bluuebunny/crossref_metadata_2025 huggingface dataset:
Aggregation of Blends of Poly(N-vinyl pyrrolidone) and End-functional Polystyrene in Aqueous Solution
Authors: Masunaga Hiroyasu , Sasaki Kanako , Akiba Isamu
Published: August 2014

Aggregation behavior of blend of poly(N-vinyl pyrrolidone) (PVP) and polystyrene having a sulfonic acid group at one end (PSS) in aqueous solution was investigated by dynamic and static light scattering (DLS, SLS) measurements and scanning electron microscopy (SEM). The angular dependence of apparent diffusion coefficients suggested that the PVP-PSS aggregate shows an anisotropic structure. Comparison of an experimental SLS profile with theoretical calculations of particle scattering functions indicated that the PVP-PSS aggregate formed rodlike structure with 1200 nm height and 20 nm cross-sectional radius. Corresponding results were obtained by SEM observations.
Influence of Porosity on the Fragmentation of Ziegler-Natta Catalyst in the Early Stages of Propylene Polymerization
Authors: Zheng Xuejing , Pimplapure Makarand S. , Weickert Günter , Loos Joachim
Published: August 2014

Catalyst fragmentation and polymer growth in the early stages of propylene polymerization has been investigated using different Ziegler-Natta catalysts. Polymerization was carried out in slurry under mild conditions and stopped at low yield. Scanning electron microscopy (SEM) has been used to characterize the surface and cross sectional morphology of polymer particles at different stages of particle growth. Different fragmentation behavior is observed, and it is found that the way that catalyst fragments in the early stages of polymerization is greatly influenced by the porosity of the catalyst. When a less porous catalyst was used, the resulting mass diffusion limitation causes layer-bylayer fragmentation, starting at the outer surface of the catalyst particle to the center. In contrast, for highly porous catalyst, monomer can easily penetrate into the pores of the catalyst / polymer particle. The polymer growing throughout the particle results in a coarse and instantaneous fragmentation.
Macroporous 4-Vinylpyridine-divinylbenzene – Estimation of Pore Volume, Surface Area, and Pore Size Distribution
Authors: Malik Muhammad Arif
Published: August 2014

4-Vinylpyridine-divinylbenzene copolymer beads of ~0.3 mm in diameter were synthesized by suspension polymerization technique. The beads were made porous by dilution of the monomers with phthalate esters. The porosity was varied by changing the diluent, by varying the degree of dilution, and by varying the ratio of divinylbenzene in the monomers. Pore volume, surface area, and pore size distribution were determined by mercury penetration method, and densities of the dried copolymers were determined by a measuring cylinder and a balance. Statistical analysis of the data shows that the surface area and swelling coefficient in acetone can be estimated from the pore volume value with a reasonable good accuracy. Pore size distribution curves for the copolymers having pore volume in the range of 0.1 ml/g to 0.8 ml/g are shown. One can approximately estimate the pore size distribution if the pore volume is known. The pore volume can be estimated with a reasonable good accuracy from the density of the copolymers.
Optically active polymer: synthesis and characterization of new optically active poly (hydrazide-imide)s incorporating L- leucine
Authors: Hajipour Abdol Reza , Zahmatkesh Saeed , Ruoho Arnold E.
Published: August 2014

This paper deals with the polycondensation between a chiral diacyl chloride (N,N′-Pyromelliticdiimido-di-L-leucine chloride) and six different dihydrazides. The corresponding poly (hydrazide-imide)s which have been obtained in quantitative yields are moderately soluble in polar aprotic solvents, have good thermal stability and optical activity. The synthetic compounds have been characterized by IR, UV and 1H NMR spectroscopy, elemental analysis and specific rotation. The thermal properties of the polymers (10 and 15) have been studied by thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC).
Synthesis, characterization and kinetics of hydrophobically associating polyacrylamide
Authors: Hongsheng Lu , Yujun Feng
Published: August 2014

HAPAM was successfully prepared in inverse microemulsion. 1H-NMR, FT-IR, DSC and TG results show that the copolymerization of acrylamide (AM) with DM16 was successful. However, the ratio of AM to DM16 is not calculated exactly due to the low percentage of hydrophobic monomer in polymer. Therein, we only proved the success of the incorporation of DM16 onto polyacrylamide backbone. According to our experiment, the conversions of monomers and molecular weight have a strong dependence on initiator concentration and aqueous phase weight fraction. But it was not completely in accordance with literature. The difference may be ascribed to the major existence of locus of DM16 (at the interface of oil/water or in droplet). Compared with literature, the influence of initiator concentration on particle size was slight due to the high surfactant weight fraction, seeming to appear independent of initiator concentration. When the surfactant weight fraction reaches a certain degree, it did not affect the conversion. For the particle size and molecular weight, it was other way around, suggesting that there was an intense chain transfer reaction to the emulsifier. In this work, we could not calculate the average number of free radical per particle n, because the part of the surfactant in excess recombines to form small micelle and the DM16 may continuously transfer from micelle to another micelle, resulting in difficulty to estimate precisely the number of the particles. This was also reflected in the difference of kinetics between our system and literature. Finally, the occurrence of nucleation at high conversion was proved indirectly.
Influence of Ionic Liquids on the Free Radical Copolymerization of Styrene with Acrylonitrile
Authors: Woecht Inga , Schmidt-Naake Gudrun
Published: August 2014

Free radical copolymerization of styrene (S) and acrylonitrile (AN) in the ionic liquids (ILs) 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6), 1,3-dimethylimidazolium dimethylphosphate ([MMIM]Me2PO4) and 1-ethyl-3- methylimidazolium ethylsulfate ([EMIM]EtSO4) were investigated. 2,2’-azobisiso butyronitrile (AIBN) and dibenzoyl peroxide (BPO) were used as initiators and dimethyl formamide (DMF) and methanol as reference solvents. The influence of the viscosity on the conversion and the molecular weights was studied by variation of the reaction temperature and the IL concentration. At reaction temperatures of 80 - 85 °C already after 30 minutes a conversion of about 80 % and almost a doubling of the molecular weights is reached for the S/AN (50/50 mol%) copolymerization. In addition the copolymerization behavior of S/AN in [EMIM]EtSO4 was investigated. With increasing concentration of AN in the monomer feed the polymerization rate as well as the molecular weights of the copolymers increase. The influence of the ionic liquid on the copolymer composition, glass-transition temperature and rheological behavior was studied.
Electrospinning of polyamide 6/modified-keratin blends
Authors: Zoccola Marina , Montarsolo Alessio. , Aluigi Annalisa , Varesano Alessio , Vineis Claudia , Tonin Claudio
Published: August 2014

Protein material resulting from chemical free steam explosion of wool was mixed in different proportion with polyamide 6 in formic acid. The viscosity of the blend solutions decreases with the increase of the protein amount in the blend. Nanofibres produced by electrospinning of these polymer blends show an increase of the filament diameters with increasing protein amounts, except for the 30/70 v/v polyamide 6/protein blend, where nanofibres with “beads” defects were produced. In blend films produced by casting, polyamide 6 crystallize in the form of large spherulites prevalently in the α crystalline structure, while protein is totally amorphous and tends to segregate in the course of drying at room temperature. Otherwise, in electrospun nanofibres polyamide 6 and protein show a better miscibility as suggested by spectroscopic and thermal analysis and polyamide 6 shows a higher thermal stability. Moisture regain and water solubility of blend cast films and electrospun nanofibres respectively were also determined.
Development of High Refractive Index Plastics
Authors: Jha G.S. , Seshadri G. , Mohan A. , Khandal R.K.
Published: August 2014

Optical plastics have been the priority area of research for material scientists worldwide, mainly, to find alternative materials to glass, a conceptual optical material in use over the years. There are numerous advantages of using plastics for optical applications, in particular for ophthalmic applications over glass. Recently, the researchers have been putting their efforts to develop novel plastic materials to meet requirements of ophthalmic industries. The present review compiles the recent developments in the area of optical plastics. The aim is to present the current state-of-the-art in the field, besides analyzing the various aspects of developing optical plastics. The review presents various possible approaches to achieve the desired properties e.g. high refractive index of the optical plastic materials.
In Vacuum Preparation of Psy-cl-poly(AAm) Superabsorbent and its Applications in Oil - Industry
Authors: Kaith B. S. , Kumar Kiran
Published: August 2014

In the present study Psyllium was modified with acrylamide through chemically induced graft co-polymerization, under the influence of vacuum using potassium persulphate as an initiator. Graft copolymers were further crosslinked with hexamethylene tetramine for their application in removal of water from different water-oil emulsions. The hydrogel was found to be selective in its absorption and maximum absorption of water was found to be 3020%.
Preparation and Characterization of PVA/Boron Polymer Produced by an Electrospinning Technique.
Authors: Uslu I. , Daştan H. , Altaş A. , Yayli A. , Atakol O. , Aksu M. L.
Published: August 2014

In this study, poly(vinyl alcohol) were cross-linked with boron in varying concentrations and blend fibers were obtained with diameters ranging from 0.3 μ to 4.0 μm with the use of electrospinning process. The resulting product was characterized by SEM, DSC, and FT-IR techniques. There is no beading tendency in either boron doped or undoped fibers. When the amount of boric acid in PVA solutions was increased the conductivity of the polymer decreased. The data indicated the existence of boron oxide in the polymeric structure and the formation of B-O-C bond. SEM micrographs reveal that higher viscosity favors the formation of thicker fibers. Boron addition seems to disturb the easy detachment of the fibers from the tip of the Taylor Cone
Sulphonated Poly(ethylene terephthalate)/Poly(3-hydroxy butyrate) Blends: Miscibility, Thermal Behavior, and Specific Interactions
Authors: Silva Rafael , Carvalho Gizilene M. , Muniz Edvani C. , Vidotti Gentil J. , Rubira Adley F.
Published: August 2014

PETs/PHB blends with different compositions were produced by “casting” method. The blends were investigated by TGA, DSC, 1H and 13C NMR and FTIR. Phase separation occurred during blend preparation. PETs and PHB were present in both formed phases. The phases presented different thermal stabilities unrelated to phase component concentration changes. The miscibility study by DSC showed that PHB-phase rich blends are immiscible, whereas the PETs-rich phase blends are miscible. The 1H NMR spectra of the miscible blends exhibited a peak close to the PHB methylene signal, which is in accordance with the interaction between the PETs SO3 - groups and the PHB carbonyl groups. This interaction result in a shift of the PHB carbonyl group absorption band in the FTIR spectra and a variation in the chemical shift of the PHB carbonyl group resonance peak in solid state 13C NMR. No specific interaction was observed for the immiscible blends.
Investigation of the properties of PBT/ABS-g-GMA blends modified with epoxy resin of mid-molecular weights
Authors: Shulin Sun , Zhicheng Chen , Zhiyong Tan , Chao Zhou , Mingyao Zhang , Huixuan Zhang
Published: August 2014

Middle molecular weight epoxy resin was used to modify the properties of polybutylene terephthalate (PBT) and glycidyl methacrylate-functionalized acrylonitrile-butadiene-styrene (ABS-g- GMA) blends. Rheological tests showed that the complex viscosity and storage modulus of PBT increased with the addition of epoxy resin due to the chemical reactions. PBT displayed non- Newtanian fluid behaviour when epoxy resin content was 10wt% or higher. SEM results showed there was no obvious difference between the morphology of PBT/ABS-g-GMA blends when epoxy resin content was low, however, agglomeration of ABS phase took place when epoxy resin content was 10wt% or higher due to the complicated reactions. DSC results showed that the addition of epoxy resin to PBT/ABS-g-GMA blends improved the compatibility according to Tm depression criterion and DMA test further testified the improved compatibility. Mechanical tests showed impact strength of 902J/m and yield strength of 42MPa was achieved when 20wt% ABS-g-GMA and 5wt% epoxy resin were used, which displayed supper-toughness and much stiffer properties.
Preparation and Characterization of PVA/Zinc Acetate/ Boron Composite Fibers
Authors: Uslu Ibrahim , Başer Burcu , Yaylı Ahmet , Aksu Mehmet Levent
Published: August 2014

The objective of this work was to synthesize boron incorporated PVA/Zinc acetate nano precursor composite polymer fibers using electrospinning technique. Produced fibers, are useful reagents in organic synthesis of zinc oxide nano structures which have gained wide interest because of their potential applications in the fabrication of microelectronic devices. Boron incorporated PVA/Zinc acetate not only improve the electrical properties of ZnO films but also has an influence on the crystal structure of ZnO films. The fibers were measured and characterized by conductiometer (with four-point probe), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The formation of boron incorporated PVA/Zinc acetate hybrid polymer was confirmed by FT-IR spectra. SEM micrographs clearly reveal that there are random-growth oriented fibers on aluminum foil with diameters ranging from 0.5 to 1 μm. According to the TGA analysis decomposition of zinc acetate from the PVA chain was observed around 273 °C, 368 °C and 447 °C. Boron incorporated PVA/Zinc acetate nano composite polymer fibers have been successfully synthesized for the first time using electrospinning technique and characterized in detail as precursor material for ZnO. Electrospinning process has been a widely used, simple and versatile method and in future may be used for large-scale preparation of nanofibers of ZnO.
Modeling of Nonlinear Viscoelastic Creep of Polycarbonate
Authors: Luo Wenbo , Jazouli Said , Vu-Khanh Toan
Published: August 2014

The creep behavior of a commercial grade polycarbonate was investigated in this study. 10 different constant stresses ranging from 8 MPa to 50 MPa were applied to the specimen, and the resultant creep strains were measured at room temperature. It was found that the creep could be modeled linearly below 15 MPa, and nonlinearly above 15 MPa. Different nonlinear viscoelastic models have been briefly reviewed and used to fit the test data. It is shown that the Findley model is a special case of the Schapery model, and both the Findley model and the simplified multiple integral representation are suitable for properly describing the creep behavior of the polycarbonate investigated in this paper; however, the Findley model fit the data better than the simplified multiple integral with three terms.
Zwitterionic Polyelectrolytes: A Review
Authors: Singh Paresh Kumar , Singh Vinay Kumar , Singh Meenakshi
Published: August 2014

Recent progress in the field of zwitterionic polyelectrolytes is reviewed. This class of polyelectrolytes is only five decades old, since the first synthesis was in 1952. Polycarboxybetaines, polysulfobetaines, polyphosphobetaines and a few more zwitterionic materials compose this class of polymers. In the current search for ‘biomimicking’ materials, this class is particularly important. The responsive properties of polyzwitterions are specific, sensitive and instantaneous to a wide variety of external stimuli, which has been reviewed in this article. The synthesis of polyampholytes and polybetaines (homopolymers, copolymers, block polymers) are reviewed. The exploitation of such materials in solid state conducting materials, chromatographic materials and other applications has been incorporated. The extensive discussion on solution properties, antipolyelectrolytic characteristics and influence of varying class of electrolytes has been qualitative as well as quantitative providing an insight into the importance and relevance of such materials, the block polymers form reversible ‘schizophrenic’ micelles also.
Characterization of Genipin Crosslinked Hydrogels Composed of Chitosan and Partially Hydrolyzed Poly(vinyl alcohol)
Authors: Nand Ashveen V. , Rohindra David R. , Khurma Jagjit R.
Published: August 2014

Chitosan and 80 % hydrolyzed poly(vinyl alcohol) (PVA) were used to prepare semi-interpenetrating networks of varying ratios of the constituents. The hydrogels were crosslinked using genipin, a naturally occurring nontoxic crosslinking agent. The swelling behavior of these hydrogels was studied in deionized water at 25, 35 and 45 °C and in media of different pH at 25 °C. The swelling behavior of the gels was found to be dependent on temperature, pH of the medium and the amount of PVA present in the gel. States of water in the hydrogels swollen at 25 °C and pH 7 were determined using Differential Scanning Calorimetry (DSC). The amount of freezing water in the swollen hydrogels increased whereas the amount of nonfreezing bound water decreased with the increase in PVA concentration in the gels. The gelation behaviour of the pregel solutions were also studied.
A Novel pH and Thermo-sensitive N,O-Carboxymethyl Chitosan-graft-Poly(N-isopropylacrylamide) Hydrogel for Controlled Drug Delivery
Authors: Prabaharan M. , Mano J. F.
Published: August 2014

A novel kind of thermo and pH-responsive hydrogels was prepared by reacting N,O-carboxymethyl chitosan (NOCC) with amino-telechelic poly(Nisopropylacrylamide) (PNIPAAm-NH2) as a drug delivery carrier. The hydrogels were characterized by FT-IR and 1H-NMR techniques. The phase transition behavior of the hydrogels was found to be dependent on the NOCC/PNIPAAm-NH2 weight ratio and pH value of the medium. The hydrogels with a higher content of PNIPAAm showed a definite phase transition at 32 °C as it occurs in pure PNIPAAm. For the release study, NOCC-g-PNIPAAm beads were prepared using glutaraldehyde (GA) as a crosslinking agent. The swelling ratio of the beads was higher in pH 2.1 than pH 7.4. Moreover, the swelling ratio of the beads decreased with the increase in PNIPAAm content of the beads. The release profile of NOCCg- PNIPAAm beads showed a slower and controlled release of the entrapped ketoprofen, and found that the release behaviour was influenced by both the pH and temperature of the medium. It is expected that these smart hydrogels may be useful to develop drug delivery systems with improved drug loading capacity and controlled release behaviour.
Preparation of fluorescent poly(methylmethacrylate) nano capsules via internal phase separation
Authors: Lv Hui , Lin Quan , Yao Tongjie , Zhang Kai , Zhang Junhu , Yang Bai
Published: August 2014

Fluorescent nanocapsules containing Eu3+ complex are prepared by the internal phase separation of poly(methylmethacrylate) (PMMA) within the droplets of oil/water nano-emulsion. The nanocapsules give bright red emission excited by UV irradiation and possess stable fluorescence properties. Their fluorescence intensity is primarily influenced by the emulsifier concentration. It is significant that the fluorescence of the nanocapsules is nearly pH-independent and can be kept for a long time in a wide pH range. In contrast, the fluorescence of Eu3+ complex is easily quenched in acidic or alkalic medium. The mean nanocapsule size is tunable with the concentration and the mode of emulsifier addition. As soft templates, oil cores have potential applications for the incorporation of functional components or drugs.
Plasma Polymerization of Amines and Acetone: Functionalized Surfaces for Microarray Applications
Authors: Jehle Heinrich , Kranewitter Wolfgang
Published: August 2014

Plasma polymerization (PP) afforded amine as well as carbonyl containing films which are suitable for use in microarray analysis. The polymerization process with acetone (AC), ethylenediamine (EDA) and diethylamine (DEA) has to be performed in the presence of argon as a carrier gas to be successful. Different activation steps of the polymer based support yield surfaces which differ significantly in their elemental composition after the PP step. Angle dependent XPS proves a take off angle dependence of the carbonyl PP film in contrast to a homogeneous PP film for amine functionalized PP layers while microarray experiments have been successful for both functional films.
Modification of Polymeric Materials via Surface-Initiated Controlled/”Living” Radical Polymerization
Authors: Liu Peng
Published: August 2014

Modification of polymeric materials has been a significant issue over last two decades in many fields of application. Among modification techniques developed to date, surface grafting has emerged as a simple, useful, and versatile approach to improve surface properties of polymers for a wide variety of applications. The synthesis of tethered block copolymer brushes via the use of controlled/”living” free radical polymerization techniques presents many significant advantages over traditional free radical polymerization techniques. This review surveys recent literature on polymer surfaces with graft chains, mainly focusing on grafting methods such as surface-initiated controlled/”living” free radical polymerization via atom transfer radical polymerization (ATRP), nitroxide-mediated radical polymerization (NMRP), reversible addition fragmentation transfer (RAFT) polymerization and iniferter techniques.
Effects of chemical structure on the electrical properties of some polymers with imidic structure
Authors: Cosutchi Andreea Irina , Hulubei Camelia , Buda Manuela , Botila Toni , Ioan Silvia
Published: August 2014

The electrical properties of two types of imidic polymers, i.e. copolymaleimides containing azobenzene groups and epiclon-based polyimides with their corresponding poly(amic acid)s, have been investigated. The dielectric constant and electrical conductance were experimentally measured over the 1-100 KHz frequency range. Also, the dielectric constants for all samples were determined from the experimentally and theoretically evaluated refractive indices at optical frequencies, when Maxwell’s relationship can be applied. From the currentvoltage characteristic I(U), electrical resistance can be determined, providing information on the relationship between the nature of the material and its electric properties. The obtained values show that epiclon-based polyimides and copolymaleimides present higher electrical resistivity than the poly(amic acid)s. The dissipation factor was evaluated, revealing low energy loss under the form of heat in the studied dielectrics. These results show that these polymeric materials are good insulators, which recommends them for microelectronic applications.
Synthesis of resin I: salicylic acid, hexamethylene diamine and formaldehyde and its ion-exchange properties
Authors: Masram Dhanraj.T. , Kariya Kiran.P. , Bhave Narayan.S.
Published: August 2014

The terpolymer resin salicylic acid-hexamethylenediamine-formaldehyde (SHMF) was synthesized by the condensation of salicylic acid and hexamethylenediamine with formaldehyde in the presence of a hydrochloric acid catalyst. The number average molecular weight of the resin was determined by non-aqueous conductometric titration. Terpolymer resin was characterized by elemental analysis, infrared (IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and UV- Visible spectral studies. Chelation ion exchange properties have also been studied for Fe3+, Cu2+, Ni2+, Co2+, Zn2+, Cd2+ and Pb2+ions employing a batch equilibrium method. It was employed to study the selectivity of metal ion uptake involving the measurements of distribution of a given metal ion between the polymer sample and a solution containing the metal ion. The study was carried out over wide pH range and in the media of various ionic strengths. The terpolymer showed a higher selectivity for Fe3+, Cu2+ and Ni 2+ions than for Co2+, Zn2+, Cd2+, and Pb2+ ions.
Preparation and characterization of styrene-methyl methacrylate In deproteinized natural rubber latex (SMMADPNR)
Authors: Man Siti Hajjar Che , Hashim Azanam S. , Akil Hazizan Md.
Published: August 2014

The graft polymerization of Styrene and Methyl methacrylate (MMA) onto deproteinized natural rubber latex (DPNR) was carried out using ammonium peroxy disulfate (N2H8O8S2) as an initiator. The suitable reaction conditions based on the higher monomer conversion was determined. The degree of grafting and the copolymers composition of the resultant SMMA-DPNR were obtained using 1H NMR Spectroscopy. As expected, composition of styrene in DPNR was higher than that of MMA due to the higher reactivity ratio of styrene monomer as compared to MMA monomer and the structure of the NR backbone. The mechanism of seeded emulsion polymerization leading to graft copolymer of styrene and MMA onto NR was studied and elucidated.
Investigation of thermal, rheological and mechanical properties of interfacially modified PP/mica composites
Authors: Khonakdar Hossein Ali , Morshedian Jalil , Yazdani Hamid
Published: August 2014

Composites of polypropylene (PP) with mica powder were produced by melt mixing in an internal mixer. In this research work, the effect of the interfacial modifiers such as maleated polypropylene (MAPP) and silane coupling agent, that encapsulated the mica (treated mica), on the mechanical, thermal and rheological characteristics of mica-filled PP have been investigated. In the literature, it can be seen that increasing mica powder leads to reduced crystallinity of PP. But our results show that reduction in crystallinity is noticeably lesser when interfacial modifier such as MAPP is used. Also, the results of thermogravimetric analysis test showed that MAPP and treated mica caused improvement of heat resistance of the composites. The degradation shifted to higher temperatures which could be due to adhesion between PP and mica powder. The mica powder when added to PP increased the viscosity considerably. However treated mica/PP composite in molten state had noticeably less viscosity in comparison with that of neat micafilled PP and thus having better moldability. Results of decrease in elongation at break with filler content have been compared with predictions of Nielsen’s model and Mitsuishi equation.
ESR and photopolymerization study of polymerizable benzophenone photoinitiators containing functional maleimide groups
Authors: Wei Jun , Liu Fang
Published: August 2014

Four 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

The 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

Low 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

The 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

Depolymerization 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

A 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

The 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

A 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

From 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

The 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

Polyamide-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

Cellular 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

A 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

The 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

Emulsion 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

The 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

The 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.