bluuebunny/crossref_metadata_2025 huggingface dataset:
The Grieving Process of Japanese Mothers who have Lost a Child to Cancer, Part II: Establishing a New Relationship from the Memories
Authors: Saiki-Craighill Shigeko
Published: August 2002

Twenty-four Japanese mothers who had lost a child to cancer were interviewed periodically as part of a qualitative study, and the resulting data were analyzed to see how their perceptions of their deceased children changed over time. In the beginning of the grieving process, the mothers applied extra care to the handling of their children's remains and belongings, such as the corpse, ashes, and burial site. Once the mother had begun to adjust to the child's death, she started to feel that her child was inside or close to her. She was no longer obsessed with her child's remains and belongings. Also, her memories of the child changed, from specific, sad memories to recollections of the child's life as a whole. At the same time, her dreams about the child became positive. As a result, she developed a new relationship with her child.
Acetabular Component Orientation as an Indicator of Implant Luxation in Cemented Total Hip Arthroplasty
Authors: Cross Alan R. , Newell Susan M. , Chambers Jonathan N. , Shultz Kristin B. , Kubilis Paul S.
Published: August 2002

Objective—To determine the sensitivity and specificity with which acetabular component angles of inclination and version could be used, alone or in combination, to predict luxation of cemented total hip arthroplasties (THA).

Study Design—Comparison of retrospectively selected cases and controls

Sample Population—All THA performed at the University of Florida between 1991 and 1998 with the BioMedtrix system and for which at least 2 months of radiographic follow‐up were available. All THA performed at the University of Georgia with the BioMedtrix system which subsequently luxated.

Methods—Acetabular component inclination angle (IA) and acetabular version angle (VA) were determined for each THA. Data were grouped according to outcome—luxation or no luxation— with the luxated cases from the 2 institutions pooled. Receiver operator characteristic (ROC) analysis was used to evaluate decision rules for using IA and VA as tests for detecting postoperative luxation. Sensitivity and specificity for luxation and 95% confidence bounds were computed with selected values of IA and VA as cut‐points.

Results—The nonluxation group consisted of 68 THA with a median follow‐up time of 5 months (range, 2–60 months). The luxation group consisted of 12 THA with a mean time to luxation of 36 days. The nonluxation group had a mean ± standard deviation (SD) IA and VA of 40.3°± 8.9° and 71.1°± 13.6°, respectively, whereas the luxation group had a mean ± SD IA and VA of 34.7°± 12.6° and 72.9°± 16.6°, respectively. An IA cut‐point of 37.8° achieved 58.3% sensitivity and 57.4% specificity. A VA cut‐point of 73° achieved 75.0% sensitivity and 51.5% specificity. IA and VA considered simultaneously achieved a 50.0% sensitivity and 88.2% specificity.

Conclusions and Clinical Relevance—ROC analysis indicated that both IA and VA considered individually or simultaneously were poor indicators of luxation. Although extreme values of IA may predict luxation with high specificity, the potential for luxation cannot be excluded based on apparently appropriate values of IA and VA. The results of this study also indicate that a successful outcome is possible with a wide range of acetabular component positions.
Cecal Amputation Within the Right Ventral Colon for Surgical Treatment of Nonreducible Cecocolic Intussusception in 8 Horses
Authors: Hubert Jeremy D. , Hardy Joanne , Holcombe Susan J. , Moore Rustin M.
Published: August 2002

Objectives—To report a surgical technique for treatment of nonreducible cecocolic intussusception and outcome in 8 horses.

Study Design—Retrospective study.

Animals—Eight horses with nonreducible cecocolic intussusception treated by cecal amputation through a right ventral colotomy.

Methods—Data were obtained from medical records and telephone conversations by using a standardized questionnaire. The large colon was exteriorized and, if necessary, evacuated of its contents through a pelvic flexure enterotomy. A second colotomy was made on the ventral surface of the right ventral colon (RVC) centered over or immediately distal to the intussusceptum. In most horses, attempts to manually reduce the intussusception by pushing the cecum from within the RVC through the cecocolic orifice were unsuccessful. Invaginated cecum was then pulled into the RVC and amputated; the cecum was either ligated with umbilical tape or sutured proximal to the site of amputation. After amputation, the remainder of the invaginated cecum was reduced. After further resection to healthy tissue, the typhlectomy was closed with a double‐inverting suture pattern.

Results—The median horse age was 2 years (range, 1 to 8 years). Duration of colic ranged from 6 hours to 6 months. Median surgical time was 180 minutes (range, 135 to 300 minutes). Median duration of antibiotic therapy was 7 days (range, 5 to 14 days). Median duration of hospitalization was 12 days (range, 6 to 21 days). All horses survived to hospital discharge. One horse died 3 months postoperatively; however, the remainder survived (median survival, 30 months; range, 6 to 96 months) and returned to or exceeded previous function.

Clinical Relevance—Despite some contamination during surgery, horses with nonreducible cecocolic intussusception that underwent this method of surgical treatment had a good prognosis.
Evaluation of Samarium‐153 for Synovectomy in an Osteochondral Fragment‐Induced Model of Synovitis in Horses
Authors: Yarbrough T.B. , LEE M.R. , Hornof W.J. , Schumacher H.R. , O'Brien T.R.
Published: August 2002

Objective—To determine the effects of intraarticular administration of Samarium‐153 (153Sm) bound to hydroxyapatite microspheres (153SmM) on an osteochondral chip–Ninduced synovitis.

Study Design—Sixty days after implantation of autogenous osteochondral fragments in the middle carpal and metacarpophalangeal joints,153SmM was administered into 1 joint of each type. The contralateral joints were used as untreated controls.

Animals or Sample Population—Fifteen horses without preexisting joint disease were randomly divided into 2 groups (7 in the carpal group, 8 in the metacarpophalangeal group).

Methods—Horses had osteochondral fragments that were harvested from the lateral ridge of the trochlea of the talus and implanted bilaterally into a middle carpal joint and a metacarpophalangeal joint; the opposite joint type served as a control. Sixty days later, 10 to 15 mCi of153SmM (20 to 50 μm diam) was injected into the fragment‐implanted joints. Three horses were treated with nonradioactive hydroxyapatite fragments. Horses were examined clinically until they were killed 14 or 30 days later. Control and treated joints were examined grossly and microscopically to determine the effects of153SmM on synovial membrane and cartilage.

Results—Intraarticular153SmM caused a transient flare with lameness, effusion, and edema for 48 to 72 hours. Implanted osteochondral chips induced a synovitis characterized by variable degrees of joint damage and synovial infiltrate. Use of153SmM resulted in synovectomy of variable depth and extent.

Conclusions—Intraarticular153SmM may be a useful method for synovectomy of inflamed synovial membrane.

Clinical Relevance—With further testing, radioactive pharmaceuticals might become useful clinical treatments for persistent synovitis not responsive to conventional techniques.
Intraoperative Hemorrhage During Patent Ductus Arteriosus Ligation in Dogs
Authors: Hunt Geraldine B. , Simpson David J. , Beck Jason A. , Goldsmid Sarah E. , Lawrence Darien , Pearson Martin R.B. , Bellenger Christopher R.
Published: August 2002

Objective—To determine the prevalence of intraoperative hemorrhage in a consecutive series of dogs undergoing patent ductus arteriosus (PDA) ligation at a veterinary teaching hospital, and to describe strategies to reduce the risk of ductus perforation and deal with hemorrhage when it occurs.

Study Design—Retrospective clinical study.

Animals—Sixty‐four dogs.

Methods—The records of all dogs undergoing PDA ligation at the University Veterinary Center, Sydney between May 1989 and February 1998 were reviewed and the prevalence and nature of complications identified.

Results—Serious hemorrhage occurred in 4 of 64 dogs (6.25 %) that underwent PDA ligation. In all cases, hemorrhage resulted from perforation of the craniomedial aspect of the ductus while attempting to expose the tips of the dissecting forceps. Hemorrhage was controlled in 3 dogs by clamping the main pulmonary artery, digital compression of the descending aorta, and completion of ductus ligation during an approximately 5‐minute period of circulatory arrest. The remaining dog exsanguinated during an unsuccessful attempt to locate, clamp, and ligate the bleeding point. The mortality rate for PDA ligation was 1 of 64 dogs (1.6 %).

Conclusions—The technique described in this report permits simple ligation of a range of different ductus morphologies in dogs of varying breeds, weights, and ages. In the event of serious hemorrhage, prompt ventricular outflow occlusion and ductus ligation followed by rapid whole blood transfusion is life saving in most cases.
A Comparative Mechanical Study of 3 External Fixator Clamps
Authors: Gilley Robert S. , Bourgeault Craig A. , Wallace Larry J. , Bechtold Joan E.
Published: August 2002

Objective—To compare external fixator clamps from Kirschner‐Ehmer (K‐E), Synthes, and Meynard with respect to 6 mechanical parameters.

Study Design—A bench test of mechanical properties.

Methods—Specially designed fixtures were used to mechanically test 6 clamps of each type at 2.5, 5.0, and 7.5 Newton‐Meters of clamp bolt‐tightening torque.

Results—Components slipped axially and torsionally in the K‐E clamp at higher forces for all parameters except for clamp bolt axis pivot. No bolt axis pivot occurred with the Synthes clamp. Instead, the clamp plastically deformed at the fixator‐pin interface. This failure occurred at a higher applied torque than the pivot torque for other clamps. The Meynard clamp withstood significantly greater force than the K‐E clamp when torsion was applied to the clamp bolt axis in the clockwise direction. Pivot forces for the K‐E clamp were significantly higher than the Meynard clamp in the counterclockwise direction.

Conclusions—Overall, the K‐E clamp was able to resist higher axial and torsional forces before slipping than the Meynard clamp or the Synthes clamp. The Synthes clamp was best able to resist torsion around the clamp bolt axis. Torsional resistance at the clamp‐fixator pin and clamp‐connecting bar interface was the weakest parameter of clamp mechanics.

Clinical Relevance—The ability to resist motion within a clamp is related to fracture‐reduction stability. Knowledge of the mechanical properties of fixator clamps will improve a clinician's ability to apply rigid fixation.
Synthesis of Polymers in Aqueous Solutions: Heterogeneous Oxidation of Poly(Amide-Sulphide) in Water
Authors: Nishikubo Tadatomi , Kameyama Atsushi , Hosono Yoshinari , Yamada Youji
Published: August 2002

The heterogeneous oxidation of N-(2-phenylthioethyl)benzamide in a dispersion of water was performed with twice the amount of hydrogen peroxide at 60 °C for 72 h as a model reaction of the oxidation of poly(amide-sulphide) (polymer 1), and the corresponding N-[2-(phenylsulphoxy)-ethyl]benzamide and N-[2-(phenylsulphonyl)ethyl]benzamide were obtained in 5% and 95% yields respectively. This suggests that the alkyl phenyl sulphide group was easily oxidized with time via the alkyl phenyl sulphoxide group into the alkyl phenyl sulphone group. On the other hand, when heterogeneous oxidation of diphenyl sulphide in a dispersion of water was carried out with twice the amount of hydrogen peroxide at 60 °C for 72 h, the corresponding diphenyl sulphoxide and diphenyl sulphone were obtained in 77% and 23% yields, respectively. Therefore, the oxidation rate of the diphenyl sulphide group was much slower than that of the alkyl phenyl sulphide group, and the heterogeneous oxidation of diphenyl sulphide with excess hydrogen peroxide in a dispersion of water primarily produced diphenyl sulphoxide under the same conditions. On the basis of these model reactions, the heterogeneous oxidation of polymer 1, which was prepared by the polyaddition of bis(4-mercaptophenyl)sulphide with m-phenylenebis(2-oxazoline), was performed with one to three times the amount of hydrogen peroxide in a dispersion of water at 60 °C, and the Tg of the resulting polymers gradually increased with reaction time from 111 °C to 165 °C. When the oxidization was carried out with three times the amount of hydrogen peroxide for 48 h, the polymer with major structure, poly(amide-sulphone) (polymer 3), was obtained. Polymer 3 was also easily prepared by the oxidization of polymer 1 with equivalent amounts of sodium periodate in a dispersion of water at 60 °C for 48 h.
One-Pot Synthesis of Aromatic Polycarbodiimide by in Situ Activation of Diamine
Authors: Mochizuki Amane , Yoshioka Masahiro , Sakamoto Michie , Fukuoka Takahiro , Ueda Mitsuru
Published: August 2002

A one-pot synthesis of aromatic polycarbodiimide from aromatic diamine has been developed. This method involves the preparation of carbamate by the reaction of 4, 4′-hexafluoroisopropylidenebis( p-phenyleneoxy)dianiline (6FPA) with phenylchloroformate, followed by the transformation of the carbamate with trimethylsilylchloride-triethylamine to diisocyanate, and then the polycondensation of the resulting diisocyanate in the presence of 3-methyl-1-phenyl-2-phosopholene-1-oxide. The polycarbodiimide (6FPCD) from 6FPA was obtained in quantitative yield having a number average molecular weight up to 5000. The thermal treatment of 6FPCD gave a crosslinkined polymer having a high glass transition temperature up to 200 °C.
Lamellar Mesophases Formed by Thermotropic Liquid Crystalline Ionic Polymer Systems without Mesogenic Units
Authors: Ujiie Seiji , Takagi Shunsuke , Sato Moriyuki
Published: August 2002

Mixtures consisting of polyamine (branched polyethyleneimine (PEI) and polyallylamine (PAA)) and n-alkanoic acid (C n: n = the carbon number of alkanoic acid) were prepared and their thermal and liquid crystalline properties were examined. The occurrence of proton transfer from the carboxylic acid to the amine groups was found by IR measurement of the mixtures. The polyamines and C n exhibited no mesophase. Also, PEI/C n with n = 3, 4, 5, which are mixtures of PEI and C n, did not show a liquid crystalline phase. However, PEI/C n with n> 5 clearly displayed a lamellar fluid liquid crystal phase having a layer structure with low order inside the layer, due to ion–ion interactions. In the lamellar mesophase, PEI/C n showed a focal-conic fan texture which resembles the fan-shaped textures in smectic A and C phases. PEI/C n with 5 < n < 13 formed a bilayer structure in the lamellar mesophase. On the other hand, a tilted bilayer structure is proposed as a packing model of PEI/C n with 13 < n< 19. PAA/C18 consisting of polyallylamine and C18 also showed a lamellar fluid mesophase and formed a similar layer structure to PEI/C18.
Semirigid Homo- and Copoly(Imide-Carbonate)s Based on 3,4,3″,4″ -p-Terphenyltetracarboxdiimide
Authors: Sato Moriyuki , Ujiie Seiji , Tada Yuji , Kato Takashi
Published: August 2002

Novel thermotropic liquid crystalline (LC) semirigid homo- and copoly(imidecarbonate)s composed of a 3, 4, 3″, 4″- p-terphenyltetracarboxdiimide ring and aliphatic chains were prepared by melt polycondensation of a dihexanol derivative of 3, 4, 3″, 4″- p-terphenyltetracarboxdiimide and/or a dioxydihexanol of biphenyl taken in a definite molar ratio with hexamethylene diphenyl dicarbonate in the presence of zinc acetate, and their thermal and mesogenic properties were evaluated. The assigned structures of polymers were characterized by FT-IR and 13C NMR spectroscopy, and elemental analyses. DSC and TG-DTA measurements, polarizing microscope observations of textures and temperature-dependent x-ray analyses demonstrated that the polymers have wider LC temperature ranges (nematic phase) than analogous semirigid poly(ester-imide)s and are thermally stable up to 300 °C in air.
Thermostable Polymers: Spectroscopies and Thermal Studies of Bismaleimide Systems in the Solid State
Authors: Grenier-Loustalot Marie Florence , Da Cunha Louis
Published: August 2002

The study by DSC of two bismaleimide monomers (binary system BMI/BMI) mixed in different proportions led us to propose a phase diagram. The concept of a eutectic mixture having special thermal properties has thus been demonstrated. The eutectic melting temperatures are very interesting because they are much lower than that of the compound with the lowest melting point, facilitating the use of these monomers in the molten state. In the eutectic mixture, the two monomers were copolymerized and the resulting cross-linked networks characterized by 13C-NMR and FT-IR analysis.

Another study by FT-IR of binary BMI/diamine systems has shown the importance of steric hindrance caused by the diamine or the BMI in the context of the two principal reactions of copolymerization and homopolymerization expected in these systems. In each mixture studied, the addition of diamine changed the melting points, with a general decrease, the first in all cases remaining lower than that of the diamine alone (the most meltable compound) and the second much lower than that of the pure bismaleimide monomer considered. It was noted that increasing hindrance on the diamine reduced the extent of the copolymerization reaction and favoured the homopolymerization reaction in the molten state.
The Effect of Conformational Rigidity on Several Physical Properties of Polymers
Authors: Ronova I A , Pavlova S S A
Published: August 2002

The phenomenological dependences of several physical properties such as the softening temperature, friction coefficient, elasticity modulus, fire-resistance parameters and quantum luminescence yield on the conformational rigidity of a polymeric chain are revealed for polyheteroarylenes. The contribution of the conformational rigidity of a polymer chain to the physical properties of this class of polymers is shown to be significant. It should be taken into account in estimation of the above-mentioned properties together with the contribution of intermolecular interactions.
Kinetic Study of Epoxy-Amine Microwave Cure Reactions. Part I: Design and Operation of a Single-Mode Resonant Microwave Cavity
Authors: Rogers D G , Bialkowski M E , Hill Djt , George G A
Published: August 2002

The design and operation of a single mode, tunable, cylindrical microwave cavity is described. The cavity has been used to monitor the cure reactions of two epoxy-amine resin systems. The cavity operates at a microwave frequency of 2.45 GHz and a typical power in the range 0–8 W. It is fitted with an adjustable shorting plate which allows six different electromagnetic modes to be tuned. The isothermal cure of the resins MY721/DDS and MY721/DDM was monitored using fibre optics coupled with a Perkin Elmer 1600 FT-IR spectrometer operating in the NIR region. This allowed simultaneous, real time monitoring of the intensities of the primary and secondary amine overtone bands, as well as that of the epoxide groups. The temperature of the resins during cure was monitored by a fibre optic thermometer and was kept constant either by adjustment of the incident microwave power or by on-off switching of the microwave field.
Space Durable Polymer Threads
Authors: Schuler Peter , Haghighat Ross , Mojazza Hamid
Published: August 2002

A unique polymer called TORTM is being developed for use in twisted and braided sewing threads that exhibits excellent space durability in comparison with other organic polymers. Existing organic polymer threads for applications in low Earth orbit (LEO) can suffer significant erosion from the combined effects of atomic oxygen and vacuum ultraviolet radiation which compromise their mechanical and physical properties over time [1–3]. Several types of thread used to stitch multilayer insulation (MLI) blankets have limited lifespans due to these environmental effects. In ground-based testing conducted at Marshall Space Flight Center, TOR threads showed much lower mass loss, and retained significantly more strength after AO simulation than many competing materials.

This paper discusses the processing of TOR into fibres, the braiding of TOR around an inner Kevlar® core, characterization of the fibre to date, and potential applications for this product.
Polyimides Containing 1, 4-Dithiine Units and their Corresponding Thiophene 2, 3, 4, 5 Tetracarboxylimide Units
Authors: Gaina C , Gaina V , Sava M , Chiriac C
Published: August 2002

Polyimides containing 1, 4-dithiine units and corresponding thiophene units were synthesized by the nucleophilic substitution reaction of bis(dichloro-maleimide) arylene derivatives with sodium sulfide. Their structures were confirmed by IR and UV spectroscopy and elemental analysis. The polymers were characterized by viscosimetric measurements, softening points and thermogravimetric data.
Synthesis, Characterization and Fibre (Glass and Carbon) Reinforced Composites of Poly(Amido-Imide)s
Authors: Patel Hasmukh S , Dixit Bharat C , Patel Nilesh P
Published: August 2002

An amino-terminated oligoimide was prepared by the Michael addition reaction of 4, 4′-diamino diphenyl ether bismaleimide (DDEBM) and 4, 4′-diamino diphenyl methane (DDM) at a DDEBM:DDM molar ratio of 1:2. The poly(amido-imide)s (PAI)s were also prepared by condensation of this DDEBM:DDM oligoimide with various aliphatic bisesters. The resultant PAIs were characterized by elemental analysis, IR spectral studies and number average molecular weight ( Mn) estimated by non-aqueous conductometric titration. The curing behaviour of the diglycidyl ether of bisphenol-A (a commercial epoxy resin) (DGEBA)–PAI system was monitored by differential scanning calorimetry (DSC). Unreinforced PAI–epoxy cured products have also been prepared and analysed thermogravimetrically. Glass and carbon fibre reinforced laminates(i.e. composites) of the PAI–epoxy resin system have been prepared and duly characterized. Their mechanical properties have been compared with commercial composites.
Polyamides 4.10 and 4.12 and their Isomers
Authors: Koning Cor , Teuwen Lilian , de Jong Ruud , Janssen Gijs , Coussens Betty
Published: August 2002

A series of aliphatic 1, 4-diaminobutane based polyamides 4. y with y = 8, 9, 10 and 12 was synthesized and characterized. For comparison, some 1, 6-diaminohexane based counterparts were also studied. PA 4.12, and in particular PA 4.10, proved to have a very beneficial combination of Tm, crystallization rate and physical properties. First indications were obtained, that for a series of aliphatic polyamide isomers, containing 16 carbon atoms in the repeating unit, the melting points are related to the number of ways to make an energetically favourable chain fold upon crystallization: isomers having two possible ways of chain folding have Tms which are 13–15 °C lower than isomers having only one possible way of chain folding upon crystallization.
New Fluorinated Polyimides Based on 2, 4, 6-Trinitrotoluene Derivatives
Authors: Rusanov A L , Komarova L G , Prigozhina M P , Shevelev S A , Dutov M D , Korolev M A , Sapozhnikov O Yu
Published: August 2002

The interaction of the demethylation product of 1, 3, 5-trinitrobenzene—2, 4, 6-trinitrotoluene—with fluorinated alcohols followed by reduction of the perfluoroalkoxy-substituted m-dinitrobenzenes thus formed led to the formation of new fluorinated diamines. The reaction of these diamines with aromatic tetracarboxylic acid dianhydrides led to the formation of new fluorinated polyimides combining solubility in organic solvents with large ‘windows’ between glass transition and degradation temperatures.
Aromatic and Heterocyclic Polymers—What Future?
Authors: Sillion B
Published: August 2002

This paper discusses the evolution observed in the field of high performance polymers and tries to forecast the future in different domains. The paper is divided into four sections: 1. From the 1960s to the 21st century. 2. What’s new in chemistry and why? 3. What could be the future for high performance polymers in structural applications, electrical industries, electronic and electro-optical industries, membrane technologies, fuel cell membranes and other fields such as conductive polymers. 4. Concluding remarks.
The Effect of Low Earth Orbit Atomic Oxygen Exposure on Phenylphosphine Oxide-Containing Polymers
Authors: Connell John W
Published: August 2002

Thin films of phenylphosphine oxide-containing polymers were exposed to low Earth orbit aboard a space shuttle flight (STS-85) as part of flight experiment designated Evaluation of Space Environment and Effects on Materials (ESEM). This flight experiment was a cooperative effort between the NASA Langley Research Center (LaRC) and the National Space Development Agency of Japan (NASDA). The thin-film samples described herein were part of an atomic oxygen exposure (AOE) experiment and were exposed to primarily atomic oxygen (∼1×1019 atoms cm−2). The thin-film samples consisted of three phosphine oxide-containing polymers (arylene ether, benzimidazole and imide). Based on post-flight analyses using atomic force microscopy, x-ray photo-electron spectroscopy and weight loss data, it was found that the exposure of these materials to atomic oxygen (AO) produces a phosphorus oxide layer on the surface of the samples. Earlier work has shown that this layer provides a barrier towards further attack by AO. Consequently, these materials do not exhibit linear erosion rates which is in contrast with most organic polymers. Qualitatively, the results obtained from these analyses compare favourably with those obtained from samples exposed to AO and/or an oxygen plasma in ground-based exposure experiments. The results of the low Earth orbit AO exposure on these materials will be compared with those of ground-based exposure to AO.
Insights into the Damage Mechanism of Teflon® FEP from the Hubble Space Telescope
Authors: de Groh Kim K , Gaier James R , Hall Rachelle L , Espe Matthew P , Cato Daveen R , Sutter James K , Scheimank Daniel A
Published: August 2002

Metallized Teflon® FEP (fluorinated ethylene propylene) thermal control material on the Hubble Space Telescope (HST) has been found to be degrading in the space environment. Teflon® FEP thermal control blankets (space-facing FEP) retrieved during the first servicing mission (SM1) were found to be embrittled on solar-facing surfaces and contained microscopic cracks. During the second servicing mission (SM2) astronauts noticed that the FEP outer layer of the multi-layer insulation (MLI) covering the telescope was cracked in many locations around the telescope. Large cracks were observed on the light shield, forward shell and equipment bays. A tightly curled piece of cracked FEP from the light shield was retrieved during SM2 and was severely embrittled, as witnessed by ground testing. A failure review board was organized to determine the mechanism causing the MLI degradation. Density, x-ray crystallinity and solid-state nuclear magnetic resonance (NMR) analyses of the FEP retrieved during SM1 were inconsistent with results of FEP retrieved during SM2. Because the retrieved SM2 material was curled while in space, it experienced a higher temperature extreme during thermal cycling, estimated at 200°C, than the SM1 material, estimated at 50°C. An investigation on the effects of heating pristine FEP and FEP retrieved from the HST was therefore conducted. Samples of pristine, SM1 and SM2 FEP were heated to 200°C and evaluated for changes in density and morphology. Elevated-temperature exposure was found to have a major impact on the density of the retrieved materials. The characterization of the polymer morphology of the as-received and heated FEP by NMR provided results that were consistent with the density results. Differential scanning calorimetry (DSC) was conducted on pristine, SM1 and SM2 FEP. DSC results provided evidence of chain scission and increased crystallinity in the space exposed FEP, which supported the density and NMR results. Samples exposed to simulated solar flare x-rays, thermal cycling and long-term thermal exposure provided information on the environmental contributions to degradation. These findings have provided insight into the damage mechanisms of FEP in the space environment.
Synthesis and Characterization of Aromatic Polyimides Bearing Nonlinear Optical Chromophores
Authors: Bes L , Rousseau A , Boutevin B , Mercier R , Sillion B , Toussaere E
Published: August 2002

The syntheses and characterizations of two aromatic polyimides with nonlinear optical (NLO) chromophore side chains were investigated through a two-step synthetic route. These two polymers were prepared by polycondensation of 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) with 4-(4-amino, 2-hydroxy) phenoxyaniline (HODA) and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAP), respectively. First the poly(hydroxy)imides were prepared by direct thermal imidization. The resulting polyimides bearing hydroxy groups were found to react easily with the terminal hydroxy group of the chromophore (Disperse Red1 (DR1)) via the Mitsunobu reaction. The high content of chromophore for the polyimide with 6FAP diamine was confirmed by UV spectroscopy and ellipsometry spectroscopy measures. The resulting NLO polyimides possess high glass transition temperatures ( Tg > 185°C), excellent solubilities and processabilities even though the extent of chromophore grafting is up to 95 mol%. The second harmonic coefficient ( d33) at the wavelength of 1320 nm is close to 30 pm V−1. The thermal and temporal stabilities of the NLO properties were investigated. The relaxation temperature of the SHG signal measured at the 50% decay of the initial SHG signal ( I 2ω/2 at 2°C min−1) was 168°C for the polyimide based on HODA and 157°C for the polyimide based on 6FAP.
The Photorefractive Effect in Monolithic Structural Polyimides
Authors: Jung Cheolsoo , Aoyama Tetsuya , Wada Tatsuo , Sasabe Hiroyuki , Jikei Mitsutoshi , Kakimoto Masa-Aki
Published: August 2002

We report here the photorefractive effect in monolithic structural polyimides containing the triphenylamino-( p-nitrophenyl)-ethylene group as a nonlinear optical (NLO) chromophore and hole transfer. Three types of polyimides were synthesized to control the loading ratio of the NLO chromophore; 50, 30 and 17 mol% for polyimides 1, 2 and 3 respectively. In the two-beam coupling experiment, asymmetric energy transfer was observed in the case of polyimides 1 and 2, providing evidence for a phaseshifted grating after corona-poling treatment, whereas the energy transfer of polyimide 3 was not observed. This result denotes that the NLO chromophore plays an important role in monolithic photorefractive materials, and a greater than 30 mol% concentration of NLO chromophore is required for creating sufficient space charge distribution.
The Curing Reaction of 3-Aryl Substituted Benzoxazine
Authors: Hayakawa Teruaki , Osanai Yoshinori , Niizeki Kouichi , Haba Osamu , Ueda Mitsuru
Published: August 2002

The reaction pathways on the curing reaction of 3-aryl substituted benzoxazine was investigated from the model reaction of 3, 4-dihydro-6, 8-dimethyl-3-phenyl-2H-1, 3-benzoxazine (1) with 2, 4-xylenol (2). The reaction was carried out at 140 °C for 5 h. N, N-Bis(2-hydroxy-3, 5-dimethylbenzyl)phenylamine (3) and N-(2-hydroxy-3, 5-dimethylbenzyl)phenylamine (4) were isolated as main products at an early stage. The reaction of 3 by the thermal treatment was studied by 1H-NMR spectroscopy. This result indicates that compound 3 produces several inter- and intramolecular rearrangement products. Based on these data, some possible reaction pathways were proposed. In the presence of p-toluenesulfonic acid monohydride, 3,3′-[4,4′-methylenediphenyl]bis(3,4-dihydro-6,8-dimethyl-2H-1,3-benzoxazine) (9) was isolated as one of the intermediates.
Adhesive Characteristics of Alder-Ene Adduct of Diallyl Bisphenol a Novolac and Bisphenol a Bismaleimide
Authors: Gouri C , Nair C P Reghunadhan , Ramaswamy R
Published: August 2002

Diallyl bisphenol A–formaldehyde copolymer (ABPF) was addition cured with bisphenol A bismaleimide (BMIP) making use of the Alder-ene reaction at high temperatures. The lap shear strength (LSS) of the system was found to depend on the conditions of cure and the stoichiometry of the reactants. Moderate cross linking achieved at a 1:1 maleimide:allylphenol stoichiometry and a stepwise cure, up to a maximum of 250 °C for 2 h, was found to be the most effective in achieving the optimum LSS properties. The system exhibited greater than 100% retention of the LSS at temperatures up to 250 °C. Matrix modification using polysulfone (PS) and polycarbonate (PC) resulted in a remarkable improvement in the adhesive characteristics, although the high-temperature retention was marginally adversely affected. The performance advantage both at room temperature (RT) and at high temperature was greater in the case of PS modification, showing an optimum improvement at 20% loading as against PC modification, exhibiting maximum properties at 10% loading. Scanning electron microscopy (SEM) analysis confirmed that the fine dispersion of PS, rather than large size nodules found in PC, was conducive for the better performance of the former. Dynamic mechanical analysis (DMA) corroborated the observations made in SEM. The existence of co-continuous phases of thermoplastic, matrix and thermoplasticdissolved matrix was evidenced in the PS modification and a clear phase separation was evident in the case of the PC modified system, manifesting independent glass transitions by the individual phases.
Synthesis and Properties of Hydroxy-ContainingOrtho-Linked Poly(Ether-Imide)s
Authors: Hsiao Sheng-Huei , Chen Yu-Jen
Published: August 2002

A series of hydroxy-containing poly(ether-imide)s having ortho-linked, main chain aromatic units were prepared via the solution polycondensation of bis(ether anhydride)s such as 1,2-bis(3,4-dicarboxyphenoxy)benzene dianhydride and 1,2-bis(3,4-dicarboxyphenoxy)-4- tert-butylbenzene dianhydride with bis( o-aminophenol)s such as 3,3′-dihydroxybenzidine, 3,3′-diamino-4,4′-dihydroxybiphenyl and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane. All the poly(ether-imide)s were amorphous, as evidenced by x-ray diffraction analysis, soluble in various polar solvents such as N,N-dimethylacetamide, and most of them afforded transparent and flexible films by solution casting. These hydroxy-containing poly(ether-imide)s had glass transition temperatures in the range from 241 to 277 °C and underwent thermal conversion to poly(ether-benzoxazole)s upon heating between 420 and 550°C under nitrogen. The thermally converted benzoxazole polymers did not show significant weight loss up to 500 °C in nitrogen.
Synthesis and Radical Polymerization of N-(3-Acetyl-4-Carboxy-Phenyl)-Maleimide
Authors: Hulubei Camelia , Morariu Simona
Published: August 2002

A new functional monomer derivative of p-aminosalicylic acid, N-(3-acetyl-4-carboxy-phenyl)-maleimide, was synthetized and polymerized with azobisisobutyronitrile as initiator at 60 °C in various solvents. The obtained structures were confirmed by IR, 1H-NMR and elemental analysis. The molecular weights and the polydispersity values of the polymers were determined in the ranges (3.4–5.9)×103 and 1.28–1.60 respectively, by gel permeation chromatography. The activation energy of the monomer polymerization in tetrahydrofuran was calculated as 26.11 kcal mol−1. The x-ray analysis shows, in all cases, the existence of two characteristic diffraction maxima ( di, do), and the influence of the length and size of the aromatic substituents on these maxima are discussed. Functional polymers members of the salicylic acid family would lead to polymers which should show chelation, catalytic, thermochromic or photochromic properties.
Synthesis and Characterization of Segmented Polyurethanes Containing Polyhedral Oligomeric Silsesquioxanes Nanostructured Molecules
Authors: Fu Bruce X , Zhang Wenhua , Hsiao Benjamin S , Rafailovich Miriam , Sokolov Jonathan , Johansson Gary , Sauer Bryan B , Phillips Shawn , Balnski Rusty
Published: August 2002

Segmented polyurethanes based on diphenylmethane-4,4′-diisocyanate and polytetra-methylene glycol were synthesized using a mixture of polyhedral oligomeric silsesquioxane (POSS)-diol and 1,4-butanediol as chain extenders. The polymers were characterized by differential scanning calorimetry, wide-angle x-ray diffraction (WAXD), small-angle x-ray scattering (SAXS) and tensile property tests. Microphase separation between the hard and soft segment domains was observed in all the samples by SAXS. The increase of the POSS concentration was found to weaken the microphase separation between the domains and increase the Tg of the soft segments. The WAXD results showed that when the POSS concentration was greater than 10 wt%, the 101 diffraction peak from the POSS crystals could be observed, which suggested the formation of POSS nanocrystals in the hard domain. The tensile property tests showed that polyurethanes containing the nanostructured POSS molecules had higher moduli, but lower maximum elongation ratios.
Spatial and Temporal Dependence of Diffusion in Polystyrene Thin Films on Silicon and Carbon Surfaces
Authors: Strzhemechny Y , Zaitsev V , Zhou K , Schwarz S A , Sokolov J , Rafailovich M H
Published: August 2002

The strong inhibition of chain diffusion in thin polystyrene (PS) films has been observed near an attractive silicon surface, and diffusion remains inhibited out to distances of several radii of gyration from the surface. The present study seeks to determine the time dependence of the diffusion coefficient, and to examine the effect of a carbon surface on this diffusion. The sputter-deposited carbon surface may serve as a model for carbon-black particles employed in nanocomposites, which have recently been observed to reduce diffusion throughout a nanocomposite layer. The experiments employed a thin (∼15 nm) deuterated polystyrene (dPS) marker layer sandwiched between two normal PS layers. Deuterium profiles were monitored in the annealed samples by secondary ion mass spectrometry. Strong segregation was observed at the silicon surface, but was inhibited at the carbon surface, allowing the diffusion behaviour to be studied in the latter case over longer annealing times. A finite-element computer program was developed to fit the observed diffusion profiles. The variation of the diffusion coefficient with depth is shown to be consistent with previous results, and diffusion is comparable at both the carbon and silicon surfaces. The diffusion coefficient decreases roughly in proportion to t−1/2, and is discussed in the context of reptation theory.
Anomalies in the Optical Index of Refraction of Spun Cast Polystyrene Thin Films
Authors: Hu Xuesong , Shin Kwanwoo , Rafailovich Miriam , Sokolov Jonathan , Stein Richard , Chan Yee , Wlwu Kurt Williams , Wu W L , Kolb Rainer
Published: August 2002

We used x-ray reflectivity in combination with optical ellipsometry to measure the optical index of refraction, n, in thin spun cast polystyrene films. We have found that n is independent of the molecular weight, but is a sharp function of the film thickness for films less than 100 nm. In all cases the deviation from the bulk, Δ n, is negative and varies linearly with wavelength in the visible region. The magnitude of Δ n, was found to be as large as 0.25 for films 7 nm thick. The bulk index of refraction was recovered in all films after annealing for2habove Tg at 160 °C. X-ray reflectivity measurements of the scattering critical angle show minimal density deviations from the bulk (less than 0.5%) between the annealed and unannealed films. Consequently the large molecular-weight-independent value of Δ n is interpreted as being due to a radially symmetric segmental orientation induced by the spinning process.
Novel Crosslinking Method for Negative Tone Photoresist having Pendant Carboxyl Moieties
Authors: Liu Jui-Hsiang , Shih Jen-Chieh
Published: August 2002

We have developed a novel photo-crosslinking method for the negative tone photoresist comprising binder resins with pendant carboxyl groups. A series of copolymers have been synthesized deriving from methacrylic acid, methyl methacrylate, n-butyl methacrylate, and α-methacryloxy-γ-butyrolactone with various feed molar ratios. The existence of lactonic methacrylate units in copolymers was found to increase the sensitivity of the photoresist. Increasing photosensitivity was investigated by using a model compound of α-acetoxy-γ butyrolactone (ACBL). Heat treatment of ACBL compounds in the presence of acid was found to cause the formation of dimers. The following were also investigated: thermogravimetric properties of binder resins, the exposure characteristic curves, and the lithographic evaluation of the negative tone photoresist of copolymers. The existence of alicyclic γ-butyrolactone groups was found to increase the etching resistance of the resists.
Hyperbranched Aromatic Polyamides Prepared by Direct Polycondensation
Authors: Jikei Mitsutoshi , Kakimoto Masa-Aki
Published: August 2002

Hyperbranched aromatic polyamides and copolymers were prepared by direct polycondensation in the presence of condensation agents. Three strategies were described: (1) self-polycondensation of AB x-type monomers, (2) copolymerization of AB2 and AB monomers and (3) polymerization of A2 and B3 monomers. The self-polycondensation of AB x monomers proceeded without gelation to form soluble powdery polymers. The degree of branching of the hyperbranched polyamides was greatly influenced by the structure of the monomers. Copolymerization of AB2 and AB monomers allowed control of the branching density of the resulting polymers. Spectroscopic measurements revealed that the copolymers were composed of five kinds of repeating units. The good solubility and adequate solution viscosity of the copolymers allowed the preparation of transparent yellow films by casting the copolymer solution onto a glass plate. The polymerization of A2 and B3 monomers was also investigated as a novel route to prepare hyperbranched polyamides without using AB x-type monomers. Gelation during the polymerization could be avoided by the optimization of the reaction conditions. The structure and properties of the resulting polymers were compared with the hyperbranched polyamide prepared from the corresponding AB2 monomer.
Synthesis and Properties of High-Molecular-Weight Poly(L-Lactic Acid) by Melt/Solid Polycondensation under Different Reaction Conditions
Authors: Moon Sung-Il , Taniguchi Ikuo , Miyamoto Masatoshi , Kimura Yoshiharu , Lee Chan-Woo
Published: August 2002

The melt/solid polycondensation of L-lactic acid (LA) was successfully conducted using a binary catalyst system comprising tin dichloride hydrate and p-toluenesulfonic acid (TSA). First, a thermal oligocondensate of LA with a degree of polymerization of eight was mixed with the binary catalyst and subjected to melt polycondensation at 180°C for 5 h to obtain a melt polycondensate with an average molecular weight of 13 000 Da. This melt polycondensate was then heat treated at 105°C for 2 h and subjected to solid-state polycondensation under various conditions to obtain a high-molecular-weight polymer of poly(L-lactic acid) (PLLA).

In a typical case, the solid-state reaction was performed by raising the temperature from 130 to 155°C, or at a constant temperature of 140 or 150°C. In the former case the molecular weight of PLLA increased linearly with the temperature increase, while in the latter case the molecular weight increased above 500 000 Da in a relatively short reaction time. The crystallization of the polycondensate was a key step of this polycondensation and the crystallinity of the PLLA product was well correlated with the increase in the molecular weight.

This method can be a direct industrial method for the manufacture of PLLA from LA, which may potentially be an alternative to the currently adopted lactide method.
New Polyheteroarylene Based Copolymers Formulation
Authors: Vygodskii Yakov S , Matieva Aza M , Sakharova Antonina A , Sapozhnikov Dmitrii A , Volkova Tat’yana V
Published: August 2002

Free radical initiated polymerization of methyl methacrylate containing 1–15 wt% of dissolved polyimide is studied by a calorimetric method. It is shown that polyimide (up to 10 wt%) addition leads to a shifting of the initial autoacceleration and initial autoretardation conversions to lower conversion values than those for polymerization of plain methyl methacrylate. It is stated that polyimide macromolecules do not create additional initiation reaction centres, but may take part in chain transfer and/or termination reactions during methyl methacrylate polymerization. Besides polyimides some other aromatic polymers, namely polyesters, polyamides, poly(ether ether ketone)s and poly(phthalide)s, have been used in similar processes. The new copolymers obtained differ in properties (solubility, thermal resistance, etc) compared to corresponding polymer components.
Polyimide Composites Reinforced with Whiskers
Authors: Zixue Qiu , Feifeng He
Published: August 2002

Polyimide composites reinforced with whiskers were prepared by two methods, a dry method and a wet method. The composites of polyimide exhibit high strength, high thermal resistance and good wear resistance, comparable to those of polyimides. The composites have been compared with other composites of polyimide filled with glass fibre powder, polytetrafluoroethylene and graphite. The surface of the composites was studied by scanning electron micrography. The composites can be applied in advanced technical fields.
A Study of the Vacuum γ-Radiolysis of Two Aromatic Polyimide Fluoropolymers Containing Phenylphosphine Oxide
Authors: Alexander Mark A , Hill David J T , Connell John W , Watson Kent A
Published: August 2002

The vacuum γ-radiolysis of two fluorinated polyimides containing phenylphosphine oxide units, TOR-RC and TOR-RC ODPA, have been studied at 77 K and 300 K. The phenyl phosphine oxide units provide protection of the polymers towards oxidation by oxygen atoms and the bulky fluoromethyl groups reduce the colouration of the polymers by limiting donor–acceptor complex formation through the aromatic units. At 77 K the radicals formed were identified to be a mixture of neutral radicals (60%) and anion radicals. At 300 K only neutral radicals were found. The G-values for radical formation were found to be 0.50 and 0.42 at 77 K and 0.051 and 0.052 at 300 K for TOR-RC and TOR-RC ODPA, respectively. Little change was observed in the visible spectra of the polyimides following vacuum radiolysis at 300 K up to a dose of 3.3 MGy, and the polymers were shown to undergo net cross linking with a gel dose of 0.45 MGy.
Thermoplastic Elastomers: 3. Poly(Ether-Ester-Imide)s Based on 1,6-Diaminohexane, Trimellitic Anhydride, 1,4-Dihydroxybutane and Poly(Tetramethylene Oxide)
Authors: Wollheim Thomas , Kricheldorf Hans R , Altstädt Volker , Koning Cor E , Buning Gerard H Werumeus
Published: August 2002

An imide dicarboxylic acid was prepared from 1,6-diaminohexane and trimellitic anhydride and esterified with ethanol. This imide monomer was polycondensed with three different poly(tetramethylene oxide) diols (PTMO-650, PTMO-1000 and PTMO-2000) and with an excess of 1,4-dihydroxybutane. When PTMO-1000 was used, and even more when PTMO-2000 was used, a partial macrophase separation occurred at the end of the polycondensation process. The resulting poly(ether-ester-imide)s (PEEIs) were characterized by IR and 1H NMR spectroscopy, by viscosity and DSC measurements. Compared to thermoplastic elastomers based on poly(butylene terephthalate) these PEEIs crystallize slowly. Selected PEEIs were also characterized by dynamic melt rheology, by dynamic mechanical thermoanalysis, by stress–strain and by hysteresis measurements.