bluuebunny/crossref_metadata_2025 huggingface dataset:
An Integrative Review of Positive Health Practices
Authors: Cannella Barbara L. , Scoloveno Mary Ann
Published: October 2003

This study presents an integrative review of published research articles on positive health practices (PHP) as defined by Muhlenkamp and Brown. Using Cooper's guidelines for accomplishing an integrative review, 29 relevant studies concerning PHP were located, reviewed, and critiqued; theoretical and methodological issues emerging from the studies were identified. Directions for future research on PHP are specified. Implications for nursing practice derived from the research findings are addressed.
Division of Labor by Gender and Postmarital Residence in Cross-Cultural Perspective: A Reconsideration
Authors: Korotayev Andrey
Published: October 2003

First theories proposed to explain determinants of postmarital residence connected it with the division of labor by gender. However, at the moment all the cross-cultural tests of this hypothesis using worldwide samples have failed to find any significant relationship between these two variables. In the meantime, the alternative explanations of the postmarital residence led the author to expect that such a relationship would be found if the societies with an extremely low female contribution to subsistence were contrasted with the rest of the world cultures. There are reasons to expect that an extremely low female contribution should predict more or less strongly the nonmatrilocal residence and less strongly (but still significantly) the patrilocal residence. A series of worldwide cross-cultural tests performed by the author using five various sets of coded data on female contribution to subsistence has fully supported this hypothesis.
Economic Systems of Foragers
Authors: Pryor Frederic L.
Published: October 2003

A variety of economic systems prevail among societies relying primarily on hunting, gathering, or fishing for subsistence. Using 10 characteristics of distribution and property ownership and a sample of 44 foraging societies, the author employs a cluster analysis to define five distinct types of economic systems. Environmental factors appear important determinants for only two of the five types of economic systems. The author also shows that these different economic systems do not correlate with many of the standard social-structural and political variables that many anthropologists believe to be the primary causal factors explaining the operation of the economy. Focusing greater attention on the economic system pro-vides a new and important perspective for understanding the functioning of these foraging societies and to analyze property and distribution institutions and organizations in a more systematic fashion.
The Relationship between Family and Sibling Functioning in Families Raising a Child with a Disability
Authors: Mandleco Barbara , Olsen Susanne Frost , Dyches Tina , Marshall Elaine
Published: October 2003

Although considerable research exists concerning families raising children with disabilities, relatively little work has examined the linkages between parent and sibling functioning. The purpose of this study, therefore, was to investigate the relationship between parental perceptions of family functioning and school-aged siblings' social skills and problem behaviors. A purposive sample of 78 sets of parents and their school-aged children participated. Half of the families were raising a child with a disability, and half of the families were not raising a child with a disability. Mothers and fathers completed the Porter-O'Leary Scale and Bloom's Family Functioning Measure. Teachers of the school-aged children completed a modification of the Gresham and Elliot Social Skills Rating System. Results indicated siblings of both groups demonstrate more social skills than problem behaviors, and siblings of children with disabilities were higher in cooperation and self-control than siblings of children without disabilities. Hierarchical regression analyses revealed fathers' perceptions of family conflict and external locus of control orientation, and mothers' perceptions of marital conflict predicted externalizing behaviors for female siblings of children with a disability.
Eminent Domain
Authors: Cypher Matthew L. , Forgey Fred A.
Published: October 2003

As downtown redevelopment occurs, eminent domain continues to be used as an economic development tool. This research evaluates the equity, effectiveness, and efficiency of certain components of eminent domain as it is used for downtown economic development projects. A survey-based methodology was employed to acquire data from city managers located in the 239 most populous cities within the United States. The findings indicate that eminent domain is effective in raising property tax values, efficient in minimizing litigation-based project delays, but inequitable to various developers seeking title to property following condemnation.
The Causes of Village Cooperation: Comment on Ragin, Shulman, Weinberg, and Gran
Authors: Wade Robert Hunter , Goldstein Markus
Published: October 2003

Village Republics (VR) (Wade 1988) explains village-based collective action in terms of intravillage conflict rooted in ecological conditions. Ragin et al. (2003 [this issue]) say that VR 's data point to intervillage conflict as the main driver—villagers organize themselves against incursions from people in other villages intent on stealing their resources. The authors show how Ragin et al. misstate VR 's argument and go on to describe problems with their measurement of key variables (intervillage density, water location, collective action). The authors end with some thoughts about a more general problem with the quantitative comparative analysis method—it throws out confidence-affecting information that both qualitative case studies and quantitative statistical analyses would use.
Complexity, Generality, and Qualitative Comparative Analysis
Authors: Ragin Charles C. , Shulman David , Weinberg Adam , Gran Brian
Published: October 2003

Qualitative comparative analysis (QCA) offers researchers the opportunity to combine the intensiveness of case-oriented research strategies and the extensiveness of variable-oriented approaches in a single framework. QCA is specifically designed for a moderate number of cases, too few for variable-oriented research designs and too many for in-depth, case-oriented analysis. To illustrate QCA's applicability to moderate-sized data sets, we analyze data on forty-one villages in southern India reported in Robert Wade's (1988) comparative study of villagewide collective action, Village Republics. Using QCA, we show that Wade's explanation of village-wide collective action is incomplete. We complement his strictly ecological explanation with a sociological perspective and show that intervillage competition is an important condition for villagewide collective action.
Research about Nursing: An Agenda whose Time has Come
Authors: Jennings Bonnie Mowinski
Published: October 2003

Research about nursing needs to be used as the foundation for both clinical and administrative practice. Concurrently, research findings about nursing need to be pushed beyond disciplinary boundaries into the larger health policy arena. To achieve these goals, the priorities of the nursing research community need to be realigned. Points to consider in setting an agenda that optimizes research about nursing include demonstrating the saliency of nursing as a variable in studies related to quality care and patient safety; exploiting a model of fast-track research to explore ideas most relevant to users and expedite getting findings to them; novel approaches for teaching clinical and administrative nurses how to use research in their practice; and developing a better understanding of how to successfully engage with policy makers.
Rural Nurse Leadership Project
Authors: Kaeding Toni H. , Rambur Betty
Published: October 2003

An innovative leadership development program in Vermont is testing the effect of nurse leadership development in a rural environment. Supported by a two-year grant from the Helene Fuld Health Trust, leadership development training is offered to a select group of outstanding nursing students who are recipients of the merit-based Freeman Nurse Scholars Award. This is a statewide project, drawing participants from all five schools of nursing in Vermont. Variables of interest are retention in the profession, professional values, rural practice, nurse satisfaction, and professional activism.
Chaos: A Leader's Friend or Foe
Authors: Edwardson Sandra R.
Published: October 2003

Chaos theory assumes that complexity is so great that scientists in the past could not rationally track it. The author applies this concept to current health care environments and offers guidance to nurses who are struggling in leadership roles to manage change and extract order and pattern in their daily practice environments. Order is seen as relative, and in our fast-moving health care system, it is apparent only in the long run.
Leadership—Not for Just a Few!
Authors: Woods Nancy Fugate
Published: October 2003

Leaving leadership to an elite is no longer an option for the nursing profession. Leadership responsibilities are discussed relative to political will, policy making, nursing education, and nurse practice environments. In particular, the role of the clinical nurse leader is portrayed as not necessarily one of administration or management but as one that manages care at the point of care/point of service to individuals and populations.
Leadership Redefined
Authors: Bednash Geraldine Polly
Published: October 2003

Strong leadership is needed to bring about dramatic change in the nursing profession. Leaders must be risk takers who are willing to show initiative, foster collaboration, and challenge the established order. An authority in nursing education issues a call for leadership and invites her colleagues to come together to move nursing's agenda forward.
The Institute of Medicine Report
Authors: Long Kathleen Ann
Published: October 2003

In response to the April 2003 Institute of Medicine (IOM) report titled Health Professions Education: A Bridge to Quality , the author assesses the report in light of the present education of professional nurses. While current educational approaches have merit, the plans under way to develop new curricula and programs are in keeping with the IOM recommendations. She also cites the importance of reform in nursing practice environments if nursing education strategies are to have a meaningful impact. The report notes that nursing graduates must possess competencies in five core areas. These are the following: the ability to deliver patient-centered care, work as a member of an interdisciplinary team, engage in evidenced-based practice, apply quality improvement approaches, and use information technology. Additionally, the report calls on accreditation, licensing, and certification organizations to ensure that students and working professionals develop and maintain proficiency in these core areas.
Medicare Quality Initiative
Authors: Harris Mary Jo
Published: October 2003

Department of Health and Human Services Secretary Tommy Thompson announced the Medicare Quality Initiative (MQI) in November 2001. With this announcement, a new era of public reporting of health care outcomes began. This policy update discusses the purposes of the MQI, its implementation, and the reports on the Nursing Home Quality Initiative and the Home Health Quality Initiative. Hospitals and physician practices are future targets of the MQI.
Defined-Contribution Health Plans: An Emerging Paradigm
Authors: Cummings Kathleen S. , Tilbury Mary S.
Published: October 2003

Many employers, especially small businesses, are looking for better ways to provide their employees with health care coverage. This goal is prompted by employer-based insurance programs that do not meet employee or employer needs. Costs are high and employee coverage is typically limited or entirely absent. One potential solution now in the marketplace is defined-contribution (DC) health plans. This insurance program allows the employee to structure the content of their coverage from an options menu. Employers pay a portion of the premium, and employee costs vary based on the coverage options selected. The implications of DC for consumers, employers, payers, and providers are far reaching. This model could dramatically affect consumer service choice and consumption patterns. It is vital that nursing analyzes this emerging product and responds so that the services covered are adequate, of high quality, and can successfully compete in today's health care marketplace.
Lessons Learned about Barriers to Hepatitis C Testing: Implications for Policy
Authors: Instone Susan L. , Gilbert Tari L. , Mueller Mary Rose
Published: October 2003

Despite primary prevention efforts to educate the public about hepatitis C, the most prevalent blood-borne human disease in the world today, most Americans remain unaware of their infection status. Widespread screening programs established to identify those at risk have been slow to emerge and difficult to implement, especially when compared to the nation's rapid response to the HIV/AIDS epidemic. Analysis of screening and testing practices among nurses and other clinicians within the Veterans Affairs Administration (VA), the site of the most comprehensive hepatitis C virus outreach program to date, reveals numerous barriers to reaching at-risk veterans. It is worthwhile to examine the VA experience for lessons in how to identify other Americans at risk, particularly those without access to primary care in well-funded, organized systems of care.
In Search of Methodology: From One Other to An-Other
Authors: Lange Mary Elizabeth
Published: October 2003

Cultural studies, encounters, and academic publications are composed of layers of subjective experiences and objective data. This article is a personalized attempt to bring together some of the layers relevant to the author's experiences of the Southern Kalahari people. It examines orality, memory, and subjectivity in the search for a methodology through which to represent the “Other.”
Objectivity, Photography, and Ethnography
Authors: Crowe Darryn
Published: October 2003

This article deals with photographic encounters in the Kalahari. The author discusses the role of photography in ethnographic fieldwork and issues surrounding photography as representation. He writes reflexively about his own experiences taking pictures in the Kalahari, his motivations and subjectivities, the reactions of his subjects, and the nature of financial demands made. The author compares his own photography with that of two photographers well known for their imaging of the San—Paul Weinberg and A. M. Duggan-Cronin—while dealing with his own subjectivity in relation to ethical and representational issues.
Insulin-like growth factor-1 protects ischemic murine myocardium from ischemia/reperfusion associated injury
Authors: Davani Ehsan Y , Brumme Zabrina , Singhera Gurpreet K , Côté Hélène CF , Harrigan P Richard , Dorscheid Delbert R
Published: October 2003

Introduction

Ischemia/reperfusion occurs in myocardial infarction, cardiac dysfunction during sepsis, cardiac transplantation and coronary artery bypass grafting, and results in injury to the myocardium. Although reperfusion injury is related to the nature and duration of ischemia, it is also a separate entity that may jeopardize viable cells and ultimately may impair cardiac performance once ischemia is resolved and the organ heals.

Method

The present study was conducted in an ex vivo murine model of myocardial ischemia/reperfusion injury. After 20 min of ischemia, isolated hearts were perfused for up to 2 hours with solution (modified Kreb's) only, solution plus insulin-like growth factor (IGF)-1, or solution plus tumor necrosis factor (TNF)-α. Cardiac contractility was monitored continuously during this period of reperfusion.

Results

On the basis of histologic evidence, IGF-1 prevented reperfusion injury as compared with TNF-α; TNF-α increased perivascular interstitial edema and disrupted tissue lattice integrity, whereas IGF-1 maintained myocardial cellular integrity and did not increase edema. Also, there was a significant reduction in detectable creatine phosphokinase in the perfusate from IGF-1 treated hearts. By recording transduced pressures generated during the cardiac cycle, reperfusion with IGF-1 was accompanied by markedly improved cardiac performance as compared with reperfusion with TNF-α or modified Kreb's solution only. The histologic and functional improvement generated by IGF-1 was characterized by maintenance of the ratio of mitochondrial to nuclear DNA within heart tissue.

Conclusion

We conclude that IGF-1 protects ischemic myocardium from further reperfusion injury, and that this may involve mitochondria-dependent mechanisms.
Synthesis and characterization of side‐chain liquid‐crystalline ionomers containing quaternary ammonium salt groups
Authors: Tong Bin , Zhang Baoyan , Hu Jianshe , Dai Rongji , Deng Yulin
Published: October 2003

A series of thermotropic side‐chain liquid‐crystalline ionomers (LCIs) containing 4‐(4‐alkoxybenzyloxy)‐4′‐allyloxybiphenyl (M) as mesogenic units and allyl triethylammonium bromide (ATAB) as nonmesogenic units were synthesized by graft copolymerization upon polymethylhydrosiloxane. The chemical structures of the polymers were confirmed by IR spectroscopy. DSC was used to measure the thermal properties of these polymers. The mesogenic properties were characterized by polarizing optical microscopy, DSC, and X‐ray diffraction. Homopolymers without ionic groups exhibit smectic and nematic mesophases. The nematic mesophases of the ionomers disappear and the mesomorphic temperature ranges decrease with increasing concentration of ionic units. The influence of the alkoxy chain length on clearing temperature (Tc) values of ionomers clearly shows an odd‐even effect, similar to that of other side‐chain liquid‐crystalline polymers. The mesomorphic temperature ranges increase with increasing alkoxy chain length when the number of alkoxy carbon is over 3. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2879–2886, 2003
Physicomechanical, optical, barrier, and WAXS studies of filled linear low‐density polyethylene films
Authors: Siddaramaiah  , Jeevananda T. , Jagadeesh K. S. , Somashekarappa H. , Somashekar R.
Published: October 2003

Linear low‐density polyethylene (LLDPE) with different fillers such as silica, mica, and soy protein isolate were compounded using a single screw extruder and blown into films by a Konark blow‐film machine. The filled LLDPE films were characterized for physicomechanical and optical properties. Barrier properties such as water vapor transmission rate and oxygen transmission rate of the filled LLDPE films were also reported. Microcrystalline parameters such as crystal size (〈N〉) and lattice distortion (g in %) of the filled LLDPE films were estimated from the wide‐angle X‐ray scattering method using Hosemann's paracrystalline model. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2938–2944, 2003
Structure–property relationship of starch‐filled chain‐extended polyurethanes
Authors: Kendaganna Swamy B. K. , Siddaramaiah
Published: October 2003

Chain‐extended polyurethane (PU) elastomers were prepared using castor oil with 4,4′‐methylene bis (phenyl isocyanate) (MDI) as a crosslinker and 4,4′‐diamino diphenyl sulphone (DDS) as an aromatic diamine chain extender. A series of starch‐filled (from 5 to 25% wt/wt) diamines chain‐extended PUs have been prepared. The starch‐filled PU composites were characterized for physico‐mechanical properties viz, density, surface hardness, tensile strength, and percentage elongation at break. Thermal stability of PU/starch have been carried out by using thermogravimetric analyzer (TGA). Thermal degradation process of PU/starch were found to proceed in three steps. TGA thermograms of PU/starch shows that all systems were stable upto 235°C, and maximum weight loss occur at temperature 558°C. The microcrystalline parameters such as crystal size (〈N〉) and lattice strain (g in %) of PU/starch have been established using wide‐angle X‐ray scattering (WAXS) method. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2945–2954, 2003
Effect of different skin permeation enhancers on peel strength of an acrylic PSA
Authors: Taghizadeh S. M. , Lahootifard F.
Published: October 2003

Different amounts of two skin permeation enhancers, Oleic acid (OA) and Propylene glycol (PG), were mixed thoroughly with solution of a commercial acrylic pressure sensitive adhesive (Duro‐Tak). Films with different adhesive layer thickness (30 and 60 μm) were prepared by casting of formulations with a film applicator on a PET 80‐μm film and drying of solvents. Peel test was done on different formulations according to ASTM D3330. Surface study and thermal analysis were used for explaining the results. It was shown that the effect of interfacial work of adhesion on peel strength was too low to be considered. PG had no significant effect on peel strength, which was related to effect of hydrogen bonds between PG and copolymer chains acting as crosslinks. OA decreased peel strength significantly, which is due to important changes in copolymer structure. These changes can be found by relatively sharp drop in Tg values. Adhesive–cohesive transition occurred in OA formulations as a result of OA crystals formation. OA migration to surface in concentrations of more than 10 (w/w %) was confirmed by results of DSC and surface study. In contrast with PG, doubling of thickness had no effect on peel strength. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2987–2991, 2003
Viable utilization of polycarbonate as a phosgene equivalent illustrated by reactions with alkanedithiols, mercaptoethanol, aminoethanethiol, and aminoethanol: A solution for the issue of carbon resource conservation
Authors: Hata Sohei , Goto Hiroko , Tanaka Saki , Oku Akira
Published: October 2003

Methods for the chemical recycling of polycarbonate (PC) wastes in the forms of bisphenol A (BPA) and cyclic heterocarbonates, such as 1,3‐dithiolan‐2‐one (DTO), 1,3‐dithiane‐2‐one (DTA), and cyclic unsymmetric heterocarbonates, were investigated to prove that PC can be utilized as a phosgene equivalent for industrial purposes. Treatment of PC pellets or waste PC compact discs with 1,2‐ethanedithiol and a catalytic amount of base (e.g., 1.5 mol % NaOH) in dioxane for a short period at 40°C produced DTO and BPA, both in nearly quantitative yields. The reaction could also be carried out in DTO, which saved the use of conventional solvents. Other cyclic heterocarbonates, that is, DTA, 1,3‐oxathiolan‐2‐one, 1,3‐thiazolidine‐2‐one, and N‐methyl‐1,3‐oxazolidine‐2‐one, were prepared in high yields under analogous conditions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2959–2968, 2003
Synthesis and characterization of novel copolymers with acid‐labile ketal moieties derived from camphor
Authors: Liu Jui‐Hsiang , Wang Hung‐Yu
Published: October 2003

Novel diastereomeric acrylic ketal monomers derived from (+)‐camphor and (±)‐camphor were synthesized. To investigate the applications of the camphor derivatives on positive‐tone photoresists, the acrylic ketal monomers were copolymerized with methyl methacrylate, methacrylic acid, and n‐butyl methacrylate. The optical activities of the chiral monomers and polymers were all evaluated. After UV irradiation and postexposure baking, the optical activity of the polymers decreased because of the decomposition of the acid‐labile pendant chiral groups. The existence of alicyclic camphyl groups increased the etching resistance of the photoresists. The thermogravimetric properties of the copolymers, the exposure curves, the lithographic evaluation of the positive‐tone photoresists, and the effects of alicyclic groups on the plasma etching resistance of the copolymers were all investigated. A resolution of a line‐and‐space pattern of 0.3 μm was achieved. Acid‐catalyzed dehydration crosslinking was also found in this system. Sufficient UV irradiation and heat treatment could cause the acid‐catalyzed dehydration crosslinking of pendant carboxyl groups and thereby increase the efficiency of the thermal resistance of the polymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2969–2978, 2003
Effect of gas channel design on the molding window of gas‐assisted‐injection‐molded polystyrene parts
Authors: Chien Rean Der , Chen Shia‐Chung , Lin Ming‐Chung , Lee Ping‐Hui , Chen Chun‐Sheng
Published: October 2003

Gas channel design plays a dominant role in determining the successful application of gas‐assisted injection molding. Although empirical guidelines for gas channel design have been proposed by the various equipment suppliers, quantitative criteria based on well‐designed experiments have not been reported yet. In this study, transparent polystyrene plates designed with semicircular gas channels of different radii and with rectangular gas channels of different width‐to‐height ratios were gas‐assisted‐injection‐molded to investigate the geometrical effects on gas penetration with various plate thicknesses. Plate parts designed with gas channels having four different types of cross sections but with the same section area were also examined. Molding windows and criteria for gas penetration were properly chosen so that the design rule could be defined quantitatively. The moldability index was also classified into five levels (excellent, good, fair, poor, and bad) based on the relative areas of the molding windows. From a plot of the moldability index versus the ratio of the equivalent gas channel radius to the plate thickness, we found that the ratio should be approximately greater than 2 for an appropriate molding window (fair moldability index) to be obtained. The dimensional ratio of the width to the height for rectangular gas channels also affected the moldability index under the same equivalent radius. Meanwhile, for four gas channel designs, both gas channel designs attached to the top rib provided better moldability than the other designs. This investigation offers part designers preliminary quantitative design and molding guidelines for choosing an effective gas channel design that allows the parts to be molded under an appropriate molding window so that the uncertainty in both simulation and process control can be overcame. Furthermore, this study provides a methodology for the establishment of quantitative gas channel design guidelines. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2979–2986, 2003
Modeling shear thickening in dilute polymer solutions: Temperature, concentration, and molecular weight dependencies
Authors: Jiang B. , Keffer D. J. , Edwards B. J. , Allred J. N.
Published: October 2003

The Two Coupled Maxwell Modes (TCMM) Model is applied to give quantitative descriptions of shear‐thickening behavior, which can be observed under certain conditions for high molecular weight polymers dissolved in low viscosity solvents. The TCMM Model is written in terms of five parameters representing the relaxation time of each mode, the concentration of each mode, and a coupling parameter between the two modes. Using all of the available experimental data for steady‐shear viscosity and dichroism we found in the literature, we performed a full parameterization of these five quantities. Furthermore, from this parameterization we can describe the functional dependencies of the relaxation times, modal concentrations, and coupling parameter as functions of temperature, concentration, and molecular weight of the polymer. These functional dependencies are explained in light of the underlying physics imbedded in the TCMM Model. We demonstrate that by optimizing to only the viscosity data, we were able to obtain the same relaxation times, modal concentrations, and coupling parameter as using both the viscosity and dichroism data. This is useful because typically the experimental dichroism data is not available. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2997–3011, 2003
Curing kinetics and chemorheology of epoxy/anhydride system
Authors: Ivankovic M. , Incarnato L. , Kenny J. M. , Nicolais L.
Published: October 2003

The curing kinetics and chemorheology of a low‐viscosity laminating system, based on a bisphenol A epoxy resin, an anhydride curing agent, and a heterocyclic amine accelerator, are investigated. The curing kinetics are studied in both dynamic and isothermal conditions by means of differential scanning calorimetry. The steady shear and dynamic viscosity are measured throughout the epoxy/anhydride cure. The curing kinetics of the thermoset system is described by a modified Kamal kinetic model, accounting for the diffusion‐control effect. A chemorheological model that describes the system viscosity as a function of temperature and conversion is proposed. This model is a combination of the Williams–Landel–Ferry equation and a conversion term originally used by Castro and Macosko. A good agreement between the predicted and experimental results is obtained. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3012–3019, 2003
Solution and solid state nuclear magnetic resonance investigation of poly(methylmethacrylate)/ poly(ethylene oxide) blends
Authors: Diniz Teresinha M. F. F , Tavares Maria I. B.
Published: October 2003

It is well known that nuclear magnetic resonance spectroscopy (NMR) is a powerful method to characterize blends compatibility at the molecular level. In this work binary blends formed by poly(methylmethacrylate)/poly(ethylene oxide), PMMA/PEO, were investigated by different solution and solid state NMR techniques to obtain information on blends homogeneity and compatibility. It was characterized that the values of T1Hρ obtained by variable contact time and delayed contact time experiments, for each composition, were distinct and this fact suggests that regions with different molecular mobilities exist, as a consequence of blending interaction. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2955–2958, 2003
Characterization of epoxy foams
Authors: Stefani P. M. , Barchi A. Tejeira , Sabugal J. , Vazquez A.
Published: October 2003

Epoxy foams were prepared from the commercial system (LY 5054 epoxy resin, HY 5054 amine as curing agent, and DY 5054 siloxane as foaming agent) supplied by Ciba‐Geigy. From the differential scanning calorimeter results the optimal epoxy–amine ratio was determined. A maximum Tg∞ value of 85°C was found for an epoxy–amine ratio of 100:35 by weight. In this system, the siloxane reacts with the amine releasing hydrogen that acts as the real foaming agent. The density decreased from 490 to 215 kg/m3 as the epoxy:blowing agent ratio increased from 100:1 to 100:3 by weight of the reactive mixture. Under the synthesizing conditions, the glass transition temperature (Tg∞) of the foam did not vary significantly as the blowing agent increased. The modulus and compressive strength of the foam exhibited a power‐law dependence with respect to density of the form: E∝(ρ)n, where n=1.8. Scanning electron microscopy analysis verified that the foam have a closed cell structure. The relation between composition, final morphology, density, and properties of the foam was analyzed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2992–2996, 2003
Poly(ether ether ketone)/poly(aryl ether sulfone) blends: Relationships between morphology and mechanical properties
Authors: Nandan Bhanu , Kandpal L. D. , Mathur G. N.
Published: October 2003

Mechanical properties such as the tensile modulus, yield (break) strength, and elongation to break (or yield) are measured for multiphase poly(ether ether ketone) (PEEK)/poly(aryl ether sulfone) (PES) blends. Specimens with three different levels of thermal histories (quenched, as‐molded, and annealed) are prepared in order to study their effects on the mechanical properties of PEEK/PES blends. Synergistic behavior is observed in the tensile modulus and tensile strength of the blends in almost the whole range of compositions. The ductility of quenched blends measured as the elongation to break (yield) shows an unexpected synergistic behavior in the blend containing 90 wt % PEEK, although a negative deviation from additive behavior is observed in the rest of the compositions. A ductile–brittle transition is observed between 50 and 75 wt % PEEK in the blend. The ductile–brittle transition in as‐molded blends shifts to 75–90 wt % PEEK. Annealed blends show predominantly brittle behavior in the whole composition range. The experimental data are further correlated with the theoretically predicted results based on various composite models. Although the prediction based on these equations fails to fit the experimental data in the whole composition range, the simplex equations that are normally used for blends showing synergistic behavior produced a reasonable fit to the experimental data. The mechanical properties obtained for different blend compositions are further correlated with their morphology as observed by scanning electron microscopy. Morphological observation shows a two‐phase morphology in PES‐rich blends, which is an interlocked morphology in which the disperse phase is not clearly visible in PEEK‐rich blends, and a cocontinuous type of morphology for a 50/50 composition. Considerable permanent deformation of both the disperse and matrix phase, especially in the case of quenched tensile specimens, demonstrates the remarkable adhesion present between the two phases. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2887–2905, 2003
Crystallization and melting behavior of poly(ether ether ketone)/poly(aryl ether sulfone) blends
Authors: Nandan Bhanu , Kandpal L. D. , Mathur G. N.
Published: October 2003

The crystallization and melting behavior of poly(ether ether ketone) (PEEK) in blends with poly(aryl ether sulfone) (PES) prepared by melt mixing are investigated by differential scanning calorimetry (DSC) and wide‐angle X‐ray scattering (WAXS). The presence of PES is found to have a notable influence on the crystallization behavior of PEEK, especially when present in low concentrations in the PEEK/PES blends. The PEEK crystallization kinetics is retarded in the presence of PES from the melt and in the rubbery state. An analysis of the melt crystallization exotherm shows a slower rate of nucleation and a wider crystallite size distribution of PEEK in the presence of PES, except at low concentrations of PES, where, because of higher miscibility and the tendency of PES to form ordered structures under suitable conditions, a significantly opposite result is observed. The cold crystallization temperature of the blends at low PES concentration is higher then that of pure PEEK, whereas at a higher PES concentration little change is observed. In addition, the decrease in heat of cold crystallization and melting, which is more prevalent in PEEK‐rich compositions than in pure PEEK, shows the reduction in the degree of crystallinity because of the dilution effect of PES. Isothermal cold crystallization studies show that the cold crystallization from the amorphous glass occurs in two stages, corresponding to the mobilization of the PEEK‐rich and PES‐rich phases. The slower rate of crystallization of the PEEK‐rich phase, even in compositions where a pure PEEK phase is observed, indicates that the presence of the immobile PES‐rich phase has a constraining influence on the crystallization of the PEEK‐rich phase, possibly because of the distribution of individual PEEK chains across the two phases. The various crystallization parameters obtained from WAXS analysis show that the basic crystal structure of PEEK remains unaffected in the blend. Further, the slight melting point depression of PEEK at low concentrations of PES, apart from several other morphological reasons, may be due to some specific interactions between the component homopolymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2906–2918, 2003
Preparation and properties of transparent cellulose hydrogels
Authors: Saito Hidenao , Sakurai Akihiko , Sakakibara Mikio , Saga Hiroshi
Published: October 2003

Highly transparent cellulose hydrogels with physical crosslinkage were prepared from nonaqueous organic cellulose solutions and viscose by coagulating and regenerating cellulose in an aqueous solution containing a water‐miscible organic solvent. Nonaqueous organic cellulose solutions used were LiCl/dimethylacetamide, paraformaldehyde/dimethyl sulfoxide, and triethylammonium chloride/dimethyl sulfoxide. Preparation conditions and physical properties of the transparent cellulose hydrogels were studied. The transparency of the cellulose hydrogels depended on the composition of the aqueous solution containing the organic solvent. Furthermore, transparent cellulose hydrogels from viscose showed high tensile strength. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3020–3025, 2003
Impact modification of poly(ethylene terephthalate)
Authors: Chapleau N. , Huneault M. A.
Published: October 2003

The tensile and impact resistance of impact‐modified poly(ethylene terephthalate) (PET) is investigated. The impact modifiers are polyolefin‐based elastomers or elastomer blends containing glycidyl methacrylate moieties to improve the adhesion with the polyester. The tensile properties are measured on injection molded specimens at room temperature while the Izod impact strength is measured from −40 to 20°C. The blend morphology is observed by scanning electron microscopy and the dispersed phase average diameter is determined by image analysis. The relation between the impact resistance and the phase morphology is discussed, and the critical ligament size for PET is determined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2919–2932, 2003
Antimicrobial effect of monomers and polymers with azole moieties
Authors: Moon Woong‐Sig , Chung Kyoo‐Hyun , Seol Du Jin , Park Eun‐Soo , Shim Jae‐Hun , Kim Mal‐Nam , Yoon Jin‐San
Published: October 2003

Five monomers with azole moieties were synthesized and their antimicrobial activities were investigated. The antimicrobial activity of the monomers was evaluated by the halo zone test method. The results strongly depended on the chemical structure of the group attached to the azole moieties. Polymers with (benzimidazol‐2‐yl)thio groups and with (5‐methyl‐1,3,4‐thiadiazol‐2‐yl)thio groups were synthesized. The shake flask test showed that the two polymers possessed excellent antimicrobial activity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2933–2937, 2003
Study of the orientation and the degree of exfoliation of nanoparticles in poly(ethylene‐vinyl acetate) nanocomposites
Authors: Cser F. , Bhattacharya S. N.
Published: October 2003

Nanocomposites formed from organically modified montmorillonite and poly(ethylene‐co‐vinyl acetate) were studied by X‐ray diffraction techniques. Wide‐ and small‐angle X‐ray scattering intensities (SAXS and WAXS) were recorded by transmission mode on test bars cut from compression‐molded plaques tilted by different angles with respect to the plane of the plaque. The height of the Bragg peaks characteristic of intercalated particles reduced to the baseline at tilt angles greater than 30°. Guinier analysis of the SAXS characteristic of particle scattering showed a radius of gyration of 0.69 nm and the scattering intensity was slightly dependent on the tilt angle. Recording of WAXS in the usual (i.e., in reflective) mode enhanced the effect of the structural features of the surface area and showed much higher degree of intercalation and particle size of the scattering particles than that in transmission mode. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3026–3031, 2003
Preparation and characterization of thermosensitive poly(N‐isopropylacrylamide)/poly(ethylene oxide) semi‐interpenetrating polymer networks
Authors: Kim Seon Jeong , Lee Chang Kee , Lee Young Moo , Kim Sun I.
Published: October 2003

Temperature‐sensitive poly(N‐isopropylacrylamide) hydrogels were successfully synthesized by using poly(ethylene oxide) as the interpenetrating agent. The newly prepared semi‐interpenetrating polymer network (semi‐IPN) hydrogels exhibited much better properties as temperature‐sensitive polymers than they did in the past. Characterizations of the IPN hydrogels were investigated using a swelling experiment, FTIR spectroscopy, and differential scanning calorimetry (DSC). Semi‐IPN hydrogels exhibited a relatively high temperature dependent swelling ratio in the range of 23–28 at room temperature. DSC was used for the determination of the lower critical solution temperature of the semi‐IPN hydrogel. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3032–3036, 2003
Synthesis and property behavior of dioctyl phthalate plasticized styrene–acrylate particles by Shirasu porous glass emulsification and subsequent suspension copolymerization
Authors: Nuisin Roongkan , Omi Shinzo , Kiatkamjornwong Suda
Published: October 2003

Two‐phase model styrene–acrylate copolymers were synthesized with a soft phase consisting of methyl acrylate, butyl acrylate, and butyl methacrylate. Besides the styrenic copolymers, copolymers containing a hard phase of methyl methacylate and methyl acrylate were also synthesized. Comonomer droplets with a narrow size distribution and fair uniformity were prepared using an SPG (Shirasu porous glass) membrane having pore size of 0.90 μm. After the single‐step SPG emulsion, the emulsion droplets were composed mainly of monomers, hydrophobic additives, and an oil‐soluble initiator, suspended in the aqueous phase containing a stabilizer and inhibitor. These were then transferred to a reactor, and subsequent suspension polymerization was carried out. Uniform copolymer particles with a mean diameter ranging from 3 to 7 μm, depending on the recipe, with a narrow particle size distribution and a coefficient of variation of about 10% were achieved. Based on the glass‐transition temperatures, as measured by differential scanning calorimetry, the resulting copolymer particles containing a soft phase of acrylate were better compatibilized with a hard phase of methyl methacrylate than with styrene with dioctyl phthalate (DOP) addition. Glass‐transition temperatures of poly(MMA‐co‐MA) particles were strongly affected by the composition drift in the copolymer caused by their substantial difference in reactivity ratios. Incorporation of DOP in the copolymer particles does not significantly affect the glass‐transition temperature of MMA‐ or MA‐containing copolymer particles, but it does affect the St‐containing copolymer and particle morphology of the copolymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3037–3050, 2003
Effect of interfacial interaction on rheological behavior of blends of a semiflexible liquid‐crystalline polyester and polycarbonate
Authors: Zhao Wei , Chua Yang Choo , Lu Xuehong
Published: October 2003

A liquid‐crystalline polyester based on hydroxybenzoic acid, hydroquinone, sebacic acid, and suberic acid (named as BQSESU) was melt blended with polycarbonate (PC) at the BQSESU concentration of 2 wt %. It was found that the extent of viscosity reduction induced by the addition of BQSESU depends on the compounding temperature and the relation between them is not monotonic. The lowest viscosity was achieved by blending at 280°C. GPC measurements indicate that molecular weight reduction induced by the compounding is not a major contributor to the viscosity reduction. SEM study shows that when compounded at 280°C the blend is partially miscible with particle size at the submicron level. At the same time a large Tg depression was observed, which indicates strong interactions between the flexible segments of BQSESU and PC in the interfacial regions. The lowest viscosity achieved by blending at 280°C is thus proposed as an interfacial phenomenon. When compounded at 265°C, BQSESU particle size is larger, which gives a small interfacial area and hence less viscosity reduction. When compounded at 300°C a nearly miscible morphology was achieved, which also leads to less viscosity reduction. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3051–3058, 2003
Effect of rubber ratio, carbon black level, and accelerator level on natural rubber/bromobutyl rubber blend properties
Authors: Lewis Chonlada , Buanpa Radtapon , Kiatkamjornwong Suda
Published: October 2003

Statistical experimental design, that is, response surface methodology, was used to predict and explain the effects of rubber ratio, carbon black, and accelerator level on the cure characteristics and physical properties of natural rubber/bromobutyl rubber (NR/BIIR) blends. With these three independent variables, 20 designed compounds were mixed by a two‐roll mill and the scorch time, cure time, cure rate index, together with physical properties (hardness, tensile property, and compression set) were all determined by one operator. Multiple linear regression analysis was used to obtain response equations and thus contour plots, which illustrate the effects of the three independent variables on each property, as shown in detail by the diversity of interactions between independent factors and each property. It was found that the carbon black level is the most significant influential factor on scorch time, cure time, tensile properties, hardness, and compression set. The difference in reactivity toward sulfur vulcanization of NR and BIIR resulted in cure behavior and physical properties that are dominated by the NR content in the rubber ratio factor. Finally, the response equations were shown to be useful for making accurate predictions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3059–3068, 2003
Water and water vapor sorption studies in polypropylene–zeolite composites
Authors: Pehlivan H. , Özmıhçı F. , Tıhmınlıoǧlu F. , Balköse D. , Ülkü S.
Published: October 2003

Water and water vapor sorption to porous polypropylene–zeolite composites prepared by hot pressing have been studied as a function of zeolite loading. This work presents the first report on the effect of the zeolite as a filler on the water‐sorption properties of PP composites. Water swelling experiments were conducted at 25°C using pure PP and PP–zeolite films samples having different zeolite loadings (6–40 wt %). Because PP is a hydrophobic polymer, it does not sorp any water, but the composites having 10, 20, 30, and 40% zeolites have sorbed 0.63, 1.00, 1.72 and 3.74% water, respectively. The zeolite itself at the same conditions sorbed 24.5% water. As the filler loading in the composites increased, equilibrium uptake values increased also. On the other hand, water vapor sorption and kinetics has been studied using a Cahn 2000 gravimetric sorption system. Within in the range of 0.35–0.95% water vapor was adsorbed by the composites containing 10–40 wt % zeolites. Experimental effective water vapor diffusivities of the composite films was about one order of magnitude higher (10‐fold) than the experimental water diffusion coefficient in composites. The transport of water in composites was slower than that in the liquid water due to the longer diffusion pathway and adsorption on the surface of the composites. Although the liquid water may fill all the voids in the composite, water vapor is adsorbed on the surface of the zeolite only. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3069–3075, 2003