bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rheological properties of grafted maleic anhydride based polypropylene composites filled with organoclay and glass fibers
Authors: Lee Seung Hwan , Youn Jae Ryoun 
Published: August 2014

AbstractExfoliated polypropylene/layered silicate nanocomposites and chopped glass fiber reinforced composites were prepared by a melt compounding process using maleic anhydride modified polypropylene (PP-g-MAH). The effect of fillers on morphological and rheological properties in melt mixing of polypropylene matrix with compatibilizer was investigated and compared with various measurements. It was observed that polypropylene/layered silicate nanocomposites exhibited remarkable reinforcement compared with the conventional composites filled with glass fibers which were dispersed at micrometer scale. The nanocomposites had larger storage modulus at low frequency region and outstanding strain hardening behavior than those of pure polypropylene or glass fiber reinforced composites. It was shown that glass fiber reinforced composites had lower elastic properties and steady state elongational viscosities than pure polypropylene melt. Contrary to glass fiber reinforced composites, it was confirmed that 3-dimensional network structure due to strong intermolecular bonding between polypropylene matrix and layered silicates affected particular rheological properties of nanocomposites.
Synthesis, Characterization, and Performance Evaluation of Polymeric Hindered Amine Light Stabilizers (HALS) in EPDM
Authors: Rana Sravendra , Singh Raj Pal 
Published: August 2014

AbstractPolymeric hindered amine light stabilizer (HALS), wherein the hindered amine functionality was attached to the brominated ethylene-propylene-diene terpolymer (EPDM) was synthesized. The brominated EPDM was synthesized as an intermediate for the synthesis of a new polymeric hindered amine light stabilizer. The grafting and functionalization reactions were characterized by FTIR and 1HNMR spectroscopy. The photostabilizing efficiency of this polymeric HALS was studied and compared with conventional HALS under accelerated weathering conditions. The results of the study give evidence for superiority of polymeric HALS over that of melt blended conventional HALS.
Residual Stress and Rheological Behavior of Polymeric Nanocomposites
Authors: Song Young Seok 
Published: August 2014

AbstractRheological and mechanical characterizations were carried out for carbon nanotubes/poly(ethylene oxide) (PEO) nanocomposites to examine the effect of surface modification of carbon nanotubes on the CNT dispersion state. Residual stress in the gap-wise direction of the nanocomposites was measured using the layer removal method. It was found that the different chemical treatments for CNT surface make a big difference in the dispersion state of the CNTs and that the nanocomposites filled with better dispersed CNTs possess higher storage and elastic moduli. From the rheological observations, rheological percolation structure was found to exist in the nanocomposites, which was confirmed by morphological experiments. The residual stress data showed that stronger residual stress is developed in the PEO nanocomposites by non-isothermal cooling than in pure PEO.
Thermal Stability and Aging Characteristics of HNBR/Clay Nanocomposites in Air, Water and Oil at Elevated Temperature
Authors: Anmin Huang , Xiaoping Wang , Demin Jia , Yanmei Li 
Published: August 2014

AbstractHydrogenated nitrile rubber (HNBR)/clay nanocomposites are prepared using conventional two-roll mill mixing technique. The structure and morphology of nanocomposites are characterized using wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). Both intercalated and exfoliated clay structures are observed in HNBR/clay nanocomposites. The thermal stability of the nanocomposites is studied using thermogravimetric analysis (TGA) and TGA-Fourier transform infrared (FTIR) spectroscopy. The effect of organoclay on physical and mechanical properties of HNBR vulcanizates before and after aging in air, water and oil at 178 °C is also investigated. It is found that adding organoclay in HNBR elastomer greatly improves material thermal stability and aging performance in different medium at elevated temperature.
Storage Modulus of Poly(vinyl alcohol) Gels Loaded with Polyelectrolyte Particles
Authors: Mitsumata Tetsu , Nagata Mitsuaki , Taniguchi Takashi , Kawaguchi Seigou 
Published: August 2014

AbstractWe have investigated the viscoelastic properties of poly(vinyl alcohol) (PVA) gels loaded with a polyelectrolyte particle of poly(styrene-co-sodium styrene sulfonate) to find the effect of electric charges on the storage modulus of the gel. The storage modulus decreased with increasing volume fraction of particles, and it was independent of the strain, indicating linear viscoelasticity. The viscoelastic properties of PVA gels containing non-charged particles of aluminium hydroxides were also studied. While the degree of swelling kept a constant value, the storage modulus largely increased with the volume fraction. PVA gels containing noncharged particles underwent a large nonlinear viscoelastic response suggesting the particles connect each other in the gel. Viscoelastic properties of the PVA gel loaded with charged and non-charged particles have also been discussed.
Synthesis and characterization of thermosensitive hydrogels with both supramolecular and hyperbranched structures
Authors: Ping Zhang , Qunfeng Liu , Yanxun Lan , Jianbo Shi , Mangeng Lu 
Published: August 2014

Abstract New novel kinds of thermosensitive hydrogels with supramolecular structures were synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization of N-isopropylacrylamide (NIPAM) and polypseudo rotaxanes in the presence of N,N- methylenebisacylamide (BIS) as a cross-linker. The polypseudorotaxanes were prepared by supramolecular self-assemblies of α- cyclodextrins threaded onto (4A-PEG) polymers. The structure of the hydrogels were characterized in detail with FTIR techniques. The analytical results demonstrated that a channel-type crystalline structure of inclusion complexes (ICs) remains in as-obtained hydrogels. Their swelling behavior was measured gravimetrically in the temperature range from 20 to 60 °C. The supramolecular structured hydrogels by RAFT polymerization (RAFT gels) showed accelerated shrinking kinetics to conventional hydrogel (CG), surprisingly.
Concrete + polyester + CaCO3: Mechanics and morphology after gamma irradiation
Authors: Martínez-Barrera Gonzalo , Espinosa-Pesqueira Manuel Eduardo , Brostow Witold 
Published: August 2014

AbstractWe have studied effects of gamma radiation on mechanical performance of polymer concrete (PC) containing varying concentrations of an unsaturated polyester resin and calcium carbonate. The compressive strength values increase from the zero dose (non-irradiated PC) to 10 kGy; afterwards we find a periodical change as a function of the resin concentration. The highest compressive strength corresponds to the highest resin concentration but the changes are not too large. Compressive strain values also go symbiotically with the resin concentration. All our composites - including irradiated and non-irradiated - have higher strength values than those reported for earlier polyester + concrete materials. The compressive modulus values follow the same pattern as the compressive strength and strain.
Partition of tert-dodecyl mercaptan in systems containing styrene, polystyrene, and polybutadiene. Its effect on the macromolecular characteristics of high-impact poly styrene
Authors: Casís Natalia , Luciani Carla Vanesa , Estenoz Diana Alejandra , Martinelli Marisa , Strumia Miriam , Meira Gregorio Raúl 
Published: August 2014

AbstractThis work investigates the distribution between phases of tert-dodecyl mercaptan (t-DDM) in systems containing styrene (St), polystyrene (PS), and polybutadiene (PB) with the aim of studying its effect on the molecular macrostructure of High-Impact Polystyrene (HIPS) produced via the bulk process. Experimental work involved the study of several St/PS/PB/t-DDM blends, and of 2 polymerizations of St in presence of PB (with and without t-DDM). Blends were prepared with increasing PS/St ratios to emulate monomer conversions of 7, 9, 11, 13, and 15%, employing 2 base PSs of different molar masses, and several total concentrations of t-DDM. Measurements by Proton Nuclear Magnetic Resonance (1H NMR) indicate that t-DDM is almost evenly distributed between the phases at room temperature. In addition, for samples taken along the 2 investigated polymerizations, monomer conversion, grafting efficiency, and free PS molecular weights were measured. Theoretical work involved first to model the species partitions through the Flory-Huggins theory [1]; and then, to combine such partition model with a polymerization model extended from that by Casís et al. [2]. Theoretical estimations were in good agreement with experimental determinations. Simulations suggest that t-DDM partition coefficients exhibit a weak dependence with temperature, but a strong dependence with its total concentration. Also, the combined partition/polymerization model indicates that the free PS contained in the occlusion regions exhibits lower molecular weights than that in the continuous matrix.
Synthesis of nicotinamide-imprinted polymers and their binding performances in organic and aqueous media
Authors: Mookda Pattarawarapan , Singha Komkham , Weeranuch Kareuhanon , Chatchai Tayapiwatana 
Published: August 2014

AbstractTo obtain molecularly imprinted polymers capable of selective rebinding with nicotinamide (NAM), NAM imprinted polymers were synthesized via bulk polymerization using various functional monomers and cross-linkers. The NAM recognition properties of these polymers were investigated in organic and aqueous solvents by equilibrium rebinding experiments. The results show that the imprinted polymer prepared using 1:4:4 molar ratio of NAM/MAA/TRIM in dichloromethane exhibited the greatest NAM binding capacity and selectivity. This polymer is potentially valuable for the analysis of NAM in complex matrices where selective isolation and identification are needed.
Preparation of polyaniline nanofibers using the organic solution of aniline as seed
Authors: Xing Shuangxi , Zheng Hongwei 
Published: August 2014

AbstractPolyaniline (PANI) nanofibers were prepared using an organic solution of aniline as seed in aqueous solution of ammonium persulfate oxidant. Two types of organic solvents were used, which are miscible and immiscible with water to investigate their effect on the properties of the resulting PANI via the aid of SEM, UV-Vis and FT-IR spectra and conductivity measurements The water dispersity of the polymer was also discussed based on the UV-Vis spectra data. Two possible mechanisms were proposed to explain the formation of the PANI nanofibers during the seed polymerization.
Viscosimetric studies of chitosan nitrate and chitosan chlorhydrate in acid free NaCl aqueous solution
Authors: Lárez Velásquez Cristóbal , Sánchez Albornoz Joel , Millán Barrios Enrique 
Published: August 2014

AbstractTwo salts of the biopolymer chitosan were prepared in aqueous medium by employing an excess of HCl or HNO3 in order to ensure neutralization of all NH2-chitosan groups. Chitosan salts were extensively dialyzed in dionised water and dried at 40 ºC until film formation. The films were characterized by thermogravimetry, FTIR and conductimetric tritration. QH+Cl− and QH+NO3− salts were viscosimetrically evaluated in free acid aqueous solutions in the presence of NaCl to control ionic strength of the medium. Unexpected high intrinsic viscosity values were obtained at low ionic strength when QH+NO3− salt were evaluated. Smidsrod´s approach was employed to estimate the stiffness parameter of both salts and B = 0.084 and 0.120 for QH+Cl− and QH+NO3−, respectively, were obtained.
Preparation and characterization of thermo-sensitive micelles composed of PSt-b-P(DEA-co-DMA)
Authors: Bian Fengling , Xiang Miao , Yu Wei , Liu Mingzhu 
Published: August 2014

AbstractThe amphiphilic block copolymer polystyrene-b-poly(N,Ndiethylacrylamide- co-N,N-dimethylacrylamide) (PSt-b-P(DEA-co-DMA)) was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization of DEA and DMA using PSt as macro chain transfer agent (PSt CTA) and N,N-azobisisobutyronitrile (AIBN) as initiator. Polymeric micelles were prepared by dialysis of the block copolymer solution in tetrahydrofuran (THF) against aqueous media. The polymeric micelles PM73 based on block copolymer P73, which was prepared with molar ratio DEA/DMA/PSt CTA/AIBN = 700:300:10:1, exhibited a lower critical solution temperature (39.2°C) in aqueous solution which was a little higher than the human body temperature. Polymeric micelles PM73 showed a unimodal size distribution with an average diameter of 24.2±0.5 nm. The micelles were thermodynamically stable in aqueous media above the critical micelle concentration (1 mg/l). The anti-inflammation drug, prednisone acetate, was incorporated into PM73 as the model drug. The loading capacity was found to be around 8 wt%, and the drug-loaded micelles showed similar size distribution patterns (monodisperse with an average diameter of 32.1±0.5 nm) and morphology (spherical) to the empty micelles. The drug-loaded micelles showed remarkable thermoresponsive drug release behavior, in response to the micellar structural change.
Studies on the synthesis, characterization and application of a novel copolymer macromonomer for polymeric solidsolid phase change materials
Authors: Xi Peng , Gu Xiao-hua , Cheng Bowen 
Published: August 2014

AbstractA novel copolymer as a macromonomer with a polyethylene glycol (PEG) unit as the phase change element and a vinyl group was synthesized for the preparation of polymeric solid-solid phase change materials. The IR, 1HNMR, DSC and WAXD and POM were employed to determine the structure and properties of the novel monomer. The results show that the novel monomer possess steady molecular structure, excellent crystal properties, higher phase change enthalpy and reactivity. Furthermore, the novel polymeric solid-solid phase change material was also prepared via the copolymerization of the novel copolymer macromonomer and styrene. The phase change properties of the polymeric solid-solid phase change material were characterized.
The curing behavior of the epoxy/dicyandiamide (DICY)/2- methylimidazole system with intercalated clays
Authors: Hong Shinn-Gwo , Kuo Chia-Wei 
Published: August 2014

AbstractThe curing behavior of the epoxy/dicyandiamide/2-methylimidazole system in the presence of montmorillonite clays intercalated with different compounds are analyzed by Fourier transform infrared spectroscopy (FTIR) and with differential scanning calorimetry (DSC). The properties of intercalated clays were analyzed by X-ray diffraction and thermal gravimetric analysis (TGA) and it was obtained that the d-spacing of different intercalated clays follows the order of the siloxane-clay>org-clay>epoxy resin-clay>pristine clay; this trend is consistent with the amount of intercalated chemicals obtained from TGA. The results of FTIR and DSC indicate that the curing exotherms, curing rates, formed functional groups, and curing mechanisms (reaction order) of the epoxy resin system are affected by the curing temperature and the type of intercalated clay used because of the stoichiometric imbalance of reactive groups resulted from the mutual diffusion of epoxy resin constituents and intercalated chemicals. The curing heats of the epoxy resins with different clays are in the order of the epoxy resin-clay> siloxane-clay>org-clay. It is shown that the Kamal model when applied can correctly describe the curing kinetics of the studied epoxy resin/clay systems at 160 and 170°C.
Preparation of poly(ε-caprolactone) and its nanocomposites in ε-caprolactam
Authors: Kredatusová Jana , Svobodová Jana , Brožek Jiří 
Published: August 2014

Abstract The solution polymerization of ε-caprolactone (CLO) initiated with stannous 2-ethylhexanoate has been studied in the temperature range 90 - 150 °C. ε-Caprolactam (CLA) was used as a solvent. Although relatively high polymerization temperature was used poly(ε-caprolactone) (PCLO) was formed solely and no CLA structural units were incorporated into its chains. The polymerization rate increased with CLO content in feed and polymerization temperature. A linear dependence of molar mass on yield of PCLO indicates living character of polymerization. When polymerization was carried out in the presence of organically modified MMT, nanocomposites PCLO - layered silicate with an exfoliated structure were obtained
Gels from acrylic acid and hydroxypropyl cellulose via free radical polymerization
Authors: Castro-Guerrero Carlos F. , Morales-Cepeda Ana , Rivera-Armenta José , Mendoza-Martínez Ana , Álvarez-Castillo Alberto 
Published: August 2014

AbstractA hydrogel from acrylic acid and hydroxypropyl cellulose was made. The percentages of raw materials and crosslinkers were varied and its swelling behavior was evaluated. Some of the gels obtained absorbed more than 300% wt. The gels with higher swelling percentages were characterized by means of IR spectroscopy, differential scanning calorimetry (DSC), dynamical mechanical analysis (DMA), and scanning electron microscopy (SEM). The FTIR showed the presence of the main reactants in the gel, while the DSC showed a phase separation in the gel. This gel is partly biodegradable because of the content of hydroxypropyl cellulose and has the viscoelastic properties of poly(acrylic acid).
First example of polystyrene end-functionalized with excited state intramolecular proton transfer (ESIPT) fluorophore by ATRP method
Authors: Lu Jianmei , Zhang Liang , Xu Qingfeng , Li Najun , Yan Feng , Xia Xuewei , Wang Lihua , Zhou Qiuxuan 
Published: August 2014

AbstractA novel initiator, 2-benzothiazol-2-yl-5-bromomethyl-phenol (BYBP) containing excited state intramolecular proton transfer (ESIPT) fluorophore was synthesized. Atom transfer radical polymerization (ATRP) of styrene was conducted successfully using BYBP as initiator, cuprous bromide (CuBr)/N,N,N’,N”,N’-pentamethyldiethylenetriamine (PMDETA) as catalyst, and cyclohexanone/DMF (mcyclohexanone: mDMF = 1: 1) as solvent. Factors such as the reaction temperature and molar ratio of catalyst to initiator, which could affect the ATRP system, were discussed in the paper. Chain extension was conducted using polymer as the macro-initiator which was characterized via 1H NMR. The optical property of initiator was well preserved in the obtained polystyrene, and the endfunctionalized polystyrene exhibited obvious fluorescent emission at about 530 nm.
Preparation and characterization of poly(hydroxyurethane) /halloysite nanocomposites via in-situ polymerization
Authors: Tang Zhaobin , Liu Peng , Guo Jinshan , Su Zhixing 
Published: August 2014

AbstractNaturally occurring halloysite nanotubes (HNTs) with hollow nanotubular structures were used as a new type filler for polyhydroxyurethane. The polyhydroxyurethane/halloysite nanocomposites (PHU/HNTs) were prepared by the in-situ surface-initiated polymerization of a five-membered cyclic carbonate 2,2- bis[p-(1,3-dioxolan-2-one-4-yl-methoxy) phenyl] propane (B5CC) and hexa methylene diamine, from the surfaces of the aminopropyl halloysite nanotubes (APHNTs) for the first time. The percentage of grafting (PG %) and the grafting efficiency (GE %) of 41% and 23% were calculated from the results of the thermogravimetric analysis (TGA) and from the results of elemental analysis (EA) respectively after the free polyhydroxyurethane was washed off. The chemical grafting of the polymer was also confirmed using FTIR; the morphology of the silica nanotubes in the nanocomposite was examined by transmission electron microscope (TEM).
Unique structure and property of cyclodextrin and its utility in polymer synthesis
Authors: Hu Jie , Huang Rong , Cao Shunsheng , Hua Yinqun 
Published: August 2014

AbstractOwing to their unique structure and property, natural cyclodextrins and their chemically modified derivatives can include many kinds of organic monomers to form guest/host complexes. The formation of these complexes results in significant changes of the solubility and activity of the guest molecules, but without chemical modification. It is found that the complexed hydrophobic monomers can be successfully polymerized directly in water without any organic solvent or surfactant, which induces a green way to polymer synthesis. It is found that this new cyclodextrin-mediated polymerization method differs strongly from classical methods. The present article reviewed the formation and the structure of the cyclodextrin/monomer inclusion complexes, and the influence of cyclodextrins on polymer synthesis. At last, the possible theory of the cyclodextrin-mediated reaction is discussed.
Application of ionic liquid [bmim]PF6 as green plasticizer for poly(L-lactide)
Authors: Zhang Puyu , Peng Lichao , Li Wenbin 
Published: August 2014

AbstractIonic liquid [bmim]PF6 (1-butyl-3-methylimidazolium hexafluoro phosphate) was synthesized and characterized. It was used as the plasticizer for poly(L-lactide) (PLLA). The glass transition temperature (Tg) and the thermal stability of the plasticized PLLA samples were measured by thermogravimetry (TG) and differential scanning calorimetry (DSC). Compared with poly(ethylene glycol) having Mw of 300 g/mol (PEG300), TG results showed that the thermal stability of PLLA plasticized with ionic liquid was better than that of PLLA plasticized with PEG300. The Tg of plasticized PLLA decrease with increasing the content of ionic liquid [bmim]PF6 from 2 wt.% to 10 wt.%. The Tg of PLLA can be reduced to 40°C when the content of ionic liquid [bmim]PF6 was 10 wt.%. The materials of PLLA with plasticizer were also investigated using polarizing microscope (POM), the results of which indicate that the movements of PLLA chains were improved when ionic liquid plasticizer was used.
Dispersion, mechanical and thermal properties of nano graphite platelets reinforced flouroelastomer composites
Authors: Xu Deng , Sridhar V. , Pham Thanh Tu , Kim Jin Kuk 
Published: August 2014

AbstractThe potential of exfoliated graphite nano platelets (xGnP™) as reinforcing fillers in flouroelastomer has been investigated. The dispersion of the nano graphite platelets in the polymer matrix has been investigated by WAXD, SEM, TEM, EPMA and AFM. WAXD studies indicated that the processing of composites did not change the inter-gallery distance (d-spacing) of the graphite platelets. The effect of increasing nano graphite loadings on mechanical properties like tensile strength, modulus and tear resistance has been studied. Formation of weld lines on the fracture surface of the composite has been observed by SEM. The thermal stability was determined using thermogravimetric analysis. The composites showed higher thermal stability in comparison with nonreinforced polymer.
AGET ATRP of Acrylamide in Aqueous Media
Authors: Tan Ying , Yang Qingbo , Sheng Dekun , Su Xuefeng , Xu Kun , Song Chunlei , Wang Pixin 
Published: August 2014

AbstractThe recently developed initiation system, the activator generated by electron transfer (AGET) was used in atom transfer radical polymerization (ATRP) to synthesize well-controlled polyacrylamide in aqueous media at 25°C. The different reducing agents involved ascorbic acid and glucosa; well-controlled polymers were obtained when ascorbic acid was used as water-soluble reducing agent. The polymerizations targeted at degrees of polymerization in the range of 400 resulted in polymers with low polydispersity indices. Moreover, first order plots were linear.