular weight of the polymer increases. For adsorbed homopolymers a marked hysteresis on decompression (separation) of the surfaces is noted due to the polymer being forced to the surface and requiring many minutes to relax. For graft copolymers no hysteresis is observed and the force, for a given molecular weight polymer, is much longer range. Polyelectrolytes of opposite charge to mica adsorb flat on the surface in low electrolyte concentrations but extend away from the mica surfaces when adsorbed at high electrolyte concentrations giving rise to a ‘steric’ component to the fores. Forces between adsorbed layers of proteins were also measured. For concanavalin A (a lectin) and cytochrome C long‐range forces are dominated by electrostatic and van der Waals forces and are well described by classical colloid science. However, for myelin basic protein a long‐range attraction was noted, due possibly to hydrophobic interactions between the adsorbed protein.
Gelation—A review
Authors: Djabourov Madeleine
Published: April 2007

This paper reviews the modern ideas on the process of gelation which have arisen from the analogy between gelation and percolation. The basic features which are common to all types of gels, colloidal or polymeric systems are first recalled; then after a simplified presentation of the percolation model, a few examples illustrating these concepts are chosen (for chemical gelation, a copolymerisation reaction and for physical gelation, the gelatin sol‐gel transition). In conclusion, electron micrographs of gel networks (gelatin gel and an inorganic gel of thorium phosphate) are shown, which reveal the great diversity and complexity of the structures.
Increase in thermal stability of vinyl polymers through radical copolymerization with N‐cyclohexylmaleimide
Authors: Otsu Takayuki , Matsumoto Akikazu , Kubota Toru
Published: April 2007

It was found that radical polymerization of N‐cyclohexylmaleimide (CHMI) occurred readily under various polymerization conditions, and that the resulting poly(CHMI) had excellent thermal stability; i.e. the onset of decomposition was 362°C and the maximum rate of decomposition was observed at 430°C by thermogravimetric analysis in nitrogen. Subsequently, radical copolymerizations of CHMI with various vinyl monomers were performed, and the monomer reactivity ratios were determined from the copolymer composition curves obtained. It was found that CHMI copolymerized alternatingly with electron‐donating monomers such as styrene and isobutene. It was also discovered that facile copolymerizations proceeded with methyl acrylate and methyl methacrylate as electron‐accepting monomers, and with vinyl acetate and vinyl chloride as non‐conjugated monomers. It was verified that the introduction of the CHMI unit increased the thermal stability of common vinyl polymers.
Liver alcohol dehydrogenase immobilized in nylon tubing: ([Substrate]) kinetic behaviour
Authors: Roig M. G. , Bello J. B. , de Celis C. , Cachaza J. M. , Kennedy J. F.
Published: April 2007

The enzyme alcohol dehydrogenase (ADH) from horse liver (EC 1.1.1.1), cross‐linked through the bifunctional reagent glutaraldehyde, was immobilized in nylon tubing (35 μg/cm2 internal surface). The intrinsic v ([S]) kinetic behaviour of the immobilized ADH, analysed graphically and by non‐linear statistical fitting, was found to fit a polynomial quotient rate equation in [S] of minimum degree 2:2.
Chemical celluloses derived from Pinus radiata wood pulps for nitrocellulose preparation
Authors: Sioumis Anthony A. , Wallis Adrian F. A. , Puri Vinod P.
Published: April 2007

The nitration capabilities of a range of chemical celluloses, including some containing the cellulose‐II polymorph, were examined. The cellulose samples, derived from Pinus radiata wood by bisulphite, prehydrolysis‐kraft or kraft pulping, were compared with a commercial nitration‐grade cellulose and two bleached cotton linters samples. All samples on nitration gave nitrocelluloses (degree of substitution ≈ 2–45) which had satisfactory stabilities and solubilities, with the exception of a P. radiata bisulphite cellulose which had a high pentosan value. The presence of cellulose‐II in the samples was not an impediment to the nitration. High performance size exclusion chromatography of the nitrocelluloses showed that the molecular weight distributions of samples derived from the P. radiata celluloses were generally similar to that derived from a commercial nitration‐grade cellulose.
Morphological and kinetics study of PEO/PVC blends
Authors: Iragorri J. I. , Cesteros L. C. , Katime I.
Published: April 2007

The kinetics of spherulite radial growth and the morphology of the compatible system PEO/PVC have been studied by optical microscopy.

The usual spherulite radial growth behaviour has been found for compatible blends with PEO content higher than 70%. For lower composition, distortion of the usual spherulite morphology has been observed; the anomalies have been attributed to partial miscibility of the components.
Reaction kinetics of irradiation‐ prepolymerized methyl methacrylate‐polyurethane interpenetrating polymer networks by FTIR
Authors: Wang Geng‐Chao , Wang Jia‐Xun , Zhang Zhi‐Ping
Published: April 2007

The reaction kinetics of irradiation‐prepolymerized MMA‐PU (polyether) IPNs have been studied by FTIR. The results indicate that the polymerization of each component in the IPN follows its normal distinct reaction mechanism with no mutual interference. Increasing the concentration of TMPTMA (crosslinking agent of PMMA) increased the formation rate of PMMA, while the formation rate of PU networks remained almost the same. Increasing the concentration of TMP (crosslinking agent of PU) increased the formation rate of PU, while the formation rate of PMMA networks decreased. The formation rate of PU was obviously faster than that of PMMA. A theory for the cage effect of the PU network has been proposed.
Characterisation of polymers for semiconductor applications
Authors: Bradley Donal D. C.
Published: April 2007

The proposed use of polymers as active semiconductors in a variety of applications ranging from electronics, through electro‐optics to photonics represents a major extension to the current widespread commercial interest in polymers as electrically passive materials. In this paper the authors highlight some of the features of the class of material, namely the conjugated polymers that are of principal interest in this context, and they discuss the characterisation of these materials and their interesting physical responses.
2D and 3D NMR for polymer characterization
Authors: Mirau Peter A. , Heffner Sharon A. , Koegler Gerhard , Bovey Frank A.
Published: April 2007

High resoluton NMR can be used for polymer characterization both in solution and in the solid state. The power of NMR as a method arises from the observation of individual carbon and proton atoms along the main chain and side chains of polymers. This makes it possible to charaterize in detail the microstructure, the conformation, and the molecular organization in the solid. NMR experiments with more than one frequency dimension (2D and 3D NMR) have revolutionized materials characterization, mainly owing to the increase in resolution and the ability to visualize interactions that were previously obscured by peak overlap. It is possible not only to assign many peaks in the spectra, but also to explore interactions between polymer chains to understand at a molecular level the formation of compatible blends. NMR experiments in two and three dimensions can be combined to determine polymer chain conformation and chain packing. The goal of these studies is to understand the relationship between the polymer properties on a molecular level and the behaviour of bulk materials.
Polymer studies by simultaneous thermal analysis techniques
Authors: Redfern John P.
Published: April 2007

Simultaneous thermal analysis techniques (notably TG‐DSC and TG‐DTA) offer many clear advantages over techniques conducted singly. The advantages are enumerated. A more complete thermal profile is provided when a thermal analyser is coupled to some form of gas analyser such as a mass spectrometer or a FTIR analyser.

A brief description of the instrumentation is given, with particular reference to the interface in the case of coupled instrumentation since the coupled instruments each need to operate under optimum conditions. Interface design is therefore critical in enabling this and allowing rapid transfer while not degrading the species being transferred.

A number of polymer studies, including the thermal behaviour of uncured polyimide resin, polytetrafluoroethylene and polybutadiene, are discussed.
Relationship between gelation and morphology of rubber‐modified epoxy resins
Authors: Pucciariello Rachele , Villani Vincenzo , Bianchi Nadia , Braglia Roberto
Published: April 2007

The addition of both a solid and a liquid rubber to an epoxy resin has been shown to strongly increase the toughness of the material. Moreover, it is well known that toughening depends on the morphology of the system, which, in turn, depends on the cure conditions.

In the present work the morphologies of epoxy resins modified with mixtures of solid and liquid rubbers have been studied through transmission electron microscopy. An investigation of the influence of the elastomers and of the gel time on the morphology of the hardened material was carried out. Gel times were evaluated, through rheological measurements, at different cure temperatures.
Low temperature modification of polymers by triazolinediones. 3—blends of poly(oxy‐2,6‐dimethyl‐1,4‐phenylene) modified with 1,2,4‐triazoline‐3,5‐diones with polystyrene
Authors: Kuhrau Martin , Stadler Reimund
Published: April 2007

Poly(oxy‐2,6‐dimethyl‐1,4‐phenylene) (PPE) reacts with 1,2,4‐triazoline‐3,5‐diones to give poly([oxy‐2,6‐dimethyl‐3‐(1′, 2′,4′‐triazolidine‐3′,5′‐dione)‐1,4‐phenylene]‐co‐poly[oxy‐2,6‐dimethyl‐1,4‐phenylene]). Miscibility of these highly polar PPE copolymer with PS is probed for varying degree of polar substitution and various functional groups in the 4‐position of the heterocycle. The copolymers are miscible with polystyrene up to concentrations of counits of about 10%. For a selected blend system of PS and PPE modified with 4% of 4‐(4‐hydroxy‐3‐nitrophenyl)‐1,2,4‐triazoline‐3,5‐dione the concentration of PS was varied. Glass tion with triazolinediones, miscibility with polystyrene, Gordon‐Taylor equation.
Kinetic model for lonic polymerization initiated by difunctional initiator with monomer transfer
Authors: Feng Jing , Yan Deyue
Published: April 2007

The kinetics of difunctional ionic polymerization with monomer transfer and without assumption of instantaneous initiation is studied theoretically. The set of kinetic differential equations is rigorously solved by way of graphical theory. Expressions for the molecular weight distribution (MWD) function, the number‐ and weight‐average degrees of polymerization, and the distribution of functionality are obtained. A procedure is proposed for calculating the MWD curve and the values of other molecular parameters.
Morphology‐properties relationship in ternary polyamide‐6/ldpe/modified ldpe blends: Part II
Authors: Raval Heta , Singh Y. P. , Mehta M. H. , Devi Surekha
Published: April 2007

Grafting of butyl acrylate‐maleic anhydride copolymer on to LDPE was carried out by a solution polymerization technique. All the PA‐6/LDPE/LDPE‐g‐(BuA‐co‐MA) blends were prepared by a two‐step melt mixing technique. The blends were characterized by their morphology, mechanical properties and water absorption. By addition of just 2·4% of the LDPE‐g‐(BuA‐co‐MA), degree of grafting 12%, a remarkable improvement in the impact strength along with a reduction in water absorption of PA‐6 was observed.
Thermal properties of strained thermoplastic polymers
Authors: Möginger Bernhard , Fritz Ulrich
Published: April 2007

Injection moulded tensile bars of several amorphous and semi‐crystalline thermoplastic polymers have been deformed uniaxially to a macroscopic strain of 40% so that they showed necked and unnecked regions. From both the necked and unnecked regions of the tensile bars the specific heat and the thermal expansion coefficient were measured. The specific heat of the necked regions decreases about 20% with respect to unstrained samples for semi‐crystalline polymers at temperatures between 40°C and 60°C and for amorphous polymers at temperatures between 50°C and 70°C. The thermal expansion coefficient becomes negative at these temperatures. A smaller negative expansion coefficient is observed even in the unnecked region although nearly no change in specific heat can be observed. There is also an increase in the heat of fusion of the semi‐crystalline specimens of the necked region. Strain rate dependent effects on specific heat and thermal expansion were not observed within the accuracy of thermal analysis.
Kinetics of curing epoxy formulations with diaminodiphenyl ether
Authors: Jagadeesh K. S. , Siddaramaiah
Published: April 2007

Kinetic parameters for the reaction between tetra‐functional and trifunctional epoxy resins of diaminodiphenyl methane and 4‐aminophenol and diaminodiphenyl ether (DDE) were studied by dynamic DSC. The curing reaction of either the neat resin or the resin formulation is independent of the concentrations of DDE in a specific range and the mechanism follows with two rate constant values. The activation energies for various epoxy systems were determined by the Kissinger and Ozawa equations and are in good agreement even for other kinetic parameters.
Blends of sulphonated polystyrene and polystyrene: Morphology and deformation modes
Authors: Hara M. , Bellinger M. , Sauer J. A.
Published: April 2007

Blends of sulphonated polystyrene, neutralized with metal ions, have been prepared in various proportions with polystyrene homopolymer. Morphology, microstructure, and deformation modes of strained, cast thin films have been examined by transmission electron microscopy. Variables studied include blend composition and ion content. In blends of low ionomer concentration, the ionomer component phase‐separates and takes the form of small dispersed particles. With the increase of ion content, the average particle size increases and, as crazes develop in the matrix, particles elongate and fibrillate. These ionic crosslinked particles adhere well to the matrix, share in carrying the applied stress and reinforce the matrix polymer. Implications of these results for mechanical performance of bulk samples are discussed.
Crystallization behaviour of isotactic polypropylene/linear low density polyethylene blends
Authors: Long Yu , Stachurski Z. H. , Shanks R. A.
Published: April 2007

Crystallization behaviour of isotactic polypropylene/linear low density polyethylene (iPP/LLDPE) blends has been investigated by optical microscopy and DSC. Crystallization of iPP depends upon blend composition and thermal history. When blended with LLDPE, the crystallization temperature of iPP, Tc, decreased slightly. Crystallinity did not change in the range 0‐80wt% LLDPE; there were only slight changes in the crystalline structure, but LLDPE seemed to resist forming the β type of spherulites. Below 80 wt% of LLDPE, iPP was a continuous phase. The iPP spherulite growth rate was almost constant; however, overall crystallization decreased due to decreasing primary nuclei density.
DSC investigation of the physical ageing and deageing of wool
Authors: Huson Michael G.
Published: April 2007

Wool can be deaged both thermally and aqueously, resulting in disruption of the network of secondary bonds. The ensuing increase in mobility of the macromolecular chains manifests itself as a decrease in the glass transition temperature; hence this property can be used to monitor the ageing/deageing process. The extent and stability of the network that forms on ageing is a function of the temperature and time of formation. If samples are allowed to age for two consecutive periods of time at different temperatures then two independent networks are formed, each with its own characteristic glass transition temperature. The moisture content, thermal history and scan rate must be carefully controlled during any thermal analysis. It has also been shown that deageing can be used to facilitate the temporary setting of wool.
Effects of frequency, molecular weight and thermal oxidation on the dynamic mechanical response of poly (ethylene oxide)
Authors: Bigger S. W. , Scheirs J. , Delatycki O. , Billingham N. C.
Published: April 2007

The technique of dynamic mechanical thermal analysis (DMTA), operated in the dual cantilever mode, was used to characterize the effects of frequency, crystallinity, molecular weight (MW) and the extent of thermal oxidation on the dynamic mechanical response of poly(ethylene oxide) (PEO). The glass transition temperature (Tg) of PEO (MW = 9 × 105 Dalton) was found to be −44°C. For PEO (MW = 1 × 105 Dalton) the Tg is −39°C and this value increases by 2–9°C for every decade increase in the measuring frequency. Two minor, second‐order transitions of PEO are also discernible at −33 and 32°C. An inverse dependence of Tg on molecular weight was found in the molecular weight range studied and this is contrary to the Fox‐Flory theory. It was also found that a partially crystalline sample is obtained despite very rapid quenching of PEO from the melt into liquid nitrogen. Thermal oxidation of PEO before processing leads to an increase in the amplitude of the loss tangent peak. This reflects the effect of oxidation products in restricting polymer crystallization and the subsequent increase in the amorphous fraction of the polymer. The position of the Tg peak in PEO remains reasonably fixed with progressive ageing and this was attributed to crosslinking having occurred in addition to chain scission during thermal oxidation.
Staining techniques for detecting localized oxidation in high density polyethylene powders and films
Authors: Scheirs J. , Delatycki O. , Bigger S. W. , Billingham N. C.
Published: April 2007

Staining techniques, which reveal the heterogeneous nature of polymer oxidation, are reviewed. A sensitive staining technique is described which identifies the location and distribution of partially oxidized areas within the morphological structure of high density polyethylene (HDPE) powders and films. Gaseous sulfur dioxide (SO2) reacts specifically with the hydroperoxide groups in oxidized HDPE, producing macromolecular sulfates. Subsequent heating leads to the elimination of sulfuric acid and the formation of conjugated sequences along the polymer chains. Such conjugated regions can be readily identified using ultraviolet microscopy. The staining of oxidized polymers with gaseous reagents avoids problems, like extraction of oligomeric material, which are encountered when using conventional solvent‐based methods, e.g. 2,4‐dinitrophenylhydrazine staining.
Synthesis and study of thermal and electrical behaviour of some polyaromatic amines
Authors: Rawat B. , Kansara S. S. , Rama H. S.
Published: April 2007

Samples of polyaromatic amines were synthesised by chemical and electrochemical methods, using different amounts of electrolytes for the purpose of doping the polymer. These polymers were found to show electrical conductivity in the range 10−12–10−6 S/cm. A study of conductivity at various temperatures indicates the semiconducting behaviour of these polymers. Thermal analysis shows that these polymers have high thermal stability.
Synthesis and evaluation of paramagnetic particulates as contrast agents for magnetic resonance imaging (MRI)
Authors: Braybrook Julian H. , Hall Laurance D.
Published: April 2007

Formulations based on novel particulate ion‐exchange resins, containing a wide range of paramagnetic transition and rare‐earth metals bound to their surfaces, have been synthesised as potential contrast agents for the magnetic resonance imaging (MRI) of the gastro‐intestinal (GI) tract of man. They have been evaluated in terms of their effects upon the spin‐lattice (R1) and spin‐spin (R2) relaxation rates of the protons of water. Careful selection of the polymer, spacer‐arm, ligand and paramagnetic ion provides a means for subtle molecular tailoring.

Further potential applications have been highlighted based on the observed properties of such formulations.
Morphology of high surface area polypyrrole structures
Authors: Atchison Shaun N. , Burford Robert R. , Darragh Terrence A. , Tongtam Tantong
Published: April 2007

In this study pyrrole was electropolymerized into polymers having three types of morphology. In the first case, convoluted tubes and dendrites were deposited on filled polymeric and roughened electrodes. Secondly, free‐standing fractals were formed, radiating from central anodes. In some instances the polymers were grown across filter papers located at the base of the anode and at the surface of the solvent. In the third instance, high surface area fibrillar forms were obtained by in‐situ polymerization within coated, γ‐alumina isoporous membrane hosts, followed by leaching in alkali. In all cases the morphology of these products is described by optical and scanning electron microscopy.
Excimer fluorescence as a probe of miscibility in styrene copolymer blends
Authors: Haines David J. , Wilson Gerard J. , Ghiggino Kenneth P. , Hill David J. T.
Published: April 2007

The miscibility of styrene‐alt‐maleic anhydride (SMA) and a series of styrene‐acrylonitrile (SAN) copolymers in blends with either PMMA or PVC were examined by fluorescence and FTIR spectroscopic techniques. In the case of the alternating copolymer intra‐molecular excimer formation is precluded and changes in the excimer/monomer fluorescence intensity (IE/IM) reflect changes in the amount of inter‐chain excimer formation. The value of IE/IM in blends, therefore, provides a sensitive measure of phase separation (miscibility). In the case of the acrylonitrile copolymers the IE/IM of the blend had to be corrected to account for intra‐molecular excimers formed between adjacent chromophores in the SAN. These results compared favourably with observed frequency shifts in the phenyl C—H out‐of‐plane bend (∼700 cm−1).
Effects of mastication on the distribution of molecular weights and on the mechanical properties of native and commercial dental gutta percha (trans‐polyisoprene)
Authors: Arvanitoyannis Ioannis , Blanshard John M. V. , Kolokuris Ioannis
Published: April 2007

Mastication of gutta percha (trans‐polyisoprene) resulted in the selective scission of molecules, producing a narrower distribution of lower molecular weights. The mechanical properties of the samples also underwent a significant change due to mastication. The greater the content of incompatible substances (salts and oxides) in commercial gutta percha. the more substantial were these effects. The atmosphere (air, N2, O2) in which the experiments were conducted yielded significantly different results. The decrease in molecular weight was far greater in an O2 atmosphere than under a current of nitrogen or air, owing to the combination of double bonds with O2.
Surface activity of aqueous solutions of cellulose acetate with low degree of substitution
Authors: Kamide Kenji , Saito Masatoshi , Akedo Takaharu
Published: April 2007

Surface activity of aqueous solutions of cellulose acetate (CA) with total degree of substitution (〈F〉) ranging from 0.58 to 0.80 was examined. Critical micelle concentration (CMC) of the aqueous CA solutions, determined from the polymer concentration dependence of surface tension (γ), is unequivocally determined by 〈F〉, and an increase in 〈F〉 of CA brings about a lowering of the CMC. From light scattering measurements on aqueous solutions of CA with 〈F〉 = 0.8 at 20°C, it was revealed that in the vicinity of the CMC the micelles in the solution consist of c. four CA molecules, which is very close to the value obtained by analysing the data obtained from the mass action model. The surface tension of aqueous solutions of CA (〈F〉 = 0.8) in the polymer concentration range above the CMC was c. 0.74 times that of pure water over the temperature range 0–80°C.
Studies on polymer latex films: III. Permeability of latex films to aqueous organic solutes
Authors: Roulstone B. J. , Wilkinson M. C. , Hearn J.
Published: April 2007

The transport of p‐nitrophenol across films formed from surfactant‐free poly(butyl methacrylate) latices has been investigated with a view to better understanding the morphology of, and morphological changes occurring in, such films. The importance of the temperature and time, both of film formation and of storage, are identified and related to the state of coalescence of the latex particles within the films. especially with respect to interparticle boundaries.
On the interactions and miscibility of PVC/PMMA blends
Authors: Li Weisheng , Shi Lianghe , Shen Deyan , Zheng Jun
Published: April 2007

A DSC thermogram showed two separate glass transition temperatures in PVC/PMMA mixtures over the entire composition range; multiphase structures were observed in an optical microscope. FTIR spectra indicate that there are no strong specific interactions between these two polymers. The earlier studies on this blend system are briefly reviewed.
Apparent solubility parameters from photophysical investigation of copolymers with pendent naphthyl chromophores
Authors: McCormick C. L. , Hoyle C. E. , Clark M. D. , Schott T. A.
Published: April 2007

The effect of solvent on the formation of excimer from copolymers of 2‐(1‐naphthylacetyl)ethylacrylate (NAEA) with both acrylamide (AM) and N‐vinyl pyrollidone (VP) in dilute solution was investigated. A minimum in excimer intensity was observed for each of the copolymers at approximately 2.20 × 104 (J/m3)0.5. It is suggested that the relatively high content of NAEA in the copolymers (between 30 and 60%) governs the overall solubility parameter of the polymer.
Photoresponsive peptide and polypeptide systems: part II. Photochromism of poly(l‐ornithine) containing various azo‐contents in side chains
Authors: Yamamoto Hiroyuki , Ikeda Kengo , Nishida Ayako
Published: April 2007

Poly(L‐ornithine)s having various azo‐contents in the side chains were synthesized by the water‐soluble carbodiimide procedure. The photochemical properties of the polypeptides poly[Nδ‐p‐(phenylazo)benzoyl‐L‐ornithine] (PPABLO) containing 3–77 mol% azobenzene were investigated by absorption and circular dichroism spectroscopy in hexafluoro‐2‐propanol (HFIP) or water, and in HFIP‐water or methanol‐water solvent mixtures. The photochromism of the dichroic bands of the PPABLOs containing 20–77 mol% azobenzene in the visible and ultraviolet wavelength regions was found to be mostly reversible as a function of irradiation time at different wavelengths due to the photostationary state (above 80% trans‐cis photoisomerization) of the azo aromatic moieties. The PPABLO containing 3.2 mol% azobenzene in water exhibited conformational changes from random coil to helix by the addition of methanol or sodium dodecyl sulphate (SDS). The photo‐induced conformational change was observed in HFIP‐water‐SDS solvent mixtures, while no conformational change was seen in water and HFIP‐water solvent mixtures.
Modelling of emulsion copolymer microstructure
Authors: van Doremaele G. H. J. , van Herk A. M. , German A. L.
Published: April 2007

A model has been developed to describe stages II and III of batch emulsion copolymerization, and its predictive capabilities have been investigated by application to the system styrene‐methyl acrylate.

The main reaction site is considered to be the monomer‐swollen polymer particle. Copolymerization rate and copolymer microstructure (molar‐mass‐chemical‐composition distribution and sequence distribution at the triad level) are controlled by the local concentrations of monomers and free radicals inside the particles. The model accounts for radical absorption and desorption processes, bimolecular termination within the particles, and transfer to monomer and chain transfer agent. Monomer partitioning is described using experimentally determined relations. The results include rate of (co)polymerization. composition drift and copolymer microstructure.

It is demonstrated that ‘apparent’ reactivity ratios are generally incapable of describing the course of emulsion copolymerizations in an adequate manner.
Plasma surface modifications for improved biocompatibility of commercial polymers
Authors: Griesser Hans J. , Chatelier Ronald C. , Gengenbach Thomas R. , Vasic Zoran R. , Johnson Graham , Steele John G.
Published: April 2007

This report describes work using low pressure gas plasma techniques for the fabrication of surfaces designed for compatibility with biological tissue and fluids. The smoothness of the surfaces was investigated using scanning tunnelling microscopy (STM) and the wettability was assessed by measurement of air/water contact angles. Plasma surface treatment rendered fluorocarbon polymers wettable by polar liquids, but the wettability decreased with time during storage of the samples in air. Plasma polymerization, on the other hand, allowed the deposition of thin coatings which were more stable with time. STM of plasma polymers, which were coated with a sputtered film of platinum or gold, showed that these coatings were smooth and continuous. The attachment and growth of human umbilical artery endothelial cells was used to assess the biocompatibility of several plasma polymer surfaces. There was some correlation between the ability of a surface to grow cells and the wettability of that surface with polar liquids, but significant differences in cell growth on surfaces with very similar hydrophilicity indicated that other factors are at least as important.
Optical data storage by novel photoelectrochromic polymer
Authors: Nagamura Toshihiko , Isoda Yuji , Sakai Kenkichi
Published: April 2007

A novel elastic polymer containing 4,4′‐bipyridinium salts with tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate as part of the main chain was synthesized. The cast film showed persistent and reversible colour changes due to photoinduced electron transfer upon excitation of an ion‐pair charge‐transfer band (ex >365 nm) in vacuo. The lifetime of the coloured state markedly depended on temperature. The optically written data were stored without decay below 0°C and were erased thermally at elevated temperatures. The colour changes were reversibly repeatable for many times.
Asbestos replacement aspects: Modification of the fibre‐matrix interphase in lonomer based composites
Authors: Papaspyrides C. D. , Poulakis J.
Published: April 2007

Asbestos fibres, of the chrysotile variety, and chopped carbon fibres were pretreated by an in‐situ polycondensation technique eventually resulting in a polyamide coating on the fibre surface. Ionomer based composites containing either carbon or asbestos fibres in random in plane fibre orientation were prepared, and the influence of this coating process on the tensile properties was investigated. It was found that for the asbestos‐filled composites the presence of the nylon 6,6 interlayer improves the tensile performance, especially at moderate polyamide depositions. This is not the case with the pretreated carbon‐filled composites for which carbon fibres with higher polyamide contents are preferred. Combinations of the treated asbestos fibres with carbon and/or aramid fibres may be used to reduce the asbestos content in asbestos‐only based engineering plastics.
Supercritical fluid extraction of polymer additives for use in biocompatibility testing
Authors: Braybrook Julian H. , Mackay Graham A.
Published: April 2007

Biocompatibility is the ability of a material to perform with an appropriate host response in a specific application. This response is poorly understood and so there exist inconsistencies in test results both between different laboratories and within the same laboratory. Standard reference materials and test protocols are essential.

Analytical‐scale supercritical fluid extraction (SFE) has been investigated as a potential standard test protocol for obtaining additives from polymer matrices. These extracts have been analysed for in‐vitro cytotoxicity using standard cell culture techniques whose clinical relevance has already been established.
Synthesis and characterization of poly(siloxane‐urethane)s
Authors: Chun Yong‐Chul , Kim Kong‐Soo , Shin Jae‐Sup , Kim Kyung‐Ho
Published: April 2007

A series of polyurethane block copolymers based on hydroxy‐terminated polydimethylsiloxane and poly(propylene glycol) soft segments of molecular weights 1818 and 2000, respectively, were synthesized. The hard segments consisted of 4,4′‐diphenylnethane diisocyanate and 1,4‐butanediol as the chain extender. Samples with different molar ratios were prepared. We tried to synthesize polydimethylsiloxane‐based polyurethanes (PDMS‐PU) containing a hard block as major fraction and a soft block as minor fraction for preparing toughened rigid systems. After a study of the pure polydimethylsiloxane‐based polyurethane and poly(propylene glycol)‐based polyurethane (PPG‐PU), (mixed polyol)‐based block copolymers and blends of PDMS‐PU and PPG‐PU were synthesized, and characterized by means of differential scanning calorimetry, tensile testing and scanning electron microscopy. In (mixed polyol)‐based copolymers and lower hard‐segment content blends, macro‐phase separation occurred, but blends with higher hard‐segment contents showed significant reduction in amounts of phase separation.
Thermal stability of polypyrroles
Authors: Truong Van‐Tan , Ennis Brian C. , Turner Terrence G. , Jenden Charles M.
Published: April 2007

The effect of dopants and level of doping on the thermal stability of polypyrrole at 90, 120 and 150°C in dry air and nitrogen was investigated by monitoring the decay of conductivity. Polymers doped with aromatic anions (p‐toluene sulphonate and p‐chlorobenzene sulphonate) exhibit better stability than polymers doped with an aliphatic anion (dodecyl sulphate). The conductivity decay appears to follow diffusion controlled kinetics. After an initial decrease in conductivity, polypyrrole doped with p‐toluene sulphonate anion maintains a constant conductivity at 150°C in air for at least 4 weeks. Dedoping results in materials of lower conductivity but greater thermal stability. Differential scanning calorimetry (DSC) and thermogravimetry (TG) were found to be useful techniques to characterize and investigate thermal stability. Oxidation of polypyrrole films, monitored by DSC, shows diffusion controlled kinetics. Although both oxidation and conductivity decay show typical diffusion kinetics, oxidation is a necessary but not sufficient condition for the decay.