bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of NCO/OH molar ratio on miscibility and properties of semiinterpenetrating polymer networks from polyurethane and benzyl konjac glucomannan
Authors: Lu Yongshang , Zhang Lina 
Published: February 2003

AbstractSemi‐interpenetrating polymer network (semi‐IPN) films with different NCO/OH molar ratios of the urethane prepolymer, coded as UB, were prepared from polyurethane (PU) and benzyl konjac glucomannan (B‐KGM) by a casting method. The effect of the NCO/OH molar ratio of the urethane prepolymer on the miscibility and properties of the UB films was investigated using Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical thermal analysis, thermogravimetric analysis, and swelling and tensile tests. The results indicated that, with an increase of the NCO/OH ratio, the crosslink density of the UB films increased, resulting in improved miscibility between PU and B‐KGM and a relatively high light transmittance of the UB films. However, the thermal stability of the UB films decreased with increase of the NCO/OH ratio of the urethane prepolymer, due to the depolymerization of the urethane bonds of the PU networks. When the NCO/OH ratio increased from 2 to 4, the tensile strength of the UB films increased from 15 to 27 MPa, while the breaking elongation decreased from 72 to 16%, resulting from the chemical and physical crosslinks, namely, the enhancement of the covalent bonds and hydrogen‐bonding networks. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1304–1310, 2003
Isothermal and nonisothermal crystallization kinetics of partially melting nylon 10 12
Authors: Li Yongjin , Zhang Guosheng , Zhu Xinyuan , Yan Deyue 
Published: February 2003

AbstractNylon 10 12, a newly industrialized engineering plastic, shows a double‐melting phenomenon during melting. Partial melts were obtained when the sample was heated to the temperature between the two melting peaks. A differential scanning calorimeter was used to monitor the energies of the isothermal and nonisothermal crystallization from the partially melted samples. During isothermal crystallization, relative crystallinity develops with a time dependence described by the Avrami equation, with the exponent n = 1.0. For nonisothermal studies, kinetics treatments based on the Avrami and Ozawa equations are presented to describe the crystallization process. It was found that the two treatments can describe the nonisothermal crystallization from the partially melted samples. The derived Avrami and Ozawa exponents are all about 1.0, which means that the partially melted samples crystallize by one‐dimensional growth, which may cause thickening of the lamellae. We calculated the crystallization activation energies for isothermal and nonisothermal crystallization from the partially melted samples. It was found that the activation energy determined by the Kissinger method was not rational, which may be attributed to the free‐nucleation process for nonisothermal crystallization from partially melted samples. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1311–1319, 2003
Rheology of poly(n‐butyl methacrylate) and its composites with calcium carbonate
Authors: Chen Jianding , Carrot Christian , Chalamet Yvan , Majeste Jean‐Charles , Taha Mohamed 
Published: February 2003

AbstractPoly(n‐butyl methacrylate) (PBMA) composites with calcium carbonate (CaCO3) were prepared by in situ radical copolymerization of butyl methacrylate (BMA) and methacrylic acid (MA) with precipitated calcium carbonate. To compare the different rheological behaviors of the monomer mixtures with CaCO3 and the composites, the steady and dynamic viscosities of BMA/MA/CaCO3 and poly(BMA/MA/CaCO3) were measured by means of steady and oscillatory shear flows. The viscosity of the mixture BMA/MA/CaCO3 was found to increase evidently with the increasing of CaCO3%. The influence of MA% on viscosity of BMA/MA/CaCO3 was slight. During the in situ polymerization, the viscosity of the reacting system was measured to be enhanced by a factor of about 104 from the monomer/CaCO3 mixture to composites. The dependency of zero‐shear viscosity on molar mass of PBMA was also investigated. The relation between the zero‐shear viscosity and molar mass is η0 = 10−15 Mw3.5. The evolution of the viscosity with the temperature for both PBMA and its composites was obtained and time–temperature superposition was used to build master curves for the dynamic moduli. The flow activation energies were found to be 115.0, 148.6, and 178.7 kJ/mol for PBMA, composite PBMA/CaCO3 (90/10), and PBMA/MA/CaCO3 (89/1/10), respectively. The viscosity of the composites containing less than 10% CaCO3 was lower than that of pure PBMA with the same molar mass. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1376–1383, 2003
Analysis and modeling of PVTX diagram of an unsaturated polyester resin, thermoplastic additive, and mineral fillers blend
Authors: Boyard N. , Vayer M. , Sinturel C. , Erre R. , Delaunay D. 
Published: February 2003

AbstractWe studied the dynamic curing of a polymer blend containing an unsaturated polyester prepolymer, styrene, and a saturated polyester as a low‐profile thermoplastic additive during heating from 40 to 160°C with a constant rate (4 or 10 K/min). This work was performed by means of a homemade dilatometer that simultaneously determined conversion degree, volume, pressure, and temperature. The various phenomena inducing volume change were identified and then separated (thermal expansion, shrinkage, and shrinkage compensation). A model based on physical consideration was built that allowed an accurate fit of the experimental results. The influence of the pressure on all this phenomena was summarized and quantified. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1258–1267, 2003
Fracture behavior of die‐drawn toughened polypropylenes
Authors: Mohanraj J. , Chapleau N. , Ajji A. , Duckett R. A. , Ward I. M. 
Published: February 2003

AbstractThe Leeds die‐drawing process has been used to make oriented sheets of toughened polypropylenes. Die‐drawn oriented sheets were produced by drawing at 110°C to draw ratios of 4, 6, and 10. Comparative measurements have been undertaken of the plane stress fracture toughness at room temperature using the essential work of fracture method for isotropic and oriented polypropylene homopolymer and the two polypropylene blends containing 10 and 25% of a polyethylene‐based elastomer. In the isotropic state, the blend containing 25% elastomer exhibited higher fracture toughness than the homopolymer and the 10% blend. The oriented sheets were tested both parallel (cracks perpendicular to the draw direction) and perpendicular (cracks parallel to the draw direction). For the latter case of cracks parallel to the draw direction, the fracture toughness of all the materials decreased with increasing draw ratio and up to a draw ratio of 4 the 25% blend exhibited higher fracture toughness than the other two materials. At higher draw ratios, however, the unfilled polypropylene was tougher than the blends. When tested parallel to the draw direction, all three materials failed with the cracks growing slowly initially followed by sudden rupture. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1336–1345, 2003
Thermal properties of poly(vinyl alcohol)/poly(diallyldi‐methylammonium chloride) interpenetrating polymer networks
Authors: Kim Seon Jeong , Yoon Seoung Gil , Lee Young Moon , Kim In Young , Kim Sun I. 
Published: February 2003

AbstractInterpenetrating polymer networks (IPNs) constructed with poly(vinyl alcohol) (PVA) and poly(diallyldimethyl ammonium chloride) (PDADMAC) using a sequential IPN method were prepared. The thermal characterization of the IPNs was investigated by differential scanning calorimetry (DSC), dielectric analysis (DEA), and thermogravimtric analysis (TGA). Decreases in the melting temperature of PVA segments in IPNs were observed with increasing PDADMAC content using DSC. DEA was employed to ascertain glass transition temperature of IPNs. The thermal decomposition of IPNs was investigated using TGA, and thermal decomposition of IPNs could be decelerated by changing PVA content. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1346–1349, 2003
Synthesis and characterization of novel soluble alternating copoly(phenylene vinylene) derivative for light‐emitting electrochemical cell
Authors: Xiang Dong , Shen Qundong , Zhang Suyang , Jiang Xiqun 
Published: February 2003

AbstractA novel alternating copolymer, poly{[2,5‐di(2‐(2‐ethoxy ethoxy)ethoxy)‐1,4‐phenylene vinylene]‐alt‐1,4‐[phenylene vinylene]}, has been synthesized through the Wittig condensation as electroluminescent material. In this copolymer, one component is phenylene vinylene with flexible oligo(ethylene oxide) side chain that facilitates ion transportation and phase miscibility between nonpolar and polar part of composite luminescent layer, and another is a rigid phenylene vinylene moiety to improve luminescent quantum efficiency and tune color. The copolymer shows good solubility and thermal stability for device fabrication compared to poly(phpeylene vinylene)(PPV). The band gap value of copolymer is between those of corresponding homopolymers, which indicates that alternating copolymerization is a suitable way to obtain luminescent polymer with desired band gap. The maximum wavelength of photoluminescence of copolymer is 539 nm (yellowish‐green). The HOMO and LUMO energy levels obtained by cyclic voltammetry measurement indicate that the electron injection ability of copolymer has been greatly improved compared with that of the PPV. A more balanced carrier injection and higher quantum efficiency are proved by electroluminescent properties of corresponding light‐emitting devices. The turn‐on voltage of LEC device (ITO/copolymer + PEO + LiClO4/Al) is found to be 2.3 V, with current comparative to LED (ITO/copolymer/Al) at 9.5 V. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1350–1356, 2003
Structural development of poly(ethylene 2,6‐naphthalene dicarboxylate) film upon solvent drawing
Authors: Kang Young Ah , Kim Kyoung Hou , Lee Yang Hun , Lee Jang Oo , Cho Hyun Hok 
Published: February 2003

AbstractTo investigate the effect of “chemical energy” by solvent on structural development, initially molded amorphous poly(ethylene 2,6‐naphthalene dicarboxylate) (PEN) films were drawn in various solvent systems and at the optimum temperatures deliberately determined, and the resulting fine structure and properties were analyzed by using several experimental techniques. Water, 1‐butanol, 1,4‐dioxane/water (20 : 80 by volume), and 1,4‐dioxane/1‐butanol (20 : 80 by volume) were chosen for drawing solvent. For this study, in view of chemical structure and solubility parameter, though, these are nearly immiscible or partially miscible liquids against PEN, with just the plasticizing actions more or less the primary concern here. Interesting enough, the temperature range near the main endothermic peak corresponding to the depressed boiling point of liquid caused by unfavorable interaction between PEN and solvent in mixtures of amorphous PEN film with various solvent systems, as determined by the DSC scans, was found to coincide with the optimum drawable range for each solvent system, over which several experiments, including the determination of maximum draw ratio (DRmax) have been carried out throughout the study. The experimental results obtained from this study could be explained, through qualitatively, in terms of the interactions between PEN and solvents. Hence, it is expected to control the fine structure and properties of PEN films resulting from the low‐temperature solvent drawing via a suitable choice of liquids and the corresponding draw temperature ranges. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1357–1365, 2003
Swelling behavior of radiation‐polymerized polyampholytic two‐component gels: Dynamic and equilibrium swelling kinetics
Authors: Bhardwaj Y. K. , Kumar Virendra , Sabharwal S. 
Published: February 2003

AbstractPolyampholytic hydrogels, with varying degrees of crosslinking and ionic content, were prepared by radiation polymerization of p‐sodium styrene sulfonate (SSS) and vinyl benzyl trimethylammoniumchloride (VBT). These gels were investigated for their dynamic and equilibrium swelling kinetics. Dynamic swelling of these gels established that the gels containing equal amounts of SSS and VBT strictly follow Fickian diffusion. The hydrogels containing excess of SSS followed the case II type of diffusion, whereas those containing excess of VBT followed anomalous diffusion. Equilibrium swelling kinetics of these gels in aqueous system, ethanol–water mixture, at different pHs, and in the presence of solutions of biological interest was studied. It was seen that gels containing equal amounts of SSS and VBT show the lowest equilibrium swelling. Swelling of the polyampholytic gel decreased with an increase in the radiation dose imparted and the amount of crosslinking agent incorporated in the gel. The gels having an excess of VBT showed higher equilibrium swelling in comparison to those having an excess of SSS. Differential scanning calorimetry (DSC) studies showed that crosslinking of the gels decreases equilibrium swelling but increases the bonded nonfreezable water content of the gels. The organic solvents like ethanol cause abrupt collapse of the polyampholyte gels containing excess of SSS and those containing equal amounts of both the monomers at some critical ratio of water and ethanol in swelling medium. However, the deswelling in the water–ethanol mixture was gradual for gels containing an excess of VBT and the extent of deswelling was also low for these gels in comparison to other gels. The swelled gels of all compositions deswelled when they were transferred to solutions at pH in the range 2–12. Biologically important solutes like urea, glucose, and surfactants like Triton‐X tend to further swell the polymer matrices, whereas NaCl causes their deswelling. The additive effect is more prominent for polyampholyte gels containing excess of either of the monomers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 730–742, 2003
Synthesis and characterization of a novel phthalazinone poly(aryl ether sulfone ketone) with carboxyl group
Authors: Xuan Yingnan , Gao Yan , Huang Yong , Jian Xigao 
Published: February 2003

AbstractSoluble, thermally stable phthalazinone poly(aryl ether sulfone ketone)s (PPESKs) containing a carboxyl group in its side chain have been synthesized by the nucleophilic displacement reaction of 4‐(4‐hydroxylphenyl)‐1(2H)‐phthalazinone with bis(4‐chlorophenyl) sulfone, 4,4′‐difluoro‐benzophenone, and phenolphthalin. The polymerization reactions were conducted in sulfolane in the presence of K2CO3 to give high molecular weight polymers, which are soluble in solvent such as nitrobenzene and pyridine at room temperature and easily cast into flexible, yellow, and transparent film. The polymers are amorphous with high glass transition temperature. The decomposition temperature of the polymers are >400°C, which indicates high thermal stability. The crosslinking reaction of PPESK can occur by using dicyandiamide (Dicy) as curing agent. The apparent energy (ΔE) is 52.2 kJ/mol and reaction order (n) is close to 1.0. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1111–1114, 2003
Preoperative assessment of prognostic factors in rectal cancer using high-resolution magnetic resonance imaging
Authors: Brown G , Radcliffe A G , Newcombe R G , Dallimore N S , Bourne M W , Williams G T 
Published: February 2003

Abstract

Background
The aim was to determine the accuracy of preoperative magnetic resonance imaging (MRI) in the evaluation of pathological prognostic factors that influence local recurrence and survival in rectal cancer.

Methods
Ninety-eight patients undergoing total mesorectal excision for biopsy-proven rectal cancer were assessed prospectively using high-resolution MRI for tumour (T) and nodal (N) staging using the tumour node metastasis classification, depth of extramural tumour spread, the presence or absence of extramural venous invasion, a threatened circumferential resection margin and serosal involvement at or above the peritoneal reflection. Preoperative magnetic resonance assessment of these prognostic factors was compared with histopathological findings in carefully matched whole-mount sections of the resection specimen.

Results
There was 94 per cent weighted agreement (weighted κ = 0·67) between MRI and pathology assessment of T stage. Agreement between MRI and histological assessment of nodal status was 85 per cent (κ = 0·68). Although involvement of small veins by tumour was not discernible using MRI, large (calibre greater than 3 mm) extramural venous invasion was identified correctly in 15 of 18 patients (κ = 0·64). MRI predicted circumferential resection margin involvement with 92 per cent agreement (κ = 0·81). Seven of nine patients with peritoneal perforation by tumour (stage T4) were identified correctly using MRI.

Conclusion
High-resolution MRI of the rectum allows preoperative identification of important surgical and pathological prognostic risk factors. This may allow both better selection and assessment of patients undergoing preoperative therapy.
Evaluation of POSSUM and P-POSSUM scoring systems in patients undergoing colorectal surgery
Authors: Tekkis P P , Kessaris N , Kocher H M , Poloniecki J D , Lyttle J , Windsor A C J 
Published: February 2003

Abstract

Background
The Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (POSSUM) and Portsmouth POSSUM (P-POSSUM) equations were derived from a heterogeneous general surgical population and have been used successfully as audit tools to provide risk-adjusted operative mortality rates. Their applicability to high-risk emergency colorectal operations has not been established.

Methods
POSSUM variables were recorded for 1017 patients undergoing major elective (n = 804) or emergency (n = 213) colorectal surgery in ten hospitals. Subgroup analysis was performed to investigate the predictive capability of POSSUM and P-POSSUM in emergency and elective surgery and in patients in different age groups.

Results
The overall operative mortality rate was 7·5 per cent (POSSUM-estimated mortality rate 8·2 per cent; P-POSSUM-estimated mortality rate 7·1 per cent). In-hospital deaths increased exponentially with age. Both scoring systems overpredicted mortality in young patients and underpredicted mortality in the elderly (P &lt; 0·001). Death was underpredicted by both systems for emergency cases, significantly so at a simulated emergency caseload of 47·9 per cent (P &lt; 0·05).

Conclusion
There is a lack of calibration of POSSUM and P-POSSUM systems at the extremes of age and high emergency workload. This has important implication in clinical practice, as consultants with a high emergency workload may seem to underperform when these scoring systems are applied. Recalibration or remodelling strategies may facilitate the application of POSSUM-based systems in colorectal surgery.
Assessment of the accuracy of transrectal ultrasonography in anorectal neoplasia
Authors: Mackay S G , Pager C K , Joseph D , Stewart P J , Solomon M J 
Published: February 2003

Abstract

Background
Accurate preoperative staging of anorectal neoplasia is required to identify patients for whom local excision or adjuvant therapy may be appropriate. The objectives of this study were to review the accuracy of endoluminal transrectal ultrasonography (TRUS) in the staging of rectal cancers and to determine the learning curve before optimal staging accuracy can be achieved.

Methods
The results of all TRUS examinations for the assessment of anorectal neoplasia performed by two colorectal surgeons at two teaching hospitals of the University of Sydney from 1991 to 2001 were collected prospectively.

Results
Of the 433 patients examined by TRUS, 356 were included, of whom 263 (73·9 per cent) had nodal status assessed histologically. Of the 77 patients excluded, 50 had undergone radiotherapy before operation. TRUS achieved excellent accuracy when compared with histopathology reports using κ statistics for standard Union Internacional Contra la Cancrum (UICC) staging (κ = 0·89), tumour wall penetration (κ = 0·70), lymph node detection (κ = 0·66) and a proposed new staging system (κ = 0·94). In addition, the increase in TRUS accuracy with operator experience demonstrates the need to perform 50 or more procedures before optimal accuracy is achieved.

Conclusion
TRUS provides an appropriate investigation with which to select patients with T1 tumours for local excision, and patients with T3 or T4 tumours for preoperative radiotherapy. The relative inaccuracy of staging T2 tumours by TRUS has led to a proposed alternative ultrasonographic staging system.
Smoking affects the outcome of transanal mucosal advancement flap repair of trans-sphincteric fistulas
Authors: Zimmerman D D E , Delemarre J B V M , Gosselink M P , Hop W C J , Briel J W , Schouten W R 
Published: February 2003

Abstract

Background
The aim of the study was to identify variables affecting the outcome of transanal advancement flap repair (TAFR) for perianal fistulas of cryptoglandular origin.

Methods
Between 1995 and 2000, a consecutive series of 105 patients (65 women, 40 men), with a median age of 44 (range 19–72) years was included in the study. The patients were recruited from the colorectal departments of two university medical centres. Patients with a rectovaginal fistula and those with a fistula due to Crohn's disease were excluded. The following variables were assessed: age, sex, number of previous attempts at repair, preoperative seton drainage, fistula type, presence of horseshoe extensions, location of the internal opening, postoperative drainage, body mass index and the number of cigarettes smoked per day. The results were analysed by means of multiple logistic regression.

Results
The median follow-up was 14 months. No differences were observed between the two centres. TAFR was successful in 72 patients (69 per cent). None of the variables affected the outcome of the procedure, except for smoking habit of the patient. In patients who smoked the observed healing rate was 60 per cent, whereas a rate of 79 per cent was found in patients who did not smoke. This difference was statistically significant (P = 0·037). Moreover, a significant correlation was observed between the number of cigarettes smoked per day and the healing rate (P = 0·003).

Conclusion
Cigarette smoking affects the outcome of TAFR in patients with a cryptoglandular perianal fistula.
Prevention of pleural effusion following hepatectomy using argon beam coagulation
Authors: Kwon A-H , Matsui Y , Satoi S , Kaibori M , Kamiyama Y 
Published: February 2003

Abstract

Background
Postoperative pleural effusion occurs frequently after hepatectomy. The value of the argon beam coagulator (ABC) for the prevention of pleural effusion after hepatectomy in patients with hepatocellular carcinoma was studied.

Methods
Sixty patients were divided randomly into two groups: an ABC group (n = 28), in which the cut surface of the hepatic ligaments and bare area of the retroperitoneum were cauterized using an ABC, and a control group (n = 32) in which the ABC was not applied. Patient characteristics, preoperative and postoperative liver function, and postoperative pleural effusion were compared between the two groups.

Results
There were no significant differences between the two groups with respect to histological findings, clinical stage, type of resection, operative data, and preoperative and postoperative laboratory data. One of 28 patients in the ABC group and nine of 32 patients in the control group had pleural effusion. The incidence was significantly lower in the ABC group than in the control group (P = 0·01). Pleurocentesis was needed in two of the ten patients and thoracic drainage in four patients.

Conclusion
Application of an ABC to the cut surface of the hepatic ligaments and bare area of retroperitoneum after liver mobilization may prevent postoperative pleural effusion.