bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of the resin/hardener ratio on yield, post‐yield, and fracture behavior of nanofilled epoxies
Authors: Pandini Stefano , Baldi Francesco , De Santis Riccardo , Bignotti Fabio 
Published: August 2011

AbstractIn this work, the effect of the resin/hardener ratio on the small deformation, yield, post‐yield, and fracture behavior of a series of DGEBA‐Jeffamine epoxy‐clay nanocomposites with a fixed organo‐clay content (6 phr), and of the corresponding unfilled resins, was investigated. The mechanical behavior at small deformation was studied by means of uniaxial tensile tests, whereas compression tests were employed to investigate the large (yield and post‐yield) deformation levels. The fracture behavior was studied by the application of fracture mechanics testing methods. The results pointed out that small variations in the resin/hardener ratio used for the preparation of the resin can give rise to remarkable differences in the mechanical behavior at large deformation levels and at fracture. These effects were related to the parameters characteristic of the macromolecular architecture of the resins (chain segments flexibility and crosslink density). The results obtained on nanofilled systems showed that the effect of the resin/hardener ratio on the mechanical behavior of the resins is reduced in presence of organoclay particles. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
The effect of interface debonding behaviors on the mechanical properties of microPCMs/epoxy composites
Authors: Wang Xin‐Yu , Su Jun‐Feng , Wang Sheng‐Bao , Zhao Yun‐Hui 
Published: August 2011

AbstractMicrocapsules containing phase change materials (microPCMs) can be filled in polymeric matrix forming smart temperature‐controlling composites. The aim of this study was to investigate the relationship between the interface behaviors and the mechanical properties of methanol‐melamine‐formaldehyde shell microPCMs containing paraffin/epoxy matrix composites. The typical microPCMs with core/shell ratio of 2/1 shapely decreased their average diameter from 26.0 ± 1.5 to 13.8 ± 3.4 μm with the increasing of stirring speed from 1,000 to 3,000 r min−1. But, both the thickness and yield point of shells had a little variation. Young's modulus of composites was almost independent on the particle size of microPCMs with lower volume fractions (5%–10%). For composites with higher microPCMs loading (20%–30%), there was a slight decrease in modulus with increasing particle size. The data of tensile strength decreased obviously with the increasing of the average diameter of microcapsules for composite samples with the same particle loading. A repeated heat‐transmission treatment was applied to enhance the interface debonding. The results show that the violent thermal transmission had decreased the mechanical properties of microPCMs/epoxy composites. The scanning electron microscopy morphologies had also proved that these phenomena attributed to the interphase separation and cracks. Moreover, a semiexperiential conclusion is that the increasing of interface area of composites will at the same time give more structure defects leading to poor mechanical properties. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Investigation of the crystalline structure of PVDF in PVDF/PMMA/graphene polymer blend nanocomposites
Authors: Mohamadi S. , Sharifi‐Sanjani N. 
Published: August 2011

AbstractIn this work, we report the preparation of poly(vinylidene fluoride)/poly methylmethacrylate (PVDF/PMMA)/graphene polymer blend nanocomposites via synthesis of PMMA/graphene as a masterbatch through in situ polymerization. The PMMA/graphene masterbatch compounded with PVDF by solution mixing in different ratios. The compounding was followed by solution casting to form polymer blend nanocomposites. Solution cast films were subjected to thermal treatments at three different temperatures. The crystalline structure of thermally treated samples was studied with X‐ray diffraction spectroscopy and Differential Scanning Calorimetric (DSC) analysis. Results indicated PMMA chains persuade the β crystalline form in PVDF but cannot stabilize them in elevated temperature; however, graphene sheets due to restricting effect on TT conformation chains are able to stabilize them. DSC data revealed the graphene sheets can increase the crystallinity of PVDF and also act as nucleating agents. Transmission Electron Microscopy demonstrated coexistence of the different stacking orders of graphene sheets in both masterbatch and polymer blend nanocomposite. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Relationship between cardiovascular outcomes and proton pump inhibitor use in patients receiving dual antiplatelet therapy after acute coronary syndrome
Authors: Hsiao Fei‐Yuan , Mullins C. Daniel , Wen Yu‐Wen , Huang Weng‐Foung , Chen Pei‐Fen , Tsai Yi‐Wen 
Published: August 2011

ABSTRACTBackgroundThere is conflicting evidence regarding the potential interaction between clopidogrel and proton pump inhibitors (PPIs), with observational studies suggesting an increased risk of adverse cardiovascular (CV) outcomes and clinical trials suggesting there is no such risk.MethodsWe conducted a retrospective cohort study to assess CV outcomes of 9753 patients taking dual antiplatelet therapy of aspirin plus clopidogrel with or without a PPI after hospitalization for acute coronary syndrome (ACS). Cox proportional hazards models were used to assess our primary endpoint of re‐hospitalization for ACS in overall sample and a propensity score matching subsample.ResultsAmong patients taking clopidogrel plus aspirin, concomitant use of PPI was not associated with the risk of re‐hospitalization for ACS (adjusted hazard ratio [HR] 1.12 [95%CI 0.72–1.73]). The findings were consistent in the propensity score matching cohort (adjusted HR 0.82 [95%CI 0.43–1.54]). Compared with PPI nonusers, there is no significant association between each specific PPI users and the risk of re‐hospitalization for ACS (adjusted HR; omeprazole 0.96 [95%CI 0.35–2.66], pantoprazole 1.05 [95%CI 0.38–2.92], rabeprazole 0.60 [95%CI 0.17–2.17], esomeprazole 0.31 [95%CI 0.10–0.99], and lansoprazole 0.82 [95%CI 0.32–2.07]).ConclusionIn conclusion, this population‐based cohort study found that concomitant use of clopidogrel and PPI in patients who received dual antiplatelet therapy after ACS was not associated with risk of ACS re‐hospitalization. Together, our study and findings of recently published clinical trials suggest that there was no apparent CV interaction between clopidogrel and PPI in patients who received dual antiplatelet therapy. Copyright © 2011 John Wiley & Sons, Ltd.
Miscibility and crystallization of biodegradable poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate)/poly(vinyl phenol) blends
Authors: Cai Haoyuan , Yu Jing , Qiu Zhaobin 
Published: August 2011

AbstractMiscibility and crystallization of biodegradable poly (3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBHHx)/poly(vinyl phenol) (PVPh) blends were investigated in this work. PHBHHx is miscible with PVPh over the whole composition range as evidenced by the single composition dependent glass transition temperature and the depression of equilibrium melting point of PHBHHx in the blends. The overall crystallization rates decrease with increasing crystallization temperature for both neat PHBHHx and its blends with PVPh; moreover, the overall crystallization rates are slower in the PHBHHx/PVPh blends than in neat PHBHHx at the same crystallization temperature. Blending with PVPh may change the crystallization mechanism of PHBHHx in the blends compared with that of neat PHBHHx. Both neat PHBHHx and the PHBHHx/PVPh blends exhibit a crystallization regime II to III transition. The crystal structure of PHBHHx is not modified in the PHBHHx/PVPh blends; however, the values of crystal layer thickness, amorphous layer thickness, and long period all become larger with increasing PVPh content in the blends. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers
Apparent volumetric shrinkage study of RTM6 resin during the curing process and its effect on the residual stresses in a composite
Authors: Magniez K. , Vijayan Arun , Finn Niall 
Published: August 2011

AbstractA comprehensive characterization of the volumetric shrinkage of a commercially important aerospace resin (RTM6) during the various stages of the curing process was studied. The apparent volumetric shrinkage, evaluated from density measurements at room temperature, was correlated with the progress of epoxide conversion. During the entire curing process, the apparent volume shrinkage was found to be less than 3% and occurred before vitrification. A slight re‐expansion of the resin, attributed to self‐antiplasticization effects, was observed during postcuring at 180°C. It was concluded that residual stresses were not generated due to chemical cross‐linking during curing but rather from thermal contraction occurring during the cooling stage after cure. A photo‐elastic method was used to characterize residual stresses during cooling in a deliberately engineered resin rich hole of a carbon fiber/RTM6 composite. The residual stress was found to reach approximately 28 MPa, which is in good agreement with the value calculated from the shrinkage and elastic moduli. It is proposed that this simple method can be provide insights useful to the design and materials selection processes by measuring and localizing residual stresses from resin during curing and or thermal cycling. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers
Isothermal and non‐isothermal crystallization behavior of PET nanocomposites
Authors: Ghasemi Hesam , Carreau Pierre J. , Kamal Musa R. 
Published: August 2011

AbstractPolyethylene terephthalate (PET)/clay nanocomposites (PCNs) containing 1 wt% Cloisite 30B (C30B) were prepared via melt compounding. Modulated differential scanning calorimetry (MDSC) for isothermally crystallized samples revealed that the third endotherm at the highest temperature may be attributed to the recrystalization and melting of crystals, reorganized during heating. The first and second endotherms may be associated with melting of the secondary and primary crystals, respectively. The overall isothermal crystallization rate in PCNs was faster than in the neat resin. Growth kinetics revealed that the work required for chain folding and the equilibrium melting temperature in PCNs were somewhat higher than for neat PET. During isothermal crystallization, the steric hurdles introduced by clay layers lead to a reduction in the transport of the PET chains into crystallites. The effective non‐isothermal activation energy for the PCNs was higher than for PET, possibly leading to less perfect crystals in the PCNs. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers
Relationship between the distribution of organo‐montmorillonite and the flammability of flame retardant polypropylene
Authors: Chen Yajun , Guo Zhenghong , Fang Zhengping 
Published: August 2011

AbstractThis article studies the relationship between the distribution of organically modified montmorillonite (OMMT) and the flammability of flame retardant polypropylene which consists of polypropylene (PP), brominated epoxy resin‐antimony oxide (BER‐AO) and OMMT. Polypropylene‐graft‐maleic anhydride (PP‐g‐MAH) was used to increase the polarity of PP and aid the dispersion of OMMT. Two model systems, PP/BER‐AO/OMMT and PP/PP‐g‐MAH/BER‐AO/OMMT composites, have been prepared by melt blending. TEM studies reveal a significant change in the distribution of OMMT for these two systems. For the first composites, OMMT platelets are aggregated in the BER‐AO domains, whereas for the second composites, OMMT platelets are dispersed in the PP matrix. The flame retardant properties of the second composite reflected by UL 94 vertical burning test and cone calorimetry are better than that of the first one. When OMMT platelets aggregate in BER‐AO domains as in the first composite, the BER‐AO associated with OMMT may agglomerate into long ribbon‐like structures during burning, inducing uneven distribution of BER‐AO. As a result, loose and uneven residues are formed at the end of combustion. In comparison, OMMT platelets dispersed in polymer matrix are more efficient at stabilizing the polymer and preventing aggregation of BER‐AO during burning, which induce thick and uniform char layers at the end of combustion. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers
Preparation of a structured acrylic impact modifier and its application in toughening polyamide 6
Authors: Zhao Haiyan , Yao Yanmei , Liu Xinran , Zhang Qingxin , Wang Nongyue , Zhang Liqun , Qu Xiongwei 
Published: August 2011

AbstractA series of poly(n‐butyl acrylate)/poly(methyl methacrylate‐co‐acrylic acid), i.e., poly(BA/MMA‐co‐AA), core‐shell structured modifiers with different contents of crosslinking agent allyl methacrylate and functional monomer were prepared, and its effects on mechanical properties of polyamide 6 (PA 6) blends were investigated. The modifiers were prepared at a solid content of 50 wt% by a seeded emulsion polymerization. Dynamic light scattering measurement showed that the particle grew without significant secondary nucleation occurring. The morphology was confirmed by means of transmission electron microscopy. Scanning electron microscopy was used to observe the morphology of the fractured surfaces. The dynamic mechanical analysis measurements indicated that the appearance of two merged transition peaks and the magnitude of the loss peak of PA 6 matrix with the addition of PBMA core‐shell modifier in the PA 6/PBMA blends were responsible for the improvement of PA 6 toughness. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers
Thermal behavior of poly(ethylene‐co‐propylene) containing carbon nanofibers
Authors: Adhikari A.R. , Georgiev G. , Sigdel K. , Iannacchione G.S. , Lozano K. , Chipara M. 
Published: August 2011

AbstractThe effect of carbon nanofiber on the thermal behavior of poly(ethylene‐co‐propylene) (PEP) as revealed by differential scanning calorimetry and thermogravimetric analysis is reported. Analysis showed faster crystallization of PEP at higher temperature upon cooling with the increase of carbon nanofiber (CNF) content. The crystallization behavior changed to a single narrow crystallization peak as compared with the broad double crystallization peak of the neat polymer. This demonstrates the nucleation ability of CNF to induce crystals with more uniform distribution. The modified‐Avrami approach was used to study the crystallization behavior. We found that the crystallization rate constant increased with addition of CNFs. The dimensionality of crystal growth was found not to depend significantly on the content of CNF. Thermal degradation in air was monitored using thermogravimetric analysis and observed that the incorporation of nanofiber greater than 2.4 vol% improves thermal stability of PEP. All these results indicate that CNFs can significantly help polymer processing and increase thermal stability of polymers. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers
In‐situ real‐time monitoring of particle size, polymer, and monomer contents in emulsion polymerization of methyl methacrylate by near infrared spectroscopy
Authors: Silva Wandeklebio K. , Chicoma Dennis L. , Giudici Reinaldo 
Published: August 2011

AbstractThis work reports the results of in‐situ real‐time monitoring of the emulsion polymerization of methyl methacrylate by near infrared spectroscopy (NIRS) under different feed conditions. Besides the monitoring of the monomer and polymer content, the results show that reasonable estimates can be obtained from the spectra for the average particle size of the growing polymer particles present in the reaction medium. This is possible because the presence of the particles affects the spectra (through scattering, diffraction, and other mechanisms). Thus, by using appropriate calibration, it is possible obtain reliable models for particle size, in addition to monitoring the monomer and polymer concentrations. Experimental results for emulsion polymerizations conducted with various feed monomer conditions indicated that, in the spectral range studied, it is not only possible to monitor the evolution of the monomer and polymer contents, but also to follow the changes in the average size of the polymer particle. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Test procedures for maximum power point tracking charge controllers characterization
Authors: Camino‐Villacorta María , Egido‐Aguilera Miguel Angel , Díaz Pablo 
Published: August 2011

ABSTRACTPhotovoltaic stand‐alone systems (PVSAS) are the most widespread technology for rural electrification of off‐grid areas, for communication systems, and for satellite applications. Such applications require high reliability to guarantee an adequate electrical supply. In these systems, charge controllers and inverters are used to fit the PV output power to the load. The power adaptation stage is essential to the proper performance of the PVSAS and to the optimization of the energy management of the system. However, there are no international standards yet approved that cover the quality requirements of this stage. This paper deals with the performance of those charge controllers that use maximum power point tracking algorithms. The aim of this work is to define the specific parameters that describe the real performance of these controllers, paying attention to their static and dynamic efficiency and establishing the acceptable minimum thresholds required for each one. A set of measurements of three commercial controllers was developed. Their behavior in real varying conditions was monitored along 1 year of operation. Results are presented here after being checked with repetitive indoor measurements using a PV array simulator. Main results of the operation in a PVSAS are included in the paper for selected representative days along the year. To perform the daily analysis, we have classified each day according to its weather conditions. The purpose is to analyze the relation between the performance of the controller and the weather variations. Within the conclusions of this work, some guidelines for the definition of test procedures for maximum power point tracking charge controllers are included. Copyright © 2011 John Wiley & Sons, Ltd.
Focussed ion beam and field emission gun–scanning electron microscopy for the investigation of voiding and interface phenomena in thin‐film solar cells
Authors: Major Jonathan D. , Bowen Leon , Durose Ken 
Published: August 2011

ABSTRACTThe use of focussed ion beam milling combined with high resolution scanning electron microscopy analysis as a characterisation tool for thin‐film photovoltaics is reported. CdTe solar cell cross sections are examined in high detail with as‐grown and CdCl2‐treated devices being compared. Observed changes in microstructure of the thin‐film layers are related to the device performance. The CdCl2 treatment is shown to cause a reduction in the CdTe defect density at regions close to the interface and induce recrystallization of the CdS layer. Furthermore, the focussed ion beam technique is shown to reveal voids formed within the device's thin‐film layers at various processing stages that have not been previously observed in working cell structures. The back‐contacting Te‐rich layer resulting from nitric–phosphoric acid etching is also observed, with the etched layer being seen to propagate down the CdTe grain boundaries. Copyright © 2011 John Wiley & Sons, Ltd.
Quality of life and mental health in the bereaved family members of patients with terminal cancer
Authors: Song Jong Im , Shin Dong Wook , Choi Jin‐Young , Kang Jina , Baek Young‐Ji , Mo Ha‐Na , Seo Min‐Jeong , Hwang Yun Hee , Lim Yeun‐Keun , Lee Ok Kyoung 
Published: August 2011

AbstractObjectiveThis study specifically aimed to compare quality of life (QOL) and mental health in bereaved family members of patients with cancer with that of the general population and to examine factors associated with QOL and mental health in this population.DesignA nationwide multicenter, cross‐sectional survey was administered to the bereaved family members of patients with terminal cancer.SettingThirty‐three palliative care centers designated by the Ministry of Health and Welfare participated in this study.ParticipantsThe participants in this study were 501 bereaved family members of patients with terminal cancer and matched control individuals from the Korean National Health and Nutrition Examination Survey.MeasurementEQ‐5D and several questions used in Korean National Health And Nutrition Examination Survey were used in to measure health‐related QOL and mental health.ResultsHealth‐related QOL, as determined by EQ‐5D, was significantly lower in bereaved family members than in controls (0.88 ± 0.20 vs 0.93 ± 0.13, p = 0.002). Bereaved family members experienced more frequent episodes of depression (33.1% vs 12.5%, p < 0.001) and suicidal thoughts (31.4% vs 16.4%, p < 0.001) during the previous year than did controls. Female sex, lower income, spousal relationship, and longer duration of survival after palliative care referral were negatively correlated with health‐related QOL. Younger age and higher mental burden of caregiving were associated with a higher risk of impaired mental health.DiscussionOur results confirm that bereaved family members of patients with cancer have lower health‐related QOL and mental health than the general population. Healthcare providers should focus more attention on this vulnerable group, and various support programs should be developed to improve their health‐related QOL. Copyright © 2011 John Wiley & Sons, Ltd.
Psychometric properties of the Chinese version of Sense of Coherence Scale in women with cervical cancer
Authors: Ding Yan , Bao Lei‐Ping , Xu Hao , Hu Yan , Hallberg Ingalill Rahm 
Published: August 2011

AbstractPurposeThe purpose of this study was to test the psychometric properties of a Chinese version of the Sense of Coherence Scale (C‐SOC‐13) in women with cervical cancer in Mainland China.MethodsThe C‐SOC‐13 and Health‐related Quality of Life scale (Functional Assessment of Cancer Therapy‐Cervix) were administered to 238 women with cervical cancer. Validity was assessed in terms of factor validity, predictive validity, divergent validity and stability, whereas reliability was evaluated using Cronbach's alpha coefficient.ResultsThis study showed that in confirmatory factor analysis, the first‐order interrelated three‐factor model and second‐order model were performed based on Antonovsky's theoretical structure of Sense of Coherence (SOC). Both models fitted the data satisfactorily when the largest modification index was released. The chi‐square value/degrees of freedom was 2.120, the goodness‐of‐fit index was 0.919, the root mean square error of approximation was 0.069, and the comparative fit index was 0.911. The Pearson correlation coefficient between SOC and Functional Assessment of Cancer Therapy‐Cervix was 0.611. Enter multiple regression with SOC as a dependent variable and medical and socio‐economic variables as independent variables showed no statistically significant partial coefficient of any independent variable in regression equation except for age. The Cronbach's alpha coefficient for the scale was 0.824.ConclusionThe factor validity, predictive validity and divergent validity of C‐SOC‐13 were reasonable, as well as the internal consistency. In general, C‐SOC‐13 showed to be suitable as an SOC measurement for women with cervical cancer in Mainland China. However, SOC may have a different meaning to Chinese people because of the philosophy and culture that shape the context of their lives. Generalizing the findings to other populations requires further psychometric evaluation of C‐SOC‐13. Further longitudinal studies are also needed to explore the stability. Copyright © 2011 John Wiley & Sons, Ltd.