bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dispersive mixing in immiscible polymer blends
Authors: Gogos C. G. , Esseghir M. , Todd D. B. , Yu D. W. 
Published: March 2011

AbstractDispersive mixing of immiscible polymer blends as well as polymer systems containing solids is achieved in compounding equipment at two stages of the system's processing experience: first, while one or more of the polymer components are melting, and second, after all polymer components have melted. That is, the first mode of dispersive mixing occurs during the melting mechanism of “dissipative mix melting” (Ref. 1), while the second is melt‐melt mixing.During the compounding of a given blend system, there are a number of processing parameters that can be changed in order to improve mixing. These range from machine operating variables to the addition of processing aids. If such processing changes fail to produce the desired morphology, the most common change to consider is the screw geometry. This, in practice involves a trial and error procedure, or the use of an existing database built from prior experience.The role which the thermomechanical and rheological properties of the blend component play in dissipative mix melting and melt‐melt mixing has not yet been well understood. The reason for this is that although most blend systems have components which are strongly non‐Newtonian and strongly viscoelastic, the thinking and rules of thumb for mixing such materials has been heavily influenced by the analysis of G. I. Taylor (Ref. 2), who in 1932 addressed the phenomenon of the dispersion of a single Newtonian droplet by a Newtonian matrix flowing in laminar shear flow.This paper addresses the strong role that the rheology of blend components, under processing conditions, play in laminar dispersive mixing of polymer blends. From a practical point of view, if the dispersion mechanisms and rates of dispersion depend on the component rheology, then such knowledge can lead us to the selection of advantageous mixing element designs and processing conditions.The experimental results were obtained in dispersive mixing carried out in devices developed in the Polymer Mixing Study (Ref. 3). Such model devices include the Couette Flow Intensive Mixer (CIM) (Ref. 4), where a constant shear stress is applied on the blend components and the Twin Screw Mixing Element Evaluator (TSMEE) (Ref. 5), where the mixing flows are those encountered in actual mixing/compounding operations. The TSMEE will be described in the body of this paper together with its on‐ and off‐line morphology determination capabilities and its in‐line rheology sensor.The low‐density polyethylene (LDPE) and polystyrene (PS) polymers studied were selected because they cover a wide spectrum of rheological properties.
Synthesis and properties of disilanylene‐containing polymers
Authors: Ishikawa Mitsuo , Kunai Atsutaka , Ohshita Joji 
Published: March 2011

AbstractAlternating polymers, poly[(disilanylene)ethynylene]s and poly[(1, 2‐diethynylenedisilanylene)(1‐silacyclopenta‐2, 4‐diene‐3, 4‐diyl)]s were prepared by the anionic ring‐opening polymerization of 1, 2, 5, 6‐tetrasilacycloocta‐3, 7‐diynes and 4, 5, 10‐trisilacyclo[6.3.0]undeca‐1(11), 8‐diene‐2, 6‐diynes, respectively.Poly[(disilanylene)butenyne‐1, 4‐diyl]s were synthesized by the reaction of 1, 2‐diethynyldisilanes with a catalytic amount of RhCl(PPh3)3. Photochemical and conducting properties of the polymers are described.
Protein de novo design: Macromolecules with tailormade properties
Authors: Eggleston Ian M. , Mutter Manfred 
Published: March 2011

AbstractIn the absence of a detailed knowledge of the folding mechanism of natural proteins, the general design of polypeptide sequences with a high propensity to fold into a predetermined three dimensional structure still appears to be out of reach. The concept of Template Assembled Synthetic Proteins (TASP) represents a means by which one can nonetheless construct macromolecules with native‐like structural features, with the result that systems with tailormade structural and functional properties are now becoming attainable.
Wetting phenomena on polymeric surfaces
Authors: Shanahan Martin E. R. 
Published: March 2011

AbstractClassic theory predicts a unique value of equilibrium contact angle, θo, for a given solid/liquid/fluid system. However, wetting phenomena are often very complicated in practice, with contact angle hysteresis being a major source of problems in interpretation. Contact angle variability is related to several factors, but we consider two which are particularly relevant to polymeric substrates ‐ effects of orientation of molecular chains near the surface and local solid strain at the wetting front. A model is proposed to explain “stick‐slip” motion of the triple line.
Photochemical hole burning in polymers
Authors: Horie Kazuyuki 
Published: March 2011

AbstractThe possibility of photochemical hole burning (PHB) for various organic dyes is studied in relation to their Stokes shifts. Dyes with a Stokes shift smaller than 1000 cm−1 show the capability of hole formation. Based on this measure, the first observation of hole burning on the Soret (So→S2) band of a zinc tetrabenzoporphin has been realized, showing strong correlation between So‐S1 and So‐S2 transitions. Low‐temperature structural relaxation of various methacrylate polymers is also studied with PHB temperature‐cycle experiments.
Resonant opto‐optical switching in organic polymer waveguides
Authors: Franke H. 
Published: March 2011

AbstractPhotochromic polymer films are prepared by doping a polymer matrix like PMMA up to a few wt% with the fulgides “Aberchrome”. Opto optical switching is achieved in planar waveguides. Optical switching with gratings in waveguides and in transparent films is reported for latent gratings activated by uniform exposure.
Photoinitiated cationic polymerisation of multifunctional systems
Authors: Decker Christian , Decker Danielle , Viet Trieu Nguyen Thi , Le Xuan Hien 
Published: March 2011

AbstractDifferent types of tridimensional polymer networks have been synthetised by photoinitiated cationic polymerisation of vinyl ether and epoxy‐functionalised oligomers and polymers. The polymerisation kinetics was followed by real‐time infrared (RTIR) spectroscopy, a technique that records directly conversion versus time profiles in a timescale as short as 1 s. The addition of a diacrylate monomer was shown to accelerate the ring‐opening polymerisation of epoxidized polyisoprene, with formation of interpenetrating polymer networks having well contrasted properties. A dual polymer network has been generated by photocrosslinking of a polyisoprene functionalised with both epoxy and acrylate groups.
A novel polar polymer via romp
Authors: Davies Geoffrey. R. , Almond Peter. J. , Hubbard Hugh.V.St. A. , Ward Ian. M. , Feast William. J. , Gibson Vernon. C. , Khosravi Ezat , Marshall Edward. L. 
Published: March 2011

AbstractWe have synthesised poly(2,3‐bis(trifluoromethyl)norbornadiene) (PBTFMND) via ring‐opening metathesis polymerisation (ROMP) to yield a glassy, highly polar polymer. The high trans polymer is ∼92% tactic and the high cis polymer is ∼75% tactic but the type of tacticity cannot be determined by NMR techniques. Thermally Stimulated Depolarisation (TSD) measurements give relaxed susceptibilities as high as 45 for the high trans material but as low as 3 for the high cis material. These data suggest that both the trans and cis materials are syndiotactic. The high trans material can be poled to yield a maximum polarisation of about 20 mC m−2 and a pyroelectric coefficient of 6 μC m−2. Though this is less than that of PVDF, the low room temperature permittivity and loss of PBTFMND results in a pyroelectric figure of merit comparable with that of PVDF.
Synthesis strategies and properties of smart amphiphilic networks
Authors: Iván Béla , Feldthusen Jesper , Müller Axel H. E. 
Published: March 2011

AbstractThis paper briefly surveys recent developments in the field of amphiphilic networks (APN) which are a new class of crosslinked polymer systems consisting of covalently bonded hydrophobic and hydrophilic chain segments. The covalent bonds between immiscible hydrophobic and hydrophilic polymer chains prevent demixing and yield polymer networks with unique structure and properties. Telechelic macromonomers provide the basis for the first generation of APNs obtained by copolymerization of the macromonomer with selected low molecular weight monomers. Synthesis of a variety of APNs using methacrylate‐telechelic polyisobutylene (PIB) macromonomers prepared by living carbocationic polymerization (LCCP) and quantitative chain end derivatization is reviewed. The second generation of PIB‐based amphiphilic networks is prepared by crosslinking of well‐defined hydroxy‐telechelic PIB and partially deprotected silylated poly(2‐hydroxyethyl methacrylate) (PHEMA) precursor chains. Other opportunities providing better structural control of APNs by crosslinking of functional amphiphilic block copolymers (or precursors) obtained by combining living carbocationic and anionic polymerizations are outlined as well. Properties of APNs, such as control of swellability by composition, pH‐response of swelling, fast surface structure reorganization by contacting with solvent, morphology, sustained release of drugs and bio‐ and blood compatibility, are also summarized.
Nonlinear optical polymers. Second harmonic generation in corona‐poled thin films
Authors: Samyn Celest , Claes Goedele , van Beylen Marcel , De Wachter Anneleen , Persoons Andre 
Published: March 2011

AbstractThe synthesis and second harmonic coefficients, d3,1 and d3,3 as well as the related susceptibilities χ(2)zzz of five series of (NLO‐dye methacrylate)‐(methyl methacrylate) copolymers were investigated. The NLO‐chromophores bound covalently to the polymer backbone were 5‐(2,2‐dicyanovinyl)‐or 4‐(2‐cyano‐2‐methoxycarbonyl)vinyl‐1‐piperidino‐2‐thiophene (P1 and P2), 4‐nitro‐4′‐alkoxy‐stilbene (P3), 4‐nitro‐3′‐methoxy‐4′‐alkoxystilbene (P4) and 4‐nitro‐4′‐alkoxy‐α‐cyano stilbene (P5). The second order nonlinear optical properties of corona‐poled aligned thin polymer films, using a needle electrode in order to induce noncentrosymmetry, were evaluated.Nonlinear susceptibilities, χ(2)zzz, of the films were derived from the analysis of full‐angle Maker fringe patterns at 1064 nm, χ(2)zzz values as high as 1.98×10−7 esu for P2 copolymers and of 1.19×10−7 esu for P3 copolymers could be achieved.
Orientational effects in novel side‐chain liquid crystalline polyolefin blends
Authors: Mucha Maria , Wolski Adam , Ganicz Tomasz , Stanczyk Wojciech 
Published: March 2011

AbstractThe paper is concerned with an analysis of the dynamic properties of novel comb‐like liquid crystalline polycarbosilane, which are related to the reorientational processes responding to the applied ac electric field. Electro‐optical and switching effects of the polymer are estimated basing on the measurements of the transmitted light intensity as a function of temperature and ac electric field. The threshold voltage, rise and decay times are measured and discussed.
Well defined columnar liquid crystalline polydiethylsiloxane
Authors: Molenberg Aart , Siffrin Stefan , Möller Martin , Boileau Sylvie , Teyssié Dominique 
Published: March 2011

AbstractThe kinetics of the anionic ring opening polymerization of hexaethylcyclotrisiloxane (D3Et) with the cryptate Li+/[211] as counterion have been studied by means of 13C NMR spectroscopy. The propagation reaction was found to be of first order in monomer as well as living end concentration. It proceeds by two decades slower than the corresponding reaction with hexamethylcyclotrisiloxane (D3Me) as monomer. The Li+/[211] system could be used to synthesize well defined polydiethylsiloxane (PDES) samples (M̄w/M̄n <1.2). However, when the polymerization was aimed at high molecular weights (≥ 600 000 g/mol), the obtained molecular weights were lower than expected, and the molecular weight distributions became broader. All PDES samples were capable of forming a columnar mesophase. The temperature range in which this phase exists was found to be strongly molecular weight dependent. Initiation of the D3Et polymerization with polybutadienyllithium and coupling of the living chain ends yielded a PB‐PDES‐PB triblock copolymer, which could be crosslinked, resulting in a mesomorphic network.
Structure and mesophase of a new series of aromatic polyesters
Authors: Zhu Zhen 
Published: March 2011

AbstractA new series of aromatic polyesters in which the polymethylene flexible spacers are connected with the rigid main chain containing benzene ring were prepared by interfacial polycondensation. The polymers were characterized by hotstage polarized microscopy, differential scanning calorimetry, wide‐angle X‐ray diffraction and Fourier‐transform infrared spectroscopy. The structure and properties of polyesters were investigated. The results showed that the textures of the thermotropic liquid‐crystalline polyesters are smectic and/or nematic. The dependence of melting point, clearing point and transition enthalpy of polyesters on length of the alkylene group revealed a regular zig‐zag trend. The thermal analysis of polyesters revealed that the clearing transition is an equilibrium process, so the entropy of this transition may be taken as an indication of the degree of the order in mesomorphic state presented in the system. Furthermore, the thermal history of polymer had a significant effect on its thermal behavior. The regular arrangement of methylene segments changed when polymer melted from the crystal state to the liquid‐crystalline state. The research also implicated that the conformational change of the methylene flexible spacer was one of the reasons for this thermal effect.
Modification of the physical properties of polymers by supramolecular interactions
Authors: Rowan Alan E. , van Nunen Johanna L. M. , Schenning Albert P. H. J. , Nolte Roeland J. M. 
Published: March 2011

AbstractUsing molecular recognition, receptors based upon diphenylglycoluril have been clipped onto paraquat polymers and styrene copolymers. In the case of the former polymers, the viscosity and electrochemical behaviour was modified. In the case of the latter, liquid crystallinity was induced upon complexation.
Graft‐copolymerization of styrene on polypropylene in the solid phase
Authors: Beenen Welmoed , Wal Douwe J. v. D. , Janssen Léon P.B. M. , Buijtenhuijs Ab , Hogt André H. 
Published: March 2011

AbstractThe graft‐copolymerization of styrene on PP in the solid phase has been studied under various reaction conditions using a radical initiator. Polymerization kinetics were investigated by DSC experiments and reactions in glass ampoules. The conversion rate and grafting efficiency of styrene appeared to be strongly influenced by the presence of the PP matrix and the styrene/PP ratio. From reactions in a lab scale reactor the concentrations of styrene and initiator, the dosing rate and the temperature were investigated to be critical parameters determining the grafting efficiency and the average length and number of grafts. The phenomena observed were explained by describing the process in relative rates of diffusion and polymerization, including swelling of the polymer by styrene monomer and diffusion limitations (Trommsdorff effect).
The increase of conductivity of ethylene/acetylene copolymers by rolling
Authors: Aleshin Andrei.N. , Guk Elena.G. , Marikhin Vyacheslav.A. , Myasnikova Liubov P. , Belov Gennadii.P. , Belov Dmitrii.G. 
Published: March 2011

AbstractRolling of compact nascent PE/PA copolymer powder allows to increase the dc conductivity of rolled films by two order of magnitudes and to receive the oriented films of good quality with dc conductivity about 10−2S/cm.
Pressure dependence of the demixing behaviour in polymer blends: I. Experimental procedure
Authors: Zeuner Volker , Lentz Harro , Kleintjens Ludo A. 
Published: March 2011

AbstractThe most common way to influence the liquid‐liquid phase behaviour in partially miscible (co‐)polymer blends is changing the blending temperature. Since most extruders can handle pressures, up to 300 bar, pressure may also be used to influence the miscibility of polymers during blending.We have developed equipment and an experimental procedure to study the pressure dependence of the liquid‐liquid demixing behaviour of high‐viscous polymer blends under equilibrium conditions.Small amounts (1–4 grams) of specially made polymers are blended in the ‘DSM MINI EXTRUDER’. After a chosen mixing time, a small portion of the blend is injected into a small capillary tube and kept at the blending temperature.The phase behaviour of the blends as a function of temperature and pressure is studied via laser light scattering (at a scattering angle of 90°) in a specially made 400 bar/250°C window autoclave, where the capillary cell is placed in a high temperature grade silicon oil.
Polymers for medical uses
Authors: Höcker Hartwig , Klee Doris 
Published: March 2011

AbstractAn increasing demand for biomaterials corresponds to the deficiency in the knowledge on biocompatibility. To increase this knowledge the modification of polymer surfaces, their characterization, and the investigation of the response of the biosystem is considered to be a suitable approach.Surface modification may be performed in the wet‐chemical way (heterogeneous reaction) or by means of treatment with a suitable plasma (glow discharge). Surface sensitive methods such as X‐ray photoelectron spectroscopy, infrared spectroscopy in the attenuated total reflexion mode as well as surface energy measurements are useful for surface characterization.To determine the bioresponse to the polymer surface, enzyme‐linked immunosorbent assays, cell growth and full blood tests may be used.In the present paper several systems are described with respect to their surface modification, characterization, and bioresponse. It is shown that the protein adsorption is triggered by the surface, that SO2 plasma treatment enhances cell growth and that there seems to be a biocompatibility window for a surface characterized by a ξ‐potential between −4 and −8 mV and a ratio of dispersive to polar contributions of surface energy around 12.It is stressed, however, that the final solution for a biomaterial is a material which, in the course of degradation, constantly presents a new biocompatible surface.
Porosity control in nylon‐6/nylon‐6, 6 membranes
Authors: Tanaka Nobuyuki 
Published: March 2011

AbstractThe possibility of porosity control in N6/N66 membranes prepared from N6/N66 blend solutions of calcium chloride – methanol mixture was investigated. For N6/N66 blend solutions at 10 °C and 20 °C, the four‐phase structure of solid, gel 1, gel 2 and solution was observed clearly in the pore formation process after adding water on a solution surface. In the boundary part between gel 1 and gel 2, the phase separation of N6 and N66 was predicted. The macroscopic pores of blend membranes prepared at 10°C and 20 °C were almost spherical.
Polymer derivatives of glucocorticoid hormones
Authors: Panarin E. F. , Baikov V. E. , Timofeevsky S. L. , Nezhentsev M. V. , Vinogradov O. V. , Kalinin G. V. 
Published: March 2011

AbstractThe activated derivatives of hydrocortisone, prednisolone, and dexamethasone, crotonates, methacrylates, and haloacetates were synthesized by acylating native hormones with chloroanhydrides of the corresponding acids. Water‐soluble conjugates of steroids which bear a positive sign were obtained by reactions in chains of copolymers of vinylpyrrolidone and vinyl‐, allylamine, diethylaminoethyl methacrylate and diethylaminoethyl crotonate with steroid haloacetates. Water‐soluble derivatives bearing a negative sign were obtained by the acylation of steroids using vinylpyrrolidone copolymer with maleic anhydride. Non‐ionogenic water‐soluble polymers were synthesized by the copolymerization of vinylpyrrolidone with steroid methacrylates and crotonates. Cationic and anionic polyelectrolytes bearing steroid units were also obtained by the ternary copolymerization of vinylpyrrolidone with steroid crotonates, diethylaminoethyl crotonate and crotonic acid. The polymer steroids exhibit high specificity in the interaction with trans‐cortine and antybodies to cortisol and to target cells, thymocytes. The in vivo experiments revealed anti‐inflammatory activity on the level of native hormones. The antishock activity of polymer conjugates exeeds that of native hormones. It was detected that negative side effects characteristic of native hormones decrease markedly after they are bonded to a molecule of water‐soluble polymer. No effect of the sign of the macromolecule on the biological activity of modified hormones was detected.
From organic conductors to bio‐conductors
Authors: Inokuchi Hiroo 
Published: March 2011

AbstractTwo major categories of organic solids are known to offer the prospect of electrical conduction. One of them consists of charge‐transfer complexes such as BEDT‐TTF salts. A large number of studies on charge‐transfer complexes have been carried out and their conductivity ranges from semiconductor to superconductor. The other group comprises single component materials. Typical examples are polycyclic aromatic compounds and also phthalocyanines; their conductivities are not as good as those of the donor‐acceptor kinds.1) As one of those single component organic semiconductors, a group of cytochromes, electron carrier in biological system, was offered. Cytochrome c3 (molecular weight = 13,995, 107 amino acid residers), an electron carrier in the reactions of very negative potentials in cells of Desulfovibrio, has four homes in the molecule.
Structure development under transient shear flow in semidilute polystyrene solution
Authors: Murase Hiroki , Kume Takuji , Hashimoto Takeji , Ohta Yasuo , Mizukami Tohru 
Published: March 2011

AbstractThe shear‐induced concentration fluctuations or phase separation of a semidilute solution comprised of polystyrene (PS) as a solute and dioctylphthalate (DOP) as a solvent (PS/DOP) was investigated by using real‐time and in‐situ shear‐small‐angle light scattering and shear‐phase‐contrast optical microscopy. When a transient shear flow with a fixed shear rate γ greater than a critical value γC was imposed on the solution, a unique anisotropic scattering pattern was observed some time after onset of shear. This pattern was found to be identical to the “butterfly pattern” previously reported for the same solutions under steady shear flow with γC. When the shear flow was ceased before the scattered intensity reached a steady state, the scattered intensity rapidly increased toward a maximum intensity, and then decreased toward the intensity of the quiescent solution with time. From the phase‐contrast microscopy, this immediate increment of the scattered intensity after the shear cessation was found to arise from the increment in amplitude of the concentration fluctuations along flow direction. The characteristic length scale of the fluctuations was about 2.5 μm in this experiment, almost independent of the shear rate imposed on the solution.