bluuebunny/crossref_metadata_2025_split huggingface dataset:
Energy needs for drying of PAAm- κC composites prepared with various κC contents
Authors: Pekcan Önder , Evingür Gülşen Akın 
Published: August 2014

AbstractVarious polyacrylamide (PAAm) - Kappa Carrageenan (κC) composite gels were prepared from acrylamide (AAm), N,N- methylenebisacrylamide (BIS) and different κC contents by free radical crosslinking copolymerization in water. Pyranine (P) was introduced as a fluorescence probe, and scattered light, Isc, and fluorescence intensities, I, from these gels were monitored during drying at different temperature. The fluorescence intensity of pyranine increased as drying time is increased for all samples. The behavior of I was quantified using the Stern-Volmer equation with moving boundary diffusion model. Desorption coefficient, D increased as temperature was increased for a given κC content. Supporting gravimetrical and volumetric experiments were also carried out during drying of PAAm-κC composite gels. The energy, △E values were measured for the drying processes for each κC content gel by using fluorescence, gravimetrical and volumetric methods, respectively. It is understood that △E values increase by increasing κC content, indicating that energy needs for the drying of high κC content gel is larger than low κC content gel.
Effects of compatilizers on the cellular structures, interfacial morphologies and mechanical properties of PP foam composites
Authors: Yang Ji-Nian , Li Zi-Quan , Liu Jin-Song 
Published: August 2014

AbstractThe short glass fiber (SGF)/polypropylene (PP) and ethylene-1-octene copolymer (POE)/SGF/PP foam composites were prepared by extrusion and subsequent post-foaming process in designed dies. The compatilizers, maleic anhydride grafted PP (PP-g-MAH) and maleic anhydride grafted POE (POE-g- MAH), were employed to improve the performance of the foam composites, respectively, and their influences on the cellular structures, interfacial morphologies and mechanical properties of PP foam composites were investigated. It was found that the compatilizers resulted in modified PP foam composites characterized by uniform cell size distribution, reduced cell size and increased cell density except POE/SGF/PP with POE-g-MAH. The obvious enhanced SGF-matrix interfacial bonding was observed from the SEM examination, and POE-g-MAH also facilitated the compatibility between elastomeric particles and matrix. Testing results indicated that, by the introduction of PP-g-MAH or POE-g-MAH, the mechanical properties of PP foam composites were significantly improved, and it seemed that the PP-g-MAH was more effective in strengthening the flexural and compressive strength while POE-g-MAH greatly increased the impact toughness.
Preparation of the high dielectric performance flexible materials achieved by polyacrylamide/poly(vinylidene fluoride) blends
Authors: Li Rui , Xiong Chuanxi , Dong Lijie 
Published: August 2014

AbstractA novel all-polymeric material with high dielectric constant (k) has been developed by blending poly(vinylidene fluoride) (PVDF) with polyacrylamide (PAM). The dependence of the dielectric constant on frequency and polymer volume fraction was investigated. When the weight fraction of PAM is 1wt%, the dielectric constant of the blend could be up to 24, and the dielectric loss tanδ can be lowered to 0.06. The SEM investigations suggest that the enhanced dielectric behavior originates from significant interfacial interactions of polymer-polymer. XRD and FTIR demonstrate that blending PAM with PVDF affects the crystalline behavior of each component. Our finding suggests that the created high-k polymeric blends represent a novel type of material that are flexible and easy to process, and is of relatively high dielectric constant and high breakdown strength; moreover find applications as flexible electronics.
The synergism of MgCO3 and 2ZnCO3·3ZnO·4H2O as flame retardants and smoke suppressants for flexible poly(vinyl chloride) (PVC)
Authors: Qu Hongqiang , Wu Weihong , Jiao Yunhong , Xie Jixing , Xu Jianzhong 
Published: August 2014

AbstractMgCO3 and 2ZnCO3·3ZnO·4H2O (AZC) as flame-retardants and smoke suppressants for flexible poly(vinyl chloride) (PVC) was evaluated using limiting oxygen index (LOI), smoke density rating (SDR) tests, scanning electron microscopy (SEM) and thermogravimetry analysis (TGA). The activation energy (Ea) of the original and flame retardant PVCs’ degradation processes was calculated by the Vyazovkin method. The results showed that the AZC can be used as a synergistic agent for MgCO3 as flame retardants agent of flexible PVC. The composites of MgCO3 and AZC cannot only decrease the initial decomposition temperature and increase the weight loss rate in the first stage, but also can promote the char formation in the second stage. The AZC decreased the Ea of the degradation reaction of PVC in the first stage and MgCO3 increased the Ea in the second stage, which means that the AZC combined with MgCO3, catalyzed the dehydrochlorination, promoted the early crosslinking for the PVC compound and improve the stability of the char residue. The SEM results also show that the char residue of MgCO3/AZC treated sample has a continuous and denser structure, which can be used as a barrier for the PVC bulk.
Obtaining of polyurethane foams with contribution of hydroxyalkylation products of oxalamide with alkylene carbonates and their properties
Authors: Zarzyka-Niemiec Iwona 
Published: August 2014

AbstractReaction products of Oxalamide (OD) with a 8- and 12-molar excess of ethylene carbonate (EC) and propylene carbonate (PC), characterized by an enhanced thermal stability due to the presence of Oxalamide arrangement, were used as polyol components for obtaining foamed polyurethane plastics. As an isocyanate agent diphenylmethane-4,4’-diisocyanate was used. The obtained new foamed polyurethane plastics are characterized by a slight water uptake, good stability of dimensions and an enhanced thermal stability.
Synthesis of aromatic polyimide bearing long alkyl chains through click reaction
Authors: Morinaga Hisatoyo , Imahashi Masamine , Takeichi Tsutomu 
Published: August 2014

AbstractA click reaction of aromatic polyimide having azide groups at both chainends (2), which was obtained by an azidation of polyimide having chloromethyl groups (1), was conducted with 1-octyne, leading to the polyimide having n-hexyl groups (3). 1H NMR spectroscopic analysis for 3 reveals that the n-hexyl groups were successfully introduced into the both chain-ends of aromatic polyimide and that a number-averaged molecular weight of the resulting polymer 3 was 6000. Differential scanning calorimetry analysis for 3 exhibited 30 °C lower glass transition temperature compared to that of 1, by introducing long alkyl groups into the aromatic polyimide chain.
Thermal behavior of epoxy blends for light emitting diode encapsulation
Authors: Tan Seah-Guan , Chow Wen-Shyang 
Published: August 2014

AbstractEpoxy encapsulant with high glass transition temperature (Tg) is required to ensure light emitting diode (LED) functions properly during its service life. Epoxy blends (cycloaliphatic epoxy, diglycidyl ethers of bisphenol-A and novolac resin) were thermally cured using methylhexahydrophthalic anhydride. Effects of the three types epoxy resins on the Tg of the ternary blends were examined. The Tg was mainly controlled by the concentration of cycloaliphatic epoxy. Optimization with constraint was conducted to produce epoxy blends formulation with optimum Tg. It was found that linear mixture model can fit well the experimental Tgof the epoxy ternary blends.
Preparation and characterization of exfoliated nanocomposite prepared by vinyl acetate, montmorillonite and dioctadecyl dimethyl ammonium bromide
Authors: Cui Huiwang , Du Guan-ben 
Published: August 2014

AbstractIn the paper, an exfoliated nano-composite was prepared by vinyl acetate (VAc), montmorillonite (MMT) and dioctadecyl dimethyl ammonium bromide (DOAB).Then it was mainly studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and static tension. Its rheology was also investigated by the power-law function equation and the Cross-Williamson model viscous equation. Results showed that the exfoliated nano-composite was obtained. Linear macromolecular chains of polyvinyl acetate (PVAc) were formed in the layers of MMT-DOAB. MMT-DOAB was exfoliated into layers or sheets of nano-particles, and randomly dispersed in the matrix of PVAc. The particle diameter of MMT-DOAB was from 25 nm to 75 nm, while PVAc’s was from 250 nm to 500 nm. They randomly dispersed together. The smaller MMT-DOAB particles were adsorbed around the bigger PVAc particles; they formed the “Strawberry” structure. In addition, PVAc and PVAc- MMT-DOAB were pseudo-plastic Non-Newtonian fluids, they all possessed the normal stress effect (or Weissenberg effect), that was the pole-climbing phenomenon. The reasonable addition of MMT-DOAB in polymerization was better but not more than 2.0 wt% of VAc.
Fabrication and characterization of poly(triazine dithiol) thin films using a two-step deposition/ photopolymerization process and micropattern
Authors: Ye Rongbin , Baba Mamoru , Ohta Koji , Suzuki Kazunori , Mori Kunio 
Published: August 2014

AbstractIn this study, polymer thin films were prepared and patterned by vapor deposition photo-polymerization of 6-diallylamino-[1,3,5]-triazine-2,4-dithiol) on SiO2/Si substrates. The characterizations of these films were investigated using FT-IR-RAS, XPS, optical microscopy and AFM. The polymerization rate of 0.10 ~ 0.14 min-1 was obtained by an ex-situ FT-IR-RAS study. The structure characterized with XPS showed that the polymer films contained disulfide bonds produced by thiol groups, and monosulfide bonds produced by the reaction between allyl and thiol groups and formed network chains. Furthermore, the 2.19 μm pattern of lines and spaces was developed sufficiently by optical observation
Synthesis and thermal properties of new copolyesters based on polycaprolactone
Authors: Maafi El Miloud , Malek Fouad , Tighzert Lan , Laoutid Fouad , Dubois Philippe 
Published: August 2014

AbstractSeveral copolyesters were synthesized from carboxytelechelic poly( - caprolactone) and bis(2-hydroxyethyl)terephthalate (BHET), using a two-step method and a one-step method providing regular and random distributions of starting comonomers in the copolyester chains, respectively. Even with an identical molar comonomer composition, the properties of obtained copolyesters depended on the synthesis method, therefore the comonomer distribution along the polymer chain. The copolyester structure was characterized by 1H and 13C NMR and FTIR spectroscopy. The thermal properties of synthesized copolyesters were also studied by DSC and TGA demonstrating the influence of aromatic rings spread along the macromolecular polyester chain.
Optimization approach for processing design in the extrusion process of plastic profile with metal insert
Authors: Mu Yue , Zhao Guoqun , Wu Xianghong 
Published: August 2014

AbstractThe extrusion process of plastic profile with metal insert is a kind of novel and advanced plastic processing method which requires rigorous control on processing conditions to ensure the quality and performance of final products. However, it is still difficult to achieve an optimal processing design by using traditional “trial and error” method. An optimization approach for the processing design in the extrusion process of plastic profile with metal insert is proposed based on finite element simulation, back propagation neural network and genetic algorithm in the study. The finite element simulation is conducted to predict polymer melts flow in the extrusion process. The simulated results are extracted for the establishment of neural network. The genetic algorithm is performed for the search of globally optimal design variable with its objective function evaluated by using the established neural network model. The proposed approach is adopted for the optimization of processing conditions in the extrusion process of plastic profile with metal insert. According to the flow balance principle, the uniformity of outlet flow distribution is taken as the optimization objective with a constraint condition on the maximum shear stress. The optimization of two processing parameters including the volume flow rate and the metal insert moving velocity is conducted in the extrusion process of plastic profile with metal insert and the optimization objective is successfully achieved.
Use of a novel pH-triggered polymer-gel system for optimal mobility-control applications
Authors: Abdel-Goad Mahmoud , Al-Wahaibi Yhya , Al-Wahaib Talal , Al-Shurji Hamed 
Published: August 2014

AbstractThere are two challenges in using polymers for conformance control applications in the petroleum industry. The first difficulty is to maintain a good injectivity to overcome the large pressure drop caused by the high viscosity of the polymers. Secondly, large polymer volumes required to be injected to compensate for polymer retention in a reservoir. The main objective of this work is to study the viability of using a pH-sensitive polyelectrolyte to alleviate the above two challenges. The results showed that the pH of the swelling medium has great effect on the swelling behavior of poly(acrylic acid) hydrogels. At low pH regime, the viscosity increases gradually as pH increases until certain pH value, ‘critical pH’ is reached. In the second regime and once critical pH value is exceeded, the viscosity increases sharply with the pH. This is followed by independency of the viscosity on pH, in the third regime. It was found that this sensitivity to the pH varies with the change in crosslink density and shear rates. At pH=4 (before the gellation), the sample (Carbopol 981) which has the lowest crosslink density exhibits the highest viscosity among the three samples. After the gellation (PH=8), the rheological behavior is reversed for the highest crosslinked density polymer (EZ-4) and the lowest crosslinked density polymer (981) which contradicts with the well known swelling ratio-crosslink density relation. It is concluded that the examined polymers are good candidates for mobility control applications. They can also be used for temporary zonal isolation since they can be easily broken down with mild acid wash and flowback
Dual phase continuity and phase inversion phenomena in natural rubber/ethylene vinyl acetate (EVA) copolymer blends
Authors: Kaewsakul Wisut , Kaesaman Azizon , Nakason Charoen 
Published: August 2014

AbstractBlending of polymers provide an attractive route to obtain new materials with unique combination of properties. Among the possible blend morphologies are dispersion of droplet, fiber, lamella in continuous phase and cocontinuous morphology. The unique feature of co-continuous is the mutual interpenetration of the phases which exhibits a number of advantageous properties and hence wider range of applications. Therefore, it is important to perform accurate determination of the co-continuous phase morphology and phase inversion phenomena. The rubber co-continuity index (solvent extraction), SEM micrographs and dynamic properties indicated the inversion occurred in the blends with rubber content 40 to 50 wt%. Furthermore, three empirical models (i.e., Ultracki, Steiman et al and Gergen et al models) could predict the phase continuity and phase inversion phenomena but other two (i.e., Paul-Barlow and Metelkin- Blekht models) failed. Therefore, based on rubber co-continuity index, SEM micrographs, dynamic mechanical properties and prediction, the inversion phenomena occurred in the blends with rubber contents in a range of 40-50 wt%. Full co-continuity was found in the blends with the rubber contents of 46 to 60 wt%.
A study on the kinetic behaviour and thermo-mechanical properties of nanoclay reinforced unsaturated polyester resin prepared under high shear conditions
Authors: Poorabdollah Mehdi , Beheshty Mohammad Hosain , Vafayan Mehdy 
Published: August 2014

AbstractKinetic behaviour and thermo-mechanical properties of composites based on unsaturated polyester (UP) resin and organically modified clay (OMC) are completely dependent on their preparation procedure. The investigation on the preparation procedure of the UP/OMC suspensions under high shear conditions alone (shear rate= 4.86 104s-1) without interference of chemical compatibility of OMC with UP resin on the intercalation and exfoliation processes has been the main aim of the present work. Reaction rate and degree of conversion of UP/3wt%OMC mixtures prepared at three mixing speeds of 1000, 3000 and 5000 rpm and several mixing times ranging from 15 min to 12 h showed an abnormal behaviour. The results showed a little decrease in the reaction rate and degree of conversion when mixing time increased from 1.5 h to 12 h at 1000 rpm, 1.5 h to 4.5 h at 3000 rpm and 30 min to 3 h at 5000 rpm. Thermo-mechanical properties of composites showed maximum values for storage modulus when plotted against the mixing time. Reaction rate, degree of conversion and morphology of UP/OMC composites indicated that cure reaction is affected by the extent of expansion of interlayer space of the OMC, the number of the expanded interlayer spaces per volume unit and the number of broken clay agglomerates.
Synthesis of polyethylene glycol diacrylate nanogel using irradiation of inverse micelles technique
Authors: Hamzah Yusof , Yunus Wan Mat Zin Wan , Isa Naurah Mat , Tajau Rida , Hashim Kamaruddin , Dahlan Khairul Zaman 
Published: August 2014

AbstractThe purpose of the work described here was to prepare covalently crosslinked nanogel from polyethylene glycol diacrylate (PEGDA) using an inverse micelle system as a template for irradiation via electron beam. Inverse micelles were formed by addition of sodium dioctyl sulfosuccinate (AOT) in n-heptane above its critical micelle concentration. These nano sized micelles were used to trap PEGDA in its water phase. Irradiation of the PEGDA containing micelles leads to formation of many radicals and recombinations thus forming crosslinked nanogel.
Synthesis and thermal properties of triblock copolymers of methyl methacrylate using combination of anionic and controlled radical polymerization: Poly(methyl methacrylate) center block bearing different microstructures
Authors: Song Zhengji , Pelletier Carole , Qi Yinghua , Ahmed Jasim , Varshney Sunil K. , Jafar Mazumder M. A. 
Published: August 2014

AbstractABA and/or ABC type triblock copolymers were synthesized by living anionic and controlled radical polymerization in which poly(methyl methacrylate) was used as central block. The structural composition of these block copolymers were determined by 1H NMR. The block length/molecular weight and microstructure of these polymers were measured by SEC. The microstructure of resultant central alkyl methacrylate block can be tailored from highly syndiotactic to highly isotactic structure by varying the solvent and/or initiator. The thermal and rheological properties of center poly(methyl methacrylate) block and poly(styreneb- methyl methacrylate-b- styrene) tri block copolymers were studied in detail.
Oligoetherols and polyurethane foams with carbazole ring
Authors: Lubczak Renata 
Published: August 2014

AbstractThe method of synthesis of oligoetherols with carbazole ring from 9-(2,3- epo-xypropyl)carbazole and glycerol and oxiranes like ethylene and propylene oxide is presented. Structure and some physicochemical properties of the products is described. The oligoetherols were demonstrated as good substrates for synthesis of polyurethane foams of enhanced thermal resistance
On the origin of the electrical response of vapor grown carbon nanofiber + epoxy composites
Authors: Silva J. , Cardoso P. , Paleo A. J. , van Hattum F. W. J. , Simoes R. , Lanceros-Méndez S. 
Published: August 2014

AbstractThe origin of the electrical response of vapor grown carbon nanofiber (VGCNF) + epoxy composites is investigated by studying the electrical behavior of VGCNF with resin, VGCNF with hardener and cured composites, separately. It is demonstrated that the onset of the conductivity is associated to the emergence of a weak disorder regime. It is also shown that the weak disorder regime is related to a hopping depending on the physical properties of the polymer matrix.
Study on the thermal degradation of chitosan-Cu/Ni/Mn complexes
Authors: Ou Chun-Yan , Li Si-Dong 
Published: August 2014

AbstractThe thermal degradation of chitosan-Cu/ Ni/ Mn complexes at different heating rates in nitrogen was studied by thermogravimetric analysis (TGA) in the temperature range 30-500 °C. Fourier transform-infrared (FTIR) was utilized to determine the microstructure of chitosan-metal complexes. The results of FTIR show that there are coordinating bonds between chitosan and cupric, manganese, nickel ions. The results of thermal analysis indicate that the thermal degradation of chitosan-Cu/ Mn/Ni complexes is a two-step reaction, which is related to water loss from the material, the deacetylation of the main chain and the cleavage of glycosidic linkages of chitosan, respectively. Characteristic temperature increases with the increment of heating rate and the impact of coordination of metal ion on the thermal degradation of chitosan is very significant. The kinetic parameters were determined by using Flynn-Wall-Ozawa method. The results show that the activation energy of the complexes is different but the variable tendency is similar
Synthesis of long chain aliphatic ester and its titanium complexes for ethylene polymerization
Authors: Makwana Umesh , Desai Bhavesh K. , Bhajiwala Hiren M. , Singh Gurmeet , Patankar Rajendra B. , Patil Harshad , Gupta Virendra K. 
Published: August 2014

AbstractLong chain aliphatic ester, isopropyl myristate, was synthesized using energy efficient microwave irradiation technique. The iso propyl myristate forms complexes with titanium tetrachloride in different mole ratios. The nature of chemical bonding between the titanium and the ester functionality was investigated by FTIR and NMR spectroscopy. The performance of synthesized complexes with methylalumoxane as co-catalyst for ethylene polymerization was found to depend on the nature of complex and polymerization parameters. Molecular weight and thermal characteristics of polyethylene was also investigated.
A Robust Iris Feature Extraction Approach Based on Monogenic and 2D Log-Gabor Filters
Authors: Aydi Walid , Fadhel Nade , Masmoudi Nouri , Kamoun Lotfi 
Published: August 2014

AbstractThis article suggests an enhancement of the Masek circle model approach usually used to find a trade-off between modeling complexity, algorithm accuracy, and computational time, mainly for embedded systems where the real-time aspect is a high challenge. Moreover, most commercialized systems (Aoptix, Mkc-series, IriScan, etc.) today frame iris regions by circles. This work led to several novelties: first, in the segmentation process, the corneal reflection removal method based on morphological reconstruction and pixel connectivity was implemented. Second, the picture size reduction was applied according to nearest-neighbor interpolation. Third, the image gradient of the convolved-reduced picture was then generated using four proposed matrices. Fourth, and to reduce the complexity of the traditional method for the detection of the top and lower eyelids, a new method based on the Radon transform and the least squares fitting method was applied. Fifth, eyelashes were detected via the diagonal gradient and thresholding method. Monogenic signal was used in the feature extraction process. Finally, two distance measures were selected as a metric for recognition. Our experimental results using CASIA iris database V3.0 reveal that the proposed method provides a high performance in terms of speed and accuracy. Using dissimilarity modified Hamming distance, the accuracy of iris recognition was improved, with a false acceptance rate equal to 3% and a speed at least eight times as compared with the state of the art.