bluuebunny/crossref_metadata_2025_split huggingface dataset:
ESR and photopolymerization study of polymerizable benzophenone photoinitiators containing functional maleimide groups
Authors: Wei Jun , Liu Fang 
Published: August 2014

AbstractFour kinds of novel polymerizable benzophenone (BP) photoinitiators MBP, BMBP, MPBP, BMPBP containing functional maleimide groups, were used as free radical photoinitiators with N-methyldiethanolamine (MDEA) as coinitiator (H donor). Such photoredox systems were studied by means of ESR spectra. The results show that all the four photoinitiators possess the same initiation mechanism as BP/MDEA system; meanwhile, two kinds of radicals were observed as the excited triplet of the photoinitiators can abstract hydrogen from the methylene groups or the methyl groups of MDEA. The photopolymerization of three monomers with different functionality, methyl methacrylate (MMA), 1,6-hexanediol diacrylate (HDDA) and trimethylolpropane triacrylate (TMPTA), initiated by these four polymerizable photoinitiators, was studied through dilatometer and photo- DSC. The results show that different photoinitiators behave differently towards monomers: MPBP system is the most efficient for all the three monomers; BMPBP is the least efficient for MMA, and BMBP is the least efficient for HDDA and TMPTA. The efficiency of the photopolymerization is greatly affected by maleimide groups and different vinyl monomers.
Monte Carlo simulation on sequence statistical structures of gradient copolymers
Authors: Shi Ying , Qiu Feng , Meng Qingmin , Xie Meiran , Zhang Yiqun 
Published: August 2014

AbstractThe simulation of controlled/living radical copolymerization (CRcP) is conducted using the method of Monte Carlo. Target Markov chains are obtained by calculating transfer probabilities instantly. The statistical results which are all the functions of conversion are obtained, including cumulative composition, segment length distribution, dyad and triad concentrations. The effect of reaction parameters on gradient structures is investigated, including initiation rates, monomer feed ratio and reactivity ratios. The results show that reactivity ratios, monomer feed ratio and conversion are more important parameters that can affect gradient structure than initiation rates. Initiation rates can cause difference in sequence structures at early stage of copolymerization and affect cumulative compositions continuously to a moderate degree. Monomer feed ratio mainly affects the fore-head of gradient copolymers while conversion simply affects the rear-end of gradient copolymers. The results of segment length distribution show that with the increase of difference in reactivity ratios, the distribution changes from Flory distribution which indicates random structure to Poisson distribution which indicates block composition
Study of tacticity and thermal rearrangement of low molecular weight 1,2- polybutadiene by NMR
Authors: Ziaee Farshid , Mobarakeh Hamid Salehi , Nekoomanesh Mehdi , Arabi Hassan 
Published: August 2014

AbstractLow molecular wieght 1,2-polybutadiene (Aldrich) tacticity was determined by 13CNMR (100.6 MHz). It was found that the olefinic methylene carbon has the highest splitting and a combination of pentad and heptad sequences was determined which is in agreement with the theoretical calculations. For the first time aliphatic methine carbon assignment of 1,2-polybutadiene was performed. Furthermore, olefinic methine carbon assignment was also performed and the results were compared with the theoretical calculations. For all carbons Bernoullian and first-order Markov-chain propagation statistics were used to fit the experimental data and a good agreement was obtained indicating an atactic polymer (Pm= 0.467). It was shown that the most probable reaction before gelation which happens by heating the polymer under vacuum at 250°C, is crosslinking accompanied with methyl group formation. The decrease in double bond intensity of the pendant group together with constant cis and trans double bond intensities were observed. During heating the syndiotactic triad sequences are consumed indicating that no cyclization has happened.
Antimicrobial activity of nanocomposites: poly(amide) 6 and low density poly(ethylene) filled with zinc oxide
Authors: Droval Guillaume , Aranberri Ibon , Bilbao Ainhoa , German Lorena , Verelst Marc , Dexpert-Ghys Jeannette 
Published: August 2014

AbstractThe antimicrobial activity against E. coli, St. aureus and A. niger of zinc oxide when blended with polymers has been measured by an applied dynamic method. Two polymers: poly(amide) 6 (PA6) and low density poly(ethylene) (LDPE) have been used as matrix. ZnO nanoparticles content as low as 1% w/w in the polymers showed great antibacterial activity but no antifungal activity. The results of bacterial slaying capability of these nanocomposites was also found to be better when zinc oxide was dispersed in PA6, where the efficiency is similar to pure ZnO particles. The composites have been investigated by means of scanning electron microscope (SEM) and differential scanning calorimeter (DSC).
Monomer recovery from polycarbonate by methanolysis
Authors: Chiu Shwu-Jer , Tsai Chou-Tso , Chang Yu-Kaung 
Published: August 2014

AbstractDepolymerization and monomer recovery from polycarbonate (PC) by methanolysis was investigated. Methanolysis with molar ratios of methanol to polycarbonate ranging from 12.5 to 50 was carried out from 170°C to 300°C for up to 30 min. Polycarbonate decomposed into two monomers, bisphenol A (BPA) and dimethyl carbonate (DMC), and two useful by-products, phenol and 4-tertbutylphenol. The percentage depolymerization of polycarbonate increased markedly from 170°C to 230°C and decomposed completely when the temperature was higher than 260°C. Reaction time and molar ratio of MeOH/PC are two other important factors that affect polycarbonate methanolysis. The optimal depolymerization condition of PC was found at 240°C with the molar ratio of MeOH/PC equal to 37.5 and the time of 5 min. Under these conditions, polycarbonate would decompose completely and the monomer recovery of BPA and DMC were 90.7% and 95.2%, respectively.
Study on superabsorbent composites XVII. Preparation and characterization of poly(acrylic acid)/attapulgite/Namontmorillonite superabsorbent composites
Authors: Zhang Junping , Zhang Kun , Wang Aiqin 
Published: August 2014

AbstractA novel superabsorbent composite simultaneously incorporated with both attapulgite and Na-montmorillonite was prepared by aqueous polymerization using N,N’-methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. The effects of the clay content on swelling ability of the superabsorbent composite were investigated. The superabsorbent composite were characterized by IR, XRD and SEM. The results indicate that Na-montmorillonite was exfoliated in the composite, whereas, attapulgite kept its crystalline structure. The content of clay has great influence on surface morphology and water absorbency of the superabsorbent composite, and the collaborative effect of attapulgite and Namontmorillonite on swelling ability is superior to that of single one.
Preparation, Characterization and Antifoaming Property of Fluorosilicone Oils with Fluoroalkyloxypropyl Group Substitution
Authors: Zhan-xiong Li 
Published: August 2014

AbstractThe current work has focused on the preparation and property of a novel fluorosilicone oil with polyfluoroalkyloxypropyl group substitution. Using fluoroalcohols as materials, three kinds of fluorosilicone oil, named [3-(2,2,2- trifluoroethyl-oxy)propyl]methylsilicone oil, [3-(2,2,3,3-tetrafluoropropyl-oxy)propyl] methylsilicone oil and [3-(2,2,3,3,4,4,5,5-octafluoropentyl-oxy)propyl]methyl silicone oil, were prepared via condensation, hydrosilylation, cyclization and ringopening polymerization. All the fluoroalkyl derivatives were characterized by NMR, FT-IR, MS and elemental analysis technique. The thermal stability of these fluoroalkyoxypropylmethylsilicone oils was identified to be excellent by thermogravimetric analysis. [3-(2,2,3,3,4,4,5,5-octafluoropentyl-oxy)propyl]methyl silicone oils with different viscosity were prepared by varying the amount of endblock reagent in the polymerization, and the antifoam property of these fluorosilicone oils was investigated. The result showed that the antifoam property of octafluorosilicone oil with higher viscosity was better than that with lower viscosity.
Effect of diisocyanates on the structure and properties of UV-curable polyurethane dispersions with nano-scale particles
Authors: Wei Yanyan , Xin Haobo 
Published: August 2014

AbstractA series of anionic polyurethane prepolymers with different molecular structures were synthesized. Different amounts of hexamethylene diisocyanate (HDI) and toluence diisocyanate (TDI) were employed in the synthesis. When the carboxylic content was 0.3 mmol/g, the colloidal stability of the polyurethane dispersions was rather good and their particle size was nano-scale. Moreover, no acetone or other solvent were used during the process of emulsification. The structures of the polyurethane prepolymers were characterized by Fourier transform Infrared spectrometry with attenuated total reflectance (FTIR-ATR) and Gel permeation chromatography (GPC). It was found that the mass ratio of HDI to TDI was able to be quantitatively analyzed by means of FTIR-ATR. The molecular weight and distribution did not show a regular trend with the changing of HDI/TDI ratio. The influence of diisocyanate on the particle size and the coating properties was investigated. It seems that hexamethylene diisocyanate was helpful for obtaining nano-scale particles. These polyurethane dispersions could obtain an average particle size less than 100 nm when mass ratio of HDI/TDI was above 0.25. The polyurethane dispersions with nano-scale particle had a transparent appearance with a bluish cast. It is indicated that the hydrophilic efficiency would be improved and the coating hardness decreased if more HDI was employed.
Effect of Curing System on Mechanical Properties of NBR/Nylon-PET Cord Composite
Authors: Bakhshandeh G. R. , Darestani Farahani T. , Emamikia M. 
Published: August 2014

AbstractFrom the results of this study it can be concluded that higher stearic acid concentration as a part of curing activator and high level of curative (i.e. sulfur and accelerator) causes higher crosslink density, tensile strength, modulus and hardness, and lower NBR to nylon-PET cord adhesion. Accelerator type also affects NBR/nylon-PET cord adhesion and using NOBS the highest coating adhesion is achieved. Using semi-efficient vulcanizing (i.e. accelerator/sulfur ratio around 1) is the most suitable way for achieving high NBR/nylon cord adhesion. And finally, independent from accelerator type, sulfur amount and efficiency of vulcanizing system, coating adhesion is a semi-linear function of crosslink density of nitrile rubber.
Migration of model contaminants (ethylene glycol, DEHA and DEHP) from PET bottles into Iranian yogurt drink
Authors: Farhoodi Mehdi , Emam-Djomeh Zahra , Ehsani Mohammad Reza , Oromiehie Abdolrasul 
Published: August 2014

AbstractThe migration of di-(2-ethylhexyl) adipate (DEHA), di-(2-ethylhexyl) phthalate (DEHP) and ethylene glycol from PET bottles into the Iranian yogurt drink was studied. According to European Commission regulations acetic acid (3% w/v) was chosen as stimulant. The acetic acid samples were stored at 4, 25 and 45 °C for four months and analyzed periodically by gas chromatography. Differential scanning calorimetry (DSC) was used to investigate if contact with the food stimulant could affect the PET material. It was concluded that the storage temperature had a great effect on the migration of DEHP, DEHA and ethylene glycol. Also increasing storage time resulted in higher concentrations of migrating substances. The concentrations of migrating substances did not exceed their specific migration limit (EEC regulations). Determination of glass transition (Tg) and crystallinity of PET bottles using DSC method showed that the variations in the migration rate of selected contaminants during the time did not relate to the change of PET material in contact with 3% acetic acid.
Polyamide-6/montmorillonite nanocomposites toughened with ABS-g-MA core-shell structural particles
Authors: Zhou Chao , Sun Lili , Sun Shulin , Tan Zhiyong , Wu Guangfeng , Zhang Huixuan 
Published: August 2014

AbstractPolyamide-6 (PA6)/montmorillonite (MMT) nanocomposites were prepared via melt compounding. Maleated acrylonitrile-butadiene-styrene (ABS-g- MA) core-shell structural rubber particles were first introduced to toughen PA6/MMT nanocomposites. Before melt intercalation, MMT was treated with an organic surfactant agent. XRD and TEM results showed that MMT platelets were completely exfoliated in the PA6 matrix. And when the core-shell rubber particles were introduced into the nanocomposites, they were well dispersed in the matrix. Tensile and impact tests showed that a small amount of MMT could increase the yield strength but sacrifice the toughness. However when core-shell rubber particles were added into the nanocomposites, the tensile ductility and impact strength improved greatly. It was reasonable to say that the addition of core-shell particles could make the balance of the stiffness and toughness of nanocomposites.
Cellular polyethylene-naphthalate films for ferroelectret applications: foaming, inflation and stretching, assessment of electromechanically relevant structural features
Authors: Fang Peng , Wirges Werner , Wegener Michael , Zirkel Larissa , Gerhard Reimund 
Published: August 2014

AbstractCellular polymer films are frequently employed for packaging, insulation, and printing. They can also be used as ferroelectrets in transducer applications. Here, we propose a preparation process for cellular polyethylene-naphthalate (PEN) films with the following steps: (1) foaming by means of supercritical carbon dioxide (CO2), (2) controlled inflation through gas diffusion and expansion, and (3) biaxial stretching. We describe and assess the cellular structure that is formed under suitable processing conditions. For foaming, the PEN films are saturated with supercritical CO2 at room temperature for a few hours, at a pressure as high as 100 bar. The subsequent temperature treatment is very critical for controlling the sample density. Additional inflation can improve the cellular geometry and higher stabilization temperatures during the inflation process cause stronger inflation and thus lower densities. Stretching may be employed in order to achieve a regular cellular structure with lens-like voids. High electromechanical responses, i.e. large piezoelectric thickness coefficients are found only on samples within the proper density range and with optimal cellular structures
Synthesis and properties of some polyaminobis maleimides thermal and mechanical characterization
Authors: Sava Mitica , Vlad Stelian 
Published: August 2014

AbstractA series of bismaleimide monomers with various structures were used to prepare poly(aminobismaleimide)s in an attempt to achieve polymers with improved mechanical and thermal properties. Structurally different bismaleimides with ester units and having chlorine substituent at the aromatic ring or hexafluoroisopropylidene(isoprpylidene) group between benzene rings were synthesized by reaction between 3(4)-maleimidobenzoylchloride with various bisphenols. The monomers and polymers were characterized by infrared (FTIR) and proton nuclear magnetic resonance (1H-NMR) spectrometry. Polymers based on these bismaleimides were prepared by Michael addition of diamines to bismaleimides. These polymers exhibited good solubility in N-methylpirrolidone and formed flexible films with good stress-strain properties. The mechanical behaviour of these polymers was investigated by stress-strain measurements on films at room temperature. The influence of the structure of these polymers on their mechanical properties was comparatively studied.
Synthesis and properties of new sulfonated naphthalenic polyimides as proton exchange membrane for fuel cell applications
Authors: Zhao L. , Huang Y.D. , Piao Y.M. 
Published: August 2014

AbstractThe diamine monomer, 5-amino-2-(p-aminophenyl)benzoxazole(ABO), was successfully synthesized and a series of new naphthalenic sulfonated polyimides (SPIs) were prepared from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), 2,2’-benzidinedisulfonic acid (BDSA), ABO and 1,10- diaminedecane (DADE) using one-step high temperature polymerization method. Their structures were characterized by FTIR, 1HNMR and TG-DSC. The sulfonated degree of the SPI copolymers was controlled through varying the molar ratio of BDSA to the non-sulfonated diamines. Tough and transparent membranes with the typical polyimide brown colour were prepared by casting from the polymer solution. They showed clear anisotropic membrane swelling in water with larger dimensional changes in the thickness direction of membrane. The sulfonated polyimide membrane containing 20mol% benzoxazole moieties (SPI-20) showed desirable thermal stability with the decomposition temperature of 272°C and mechanical stability with the maximum stress of 42 MPa. The proton conductivity (6.2×10-3S/cm) of SPI-20 membrane was comparable to that of Nafion®117 membrane measured under the same condition (9.8×10-3 S/cm). The effects of temperature on the proton conductivity, and highly anisotropic proton conductivity in the thickness and plane direction were also investigated.
Polysiloxane nanoparticles prepared by emulsion polymerization under microwave irradiation
Authors: Bo Yang , Hui He , Riping Chen , Demin Jia 
Published: August 2014

AbstractEmulsion polymerization of octamethyl cyclotetrasiloxane (D4) under microwave irradiation (MI) was studied. The polysiloxane (PSi) nanoparticles via cationic ring-opening polymerization of D4 were obtained by using the dodecylbenzene sulphonic acid (DBSA), sodium dodecylbenzene sulphate (SDBS) and poly(ethylene glycol) monooctylphenyl ether (OP-10) as the catalyst and the emulsifiers respectively. The particle size analyzer and transmission electron microscope (TEM) were used to determine the particle size of PSi emulsions. The results show that, the particle size of PSi emulsions prepared under MI is substantially smaller and the particle distribution is narrower compared with that under conventional heating (CH). With the aid of MI, the polymerization rate and the equilibrium conversion are enhanced. The polydispersity index (PDI) and molecular weight (Mw) measured by GPC indicate that under MI, PDI of PSi is narrower and Mw of PSi at high temperature is lower than those under CH.
Structures and potential applications of multihydroxyl branched polyethers obtained by cationic ring-opening polymerization involving activated monomer mechanism
Authors: Bednarek Melania 
Published: August 2014

AbstractThe synthesis and potential applications of functional, branched polyethers prepared by cationic ring-opening polymerization is reviewed, mainly on the base of the work from the author’s laboratory. Polymerization of cyclic monomers of ABx type, including highly strained 3- and 4-membered as well as weakly strained 5-membered cyclic ethers substituted with hydroxyl groups is discussed. Cationic polymerization of such monomers proceeds with participation of activated monomer mechanism which leads to the formation of branches. Hydroxy-substituted 4-membered cyclic ethers are highly strained; thus there are no thermodynamic restrictions for their polymerization, but these monomers are not easily available. Thus the possibility of using easily accessible 5-membered hydroxy-substituted cyclic ethers as monomers for cationic ring-opening polymerization was explored in spite of expected thermodynamic limitations due to low ring strain of those monomers. It was found that 5-membered hydroxysubstituted cyclic ethers undergo polymerization; however only low molecular weight products may be obtained from these monomers. It is shown in this review that such products may be useful and some examples of their applications in further synthesis e.g. in the preparation of star polymers and as surface modifying agents in the synthesis of organic/inorganic hybrid materials are described.
A novel analytical approach to estimate isothermal and dynamic crystallization Avrami kinetic parameters
Authors: Khonakdar Hossein Ali , Shiri Masoud , Asadinezhad Ahmad , Jafari Seyed Hassan , Golriz Mahdi 
Published: August 2014

AbstractThe Avrami equation has been extensively used to describe the polymer crystallization kinetics. Evaluation of kinetic parameters of this equation is quite troublesome, calling for properly predetermining induction time. To avoid this problem, an analytical approach in terms of differential scanning calorimetry exotherm maximum point was adopted here so as to conveniently estimate the Avrami equation kinetic parameters both in isothermal and dynamic crystallization mode. In the case of dynamic crystallization under isokinetic conditions, a modified version of the Avrami model by Nakamura was employed and adequate predictions based on the derived formulas were obtained. However, due to the simplified assumptions of the Avrami theory, our adopted relations are only applicable to earlier stages of crystallization process and do not account for secondary crystallization.
Synthesis of butyl acrylate grafted polypropylene fibre and its applications on oil-adsorption in floating water
Authors: Yuan Feng , Wei Jun-fu , Tang En-qi , Zhao Kongyin 
Published: August 2014

AbstractPolypropylene oil-absorption fibre (PP-g-BA) was prepared by radiationinduced graft polymerization of butyl acrylate (BA) onto polypropylene (PP) using divinylbenzene (DVB) as cross-linking agent. The original and grafted PP fibres were characterized by Fourier transform infrared (FT-IR) spectrometer and Scanning Electron Microscopy (SEM), and the result indicated that butyl acrylate was successfully grafted onto PP fibre. The factors that influenced the grafting degree of PP were discussed, such as the concentration of monomer and crosslinking agent. When the concentration of DVB was 2% and the concentration of BA was 10%, the maximum grafting degree reached 20.53%. The oil absorption properties of PP and PP-g-BA fibre were investigated and the results showed that the maximum adsorption capacity of PP-g-BA reached 19.74 g/g for toluene and 18.8 g/g for kerosene. Simulating absorption in the oil floating on the surface of water showed that the oil could be absorbed quickly and completely in three minutes. PP-g-BA exhibited quicker adsorption rate and higher adsorption capacity than PP fibre did.