bluuebunny/crossref_metadata_2025 huggingface dataset:
Ischemic injury and repair process after transection in hypothyroid rat muscles
Authors: Ozawa Junya , Kawamata Seiichi , Kurosaki Tomoyuki , Iwamizu Yusuke , Matsuura Natsue , Abiko Sachiko , Kai Satoru
Published: April 2003

Hindlimb ischemia for 4 h, followed by reperfusion, resulted in necrosis of most soleus muscle in euthyroid rats, whereas only slight damage occurred in hypothyroid rats. Muscle repair after transection of the tibialis anterior muscle of hypothyroid rats showed delayed debris removal, initial retardation of myotube formation, and a higher incidence of aberrant sarcomeres in newly formed muscle fibers by electron microscopy. The protective mechanism against ischemia in hypothyroid muscles can probably be attributed to decreased degradation of high‐energy phosphates, reduced formation of substrates for xanthine oxidase during ischemia, and attenuated generation of harmful oxygen free radicals during reperfusion. Initial delay of myotube formation seems to reflect retarded proliferation of muscle precursor cells. Prolonged occurrence of aberrant sarcomeres in hypothyroidism is perhaps due to a delay or imbalance in the synthesis of proteins that assemble sarcomeres. These findings demonstrate the significant roles of thyroid hormones in ischemic injury and muscle repair. Muscle Nerve 27: 595–603, 2003
Force impairment in calpain 3–deficient mice is not correlated with mechanical disruption
Authors: Fougerousse Françoise , Gonin Patrick , Durand Muriel , Richard Isabelle , Raymackers Jean‐Marc
Published: April 2003

Defects in human calpain 3 are responsible for limb‐girdle muscular dystrophy type 2A, an autosomal‐recessive disorder characterized mainly by late‐onset proximal muscular atrophy. A corresponding murine model has previously been generated by gene targeting. In this report, muscular activity of calpain 3–deficient (capn3−/−) mice was evaluated at different ages. Growth curves showed a progressive global muscular atrophy. Histological examination throughout the lifespan of mice confirmed the dystrophic lesions. Whole animal tests showed only a mild significant impairment of the forelimbs. Studies of the mechanical properties of selected isolated fast‐ and slow‐twitch muscles demonstrated that slow‐twitch muscles were significantly weaker in capn3−/− mice than in wild‐type mice. Three different tests showed that there was no membrane disruption, suggesting a nonmechanical etiology of capn3−/− mice dystrophy. These findings are consistent with a mechanism involving signaling systems. Muscle Nerve 27: 616–623, 2003
Comparison of tension‐free vaginal taping versus modified burch colposuspension on urethral obstruction: A randomized controlled trial
Authors: Wang Alex C. , Chen Min‐Chi
Published: April 2003

Aims

To determine whether the tension‐free vaginal tape (TVT) procedure affects the mechanics of voiding in women with genuine stress incontinence (GSI).

Methods

Between July of 1997 and July of 1999, 116 women with GSI in the absence of pelvic prolapse underwent a randomized controlled study of TVT vs. modified Burch colposuspension. The trial was conducted by using a standardized protocol, including strict criteria for excluding preexisting bladder outlet obstruction (BOO). Urodynamic studies including free flowmetry, filling (provocative) and voiding cystometry, and 1‐hour pad test were performed before and at least 1 year after the operation. The Blaivas and Groutz nomogram was used as another criteria to assess the pre‐ and postoperative BOO.

Results

Eighteen women were excluded from the study as a result of having preexisting BOO and an additional 8 were lost to follow‐up. The comparison between pre‐ and postoperative variables for each procedure revealed that maximal flow rate of noninvasive uroflowmetry was significantly lower after operation in both groups (P = 0.009, P = 0.010, respectively). Detrusor pressure at maximal flow and urethral resistance were significantly higher and micturition volumes significantly lower after operation in the Burch group (P < 0.001, P < 0.001, P = 0.029, respectively). The difference between pre‐ and postoperative distribution of the obstruction nomogram of the Burch group was significantly different (P = 0.023).

Conclusions

Based on strict exclusion criteria for preoperative BOO, our findings strongly suggest that with a median 22 months (range, 12 to 36 months) of follow‐up, a properly performed tension‐free vaginal tape procedure does not cause urethral obstruction. Neurourol. Urodynam. 22:185–190, 2003. © 2003 Wiley‐Liss, Inc.
Falsely elevated postvoid residual urine in pregnant women
Authors: Tan Thai Lian , Logue Elizabeth , Griffiths Derek , Resnick Neil M.
Published: April 2003

Portable ultrasound assessment of postmicturition bladder for residual urine volume is rapid, accurate, and precise. However, other cystic pelvic pathologic conditions may present as a false‐positive finding on the ultrasound. We describe two cases in which the residual urine was falsely detected as being elevated due to unsuspected pregnancy. Neurourol. Urodynam. 22:261–262, 2003. © 2003 Wiley‐Liss, Inc.
Voiding urgency and detrusor contractility in women with overactive bladders
Authors: Cucchi A. , Siracusano S. , Guarnaschelli C. , Rovereto B.
Published: April 2003

Aims

To check whether the contractility of overactive bladders would be affected by voiding urgency.

Methods

We urodynamically studied 100 women: 20 normal controls (group 1), 60 patients with idiopathic detrusor overactivity (DO), and 20 with neurogenic DO from intracerebral lesions. The idiopathic DO groups 2A (n = 20), 2B (n = 20), and 3 (n = 20) had moderate, severe, and no voiding urgency, respectively. The neurogenic DO group 4 had severe urgency. The delay time of urgent void at cystometry (2 minutes or more or, respectively, less than 2 minutes) defined moderate or severe urgency. Detrusor contractility was defined by the maximum bladder external voiding power (WFmax).

Results

WFmax was higher in the idiopathic DO patients than in the controls, had the highest values in group 2B, and did not differ significantly between groups 1–4 and 2A–3.

Conclusions

We inferred from our data that idiopathic DO suggests a facilitation of voiding contractions and that such facilitation might be centrally amplified by severe urgency. This amplifying effect would probably be impaired in cases of neurogenic DO from intracerebral lesions. Neurourol. Urodynam. 22:223–226, 2003. © 2003 Wiley‐Liss, Inc.
Percutaneous tibial nerve stimulation in the treatment of overactive bladder: Urodynamic data
Authors: Vandoninck Vera , van Balken Michael R. , Finazzi Agrò Enrico , Petta Filomena , Micali Francesco , Heesakkers John P.F.A. , Debruyne Frans M.J. , Kiemeney Lambertus A.L.M. , Bemelmans Bart L.H.
Published: April 2003

Aim

The aim of this study was to evaluate urodynamic changes after percutaneous tibial nerve stimulation (PTNS) for the treatment of complaints related to overactive bladder syndrome and to search for urodynamic‐based predictive factors.

Methods

Ninety consecutive patients with symptoms related to overactive bladder syndrome were enrolled in this study. Patients underwent 12 PTNS sessions. For evaluating objective success, the primary outcome measure was a reduction in number of urinary leakage episodes of 50% or more per 24 hours. Patients' request for continuation of therapy was considered subjective success. This study focussed on urodynamic features at baseline and on changes found after 12 PTNS treatments.

Results

The objective success rate was 56% (leakages/24 hours). Subjective success rate was 64%. Frequency/volume chart data and quality of life scores improved significantly (P < 0.01). Pre‐ and posturodynamic data were available from 46 participants. Detrusor instabilities (DI) could be abolished in a few cases only. Increments in cystometric bladder capacity and in volume at DI were significant (P = 0.043 and 0.012, respectively). Subjects without detrusor instabilities at baseline were 1.7 times more prone to respond to PTNS (odds ratio, 1.75; 95% confidence interval [CI], 0.67–4.6). The more the bladder overactivity was pronounced, the less these patients were found to respond to PTNS, the area under the receiver operating curve was 0.644 (95% CI, 0.48–0.804).

Conclusion

PTNS could not abolish DI. PTNS increased cystometric capacity and delayed the onset of DI. Cystometry seemed useful to select good candidates: patients without DI or with late DI onset proved to be the best candidates for PTNS. Neurourol. Urodynam. 22:227–232, 2003. © 2003 Wiley‐Liss, Inc.
Mechanism and process of chemomechanical contraction of polyelectrolyte gels under electric field
Authors: Kishi R. , Hasebe M. , Hara M. , Osada Y.
Published: April 2003

When a water‐swollen polyelectrolyte gel is interposed between a pair of electrodes and DC current is applied, the gel undergoes electro‐chemomechanical contraction and concomitant water exudation both in water and in the air. In order to clarify the mechanism of the phenomenon, contractile experiments were carried out under various conditions and led to the conclusion that the contraction is essentially associated with electrically driven movement of hydrated micro‐ and macroions in the gel (electrokinetic process).
Evaluation of nonlinear optical susceptibility of polydiacetylenes by third harmonic generation
Authors: Nakanishi H. , Matsuda H. , Okada S. , Kato M.
Published: April 2003

Nonlinear optical susceptibility χ(3) of polydiacetylenes has been evaluated by third harmonic generation. First, in order to obtain the χ(3) tensor component along the polymer main chain, thin single crystals of two representative polydiacetylenes, poly‐PTS and poly‐DCHD were made by utilization of sampling technique in microscopy, i.e., the microtome cutting of single crystal embedded in plastic resin. The THG intensity observed was proportional to cos8θ, where θ was the angle between the polymer main chain and the polarization of laser light. The χ(3) value of poly‐DCHD was found to be rather higher than that of poly‐PTS. At resonant wavelength of 1.97 μm, the χ(3) of poly‐DCHD attained 8 x 10−10 esu. Furthermore, it was confirmed that when geometrical correction were properly made, the χ(3) obtained from polycrystalline thin film of poly‐PTS agreed well with that from thin single crystals. Secondary, regarding poly‐diphenyldiacetylene derivatives, it was found that the π‐conjugation between the polymer main chain and aromatic substituents was effective on the improvement of χ(3) values. The χ(3) magnitudes of poly‐BTFP and poly‐DFMP reflect well the dihedral angles between polymer main chain and the phenyl substituents (58° for poly‐BTFP and 67° for poly‐DFMP) as a measure of π‐conjugation. Especially, at nonresonant region of 2.1 μm the χ(3) of poly‐BTFP is about 5 times greater than that of poly‐PTS.
Studies of the structure of blends containing two liquid crystal polymers
Authors: DeMeuse Mark T. , Jaffe Michael
Published: April 2003

Blends in which both of the component materials are capable of forming liquid crystalline phases are considered in the present work. Solid‐state characterization data are presented that suggest that chemical reaction is not a dominant event when two such materials are blended in the melt. Also, ideas of small‐molecule liquid crystal mixing are shown to be not applicable to describe the behavior of this system. A formalism for describing blends of liquid crystal polymers, based on Windle's sequence matching arguments, is proposed.
Electrooptical properties of liquid crystalline side chain polymers with laterally attached mesogenic units
Authors: Hirschmann H. , Jungbauer D. A. , Wolf M. , Wendorff J. H. , Finkelmann H. , Hessel F.
Published: April 2003

The electrooptical properties of side‐chain liquid crystalline polymers were investigated for the case that the mesogenic units were attached laterally rather than longitudinally to a flexible chain backbone via flexible spacer units. The experimental finding is that these polymers display unusual electrooptical properties within the isotropic phase in the neighborhood of the transition into the nematic phase.

The polymers are characterized by the occurrence of a fast and a slow electrooptical response both of which show a critical divergence of the Kerr constant and the Kerr relaxation time. In addition, they show deviations between the rise and the decay values of the Kerr constants and in certain cases also of the Kerr relaxation times. Finally an overshoot of the induced birefringence following a sudden stepwise increase of the applied electric field has been found for one of these polymers. All these features can be accounted for on the basis of a newly developed theoretical approach that considers the particular dipolar and optical polarization configurations of these polymers.
Photocrosslinking of ultra high strength polyethylene fibers
Authors: Chen Yong Lie , Rånby Bengt
Published: April 2003

Ultra high strength polyethylene (HSPE) fibers have been successfully photocrosslinked using benzophenone as photoinitiator. The introduction of photoinitiator without disturbing the fiber structure is a difficult problem which was solved by vapor absorption at elevated temperature while keeping the fiber under constant strain. The crosslinked fiber showed no decrease in mechanical properties at room temperature as is the case when fibers are crosslinked by other reported methods such as radiation and chemical crosslinking. The crosslinked fiber showed enhanced high temperature resistance as well as much lower creep rate on prolonged stressing. Photocrosslinking of HSPE fiber is superior to other crosslinking methods reported in the literature.
New synthetic route of polyoxytetramethyleneglycol by use of heteropolyacids as catalyst
Authors: Aoshima Atsushi , Tonomura Shoichiro , Yamamatsu Setsuo
Published: April 2003

Polyoxytetramethyleneglycol (PTMG) can be directly prepared from tetrahydrofuran (THF) and water in the presence of heteropolyacids (HPA), without the hydrolysis step. The reaction is carried out by mixing two liquid phases: the THF phase and a heteropolyacid catalyst phase. In this reaction the molar ratio of water to a heteropolyacid (H2O/HPA) in the catalyst phase plays an important role in the THF polymerization activity and the molecular weight of PTMG. IR spectrometric studies revealed that THF is coordinated to a heteropolyanion through either a water molecule or a proton in the catalyst phase. The latter type of coordination bings about the activation of THF capable of initiating the ring‐opening polymerization even in the presence of water at a lower acid strength. The PTMG prepared by this method has a narrow molecular weight distribution (M̄w/M̄n = 1.5 or less) and a number average molecular weight of 500–2000 which are requisite for the production of polyurethane elastomers. A new polymerization mechanism named “Phase Transfer Polymerization” is proposed for elucidating a narrow molecular weight distribution.
Reinforcement of amorphous thermoplastics by blending with a para‐linked aromatic LC‐polyester
Authors: Claßen M. S. , Schmidt H.‐W. , Wendorff J. H.
Published: April 2003

The preparation and the mechanical properties of binary blends of amorphous thermoplastics and a para‐linked liquid crystalline polyester, which is expected to act as a reinforcement, are reported. The LC‐polyester has the advantage that it is soluble in common organic solvents, that it has a low transition temperature, and that it does not crystallize readily. Polycarbonate, polystyrene, poly(methyl methacrylate), and poly(ether sulfone) were selected as matrix materials. Most of the films cast from the blends turned out to be turbid and thus phase separated, the sizes of the dispersed phases ranging between 0.2 μm (in polycarbonate) and 1 μm (in polystyrene).

The LC‐polyester causes a substantial increase of the stiffness in blends with polycarbonate, poly(methyl methacrylate), and poly(ether sulfone) and almost no increase in the case of polystyrene. These differences are attributed to the particular magnitudes of the strength of the phase coupling between the matrix and the dispersed phase, which is controlled by their compatibility.
Features and origin of the dynamic and the nonlinear piezoelectricity in poly(vinylidene fluoride)
Authors: Harnischfeger P. , Jungnickel B.‐J.
Published: April 2003

Some of the piezoelectric coefficients of poly(vinylidene fluoride) are distinctly stress dependent. We report on their dependence on the frequency of an oscillatory stress excitation, on the amount of the remanent polarization in the sample materials, and on the magnitude of an offset stress. In order to explain the observed dynamic and nonlinear piezoelectric properties, a model is developed that attributes them to changes in the local polarization in an interphase between the crystalline and amorphous phases in this semicrystalline polymer.
Poled amorphous polymers for second‐order nonlinear optics
Authors: Eich Manfred , Bjorklund Gary C. , Yoon Do Y.
Published: April 2003

Recent advances in poled amorphous polymers for second‐order nonlinear optics are discussed with emphasis on stabilizing the frozen‐in nonlinearity via chemical crosslinking under electric fields. Specific examples of a linear polymer and a crosslinked polymer, both with nitroaniline‐type chromophores covalently attached as side groups, are presented and compared in their glass transition behavior, linear optical properties, poling dynamics, and stability of frozen‐in nonlinearity. It is demonstrated that by employing chemical crosslinking under electric fields one can prepare highly efficient and stable poled polymers that exhibit no decay in nonlinearity at ambient conditions and no apparent tendency of decay even at 85°C as well as excellent optical properties. The historical development of organic materials for second‐order nonlinear optics and recent advances in device fabrication based on poled polymers are also discussed briefly.
Curing and phase separation behavior of amine terminated butadiene acrylonitrile copolymer (ATBN) modified epoxy
Authors: Kim D. S. , Kim S. C.
Published: April 2003

The vitrification effect during the curing reaction of amine terminated butadiene acrylonitrile copolymer‐(ATBN)‐modified epoxy resin is studied by the differential scanning calorimetry. A new reaction kinetic equation is derived to describe the effect of vitrification on the reaction rate at both glassy and rubbery state of reactants. ATBN is added to improve the impact properties of the cured epoxy resin. The phase separation behavior during the curing reaction is analyzed by the light scattering and turbidity experiments. From the results of the cloud point measurements, it is observed that the ATBN‐epoxy system showed upper critical solution temperature (UCST) behavior. From the results of the light scattering experiments, the domain correlation length increases as the content of ATBN increases.
Gas transport in polyurethane–polystyrene interpenetrating polymer network membranes
Authors: Lee Doo Sung , Tak Tae‐Moon , Kim Geon Seok , Kim Sung Chul
Published: April 2003

The gas (oxygen and nitrogen) transport characteristics of the IPN membranes of polyurethane/polysturene were studied. The effect of synthesis temperature, composition, and crosslink density of the IPN membranes were analyzed. Polyurethane was prepared thermally and polystyrene was prepared by photolytic polymerization methods at various temperatures. The degree of intermixing between component polymers in the IPN membrane increased with decreasing synthesis temperature from 50°C to −10°C. The PS phase Tg was shifted inwardly up to 12°C. The permeability coefficient decreased and ideal separation factor increased also with decreasing the synthesis temperature due to the increase of miscibility. The permeability coefficient of oxygen and nitrogen ranged in the 10−10 and 10−10 order of magnitude. The permeability coefficient showed the minimum value and the ideal separation factor showed the maximum value at about 40 wt% polyrethane composition. The permeability data agreed well with the simple free volume model proposed by Lee [18].
Oxygen‐binding and transport in the liquid crystal membrane containing cobaltporphyrin as an oxygen carrier
Authors: Kawakami H. , Tsucla K. , Yamane K. , Nishide H. , Tsuchida E.
Published: April 2003

Composite membrane is prepared from (N‐methoxybenzylidene)‐4‐butylaniline as a liquid crystalline phase, poly(methyl‐methacrylate) as a support, and α,α,α,α‐tetrakis(o‐pivalamidophenyl)‐porphinatocobalt(II) (CoP) as an oxygen carrier. Phase separation and transitions for the liquid crystal containing CoP in the composite membrane are confirmed by SEM and DSC. Kinetic and equilibrium constants of oxygen‐binding to CoP moiety fixed in the liquid crystal phase are spectroscopically determined in situ, and are discontinuously changed at the phase transition temperatures. Oxygen transport in the composite membrane is facilitated, because CoP moiety effectively acts as a fixed carrier for the oxygen transport.
Structure and properties of dynamically cured EPDM and ionomer blends
Authors: Ha C. S. , Cho W. J. , Hur Y. S. , Kim S. C.
Published: April 2003

The structure and properties of dynamically cured ethylene‐propylene‐diene terpolymer (EPDM) and ionomer blends have been studied. The blends were prepared in a laboratory internal mixer, where EPDM was cured under shear in the presence of ionomer with dicumyl peroxide (DCP) under different shear conditions. The effects of EPDM/ionomer compositions, DCP concentration and the intensity of shear mixing were investigated using capillary rheometer, differential scanning calorimeter (DSC) and scanning electron microscopy (SEM) techniques. Two kinds of poly(ethylene‐co‐methacrylic acid) ionomers containing different metal ions(Na+ and Zn++) were compared and the effect of the metal ion type for neutralization was considered. The Zn‐neutralized ionomer showed better miscibility with EPDM than the Na‐neutralized ionomer. It is concluded from the rheological properties, crystallization behavior and morphology that the dynamically cured EPDM and Zn‐ion ionomer blends show the behavior of a thermoplastic interpenetrating polymer network (IPN).
Fluorescence study of polyelectrolyte complex formation III: Mobility of probes in microdomains
Authors: Itoh Yoshihiro , Hachimori Akira , Abe Koji
Published: April 2003

The mobility of fluorescent probe molecules in the microdomains formed by polyelectrolyte complexes (PEC) in aqueous solution was investigated by the fluorescence polarization method. The degree of fluorescence polarization (p) for the anthracene (Anth) chromophores attached to anionic polyelectrolytes increased with complexation, indicating the restricted mobility of probe molecules in the PEC microdomains. These p values depended on the properties of added polycations, which were not in parallel with the fluorescence intensities of the Anth chromophores.
Study of the carbon fiber–poly(ether–ether–ketone) (PEEK) interfaces, 1: surface characterization of fibers and matrices, and interfacial adhesion energy
Authors: Nardin M. , Asloun E. M. , Schultz J.
Published: April 2003

The aim of this general study is to determine the physicochemical characteristics and mechanical properties of carbon fiber–PEEK interfaces.
In the first part, the dispersive component of the surface energy and the electron acceptor–donor (acid–base) characteristics of PEEK polymer and different types of untreated and surface‐treated carbon fibers are determined by means of inverse gas–solid chromatography at infinite dilution. It appears, in particular, that the acid–base surface properties of PEEK and, consequently, the orientation of macromolecules near the surface, depend on the processing of this polymer. Moreover, according to previous work, an estimation of the adhesion energy, corresponding to physical interactions (London and acid–base interactions) at carbon fiber–PEEK interfaces is proposed. Whatever the surface characteristics of PEEK, the highest level of carbon fiber–PEEK adhesion is achieved in systems involving oxidized or sized carbon fibers.
Study of the carbon fiber–poly(ether–ether–ketone) (PEEK) interfaces, 2: relationship between interfacial shear strength and adhesion energy
Authors: Nardin M. , Asloun E. M. , Schultz J.
Published: April 2003

In the second part of this general study, the carbon fiber–PEEK interfacial shear strength is measured by means of a fragmentation test on single‐fiber composites. Different thermal treatments (continuous cooling from the melt, isothermal treatments and long melting temperature time) are applied to these model composites prior to testing. The results are systematically compared with the previously determined reversible work of adhesion between carbon fiber and PEEK. It is shown that physical interactions at the interface determine, to a large extent, the magnitude of the interfacial shear strength between both materials. However, it appears that the magnitude of the stress transfer from the matrix to the fiber is affected either by the existence of an interfacial layer or by a preferential orientation of the polymer chains near the fiber surface. The results obtained on systems that have been subjected to isothermal treatments (isothermal crystallization of PEEK) seem to confirm the existence of a transcrystalline interphase, the properties of which are dependent upon the crystallization rate of the matrix and the interfacial adhesion energy.
Influence of sorbed carbon dioxide on transition temperatures of poly(p‐phenylene sulphide)
Authors: Schultze J. D. , Engelmann I. A. D. , Boehning M. , Springer J.
Published: April 2003

Static pressure usually increases the transition temperatures of polymers by decreasing their free volume. If the pressurizing medium is soluble in the polymer matrix, the opposing effect of increasing the free volume is possible. Those shifts of transition temperatures were monitored with a medium‐pressure Differential Scanning Calorimetry (DSC) device. The influences of sorbed and surrounding gas molecules are demonstrated by changes occurring in the transition temperature regions. The results show the severe plasticizing effect of CO2 on poly(p‐phenylene sulphide) (PPS). The glass transition temperature TG and the temperature of crystallization TC are influenced by sorbed gas molecules. They decrease due to sorbed CO2 molecules. Glass transition is lowered, but is difficult to interpret, as relaxation phenomena which diminish with increasing pressure occur during DSC runs. In crystallites no gas solution is usually possible, so that the melting point of PPS is mainly affected by influences other than plasticization.
Photoreactive Langmuir–Blodgett–Kuhn multilayer assemblies from functionalized liquid‐crystalline side chain polymers, I. Homopolymers containing azobenzene chromophores
Authors: Sawodny Michael , Schmidt Albert , Stamm Manfred , Knoll Wolfgang , Urban Claus , Ringsdorf Helmut
Published: April 2003

Stable monomolecular layers of a liquid‐crystalline homopolymer bearing azobenzene chromophores in the mesogenic side groups could be prepared at the water–air interface by slow compression at room temperature. From the area per monomer unit of A0≈0.25 nm2 a structural model with tightly packed azobenzene groups oriented nearly parallel to the surface normal was deduced. After transfer to a solid support in a Y‐type mode the obtained Langmuir–Blodgett–Kuhn (LBK) multilayer assemblies of varying thicknesses (from a double layer to a thick film of d = 238 nm, capable of guiding optical modes) were prepared and analyzed by X‐ray reflection and optical evanescent wave techniques. A monolayer thickness of d0 = 2.52 nm, as well as the anisotropic index of refraction of these layers, could thus be evaluated.

Photo‐isomerization by UV‐irradiation (at λ = (360±30)nm) was examined by UV‐VIS absorption spectroscopy. X‐ray reflectivity data of samples illuminated for 30 min showed a complete loss of the layered structure of the LBK samples. As a result strongly light‐scattering films were obtained. Surface plasmon microscopy was used to demonstrate the usefulness of this photo‐induced order–disorder transition for optical information storage.
Investigation of phase morphology of incompatible polyethylene/nylon 6 blends containing EPDM‐based functionalized compatibilizers
Authors: Kim Jung Whan , Kim Sung Chul
Published: April 2003

Graft copolymer and graft terpolymer were prepared by solution grafting of maleic anhydride (MAH) or acrylonitrile (AN) alone and mixture of MAH and AN on to ethylene–propylene–diene terpolymer (EPDM) using benzoyl peroxide (BPO) as an initiator. The resulting EPDM‐g‐MAH, EPDM‐g‐AN and EPDM‐g‐(MAH‐co‐AN) have been used to obtain a binary blend of Nylon 6/functionalized EPDM and a ternary blend of polyethylene/Nylon 6/functionalized EPDM by melt blending. The effects of the nature and the amount of the grafted species on the phase morphology, crystallization behavior and mechanical properties of the blends were characterized through scanning electron microscopy, optical microscopy, infrared spectroscopy and using a dynamic mechanical analyzer. From the morphological study, it can clearly be seen that the presence of the functionalized EPDMs in these blends resulted in an improvement of the dispersion degree in incompatible polyethylene/Nylon 6 blends.
Glass‐reinforced epoxy novolac composites
Authors: Patel R. D. , Patel M. B. , Patel R. G. , Patel V. S.
Published: April 2003

Epoxy Phenolic novolac resins were prepared from the acid catalyzed condensation products of various phenols such as phenol, p‐cresol, p‐tert‐butyl‐phenol and cardanol with formaldehyde. All of these resins have been utilized to prepare the glass‐reinforced composites. The fabricated composites were evaluated for their mechanical and dielectric properties. The incorporation of an epoxy fortifier yielded a significant improvement in mechanical properties.
Interfacial tension of blends containing thermotropic liquid crystalline polymers
Authors: Kenig S.
Published: April 2003

A method is proposed to determine the interfacial tension of immiscible blends containing a liquid crystalline polymer (LCP) and a flexible‐molecule polymer, under flow conditions.

The method is based on Taylor's theorem for immiscible fluids, i.e., that a suspended drop of liquid A in liquid matrix B is deformed in shear or elongational flow in proportion to the ratio of interfacial to viscous stresses. Taylor's theorem, as originally derived, applies to low concentrations, Newtonian fluids and small deformations. Thus, the theorem was modified to account for “Power Law” fluids in elongational flow and large deformations, more applicable to the system under investigation.

The elongational viscosities of the LCP and the flexible polymer (polycarbonate) as a function of elongational rate were determined using converging type flow. The two polymers exhibited a Power‐Law behavior in elongational flow and, hence, the experimental constitutive equations of state were used to quantify the viscous stresses.

The interfacial stresses were modified for large deformations by taking into consideration the deformed shape and hence increased surface area of the elongated LCP particle. Using the modified expression, the interfacial tension of LCP and PC was determined to be in the range of 5–6.6 dyne/cm.
The Poole–Frenkel effect on nitrated poly(N‐vinylcarbazole)
Authors: Zamora F. , Franco A. D. , González M. C.
Published: April 2003

In studying electrical conduction of nitrated poly(N‐vinylcarbazole) (PNVC), several homodispersed samples of PNVC were nitrated by using two different nitration methods, resulting in mononitrated and dinitrated PNVC, respectively, with a really distinct polymer bulk structure which is responsible for the response of the charge carriers to an applied electric field. Electrical behavior in mononitrated PNVC is due to charge transfer complexes, while in dinitrated PNVC it is due to a dipole orientation effect.
Design of oxidation‐resistant coatings for high‐temperature composites
Authors: Jung Holger , Economy James
Published: April 2003

Fabrication of oxidation‐resistant carbon fiber reinforced carbon composites requires use of high‐temperature CVD deposition of coatings such as SiC. In this paper the use of low‐temperature chemical approaches for depositing oxidation‐resistant coatings was explored. Coatings of SiO2, B2O3, and SiC were examined, with the intent of distinguishing possible failure mechanisms. Factors contributing to poor oxidation resistance of these coatings include presence of microcracks in the original preparation of the coating and diffusion of oxygen through the coating at high temperatures.
Precipitation temperature of poly(ethylene glycol) in some electrolyte solutions
Authors: Oun A. M. , Daudi B. M. , Omar M. M.
Published: April 2003

The effect of sodium fluoride, sodium bromide, tetramethyl ammonium chloride, tetramethyl ammonium bromide and sodium formate on both precipitation and θ‐temperatures of poly(ethylene glycol) (Mw = 4000) in aqueous solution have been determined. Curves have been drawn to represent the effect of such ions on both the θ and the precipitation temperatures of the polymer. The effectiveness increases in the order (CH3)4 NBr, NaBr, (CH3)4NCl, NaF and HCOONa. The Mw‐temperatures obtained at infinite dilution are 445 K for NaBr, NaF, (CH3)4 NBr and (CH3)4NCl and 415 K for HCOONa.
Properties of glass‐fiber reinforced composites based on liquid diglycidyl ether of bisphenol‐c‐epoxy resin
Authors: Soni H. K. , Patel V. S. , Patel R. G.
Published: April 2003

Glass‐fiber reinforced epoxy composites were fabricated from the matrix resin liquid diglycidyl ether of bisphenol‐C (DGEBC) using various amines as curing agents with and without fortifier (20 phr). The epoxy laminates were evaluated for their mechanical properties, such as flexural strength, interlaminar shear strength (ILSS), tensile strength and shore‐D hardness. Dielectric properties, such as the dielectric constant, tan δ, dielectric loss and the resistivity of the laminated samples, were measured. The effect of the chemical reagents on the mechanical properties (i.e. flexural strength, lLSS) was also studied.
Positive working resists sensitive to visible light, I: poly(tert‐butyl and 2‐phenylpropyl‐2 methacrylates) sensitized with diphenyliodonium salt — p‐aminobenzylidene dye system
Authors: Ohe Yasushi , Ichimura Kunihiro
Published: April 2003

Visible‐light‐sensitive positive type resists have been developed. The chemistry to form images is based on the cleavage of side chain ester bonds of poly(methacrylates) catalyzed by an acid which is generated on sensitized photodecomposition of a diphenyliodonium (DPI) salt. Homopolymers and copolymers of tert‐butyl methacrylate (BMA) and 2‐phenylpropyl‐2 methacrylate (PPMA) were used as acid labile polymers. Exposure of thin films of the poly(methacrylates) containing DPI salt and p‐dimethylaminobenzylidene derivatives to an Ar laser beam emitting 488 nm light and subsequent heat treatment resulted in solubility alteration of the polymers, which became soluble in a protic solvent system. Considerable reduction of film thickness was observed after heating an image‐wise exposed thin film of PPMA polymers. The minimum exposure energies of 488 nm light for the positive image formation were 60 mJ/cm2 and 40 mJ/cm2 for BMA and PPMA homopolymers, respectively.
Phase transition of layer structure of poly(p‐benzenedithiol‐co‐p‐diethynylbenzene) by heat or photon mode
Authors: Kobayashi Eiichi , Ohashi Toyoshi , Furukawa Junji
Published: April 2003

Phase transition of the layer structure of poly(p‐benzenedithiol‐co‐p‐diethylbenzene) obtained in solid state polymerization was studied by a thermal treatment or UV irradiation under a nitrogen atmosphere. The peak intensities in the X‐ray diffraction diagram of polymers gradually decreased with the thermal treatment time above 55°C. Below 50°C the layer structure of polymers hardly changed. The apparent activation energy for the phase transition was about 15 Kcal/mol [63 KJ/mol] at the initial stage and gradually decreased to a few Kcal/mol [ca. 2 KJ/mol]. UV light from a high‐pressure mercury lamp also gradually induced the phase transition from the layer structure to an amorphous one. The pristine polymer possesses phase transition points at 75, 95 and 130°C. The exothermic transition at 75°C can be understood as the thermal destruction of the semistable layer structure. The exothermic transition at 95°C may be correspond to the cis → trans thermal isomerization of the C°C bond in the polymer main chain.

The diffuse reflectance spectrum of the pristine polymer differed from that of the amorphous polymer obtained by the thermal treatment of the pristine polymer. SEM photographs of the pristine polymer showed a particular surface structure, i.e. entangled fibrous material. TEM photographs of the pristine polymer exhibited a bright valley‐and‐hill structure, whereas that of the amorphous polymer obtained by thermal treatment exhibited a plain surface.
The effect of PVAc on the efficiency of thermal reactions in PS/PVAc blends in relation to the atmosphere
Authors: Kamińska A. , Kaczmarek H.
Published: April 2003

The thermal stability of polystyrene (PS) blends with polyvinyl acetate (PV Ac) has been investigated. It was found that PV Ac acts as a sensitizer of the thermal degradation of these blends when the process takes place in a nitrogen atmosphere. In air PV Ac acts as a stabilizer, and the temperature of the decomposition of these blends is higher than that of pure PS. This stabilization is caused by PV Ac favoring an oxidation reaction without breaking the polymer chains.
Modification of mono‐dispersed silica colloid particles with polymer silane coupling agents
Authors: Yoshinaga Kohji , Horie Ryouhei , Saigoh Futoshi , Kito Taketoshi , Enomoto Naoyuki , Nishida Hiroyasu , Komatsu Michio
Published: April 2003

The reaction of monodispersed silica colloid with hydrophobic and hydrophilic polymer coupling agents in the presence of ammonia afforded dispersible polymer/SiO2 composites into organic solvents without aggregation.
Diacetylenes and mesophases
Authors: Milburn  , Campbell
Published: April 2003

During the past five years, over 600 papers have been published on research work carried out with diacetylenes. Far fewer papers can be found on diacetylene mesophase studies, and these are reviewed in this paper. Some new findings by the authors are also presented.
Acid generation and deprotecting reaction by diphenyliodonium 9,10‐dimethoxyanthracene‐2‐sulfonate in a novolak positive photoresist based on chemical amplification
Authors: Naitoh Kazuhiko , Yamaoka Tsuguo , Umehara Akira
Published: April 2003

In a positive photoresist composed of diphenyliodonium 9,10‐dimethoxyanthracene‐2‐sulfonate as a novel photoacid generator, bisphenol A protected with tertbutoxycarbonyl group as a dissolution inhibitor, and a novolak resist matrix, the efficiency of photo‐acid generation and deprotective reaction were investigated by means of UV‐visible and IR spectroscopies. The quantitative measurement of photogenerated acid by using the acid‐sensitive dye exhibited 0.18 as the quantum yield of acid generation in novolak resin film. The lithographic evaluation of this system as a chemically amplified resist was studied. The catalytic chain length for the acid‐catalyzed deprotection step was determined as about 100 when 10 min post‐exposure bake (PEB) at 80°C was given. The sensitivity and the resolution as a positive resist are 180 mJ/cm2 and higher than 1 μm, respectively under the PEB conditions mentioned above.
Dielectric, magnetic and mechanical properties of ferrite composites
Authors: Biernholtz H. , Kenig S. , Dodiuk H.
Published: April 2003

The dielectric and magnetic properties of carbonyl—iron (CI) and nickel zinc ferrite polymer composites were studied with respect to the ferrite particulate content and microwave frequency. From the experimental data and using empirical models that relate the composite dielectric and magnetic properties, the respective dielectric and magnetic properties of the neat fillers were estimated. The tensile properties of the particulate composites comprising CI were shown to follow qualitatively Mooney's equation for the elastic modulus. The tensile strength of an elastomeric polyurethane and PVC composites containing CI increased with particulate content, while the elongation to break decreased with filler content. SEM micrographs of tensile fracture surfaces indicated that somewhat better adhesion is obtained in the case of the polyurethane‐based composites compared to the PVC ones.
Temperature‐dependences of cationic mobility and carrier generation in solid polyether media
Authors: Xu Kang , Wan Guoxiang , Tsuchida Eishun
Published: April 2003

The temperature‐dependences of cationic conductivity and mobility in a macromolecular lithium salt/copolyether blend were investigated by means of complex impedance analysis and a time‐of‐flight technique, respectively. The transient ionic current after reversing the d.c. bias polarity exhibits two peaks, corresponding to cationic and anionic movement respectively, and verifying a cationic transfer number of 0.99 at 50°C. The comparison between conductivity and mobility makes it possible to reveal the temperature‐dependence of the cation carrier number. As a result, the population of free ions was found to decrease exponentially with increasing temperature. However, this “anomalous” behavior of salt dissociation has little effect on the temperature‐dependence of conductivity, since it is cation carrier mobility rather than its number which is the main factor influencing the ion transport process.
A new method of growing crystalline networks in polymer matrices by simultaneous CT complex formation and in situ crystallization
Authors: Jeszka Jeremiasz. K. , Tracz Adam
Published: April 2003

A new method of preparing conductive polymer composites by growing crystalline networks of conductive additives in polymer matrices (reticulate doping) is described. The method consists of treating the polymer containing molecularly dispersed donor additive with acceptor/solvent vapors. In the swollen polymer layer simultaneously CT complex formation and crystallization takes place which for proper conditions leads to the formation of a network of the CT complex crystallites, making the film surface‐conducting.

The preparation and properties of surface conductive films using several electron donors and an iodine acceptor are described. The films obtained show surface resistivities of 104–106 ohm and are generally stable under ambient conditions.
Synthesis of polymers having photocrosslinkable moieties for second‐order nonlinear optics
Authors: Hashidate Sadahito , Nagasaki Yukio , Kato Masao , Okada Shuji , Matsuda Hiro , Minami Nobutsugu , Nakanisi Hachiro
Published: April 2003

Second‐order non‐linear optical polymers having photocrosslinkable moieties were synthesized by cationic polymerization of monomer (I) and monomer (II). The polymerization proceeded rapidly to give linear polymers in high yields. Monomer reactivity ratios were calculated to be r1 = 0.90 and r2 = 0.96 (r1r2 = 0.86), indicating that these monomers copolymerized through the almost ideal copolymerization mechanism. The photocrosslinking reaction of an equimolar copolymer film underwent the conversion of up to ca. 70% upon irradiation with a 500 W high‐presure mercury lamp for 5 min. The electric field induced polar orientation of the chromophores (pendant 4‐nitrophenyloxy groups) in a photocrosslinked polymer was stable for more than 10 days. This polymer exhibits a nonlinear coefficient d33 of 5.6 × 10‐10 esu measured at a pumping wavelength of 1064 nm.
Thermal properties of solvolysis lignin‐derived polyurethanes
Authors: Nakamura K. , Hatakeyama T. , Hatakeyama H.
Published: April 2003

Thermal properties of polyurethane (PU) films prepared from solvolysis lignin (SL), polyethylene glycol (PEG) and diphenylmethane diisocyanate (MDI) were examined by differential scanning calorimetry and thermogravimetry. In the SL—PEG—MDI system, the SL content, the molecular weight (Mn) of PEG and the NCO/OH ratio were changed in order to control the thermal properties. Glass transition temperatures (Tg's) of the prepared PU's were dependent on the SL content, the Mn of PEG and the NCO/OH ratio. However, the Tg of PU was significantly influenced by the SL content: the increment of Tg was ca. 150 K when the SL content in PEG increased from 0 to ca. 50%. The decomposition of the PU's was markedly dependent on the content of SL. Other factors, such as the NCO/OH ratio and the Mn of PEG, are less dominant compared with the SL content. This fact suggests that the dissociation between the isocyanate groups and the phenolic OH groups in SL may be the major factor in the whole process of the thermal decomposition of the PU containing SL
Helical unwinding in polymer‐dispersed ferroelectric liquid crystals
Authors: Kitzerow Heinz‐ S. , Molsen Henning , Heppke Gerd
Published: April 2003

We demonstrate that ferroelectric liquid crystals dispersed in a polymer matrix can form uniaxially aligned elliptical droplets. The alignment is controlled by mechanical shear during the polymerization of a UV‐curable adhesive. The possibility of prealignment makes polymer‐dispersed ferroelectric liquid crystals suitable for application in flexible electro‐optical displays. In contrast to surface stabilized ferroelectric liquid crystal displays, the electro‐optical effect in our system is due to the deformed‐helix ferroelectric (DHF) effect.
Probing the surface chemical structure of some novel poly(ortho esters) prepared with N‐methyl and N‐phenyl ethanolamine by time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS)
Authors: Davies M. C. , Leadley S. R. , Paul A. J. , Vickerman J. C. , Heller J. , Franson N. M.
Published: April 2003

The surface chemical structures of a series of novel poly(ortho ester) homopolymer and copolymer films prepared using N‐methyl‐ and N‐phenyl‐ethanolamine (MDE and PDE) have been investigated using time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS). Systematic fragmentation patterns were observed within the ToF‐SIMS spectra up to m/z = 1600, which were readily interpreted in terms of the polymer structures. Cations were detected which could be assigned to structures arising from the diols, the ortho ester species and diads, triads etc. of the monomer, from both the homopolymer and the random portion of the copolymer chains. The analysis of the proposed ion structures suggested two major mechanisms of fragmentation based on the cleavage of the ortho ester bonds involving either the exocyclic or the endocyclic alkoxy group. The Tof‐SIMS peak area ratios for ions diagnostic of the diols and the ortho ester species reflected the bulk copolymer composition in a semi‐quantitative fashion. The observation of such relationships for high mass cations (up to m/z = 500) is particularly noteworthy and has not been reported previously. These studies allow a dramatic insight into the surface chemical structure of these poly(ortho esters), information which has formed the foundation of current investigations on the mechanisms of the acid‐catalysed surface degradation of these polymers.