bluuebunny/crossref_metadata_2025_split huggingface dataset:
Decreasing miscibility with greater heterogeneity in ternary polymer blend: poly(cyclohexyl methacrylate), poly(α‐methyl styrene) and poly(4‐methyl styrene)
Authors: Chang Li Ling , Woo E M 
Published: January 2003

AbstractA ternary blend system comprising poly(cyclohexyl methacrylate) (PCHMA), poly(α‐methyl styrene) (PαMS) and poly(4‐methyl styrene) (P4MS) was investigated by thermal analysis, optical and scanning electron microscopy. Ternary phase behaviour was compared with the behaviour for the three constituent binary pairs. This study showed that the ternary blends of PCHMA/PαMS/P4MS in most compositions were miscible, with an apparent glass transition temperature (Tg) and distinct cloud‐point transitions, which were located at lower temperatures than their binary counterparts. However, in a closed‐loop range of compositions roughly near the centre of the triangular phase diagram, some ternary blends displayed phase separation with heterogeneity domains of about 1 µm. Therefore, it is properly concluded that ternary PCHMA/PαMS/P4M is partially miscible with a small closed‐loop immisciblity range, even though all the constituent binary pairs are fully miscible. Thermodynamic backgrounds leading to decreased miscibility and greater heterogeneity in a ternary polymer system in comparison with the binary counterparts are discussed.© 2003 Society of Chemical Industry
Hyperbranched polyacrylates prepared by self‐condensing vinyl copolymerization in the presence of a tetrafunctional initiator
Authors: Hong Chun‐Yan , Zou Ying‐Fang , Pan Cai‐Yuan 
Published: January 2003

AbstractHyperbranched copolymers were synthesized by self‐condensing vinyl copolymerization (SCVCP) of 2‐[(2‐bromopropionyl)oxy]ethyl acrylate (BPEA) and methyl acrylate (MA) in the presence of a tetrafunctional initiator, 6,6‐bis[5‐(α‐bromoisobutyryloxy)‐2‐oxapentyl]‐4,8‐dioxaundecane‐yl‐1,11 dibromoisobutyrate (THABI). The structures of the polymers obtained were characterized by NMR and size exclusion chromatography/right‐angle laser‐light scattering/differential viscometry/differential refractometry. Molecular weight, molecular weight distribution and degree of branching were influenced by conversion and initial feed molar ratio of BPEA, MA and THABI. The addition of THABI can narrow the polydispersity of the hyperbranched copolymers obtained. The results are consistent with our previous simulation work.© 2003 Society of Chemical Industry
Alignment behaviour of liquid crystals on ethyl cellulose films with banded‐texture structure
Authors: Yan Lifeng , Zhu Qingshi , Ikeda Tomiki 
Published: January 2003

AbstractFilms were formed by casting and shearing ethyl cellulose in chloroform at high coating speed and thin coating thickness. The films were used as alignment layers for liquid crystals. Atomic force microscopy and polarizing optical microscopy (POM) were used to identify the banded‐texture structure of the films. The alignments of nematic liquid crystal 4‐cyano‐4′‐n‐pentylbiphenyl (5CB) droplets on the films were observed by POM. Furthermore, the time‐dependent alignment behaviour of 5CB on the films was recorded and studied.© 2003 Society of Chemical Industry
Part 7. Effects of poly(L‐lactide‐co‐ϵ‐caprolactone) on morphology, structure, crystallization, and physical properties of blends of poly(L‐lactide) and poly(ϵ‐caprolactone)
Authors: Tsuji Hideto , Yamada Tamami , Suzuki Masakazu , Itsuno Shinichi 
Published: January 2003

AbstractBlended films of poly(L‐lactide) [ie poly(L‐lactic acid)] (PLLA) and poly(ϵ‐caprolactone) (PCL) without or mixed with 10 wt% poly(L‐lactide‐co‐ϵ‐caprolactone) (PLLA‐CL) were prepared by solution‐casting. The effects of PLLA‐CL on the morphology, phase structure, crystallization, and mechanical properties of films have been investigated using polarization optical microscopy, scanning electron microscopy, differential scanning calorimetry and tensile testing. Addition of PLLA‐CL decreased number densities of spherulites in PLLA and PCL films, and improved the observability of spherulites and the smoothness of cross‐section of the PLLA/PCL blend film. The melting temperatures (Tm) of PLLA and PCL in the films remained unchanged upon addition of PLLA‐CL, while the crystallinities of PLLA and PCL increased at PLLA contents [XPLLA = weight of PLLA/(weight of PLLA and PCL)] of 0.4–0.7 and at most of the XPLLA values, respectively. The addition of PLLA‐CL improved the tensile strength and the Young modulus of the films at XPLLA of 0.5–0.8 and of 0–0.1 and 0.5–0.8, respectively, and the elongation at break of the films at all the XPLLA values. These findings strongly suggest that PLLA‐CL was miscible with PLLA and PCL, and that the dissolved PLLA‐CL in PLLA‐rich and PCL‐rich phases increased the compatibility between these two phases.© 2003 Society of Chemical Industry
Flow behaviour and microstructure evolution in novel SiO2/PP/LCP ternary composites: effects of filler properties and mixing sequence
Authors: Lee Mun Wai , Hu Xiao , Li Lin , Yue Chee Yoon , Tam Kam Chiu 
Published: January 2003

AbstractWhen silica (SiO2) fillers were introduced into the polypropylene (PP) and liquid‐crystalline polymer (LCP) blend, it was found that the mixing sequence, the filler size, and the filler surface nature affected the rheology of the composites and the morphology of the LCP phase in the ternary composite. In particular, the compatibility between the filler and the PP matrix was found to exert a strong influence on the droplet‐fibril transition. The incorporation of the hydrophobic silica to the LCP/PP blend facilitated the fibrillation of LCP because the hydrophobic filler demonstrated affinity towards the hydrophobic PP matrix. The preferential residence of the hydrophobic silica in the PP phase would minimise the LCP domain disruption leading to the formation of LCP fibrils with high aspect ratios. The use of fine filler and in situ blending, which promoted the filler–LCP interaction, could prevent coalescence, inhibit deformation and hinder fibril development as well.© 2003 Society of Chemical Industry
Influence of chitosan characteristics on polymer properties. I: Crystallographic properties
Authors: Jaworska Malgorzata , Sakurai Kensuke , Gaudon Pierre , Guibal Eric 
Published: January 2003

AbstractThe properties of chitosan depend on several parameters including its origin (shrimp, squid, fungi etc), characteristics (mol fraction of N‐acetylation; molecular weight) and treatments used to condition it (dissolving, precipitation, drying). These parameters can influence the material's sorption properties for metal ions. It has been suggested that the changes in sorption properties are related to the crystallinity of the material. The present work focuses on the study of the crystallographic properties of samples prepared from shrimp, squid and fungi sources, with different characteristics and conditioned by several physical treatments (dissolving, reprecipitation and drying, including oven‐drying, freeze‐drying), prior to subsequent studies of their sorption properties for platinum (discussed in Part II of this manuscript).© 2003 Society of Chemical Industry
Influence of chitosan characteristics on polymer properties: II. Platinum sorption properties
Authors: Jaworska Malgorzata , Kula Karolina , Chassary Philippe , Guibal Eric 
Published: January 2003

AbstractThe sorption of platinum on glutaraldehyde cross‐linked chitosan was investigated at pH 2, using several chitosan samples prepared from different origins and characterized by different mol fractions of N‐acetylation (FA). The influence of material conditioning was also tested: chitosan was dissolved and then re‐precipitated and/or dried (using either oven‐drying or freeze‐drying). The influence of the different characteristics and treatments on both sorption isotherms and uptake kinetics was checked. Part I has studied the effect of preparation and source on sample crystallinity. Shrimp chitosan has a greater sorption affinity for platinum than fungal chitosan and squid chitosan respectively. Sorption kinetics were found comparable for fungal chitosan and shrimp chitosan, while diffusion was more restricted in squid chitosan due to the higher crystallinity. Decreasing the FA increased sorption capacity for shrimp chitosan but decreased sorption levels for squid material. While FA did not influence sorption kinetics for shrimp material it strongly decreased kinetics for squid chitosan. The type of drying procedure hardly affected sorption kinetics and isotherms but when a re‐precipitation step was included in the preparation procedure, the material had to be freeze‐dried to maintain high sorption properties. The freeze‐drying did not control sorption performance, except in the case of re‐precipitated material.© 2003 Society of Chemical Industry
Segmented polymer networks containing amino‐dendrimers
Authors: Tanghe Leen M , Goethals Eric J , Du Prez Filip 
Published: January 2003

AbstractPolymer networks in which poly(propylene imine) dendrimers (Astramol™) are connected to each other by linear polytetrahydrofuran (polyTHF) segments, were prepared by two methods. The first method was a one‐step procedure in which bifunctionally living polyTHF, obtained by initiation of the THF polymerization with trifluoromethane sulfonic anhydride (triflic anhydride), was reacted with an amino‐dendrimer. This reaction was very fast but did not allow formation of the end products. The second method was a two‐step procedure. In a first step, living polyTHF, prepared with acryloyloxybutyl triflate as initiator, was grafted on an amino‐dendrimer, to form a star‐like, acrylate‐terminated polyTHF multi‐macromonomer with the dendrimer as core. In a second step, networks were obtained by Michael addition between the acrylate end‐groups and unreacted amino‐groups of the dendrimer. This cross‐linking reaction occurred spontaneously upon heating of the solution of the multi‐macromonomer with gelation times varying from a few minutes to a few hours, depending on the temperature and the composition of the prepolymers. With this method it was possible to prepare networks in the form of coatings or films.© 2003 Society of Chemical Industry
Polyimides containing s‐triazine rings
Authors: Patel Hashmukh S , Patel Vimal C 
Published: January 2003

AbstractA series of new polyimides containing s‐triazine rings have been synthesized via Diels–Alder intermolecular polymerization of 2,6‐bis(2‐furanylmethylimino)‐4‐isopropoxy‐1,3,5‐triazine with various bis(maleimide)s. All the poly(imino‐s‐triazine imide)s were characterized by elemental analyses, FTIR spectral studies, number average molecular weight (
M
n) by non‐aqueous conductometric titration and thermogravimetry. Glass‐fibre reinforced composites were prepared via an in situ Diels–Alder intermolecular reaction between 2,6‐bis(2‐furanylmethylimino)‐4‐isopropoxy‐1,3,5‐triazine and various bis(maleimide)s. The composites were characterized for chemical resistivity and mechanical properties.© 2003 Society of Chemical Industry
Random orientation of in situ composites based on liquid‐crystalline polymers by compression moulding
Authors: Xie X L , Yang T Q , Tang C Y 
Published: January 2003

AbstractIn this study, randomly oriented in situ composites based on liquid‐crystalline polymers (LCPs) were prepared by thermal compression moulding. The LCP employed was a semi‐flexible liquid‐crystalline copolyesteramide with 30 mol% of p‐aminobenzoic acid (ABA) and 70 mol% of poly(ethylene terephthalate) (PET). The matrices were poly(butylene terephthalate) (PBT) and polyamide 66 (PA66). The rheological properties, compatibility and morphological structures of these in situ composites were investigated. The results showed that PA66‐LCP and PBT–LCP component pairs of the composites are miscible in the molten state, but partially compatible in the solid state. The ratios of viscosity, λ1 = ηLCP/ηPA66 and λ2 = ηLCP/ηPBT, are all greater than 1.0. However, the melt viscosity of the LCP/PBT and LCP/PA66 blend is much lower than that of PBT and PA66, and it decreases markedly with increasing LCP content. When the LCP/PA66 or LCP/PBT blends are compression moulded, the LCP/PA66 or LCP/PBT melts and flows easily due to their low viscosity, and the LCP phases in the melts deform easily along the flow directions, which are random. It leads to uniformly dispersed LCP micro‐fibres randomly orientation in the thermoplastic matrix due to the compatibility between the blending components.© 2003 Society of Chemical Industry
Monte Carlo simulation of gas phase polymerization of 1,3‐butadiene. Part II: Kinetics optimization and confirmation
Authors: Ling Jun , Ni Xufeng , Zhang Yifeng , Shen Zhiquan 
Published: January 2003

AbstractStudies on the deactivations and initiations of gas phase polymerizations of 1,3‐butadiene have been achieved by Monte Carlo simulation. Initiation and deactivation control the reaction before and after the peak of the polymerization rate, respectively. The influence of polymerization temperature has been studied. Monte Carlo modeling of polymerization kinetics and mechanism was confirmed by the agreement of experimental data and simulation results of polymerizations run with a temporary evacuation of monomer. The balance of catalysts and active chains is established by both initiation and chain transfer reactions with cocatalyst, which causes a ‘pseudo‐stability’ stage.© 2003 Society of Chemical Industry
Melt polycondensation of L‐lactic acid to poly(L‐lactic acid) with Sn(II) catalysts combined with various metal alkoxides
Authors: Moon Sung Il , Kimura Yoshiharu 
Published: January 2003

AbstractMelt polycondensation of L‐lactic acid (LA) was examined in the presence of binary catalyst systems consisting of SnCl2·2H2O and metal alkoxides as co‐catalysts. Among the co‐catalysts examined, viz (Al(O
iPr)3,Ti(O
iPr)4,Y(O
iPr)3,Si(OEt)4 and Ge(OEt)4), Ge(OEt)4 was found to be the most effective in enhancing the catalytic activity of Sn(II). With an optimized composition of SnCl2·2H2O–Ge(OEt)4, the molecular weight (Mn) of PLLA reached 40 000 Da in a short reaction time (<15 h) at the optimum reaction conditions of 180 °C and 10 Torr. This catalyst system was also superior to the conventional single metal ion catalysts such as Sn(II) in terms of racemization and discolouration of the resultant polymer. The metal alkoxides, added as co‐catalysts, should work as oxo acids that can effectively control the catalytic activity of Sn(II) ion in the direct polycondensation of LA, in a manner similar to that of proton acids.© 2003 Society of Chemical Industry
Electrosynthesis and characterization of a new electro‐active polymer from 2‐phenylazo‐1‐naphthol
Authors: Rehan Hyman H 
Published: January 2003

AbstractCyclic voltammetry was used to electropolymerize 2‐phenylazo‐1‐naphthol in 0.2 M NaOH in 30% ethanol/water and in acetonitrile (MeCN). Very thin electro‐inactive polymer films were obtained in alcoholic NaOH while the films formed in MeCN were much thicker and electro‐active in acid solutions. Based on IR and electrochemical behaviour, poly (2‐phenylazo‐1‐naphthol) (PPAN) is assumed to consist of two polymeric segments, in ratios that depend on the nature of the polymerization solvent. Head‐to‐tail coupling led to formation of ether linkages and the electro‐inactive segments, while tail‐to‐tail coupling led to formation of aromatic CC and quinone moieties in the polymer skeleton and the electro‐active segments. The redox processes of the quinone/quinol transformations were studied by cyclic voltammetry and chronocoulometry. NaOH‐formed films were superior in corrosion protection of steel in 0.5 M sulfuric acid than MeCN‐formed films. PPAN films formed in MeCN were found to mediate the oxidation of ascorbic acid at lower oxidation potential.© 2003 Society of Chemical Industry
From science teacher to teacher leader: Leadership development as meaning making in a community of practice
Authors: Howe Ann C. , Stubbs Harriett S. 
Published: January 2003

AbstractThe process through which three science teachers became active, effective teacher leaders in their schools, their profession, and their communities was investigated. A model of leadership development, proposed by Palus and Drath (Evolving leaders: A model for promoting leadership development in programs, Center for Creative Leadership, Greensboro, NC, 1995), was used as a framework for analyzing and understanding the experiences and forces that led these teachers to become leaders. Development of the teacher leaders was prompted by their involvement in SCI‐LINK, a program that began as a way to link environmental scientists and science teachers, and grew over a period of 6 years to become a constellation of activities and a learning community of teachers, scientists, and science educators. Four elements of SCI‐LINK that promoted and supported leadership development are identified. Implications for leadership development in science education and other subject areas are discussed. © 2003 Wiley Periodicals, Inc. Sci Ed 87:281–297, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/sce.10022
An instructional model for a radical conceptual change towards quantum mechanics concepts
Authors: Kalkanis George , Hadzidaki Pandora , Stavrou Dimitrios 
Published: January 2003

AbstractWe believe that physics education has to meet today's requirement for a qualitative approach to Quantum Mechanics (QM) worldview. An effective answer to the corresponding instructional problem might allow the basic ideas of QM to be accessed at an early stage of physics education. This paper presents part of a project that aims at introducing a sufficient, simple, and relevant teaching approach towards QM into in‐/preservice teacher education, i.e., at providing teachers with the indispensable scientific knowledge and epistemological base needed for a reform of science education along the aforementioned line. The investigation of teacher–learners' (t‐ls') initial knowledge indicated that their main misconceptions appear to be the result of their pre‐/inuniversity traditional instruction, which causes the overlapping/mix‐up of the conceptual frameworks of Classical Physics (CP) and QM. Assuming that these misconceptions form by nature epistemological obstacles to the acquisition of QM knowledge, the educational strategy proposed here aims at leading t‐ls to form a conceptual structure that includes CP and QM as two totally independent conceptual systems. Accepting, furthermore, that the complete distinction of these systems demands a radical reconstruction of t‐ls' initial knowledge, we present here an instructional model that bases the required reconstruction on the juxtaposition of two models that constitute the signal point of twentieth century's “paradigm shift”: (a) Bohr's semiclassical atom model, and (b) the model of the atom accepted by modern physics theory. © 2003 Wiley Periodicals, Inc. Sci Ed 87:257–280, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/sce.10033
Science and technology education for citizenship: The potential role of the press
Authors: Dimopoulos Kostas , Koulaidis Vasilis 
Published: January 2003

AbstractThis paper aims to explore the potential suitability of the press as a teaching resource for raising scientific literacy for citizenship within science education. Our methodology is based on a content analysis of a sample of 1867 articles about science and technology from four Greek newspapers. The analysis showed that the press is potentially a useful tool for teaching certain aspects of science and technology for citizenship since it (a) provides a constant flow of relevant articles on a regular basis, (b) gives prominence to techno‐scientific issues that prevail in the public arena (digital technologies, advances in biotechnology and genetic engineering, environmental degradation), (c) identifies the various social actors and forces (mainly coming from the world of politics and the business world) that impinge on the collective decision‐making procedures about these issues, (d) portrays the kind of the social impacts of science and technology in an optimistic way, albeit tempered by considerable levels of concern, and (e) presents all the relevant news in context, thereby adding relevance and meaningfulness to the techno‐scientific concepts under discussion. In addition to strong points, the press has also weak points as a teaching resource in science classes. These weaknesses are mostly related to the underpresentation of techno‐scientific subject matter and the internal mechanisms that lead to the production of the corresponding knowledge. Consequently, press material can be used in the science classes in a complementary way to the conventional material already used so as to illuminate crucial aspects of science and technology in the public that seem to be missing from the official pedagogic discourse of science education. © 2003 Wiley Periodicals, Inc. Sci Ed 87:241–256, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/sce.10054
Study of classroom practice and classroom contexts amongst senior high school biology teachers in Harare, Zimbabwe
Authors: Gwimbi Eric M. , Monk Martin 
Published: January 2003

AbstractThirty‐three senior high‐school biology teachers in Harare, Zimbabwe, participated in the study. Self‐report data on school contexts was used to cluster the teachers according to their own perceptions of the contextual circumstances in their schools. The clustering differentiated self‐perceived better and poorer resourced schools. In theory lessons, teachers from the self‐perceived better resourced schools were observed to use less individual organization, less written exercises, more whole class organization, and more listening to the teacher than to the teachers in the poorer schools. In practical lessons teachers in the better self‐perceived better resourced schools were observed to use less whole class organization, less small group organization, more individual organization, less listening to teacher, less teacher explanation, less teacher questioning, and to conduct more practical. An interpretation of these findings is made in terms of the fit between a teacher's classroom practice and their self‐perceived classroom context. © 2003 Wiley Periodicals, Inc. Sci Ed 87:207–223, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/sce.10056
Genetics inquiry: Strategies and knowledge geneticists use in solving transmission genetics problems
Authors: Thomson Norman , Stewart James 
Published: January 2003

AbstractScientists are increasingly challenged to solve problems that require conceptualizing and understanding dynamic complex natural systems. Computer simulations have become an integral tool in helping solve complex problems because they can be effectively used to model dynamic systems. Today's reform standards advocate that science teachers and students be involved in scientific inquiry that is consistent with the practice of science. The goal of this research is to determine methods of inquiry geneticists' use in solving dynamic complex computer‐generated transmission genetics problems, specifically, their strategies and conceptual knowledge. Six geneticists representing three areas of genetics (transmission, molecular, and population) solved four problem types. Using their solution protocols, and through interviews, a hierarchical framework and pathway for solving the problems were developed. For science education researchers, teachers, and students, it is hoped the geneticists' insights and the framework developed can provide a guide for inquiry‐based problem solving that extends beyond genetics. © 2003 Wiley Periodicals, Inc. Sci Ed 87:161–180, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/sce.10065