bluuebunny/crossref_metadata_2025_split huggingface dataset:
Catalyzed chain extension of poly(butylene adipate) and poly(butylene succinate) with 2,2′‐(1,4‐phenylene)‐bis(2‐oxazoline)
Authors: Huang Chao Qun , Luo Si Yang , Xu Shao Yi , Zhao Jing Bo , Jiang Sheng Ling , Yang Wan Tai 
Published: October 2009

AbstractLow‐molecular‐weight HOOC‐terminated poly(butylene adipate) prepolymer (PrePBA) and poly(butylene succinate) prepolymer (PrePBS) were synthesized through melt‐condensation polymerization from adipic acid or succinic acid with butanediol. The catalyzed chain extension of these prepolymers was carried out at 180–220°C with 2,2′‐(1,4‐phenylene)‐bis(2‐oxazoline) as a chain extender and p‐toluenesulfonic acid (p‐TSA) as a catalyst. Higher molecular weight polyesters were obtained from the catalyzed chain extension than from the noncatalyzed one. However, an improperly high amount of p‐TSA and a high temperature caused branching or a crosslinking reaction. Under optimal conditions, chain‐extended poly(butylene adipate) (PBA) with a number‐average molecular weight up to 29,600 and poly(butylene succinate) (PBS) with an intrinsic viscosity of 0.82 dL/g were synthesized. The chain‐extended polyesters were characterized by IR spectroscopy, 1H‐NMR spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis, wide‐angle X‐ray scattering, and tensile testing. DSC, wide‐angle X‐ray scattering, and thermogravimetric analysis characterization showed that the chain‐extended PBA and PBS had lower melting temperatures and crystallinities and slower crystallization rates and were less thermally stable than PrePBA and PrePBS. This deterioration of their properties was not harmful enough to impair their thermal processing properties and should not prevent them from being used as biodegradable thermoplastics. The tensile strength of the chain‐extended PBS was about 31.05 MPa. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Surfactant‐dispersed carbon black in polyimide nanocomposites: Spectroscopic monitoring of the dispersion state in the polymer matrix
Authors: Romyen Natthakarn , Thongyai Supakanok , Praserthdam Piyasan 
Published: October 2009

AbstractThe effects of an anionic surfactant on the dispersion of carbon black (CB) for the purpose of forming conducting composite films were examined with ultraviolet–visible (UV–vis) absorption spectroscopy. To obtain a good dispersion and size reduction of aggregated CB in a polymer matrix, sodium dodecyl sulfate (SDS), used as a surfactant, was introduced into a CB suspension. A set of concentrations with various ratios of CB to SDS (ranging from 1 : 0.4 to 1 : 10) was established before mixing with poly(amic acid) (PAA), a precursor of pyromellitic dianhydride and oxydianiline, was performed. The CB/PAA solution mixtures were submerged under an ultrasonic bath for several hours, then cast onto dry plate glasses, and finally subjected to thermal imidization to produce CB/polyimide (PI) nanocomposite films with various CB weight fractions ranging from 0.025 to 0.50 wt %. A method for evaluating the absorbance at 500 nm of the CB/PI nanocomposite films was established. The absorbance of CB/PI nanocomposite samples of various thicknesses was also normalized to get rid of the effects of the different thicknesses. UV–vis spectra showed that the minimum weight ratio of CB to SDS in the nanocomposite films that achieved well‐dispersed CB and still had transparent properties was 1 : 2.0. Transmission electron microscopy demonstrated that CB was dispersed homogeneously in the PI matrix, and the size of the aggregated CB was affected by the amount of the surfactant. The dielectric properties of the nanocomposite films without the surfactant increased by approximately 2 orders of magnitude with an increasing mass weight fraction of CB and decreased when the surfactant was added. The surfactant also reduced the tensile strength of the CB/PI nanocomposites when the CB/SDS ratio was higher than 1 : 2.0. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Molecularly imprinted polypyrrole prepared by electrodeposition for the selective recognition of tryptophan enantiomers
Authors: Kong Yong , Zhao Wei , Yao Shiping , Xu Juan , Wang Wenchang , Chen Zhidong 
Published: October 2009

AbstractHerein we report the electrosynthesis of polypyrrole with L‐tryptophan (L‐Trp) as a template to prepare molecularly imprinted polymers (MIPs). Overoxidized polypyrrole films with cavities complementary to the template were used for the enantioselective detection of L‐Trp and D‐tryptophan (D‐Trp). Important parameters, such as the electropolymerization potential, overoxidization potential and time, thickness of the polypyrrole films, and scanning rate of the stripping voltammetric experiments, were varied to achieve an optimum sensor response. We found that L‐Trp was inserted about 2 times higher into the imprinted polymer film than D‐Trp. Also, in this study, an electrochemical quartz crystal microbalance technique was used to investigate the performance of overoxidized polypyrrole films. The enantioselectivity of the MIPs was attributed to the cavities in the imprinted films, which were complementary to the target molecules, both in shape and in positioning of the functional groups. The results also suggest the feasibility of preparing MIPs by electropolymerization for the enantioselective recognition of other amino acid enantiomers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Silver‐nanoparticle‐loaded chitosan lactate films with fair antibacterial properties
Authors: Tankhiwale Rasika , Bajpai S. K. 
Published: October 2009

AbstractFood quality and safety are major concerns in the food industry. Antimicrobial packaging can be considered an emerging technology that could have a significant impact on life and food safety. Antimicrobial agents in food packaging can control the microbial population and target specific microorganisms to provide greater safety and higher quality products. In this work, a lactic acid grafted chitosan film was synthesized. Silver nanoparticles were loaded into the chitosan lactate (CL) film by equilibration in a silver nitrate solution, which was followed by citrate reduction. The presence of silver nanoparticles was confirmed with transmission electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis of the film. The silver‐nanoparticle‐loaded CL film was investigated for its antimicrobial properties against Escherichia coli. This newly developed material showed strong antibacterial properties and thus has potential for use as an antibacterial food‐packaging material. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation of nanoscale azo pigment yellow 13/poly(styrene–maleic acid) composite dispersions via free‐radical precipitation polymerization
Authors: Fu Shaohai , Xu Changhai 
Published: October 2009

AbstractNanoscale azo pigment yellow 13 (PY13) was coated by poly(styrene–maleic acid) (PSMA) with a free‐radical precipitation polymerization, followed by the preparation of the dispersion. The effects of the PSMA structure on the particle size and centrifugal stability were investigated. The experimental results revealed that the particle size was large, and the stability of the PY13/PSMA dispersions was high when the molar ratio of the feeding maleic acid to styrene, the weight ratio of the feeding initiator to monomer, and the weight ratio of the feeding monomer to pigment were about 1.0, 0.6, and 20%, respectively. Fourier transform infrared spectroscopy, dynamic light scattering, and transmission electron microscopy indicated that PY13 was coated by PSMA. The PY13/PSMA dispersion was stable in the pH range 5.6–10.5. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Tribological behavior of poly(ether ether ketone) composites filled with potassium titanate whiskers sliding in different media
Authors: Wang Huai‐Yuan , Lu Xiao‐Hua , Shi Yi‐Jun , Feng Xin 
Published: October 2009

AbstractThe friction and wear properties of poly (ether ether ketone) (PEEK) composites filled with potassium titanate whiskers (PTWs) under alkali, water, and dry conditions were investigated. The wear mechanisms in different lubrication situations were studied on the basis of examinations of the worn and counterpart surfaces with scanning electron microscopy and optical microscopy. The results showed that PTWs could obviously increase the wear resistance and reduce the friction coefficient of the PEEK composites under dry sliding conditions. Only when the PTW content was greater than 35 wt % did the wear resistance and friction coefficient deteriorate. Sliding in water caused increases in the wear rate and friction coefficient of the PEEK composites, and the PTW‐filled PEEK composites showed the highest friction coefficient and wear rate under this lubrication condition. On the contrary, sliding in an alkaline solution, the PTW‐filled PEEK composites showed the lowest friction coefficient and almost the same level of wear resistance as that found under the dry condition. Furrows and abrasive wear were the main mechanisms for the PTW‐filled PEEK composites sliding in water. The transfer onto the counterpart rings was significantly hindered with sliding under water and alkali conditions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Novel observations on kinetics of nonisothermal crystallization in fly ash filled isotactic‐polypropylene composites
Authors: Nath Dilip Chandra Deb , Bandyopadhyay Sri , Yu Aibing , Blackburn Darryl , White Chris 
Published: October 2009

AbstractA study on nonisothermal crystallization kinetics in fly ash (FA) filled isotactic‐polypropylene (PP) composites has revealed some interesting phenomena. Composites made by injection moulding of PP with 0, 20, 45, and 60 wt % of FA were nonisothermally studied using differential scanning calorimetry at cooling rates 10°C, 15°C, and 20°C per min from a melt temperature of 200°C cooled to −30 °C. Whilst neat PP showed a mono modal α crystalline phase‐ only structure, presence of FA led to bimodal thermographs revealing partial transcrystallisation of α into β, to maximum 14%. The onset and peak crystallization temperatures of all samples decreased by ∼ 3°C with each 5°C/min increase in cooling rate. Parameters such as crystal growth rate, dimensions, and activation energy were determined using a series of established models. The Avrami graphs showed that contrary to the published data, there are two sets of straight lines (a) with a lower slope at low cooling rate and (b) with a distinctly higher slope for high cooling rate. Activation energy of the materials reached a maximum at 45% FA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Assessment degradation of natural rubber by moving die processability test and FTIR spectroscopy
Authors: Narathichat M. , Sahakaro K. , Nakason C. 
Published: October 2009

AbstractThermal and mechanical degradation of natural rubber (NR) mixed with N‐(1,3‐dimethylbutyl)‐N′‐phenyl‐p‐phenylenediamine (6PPD), polymerized 1,2‐dihydro‐2,2,4‐trimethyl‐quinoline (TMQ), and 50/50 weight basis mixture under high temperature and shearing conditions were investigated using a moving die processability test and FTIR spectroscopy. Relationship between dynamic properties in terms of tan δ value and chemical changes of NR molecules during degradation were correlated. The results indicated that the NR mixed with antioxidants caused decreased level of chain scission and oxidative degradation. The 6PPD provided better protection of NR against degradation at elevated temperature than TMQ. Furthermore, it was found that a prolonged mixing time caused more pronounced oxidative degradation on NR molecules than increased mixing temperature. The antioxidative capability of those antioxidants on NR was ordered based on their effectiveness as follows: 6PPD > 6PPD mixed with TMQ > TMQ. It was also found that the moving die processability test and FTIR spectroscopy are efficient routes to estimate the oxidative degradation of NR molecules. Therefore, the techniques could be applied to assess or compare antioxidative capability of various types and amounts of antioxidants used in the rubber formulation within a reasonable testing time. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Aggregation phenomena of amphiphilic UVB absorptive oligoesters containing p‐alkoxycinnamate and poly(ethylene oxide) blocks
Authors: Changhin P. , Wanichwecharungruang S. P. , Luadthong C. , Sritana‐Anant Y. 
Published: October 2009

AbstractThe synthesis of new amphiphilic oligoesters containing a hydrophobic block based on p‐alkoxycinnamate and hydrophilic poly(ethylene oxide) is reported. Two hydrophobic monomers, 1,2‐(bis(4‐(2‐carboxyvinyl)phenoxy))ethane (M2) and 1,12‐(bis(4‐(2‐carboxyvinyl) phenoxy))dodecane (M12), were synthesized. Four oligoesters, poly((1,2‐(bis(4‐(2‐carboxyvinyl)phenoxy))ethane) ‐co‐(poly(ethylene oxide)200)) (P2‐200), poly((1,2‐(bis(4‐(2‐carboxyvinyl)phenoxy))ethane)‐co‐(poly(ethylene oxide) 400)) (P2‐400), poly((1,12‐(bis(4‐(2‐carboxyvinyl)phenoxy)) dodecane)‐co‐(poly(ethylene oxide)400)) (P12‐400), and poly((1,12‐(bis(4‐(2‐carboxyvinyl)phenoxy))dodecane)‐co‐ (poly(ethylene oxide)1000)) (P12‐1000) were then constructed by reacting the M2 or M12 with poly(ethylene oxide) (PEO) with lengths of ∼ 4 (PEO 200), ∼ 10 (PEO 400), or ∼ 23 (PEO1000) units using multiple esterifications. These oligoesters possess UVB absorption properties and show good solubility in various organic solvents. Self‐assembly of the oligoesters into aqueous spherical colloids could be induced through an acetone to water solvent displacement technique. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Alternating tangent approach for the optimal vulcanization of 2D‐3D EPM/EPDM thick elements
Authors: Milani G. , Milani F. 
Published: October 2009

AbstractThe main problem in industrial practice when dealing with the curing process of thick EPM/EPDM elements is constituted by the different temperatures, which undergo internal (cooler) and external regions. Indeed, while internal layers remain essentially under‐vulcanized, external coating is always over‐vulcanized, resulting in an overall average tensile strength insufficient to permit the utilization of the items in several applications where it is required a certain level of performance. A possibility to improve rubber output mechanical properties is the utilization of mixtures of at least two peroxides, the first highly active at high temperatures (i.e., for external layers), the second at low temperatures (internal regions). In this framework, in this article, a simple numerical procedure for the optimization of final mechanical properties of vulcanized 2D and 3D thick rubber items is presented. In particular, a so called alternating tangent approach (AT) for the determination of the optimal input parameters to use during the production of complex 2D/3D thick items is presented. Vulcanization external temperature Tc and rubber exposition time t are assumed as input production parameters, whereas output mechanical property to optimize is represented by the average tensile strength of the item. In the algorithm, a sufficiently large interval of exposition times at fixed Tc (or curing temperatures at fixed exposition times) is chosen at the initial iteration, namely evaluating rubber tensile strength at a very under‐vulcanized and at a very over‐vulcanized exposition time. For each extreme of the interval, first derivatives of final tensile strength with respect to exposition time (or curing temperature) are evaluated numerically. At the successive iteration, search exposition interval is reduced to one‐half through bisection, selecting the right or left semi‐interval basing the choice on first derivative sign evaluated at the middle point. The approach proposed converges very quickly to the optimal solution, competing favorably both with a very expensive method based on the subdivision of the domain in a refined grid of points and with recently presented GA approaches. Two meaningful examples of engineering interest, consisting of an high voltage electric cable and a 3D thick rubber docks bumper are illustrated. When dealing with the 3D item, due to its thickness, different mixtures of two peroxides (50%‐50%, 25%‐75% and 75%‐25% molar ratios) are also used to improve drastically final mechanical properties. Optimal production Tc and t parameters are obtained for all the cases analyzed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Effect of chlorine dioxide gas on physical, thermal, mechanical, and barrier properties of polymeric packaging materials
Authors: Rubino Maria , Netramai Siriyupa , Auras Rafael , Annous Bassam A. 
Published: October 2009

AbstractThe effects of gaseous chlorine dioxide (ClO2) on properties and performance of 10 selected polymeric packaging materials, including polyethylene (PE), biaxially oriented poly(propylene), polystyrene, poly(vinyl chloride), poly(ethylene terephthalate) (PET), poly(lactic acid), nylon, and a multilayer structure of ethylene vinyl acetate (EVA)/ethylene vinyl alcohol (EVOH), were evaluated. Physical, mechanical, barrier, and color properties as well as infrared (IR) spectra were assessed before and after polymer samples were exposed to 3600 ppmV ClO2 gas at 23°C for 24, 168, and 336 h. The IR spectra of the ClO2‐treated samples revealed many changes in their chemical characteristics, such as the formation of polar groups in the polyolefin, changes in functional groups, main chain scission degradation, and possible chlorination of several materials. The ClO2‐treated PE samples showed a decrease in tensile properties compared with the untreated (control) films. Decreases in moisture, oxygen, and/or carbon dioxide barrier properties were observed in the treated PE, PET, and multilayer EVA/EVOH/EVA samples. A significant increase (P < 0.05) in the barrier to O2 was observed in the ClO2‐treated nylon, possibly the result of molecular reordering, which was found through an increase in the crystallinity of the material. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis and characterization of PMMA/SiO2 nanocomposites by in situ suspension polymerization
Authors: Zheng Junping , Zhu Ran , He Zhihui , Cheng Gang , Wang Hongyan , Yao Kangde 
Published: October 2009

AbstractPoly(methyl methacrylate) (PMMA)/SiO2 nanocomposites were prepared by in situ suspension polymerization. Two types of modified methods were used to modify nano‐SiO2: one was modification by γ‐methacyloxypropyl trimethoxy silane (KH570) and lauryl alcohol (12COH) while the other was grafting PMMA onto the surface of KH570 treated SiO2. Transmission electron microscopy (TEM) and Fourier transformed infrared (FTIR) were used to characterize the structures of the nanocomposites. The influence of synthetic conditions, for instance, surface modification, initial SiO2 contents and reaction temperature, on the microsphere's size and molecular weight of the extracted PMMA were studied by gel permeation chromatograph (GPC) and optical microscopy (OM) in details. Thermal property of the nanocomposites was investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results indicate that the presence and content of SiO2 have a vital effect on the shape and size of the nanocomposite microspheres, as well as molecular weight of the extracted PMMA. Grafting polymer to the surface of SiO2 is an effective way for the purpose of effective in situ suspension polymerization. Compared to pure PMMA, the thermal properties of the nanocomposites were improved. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Impact of the steric position of phosphonate groups in poly(N,N‐dimethylacrylamide‐co‐2‐acrylamido‐2‐methylpropanesulfonate‐co‐2‐X‐phosphonate) on its adsorbed conformation on cement: Comparison of vinylphosphonic acid and 2‐acrylamido‐2‐methylpropanephosphonate modified terpolymers
Authors: Plank Johann , Dugonjić‐Bilić Fatima , Lummer Nils Recalde 
Published: October 2009

AbstractFor phosphonated copolymers, the effect of distance of the phosphonate group from the polymer backbone on the Ca2+ chelating capability and the adsorption behavior on cement was studied. For this purpose, 2‐acrylamido‐2‐methylpropane phosphonic acid (AMPPA) and vinyl phosphonic acid (VPA), respectively, were reacted in an aqueous free‐radical polymerization with N,N‐dimethylacrylamide (NNDMA) and 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS®) to give poly(N,N‐dimethylacrylamide‐co‐2‐acrylamido‐2‐methylpropanesulfonate‐co‐2‐acrylamido‐2‐methylpropanephosphonate) (CaAMPS®‐co‐NND MA‐co‐CaAMPPA) and poly(N,N‐dimethylacrylamide‐co‐2‐acrylamido‐2‐methylpropanesulfonate‐co‐vinylphosphonate) (CaAMPS‐co‐NNDMA‐co‐CaVPA), respectively. Adsorption behavior and thus performance of the terpolymers strongly depend on their calcium binding capacity. Ca2+ selective conductivity measurements show that the AMPPA modified terpolymer chelates less calcium than the VPA polymer. Therefore, it interacts less with surfaces containing calcium atoms/ions. To investigate the consequences for practical applications adsorbed amounts on cement surface and effectiveness as water retention agent (fluid loss additive, FLA) in oil well cement slurries with and without acetone‐formaldehyde‐sulfite (AFS) dispersant were determined. CaAMPS‐co‐NNDMA‐co‐CaAMPPA and AFS adsorb simultaneously whereas CaAMPS‐co‐NNDMA‐co‐CaVPA does not allow dispersant adsorption. The reason is that affinity of phosphonate functions towards Ca2+ ions is reduced with increasing distance from the polymer backbone. Thus, AMPPA is a weaker anchor group than VPA. Zeta potential measurements indicate that the increased length of the side chain holding the phosphonate function decreases the anionic charge density of the polymer. Accordingly, CaAMPS‐co‐NNDMA‐co‐CaAMPPA appears to develop weaker bonds with the cement surface. Upon addition of AFS, the AMPPA modified FLA can change its adsorbed conformation from “train” to “loop” or “tail” mode and thus provide space for the dispersant to adsorb as well. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation and characterization of iron(III) complex of an amino‐functionalized polyacrylamide‐grafted lignocellulosics and its application as adsorbent for chromium(VI) removal from aqueous media
Authors: Anirudhan Thayyath S. , Rijith Sreenivasan , Suchithra Padmajan S. 
Published: October 2009

AbstractThis study concerns with the development of a new adsorbent, iron(III) complex of an amino‐functionalized polyacrylamide‐grafted coconut coir pith (CP), a lignocellulosic residue, for Cr(VI) in water and industry effluents. The adsorbent (AM‐Fe‐PGCP) was characterized by FTIR, EDS, Mössbauer, surface area analyzer, TG/DTG, and potentiometric titration. The effects of contact time, initial sorbate concentration, pH, dose of adsorbent, and temperature on Cr(VI) adsorption were studied to optimize the conditions for maximum adsorption. The kinetics of sorption was investigated using pseudo‐first‐order and pseudo‐second‐order rate equations with the later giving a better fit to the experimental data. The mechanism of sorption was found to be film diffusion controlled. The Langmuir isotherm model yields a much better fit than the Freundlich and Dubinin–Radushkevich models with maximum adsorption capacity of 142.76 mg/g at 30°C. Simulated industry wastewater sample was treated with AM‐Fe‐PGCP to demonstrate its efficiency in removing Cr(VI) from wastewater. The alkali treatment (0.1M NaOH) and re‐introduction of Fe3+ lead to a reactivation of the spent adsorbent and can be reused through many cycles of water treatment and regeneration without any loss in the adsorption capacity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010