bluuebunny/crossref_metadata_2025_split huggingface dataset:
Barrier and Mechanical Properties of Poly(caprolactone)/organoclay Nanocomposites
Authors: Di Yingwei , Iannac Salvatore , Sanguigno Luigi , Nicolais Luigi 
Published: September 2005

AbstractIn this study, biodegradable poly(caprolactone) (PCL) hybrids with two types of organoclays: Cloisite 30B (30B) and Cloisite 93A (93A) have been prepared by melt mixing and their barrier performance to air permeation and mechanical properties were investigated. The hybrids of PCL/30B were found to be nanocomposites resulted from the strong interaction between organic modifier of 30B and PCL and those of PCL/93A were microcomposites. The barrier performance of PCL/30B nanocomposite film to air permeation was much more improved than pure PCL and PCL/93A microcomposites at low organoclay concentration. With the increase of organoclay content the permeability coefficient was also increased that could attributed to the extra tortuous pathway for gas permeation caused by organoclay exfoliation. The barrier behaviour of PCL/30B nanocomposites could be approximately described by a theoretical model developed for composites. The mechanical properties measurements showed that the reinforcement of organoclay 30B in nanocomposites is more significant than 93A in microcomposites. Both tensile modulus and tensile strength were increased in PCL/30B nanocomposites even at at low amount of organoclay without much loss of strain at break as compared to pure PCL. The significant improvements in both barrier and mechanical properties in PCL nanocomposites could be attributed to the fine dispersion state of organoclay 30B platelets in PCL matrix and the strong interaction between organic modifier of 30B and matrix molecules.
Thin Silicon Films on Polymeric Substrate
Authors: Imparato Antonio , Minarini Carla , Rubino Alfredo , Tassini Paolo , Villani Fulvia , Guerra Alfredo , Amendola Eugenio , Della Sala Dario 
Published: September 2005

AbstractLaser crystallization of amorphous silicon film on polymeric substrate is reported. Intrinsic amorphous films 1000 Å thick have been deposited on Polyethersulphone (PES) by PECVD technique in the deposition temperature range of 120‐200 °C. Dehydrogenation and crystallization of the thin films have been obtained by high energy (10 J) XeCl pulsed excimer laser. The irradiation conditions have been varied to study their influence on dehydrogenated and crystallized material properties. Electrical and optical properties of as‐deposited and crystallized films have been investigated. Structural characterization (SEM, XRD, AFM) has been performed. Average crystallite size and grain distribution have been evaluated.For the substrate, the glass transition temperature (Tg) and the coefficient of thermal expansion (CTE) have been evaluated by DSC (Differential Scanning Calorimetry) and TMA (Thermo Mechanical Analysis) measurements and the compatibility with the deposition and crystallization processes have been verified.
Polyurethane Films for Wound Dressing Applications
Authors: Ozkaynak Mert Umut , Atalay‐Oral Cigdem , Tantekin‐Ersolmaz S. Birgül , Güner F. Seniha 
Published: September 2005

AbstractPolyurethane films based on renewable sources were prepared as an alternative to petroleum‐based polyurethane. The effects of the structure and ratio of diisocyanate components on polymer properties were investigated. Hexamethylene diisocyanate (HMDI) and diphenylmethylene diisocyanate (MDI) were chosen as the diisocyanate components in polymer synthesis. Membranes were prepared by casting‐evaporation technique and characterized for their gas permeability, film and mechanical properties. The oil‐based membranes were found to be suitable for wound dressing applications.
Chain Extension and Foaming of Recycled PET in Extrusion Equipment
Authors: Di Maio L. , Coccorullo I. , Montesano S. , Incarnato L. 
Published: September 2005

AbstractIn this work industrial scraps of poly(ethylene terephthalate) (PET) were used for the production of foamed sheets. The process was performed by making use of a chemical blowing agent (CBA) in the extrusion process. Due to the low intrinsic viscosity of the recycled PET (IV=0.48dl/g), a chain extender was also used in order to increase the molecular weight of the polymer matrix. Pyromellitic dianhydride (PMDA) and Hydrocerol CT 534 were chosen as chain extender and CBA, respectively. The reactive extrusion and foaming were performed in a two step process, analyzing the feasibility regarding an eventual use in an industrial context. Rheological characterization was carried out on PET samples previously treated with PMDA, as well as the morphological study was performed to define the cellular structure of the foams produced. Moreover, in order to correlate the working conditions in the reactive and the foaming processes with the final morphology of the foams, a mathematical modelling of the foaming process was applied.
Effect of Molecular Modification on PCL Foam Formation and Morphology of PCL
Authors: Di Maio E. , Iannace S. , Marrazzo C. , Narkis M. , Nicolais L. 
Published: September 2005

AbstractPoly(ϵ‐caprolactone) was chemically modified by using dicumyl peroxide from 0.25 to 2 % (w/w) and the effects of molecular architecture on the density and morphology of PCL foams were examined. The polymer was first blended with dicumyl peroxide at a low temperature (80°C), to prevent premature peroxide decomposition. The peroxide modification was then performed at different temperatures, from 110°C to 150°C. The reaction kinetic was followed by measuring the dynamical rheological properties of the melt in isothermal experiments by using a parallel plate rheometer. The evolution of the macromolecular structure during the chemical reaction was followed by analyzing the time evolution of the complex viscosity. Foams were prepared from the peroxide modified PCL with a batch foaming process using nitrogen as the foaming agent under different process conditions. As expected, the increase of the molecular modification led to a shift towards higher temperatures of the foaming window and, moreover, influenced the viscoelastic behavior of the expanding polymeric matrix so that the final foam properties are affected.
Production of Viscosity Improvers for PVC
Authors: Bostanci Taner , Güner F. Seniha , Erciyes Tuncer 
Published: September 2005

AbstractSome oil‐based samples having oxygen, ester, amide, acid and/or hydroxyl structure were prepared for using as lubricants in PVC extrusion. After characterization studies, all samples were tested in PVC formulation using Brabender W50 EHT Lab‐Station mixer and extruder. The results were compared with that of a commercial product. From the mixer results, it can be noted that energy consumption was lowered for samples containing acid and amide structures. Surface roughness and opacity of the products were improved when the extruder screw speed was increased from 20 rpm to 60 rpm.
In situ Polymerisation of Urethane‐Urea Copolymers for Tuff Consolidation
Authors: Cocca M. , D'Arienzo L. , D'Orazio L. , Gentile G. , Martuscelli E. 
Published: September 2005

AbstractTwo different diisocyanates were investigated as co‐monomers for in situ polymerisation of poly(urethane‐urea) into Neapolitan yellow tuff for conservation and restoration purpose. The obtained copolymers were characterised by means of FTIR spectroscopy, whereas the protective and consolidating efficiency of the performed treatments was evaluated through water capillary absorption, water vapour permeability and abrasion resistance measurements. The distribution and the penetration depth of the synthesized copolymer were also analysed applying micro‐FTIR. The morphology of treated tuff was investigated by SEM. It was shown that comparatively higher protective and consolidating properties are achieved by using 1,6‐diisocyanatohexane as monomer for in situ polymerisation.
Diffusion of Organic Vapors in Materials for Gas Sensing Application
Authors: Penco Maurizio , Sartore Luciana , Della Sciucca Stefania , D'Amore Alberto 
Published: September 2005

AbstractMass‐variation measurements were carried out on carbon black (CB)‐poly(vinyl chloride) (PVC) composite film with 40% by weight of di(2‐ethylhexyl)‐phthalate (DOP), cast on resonant piezo‐layer (RPL) elements of lead zirconat titanate (PZT). Even if anomalous diffusion is predicted by fitting the data with Mt/M∞=ktα, the fractional uptake Mt/M∞ is linear with the square root of the time up to Mt/M∞=0.6, suggesting Fickian behavour. The anomalous values of α are probably due to experimental time lag. A dependence of the diffusion on the morphology of the material and the penetrant shape and flexibility has been found.
Analysis of Composites with Infrared Thermography
Authors: Meola Carosena , Carlomagno Giovanni Maria , Squillace Antonino , Prisco Umberto , Morace Renata Erica 
Published: September 2005

AbstractThe aim of this study was a non‐destructive evaluation of composites through their behaviour under thermal stimulation. Such behaviour was monitored by infrared thermography. Several specimens were fabricated involving: glass/epoxy with inclusion of foreign materials; carbon/epoxy with backdrilled holes; carbon/epoxy with impact damage; Glare® failed in bearing way. The obtained results prove that infrared thermography is capable of detecting the materials inhomogeneities and/or damage listed above. In particular, lock‐in thermography is capable of supplying useful information about: the distribution of the adhesive thickness in composite structures; the distribution of the paint thickness; the behaviour under load of aluminium layers and glass fibres in Glare®.
Achievements and Research Tasks for Poly(vinyl chloride) Ageing and Stabilization
Authors: Minsker K.S. , Zaikov G.E. , Zaikov V.G. 
Published: September 2005

AbstractPerspectives of PVC manufacture, not containing of labile groups in a backbone are considered. It will provide drastic increase of an intrinsic stability of polymeric products, possibility of PVC processing with the minimal contents or in total absence of stabilizers and other chemicals ‐ additives and opportunity of creation of materials and products on a PVC basis with the essentially increased service life‐time. Presented data allow to create rigid, semi‐rigid and flexible (plasticized) materials and products with the minimal contents of chemicals ‐ additives and increased life‐time of their service at exploitation in natural and special conditions.
Benzodiazepine analogues. Part 21. 13C NMR analysis of benzoxathiepine derivatives
Authors: Gelebe Aifheli C. , Kaye Perry T. , Klein Rosalyn , Sewry Joyce D. , Soper Andrew G. 
Published: September 2005

AbstractThe influence of substituents and structure on the 13C NMR spectra of four series of benzoxathiepine derivatives has been investigated. Signal assignments in the 13C NMR spectra have been facilitated by the use of several predictive methods, permitting comparison of their relative efficacy. Copyright © 2005 John Wiley & Sons, Ltd.
Synthesis and characterization of novel biodegradable block copolymer poly(ethylene glycol)‐block‐poly(L‐lactide‐co‐2‐methyl‐2‐carboxyl‐propylene carbonate)
Authors: Guan Hui‐Li , Xie Zhi‐Gang , Zhang Pei‐Biao , Wang Xin , Chen Xue‐Si , Wang Xian‐Hong , Jing Xia‐Bin 
Published: September 2005

AbstractAn amphiphilic block copolymer, poly(ethylene glycol)‐block‐poly(L‐lactide‐co‐2‐methyl‐2‐benzoxycarbonyl‐propylene carbonate) [PEG‐b‐P(LA‐co‐MBC)], was synthesized in bulk by the ring‐opening polymerization of L‐lactide with 2‐methyl‐2‐benzoxycarbonyl‐propylene carbonate (MBC) in the presence of poly(ethylene glycol) as a macroinitiator with diethyl zinc as a catalyst. The subsequent catalytic hydrogenation of PEG‐b‐P(LA‐co‐MBC) with palladium hydroxide on activated charcoal (20%) as a catalyst was carried out to obtain the corresponding linear copolymer poly(ethyleneglycol)‐block‐poly(L‐lactide‐co‐2‐methyl‐2‐carboxyl‐propylenecarbonate) [PEG‐b‐P(LA‐co‐MCC)] with pendant carboxyl groups. DSC analysis indicated that the glass‐transition temperature (Tg) of PEG‐b‐P(LA‐co‐MBC) decreased with increasing MBC content in the copolymer, and Tg of PEG‐b‐P(LA‐co‐MCC) was higher than that of the corresponding PEG‐b‐P(LA‐co‐MBC). The in vitro degradation rate of PEG‐b‐P(LA‐co‐MCC) in the presence of proteinase K was faster than that of PEG‐b‐P(LA‐co‐MBC), and the cytotoxicity of PEG‐b‐P(LA‐co‐MCC) to chondrocytes from human fetal arthrosis was lower than that of poly(L‐lactide). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4771–4780, 2005
Cyclic poly(pyridine ether)s by the polycondensation of 2,6‐difluoropyridine with various diphenols
Authors: Kricheldorf Hans R. , Garaleh Mazen , Schwarz Gert 
Published: September 2005

AbstractThe bistrimethylsilyl derivatives of six different diphenols were polycondensed with 2,6‐difluoropyridine in N‐methylpyrrolidone in the presence of K2CO3. On the basis of previous studies, the reaction conditions were optimized for almost quantitative conversions. The feed ratio was systematically varied to optimize the molecular weight. A 2 mol % excess of 2,6‐difluoropyridine was needed to obtain maximum molecular weights. In the matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectra of the optimized polyethers, only cycles were found (detectable up to 5000 Da). Obviously, the relatively low molecular weights obtained under optimized conditions resulted from a limitation of the chain growth by cyclization, indicating a high cyclization tendency for poly(pyridine ether)s. The size exclusion chromatography measurements not only proved low molecular weights but also demonstrated the existence of bimodal mass distributions and high polydispersities. Protonation of the poly(pyridine ether)s required strong acids such as methane or trifluoromethane sulfonic acid. The solubilities of the neutral and protonated polyethers derived from bisphenol A were studied in various solvents. The MALDI‐TOF mass spectra proved that protonation at 20–25 °C did not cause cleavage of ether bonds. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4781–4789, 2005
Influence of the chemical structure of dithiocarbamates with different N‐groups on the reversible addition–fragmentation chain transfer polymerization of styrene
Authors: Zhou Di , Zhu Xiulin , Zhu Jian , Yin Haishu 
Published: September 2005

AbstractPolymerizations of styrene with azobisisobutyronitrile initiation or thermal initiation have been performed in the presence of dithiocarbamates with different N‐groups, that is, benzyl 4,5‐diphenyl‐1H‐imidazole‐1‐carbodithioate (2a), benzyl 1H‐1,2,4‐triazole‐1‐carbodithioate (2b), benzyl indole‐1‐carbodithioate (2c), benzyl 2‐phenyl‐indole‐1‐carbodithioate (2d), benzyl phenothiazine‐10‐carbodithioate (2e), benzyl 9H‐carbazole‐9‐carbodithioate (2f), and benzyl dibenzo[b,f]azepine‐5‐carbodithioate (2g). The results show that the structure of the N‐group of dithiocarbamates has significant effects on the activity of dithiocarbamates for the polymerization of styrene. 2a, 2b, 2c, 2d, and 2f are effective reversible addition–fragmentation chain transfer (RAFT) agents for the RAFT polymerization of styrene, and the polymerizations have good living characteristics. However, in the cases of 2e and 2g, the obtained polymers have uncontrolled molecular weights and broad molecular weight distributions. The polymerization rate is markedly influenced by the conjugation structure of the N‐group of the dithiocarbamate, and the polymerization rate of 2b is greater than that of 2a. For 2b, the rate of polymerization seems independent of the RAFT agent concentration. However, a significant retardation in the rate of polymerization can be observed in the case of 2c. 2d is more effective than 2c, and the substitution group of phenyl on this dithiocarbamate has obvious effects on the effectiveness of the controlled polymerization of styrene. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4849–4856, 2005
Synthesis of triblock copolymers based on two isomer acrylate monomers by atom transfer radical polymerization
Authors: Muñoz‐Bonilla Alexandra , Cerrada María L. , Fernández‐García Marta 
Published: September 2005

AbstractThe syntheses of triblock copolymers by the atom transfer radical polymerization of tert‐butyl and iso‐butyl acrylates as inner blocks with cyclohexyl methacrylate as outer blocks are reported. The living behavior and blocking efficiency of these polymerizations were investigated in each case. The use of difunctional macroinitiators led to ABA triblock copolymers with narrow polydispersities and controlled number‐average molecular weights. These copolymers were prepared from bromo‐terminated macroinitiators of poly(tert‐butyl acrylate) and poly(iso‐butyl acrylate), with copper chloride/N,N,N′,N″,N″‐pentamethyldiethylenetriamine as the catalytic system, at 40 °C in 50% (v/v) toluene solutions. The block copolymers were characterized with size exclusion chromatography and 1H NMR spectroscopy. Differential scanning calorimetry measurements were performed to reveal the phase segregation. The glass transition of the inner block was not clearly detected, with the exception of the copolymer synthesized with the longest poly(iso‐butyl acrylate) macroinitiator length. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4828–4837, 2005
Radical‐mediated modification of polypropylene: Selective grafting via polyallyl coagents
Authors: Sengupta Saurav S. , Parent J. Scott , McLean J. Keith 
Published: September 2005

AbstractSelective graft modifications of polypropylene (PP) are demonstrated in which desirable functionality is introduced without the degradation that accompanies conventional radical‐mediated processes. A range of modification strategies is presented, each exploiting triallyl trimellitate (TATM) or its derivatives to counteract the effects of macroradical fragmentation on the molecular weight. Model compound studies, as well as examinations of atactic PP reaction products, show that allylic ester activation occurs predominately by a radical‐addition/hydrogen‐transfer sequence, with a limited propensity for telomerization. The cografting of TATM and maleic anhydride leads to maleated PP of a high melt viscosity, whereas the apparent incompatibility of TATM with vinyltrimethoxysilane requires the use of TATM‐assisted thiol–ene addition and/or diallyl silane grafting to produce moisture‐curable PP derivatives. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4882–4893, 2005
Synthesis and characterization of biodegradable triblock copolymers based on bacterial poly[(R)‐3‐hydroxybutyrate] by atom transfer radical polymerization
Authors: Zhang Xueqin , Yang Hu , Liu Quanwei , Zheng Yun , Xie Hongfeng , Wang Zhiliu , Cheng Rongshi 
Published: September 2005

AbstractBiodegradable poly(tert‐butyl acrylate)–poly[(R)‐3‐hydroxybutyrate]–poly (tert‐butyl acrylate) triblock copolymers based on bacterial poly[(R)‐3‐hydroxybutyrate] (PHB) were synthesized by atom transfer radical polymerization. The chain architectures of the triblock copolymers were confirmed by 1H NMR and 13C NMR spectra. Gel permeation chromatography analysis was used to estimate the molecular weight characteristics and lengths of the PHB and poly(tert‐butyl acrylate) blocks of the copolymers. The thermal properties of the copolymers were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA showed that the triblock copolymers underwent stepwise thermal degradation and had better thermal stability than their respective homopolymers, whereas DSC analyses showed that a microphase‐separation structure was formed only in the triblock copolymers with the longer PHB block. As a similar result, from wide‐angle X‐ray diffraction experimentation, the crystalline phase of PHB could not be seen evidently in the triblock copolymers with the shorter PHB block. The enzymatic hydrolysis of the copolymer films was carried at 37 °C and pH 7.4 in a potassium phosphate buffer with an extracellular PHB depolymerase from Penicillum sp. The biodegradability of the triblock copolymers increased with an increase in the PHB block content. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4857–4869, 2005
Using scanning electron, confocal and optical microscopes to measure microscopic holes in trays
Authors: Bix Laura , Kassarjian Ondrea , Cardoso Fernando , Lockhart Hugh 
Published: September 2005

AbstractPackage integrity is of paramount importance to the medical device industry. As healthcare costs soar and integrity testers become more and more sensitive, concern with the question ‘what hole size allows microbial penetration into device packages?’ is re‐ignited. However, producing a consistent and measurable defect in the microcosm presents challenges. Varying techniques are currently employed to produce these defects. Use of an excimer laser is one of the most precise and accurate techniques, and holes ‘certified’ to be a given size can be purchased at a significant cost. To verify the accuracy and precision of holes drilled with an excimer laser, researchers measured laser‐drilled ‘exit’ and ‘entry’ holes in glycol‐modified polyetheylene terephthalate (PETG) trays using scanning electron microscopy (SEM) and confocal microscopy. This data and the certification data provided by the laser driller were analysed using a mixed‐model analysis of variance (ANOVA). Both the effect of measuring technique and hole side (entry vs. exit) were found to be significant. These significant differences have the potential to impact the question that the industry faces with regard to penetration threshold. This suggests that a shift in thinking is needed. Perhaps it would be better if the industry stops thinking about hole size and begins to think in terms of what researchers have referred to as the ‘effective hole’, which is defined as the volume of gas that will flow through a hole of defined size per unit time. Copyright © 2005 John Wiley & Sons, Ltd.
Response surface optimization of the feed compositions of biodegradable packaging foams
Authors: Peng Jinchyau , Wei Kaishuen , Lui Wai‐Bun 
Published: September 2005

AbstractResponse surface methodology (RSM) was used to analyse the effects of polyvinyl alcohol (PVOH) and calcium carbonate (CaCO3) on the physical and mechanical properties (radial expansion ratio, bulk density, compressibility and spring index) of a biodegradable cushioning extrudate. A rotatable central‐composite design (CCD) was used to develop models for the objective responses. The experiments were run at 125°C with a feed rate of 27.8 l/h, screw speed of 215 r.p.m. and die diameter of 3.92 mm. Responses were most affected by changes in PVOH levels and to a lesser extent by CaCO3 levels. Individual contour plots of the different responses were overlaid. An optimum radial expansion ratio of 3.39, bulk density of 0.065 (g/cm3), compressibility of 32.27(N), and spring index of 0.906 were identified at 36% PVOH and 5% CaCO3. Copyright © 2005 John Wiley & Sons, Ltd.