bluuebunny/crossref_metadata_2025 huggingface dataset:
Swelling characteristics and in vitro drug release study with pH‐ and thermally sensitive hydrogels based on modified chitosan
Authors: El‐Sherbiny I. M. , Abdel‐Bary E. M. , Harding D. R. K.
Published: July 2006

The grafting of a poly(ethylene glycol) diacrylate macromer onto a chitosan backbone was carried out with different macromer concentrations. The grafting was achieved by (NH4)2Ce(NO3)6‐induced free‐radical poly merization. Biodegradable, pH‐ and thermally responsive hydrogels of poly(ethylene glycol)‐g‐chitosan crosslinked with a lower amount of glutaraldehyde were prepared for controlled drug release studies. Both the graft copolymers and the hydrogels were characterized with Fourier transform infrared, elemental analysis, and scanning electron microscopy. The obtained hydrogels were subjected to equilibrium swelling studies at different temperatures (25, 37, and 45°C) in buffer solutions of pHs 2.1 and 7.4 (similar to those of gastric and intestinal fluids, respectively). 5‐Fluorouracil was entrapped in these hydrogels, and equilibrium swelling studies were carried out for the drug‐entrapped gels at pHs 2.1 and 7.4 and 37°C. The in vitro release profile of the drug was established at 37°C and pHs 2.1 and 7.4. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 977–985, 2006
Wetting behavior of thermally bonded polyester nonwoven fabrics: The importance of porosity
Authors: Zhu Lu , Perwuelz Anne , Lewandowski Maryline , Campagne Christine
Published: July 2006

The wetting properties of thermally bonded polyester nonwoven fabrics with different basis weights were studied. These nonwovens had the same composition: 85% poly(ethylene terephthalate) and 15% poly(butylene terephthalate) fibers. Two techniques, the 3S wicking test and sessile drop method, yielded similar water contact angles for all the nonwovens, but these results differed from the values obtained with the single fibers. In the nonwoven fabrics, the pore structure played a dominant role in the wetting properties: the existence of large pores in the thinner nonwovens reduced the dimensions of the liquid–solid interfacial perimeter. Compared with the water contact angle of the constituent single fibers, the contact angle of the fabrics was increased. A crenellated surface model was created to quantify the influence of pores on the wettability of nonwovens. It was possible to deduce the surface porosity of the fabric with this model, but only in the case of contact with nonwetting liquids such as water: this surface porosity corresponded only to the outermost layers of the fabric structure. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 387–394, 2006
Swelling and release kinetics of larvicide‐containing chitosan/cashew gum beads
Authors: Paula Haroldo C. B. , de Paula Regina C. M. , Bezerra Sterlane K. F.
Published: July 2006

A new pesticide formulation (bead) based on chitosan (CH) and cashew gum (CG) containing dichlorvos [2,2‐dichlorovinyldimethyl phosphate (DDVP)] was prepared and investigated as a larvicide for Aedes aegypti control. Beads were characterized with respect to their size, shape, larvicide loading, swelling, and in vitro and in vivo release kinetics. CH and CH/CG beads were loaded with DDVP from 5.15 to 71.4%. In the first hour, the in vitro release was similar for CH and CH/CG beads, faster release being observed after 5 h for CH/CG beads; at equilibrium (30 h), CH beads released up to 55% of the larvicide, and CH/CG beads reached 66%. The data were fitted to a mathematical model, being in good agreement with the literature. In vivo release showed that CH/CG beads reached a plateau after 30 h, resulting in a highest mortality of approximately 60%, whereas CH beads killed only 42% of the larvae by 30 h and seemed not to have released their whole larvicide content even after 72 h. The DDVP lethal dose for 50% mortality was found to be 0.01 ± 0.002 ppm; the persistence studies revealed that after 168 h, 42.5% larval mortality was obtained by CH beads, and only approximately half of that was obtained by CH/CG beads. DDVP‐loaded beads were effective up to 336 h. It could be concluded that beads containing DDVP at an average concentration of 7.2 ppm could provide good larval control up to 7 days. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 395–400, 2006
Flocculation studies based on water‐soluble polymers of grafted carboxymethyl cellulose and polyacrylamide
Authors: Biswal D. R. , Singh R. P.
Published: July 2006

Graft copolymers of carboxymethylcellulose and polyacrylamide were synthesized by a ceric‐ion‐induced solution polymerization technique. By the variation of the monomer and catalyst concentrations, six grades of graft copolymers were synthesized. The synthesized graft copolymers were characterized with intrinsic viscosity measurements, IR spectroscopy, and X‐ray diffractometry. The flocculation characteristics of the graft copolymers were studied in kaolin (5 wt %), iron‐ore (10 wt %), and silica (10 wt %) suspensions. The flocculation characteristics of the best performing graft copolymer were then compared with those of various commercially available flocculants. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1000–1007, 2006
Using polymer compounds in place of metal material to make cost‐effective parts
Authors: Huang C. K. , Lee C. S. , Yang C. T.
Published: July 2006

The use of plastic materials in place of metals is attractive because of their versatility and ease of batch fabrication, which reduces costs. This article investigates the possibility of using nylon compounds in place of metal materials to make cost‐effective parts through microinjection molding. Experimental results showed that the plastic parts were well formed with high accuracy and reproducibility through microinjection molding. The average tolerance in the dimensions of the plastic parts was less than 20 μm. The resulting composites with 15 wt % carbon particles exhibited the optimum improvement in accuracy, reproducibility, and wear resistance. In addition, the wear loss of the metal parts without lubrication was 4–10 times higher than that of the polymer compounds. The results revealed that the ball‐screw plates made with nylon compounds exhibited high accuracy, reproducibility, and wear resistance, could be produced at low cost, and they could successfully replace S316 metal parts in microinjection molding. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1645–1652, 2006
Linear dimensional changes of denture base and hard chair‐side reline resins after disinfection
Authors: Gonçalves Alessandro Ribeiro , Machado Ana Lucia , Giampaolo Eunice Teresinha , Pavarina Ana Cláudia , Vergani Carlos Eduardo
Published: July 2006

Objectives

This study evaluated the effect of disinfection by immersion in sodium perborate (50°C/10 min) or microwave irradiation (650 W/6 min) on the linear dimensional change (LDC) of four reline resins (Kooliner‐K, New Truliner‐N, Tokuso Rebase Fast‐T, Ufi Gel Hard‐U) and one heat‐polymerizing denture base resin (Lucitone 550‐L).

Methods

Specimens (50.0 mm diameter, 0.5 mm thickness) were made using a split mold with reference points, and divided into two controls and four test groups (n = 8). The distances between the points were measured on the mold (baseline readings), and compared to those obtained from the specimens after: polymerization or immersion in water (37°C) for 7 days (controls); 2 or 7 cycles of disinfection by immersion or microwave irradiation.

Results

The two‐way ANOVA and Tukey's test (α = 0.05) showed that microwave disinfection significantly increased the mean LDC of materials L (−1.43%), N (−1.27%) and K (−1.06%). Material N also exhibited a significant increase in LDC after two cycles of chemical disinfection (−0.73%). For U (−0.47%) and T (−0.21%) materials, no significant changes in LDC were found.

Conclusions

Microwave disinfection increases the shrinkage of materials L, N, and K. The dimensional stability of resins U and T was not affected by the disinfection methods evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1821–1826, 2006
Thermal and mechanical properties of poly(trimethylene terephthalate) (PTT)/cationic dyeable poly(trimethylene terephthalate) (CD‐PTT) polyblended fibers
Authors: Hsiao Kai‐Jen , Lee Shu‐Pyng , Kong Dan‐Cheng , Chen Frank L.
Published: July 2006

Poly(trimethylene terephthalate) (PTT) and cationic dyeable poly(trimethylene terephthalate) (CD‐PTT) were extruded (in the proportions of 80:20, 60:40, 40:60, and 20:80) from one melt twin‐screw extruder to prepare four PTT/CD‐PTT polyblended fibers. The molar ratio of 5‐sodium sulfonate dimethyl isophthalate (5‐SSDMI) for CD‐PTT polymer was 2%. This study investigated the thermal and mechanical properties of PTT/CD‐PTT polyblended fibers using gel permeation chromatograph, differential scanning calorimetry (DSC), thermogravimetric analysis, potentiometer, a rheometer, the density gradient, wide‐angle X‐ray diffraction, extension stress–strain measurement, and scanning electron microscope (SEM). Melting behavior of PTT/CD‐PTT polyblended polymers exhibited positive‐deviation blends, and the blend of PTT/CD‐PTT between 60:40 and 40:60 showed a maximum value of the melt viscosity. Experimental results from the DSC indicated that PTT and CD‐PTT molecules formed a miscible system. The tenacity of PTT/CD‐PTT polyblended fibers declined as the 5‐SSDMI content increased. Crystallinities and densities of PTT/CD‐PTT polyblended fibers were also found decrease as the 5‐SSDMI content increased. The surface of PTT/CD‐PTT polyblended fibers exhibited a uniform morphology, from the SEM observation. It indicated that PTT and CD‐PTT polymers were identified to be a miscible system. Though there is a good interfacial adhesion between PTT and CD‐PTT polymer, the mechanical properties of PTT/CD‐PTT ployblended fibers were largely affected by the 5‐SSDMI content. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1008–1013, 2006
Superabsorbent polymeric materials. XIII. Effect of oxyethylene chain length on water absorbency for the sodium acrylate and poly(ethylene glycol) methyl ether acrylate (PEGMEAn) copolymeric gels
Authors: Lee Wen‐Fu , Yang Lin‐Gi
Published: July 2006

In a previous study, we prepared a series of xerogels based on sodium acrylate (NaA) and 2‐hydroxyethyl methacrylate (HEMA, OE = 1) or poly(ethylene glycol) methacrylate (PEGMA, OE = 6) with different oxyethylene (OE) units. The effect of the contents of HEMA and PEGMA in the copolymeric gel on the swelling behavior in deionized water and various saline solutions was studied. Their results showed that the water absorbencies for these two series gels were effectively improved by adding a small amount of HEMA or PEGMA. In this article, a series of novel xerogels based on NaA and hydrophilic monomer poly(ethylene glycol) methyl ether acrylate (PEGMEAn), which was synthesized from acryloyl chloride and poly(ethylene glycol) monomethyl ether with three oxyethylene (OE = 9, 16, 45) chain lengths, were prepared by inverse suspension polymerization. The effects of OE chain length in the copolymeric gel on the water absorption behavior and initial absorption rate for the present xerogels were investigated. Results showed that adding a small amount of PEGMEAn could effectively increase the water absorbency of the gels. In addition, the water absorbency decreased with an increase of the OE chain length in PEGMEAn. The initial absorption rate for the present copolymeric gels increased with increasing OE chain length in PEGMEAn and the content of PEGMEAn in the copolymeric gels. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 927–934, 2006
Application of radio frequency glow discharge plasma for enhancing adhesion bonds in polymer/polymer joints
Authors: Lapèíková B. , Lapèík L. , Smolka P. , Dlabaja R. , Hui D.
Published: July 2006

It was found in this study, that air radio frequency glow discharge (rfGD) plasma is increasing surface roughness and is enhancing wettability of poly(propylene) (PP), poly(ethylene) (PE), and poly(carbonate) (PC). As an addition, the increased surface microhardness of PP and PE was found. Results indicate that rfGD air plasma treatment is very effective tool for improvement of adhesive properties of studied polymers as tested on single lap and double lap joints. The value of maximum load rise from 107 to 1926 N (approximately 18‐fold increase) for 20‐min‐treated PE and from 314 to 834 N (approximately three‐fold increase) for PP. Artificial accelerated ageing rapidly decreased the quality of adhesive joint. The value of maximum load decreased from 1926 to 221 N (approximately nine‐fold decrease) in the case of 20‐min‐treated PE. This result indicates that the ageing of the adhesive joint of plasma treated polymers can be a limitation factor in the possible application of the final component because of the extremely high loss of its initially‐enhanced mechanical properties. However, the strength of the thus prepared joints was higher in comparison to the plasma nontreated virgin samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1827–1833, 2006
Dynamic rheological behavior of polypropylene melts with pulsatile pressure flow in a dynamic capillary rheometer
Authors: He Guang Jian , Qu Jin Ping , Chun Yin Xiao
Published: July 2006

A self‐made dynamic capillary rheometer (DCR) was designed to investigate the dynamic viscoelastic characteristic of polypropylene (PP) melt during the pulsatile pressure extrusion. A vibration force field was parallel superposed upon steady shear flow in this DCR by means of a vibration driven piston. During the pulsatile pressure extruding process in DCR, the PP melt displayed apparent viscoelasticity. The experiment results proved the pressure pulsatile extrusion could reduce the viscosity of polymer melts effectively. The phase difference between the shear stress and the shear rate decreased with the superposed vibration. But, at large amplitude conditions, the viscosity has an increasing tendency. This maybe illuminated that large amplitude could be harmful for the vibration‐assistant polymer processing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1834–1838, 2006
Syntheses and properties of polyimides derived from diamines containing 2,5‐disubstituted pyridine group
Authors: Xia Aixiang , Guo Haiquan , Qiu Xuepeng , Ding Mengxian , Gao Lianxun
Published: July 2006

A series of novel homo‐ and copolyimides containing pyridine units were prepared from the heteroaromatic diamines, 2,5‐bis (4‐aminophenyl) pyridine and 2‐(4‐aminophenyl)‐5‐aminopyridine, with pyromelltic dianhydride (PMDA), and 3,3′, 4,4′‐biphenyl tertracarboxylic dianhydride (BPDA) via a conventional two‐step thermal imidizaton method. The poly(amic acid) precursors have inherent viscosities of 1.60–9.64 dL/g (c = 0.5 g/dL in DMAC, 30°C) and all of them can be cast and thermally converted into flexible and tough polyimide films. All of the polyimides show excellent thermal stability and mechanical properties. The polyimides have 10% weight loss temperature in the range of 548–598°C in air. The glass transition temperatures of the PMDA‐based samples are in the range of 395–438°C, while the BPDA‐based polyimides show two glass transition temperatures (Tg1 and Tg2), ranging from 268 to 353°C and from 395 to 418°C, respectively. The flexible films possess tensile modulus in the range of 3.42–6.39 GPa, strength in the range of 112–363 MPa and an elongation at break in the range of 1.2–69%. The strong reflection peaks in the wide‐angle X‐ray diffraction patterns indicate that the polyimides have a high packing density and crystallinity. The polymer films are insoluble in common organic solvents exhibiting high chemical resistance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1844–1851, 2006
Preparation of porous carbon microspheres
Authors: Lu Yonggen , Yang Changling , Rong Haiqin , Pan Ding
Published: July 2006

Porous carbon microspheres with good morphology, high yield, and controllable particle size were prepared from phenolic resin. The particle size and pore structure of the carbon microspheres were mainly inherited from their precursors, resol microspheres, which were made through curing emulsified resol in water at 120°C under saturated pressure. The average particle size and specific surface area of the porous carbon microspheres was related to the concentration of resol and polyvinyl alcohol along with the heating program. The carbonization yield to 700°C was 55 wt %. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 798–803, 2006
Using maleic anhydride grafted poly(lactic acid) as a compatibilizer in poly(lactic acid)/layered‐silicate nanocomposites
Authors: Petersson L. , Oksman K. , Mathew A. P.
Published: July 2006

The goal of this work was to prepare exfoliated poly(lactic acid) (PLA)/layered‐silicate nanocomposites with maleic anhydride grafted poly(lactic acid) (PLA–MA) as a compatibilizer. Two different layered silicates were used in the study: bentonite and hectorite. The nanocomposites were prepared by the incorporation of each layered silicate (5 wt %) into PLA via solution casting. X‐ray diffraction of the prepared nanocomposites indicated exfoliation of the silicates. However, micrographs from transmission electron microscopy showed the presence of intercalated and partially exfoliated areas. Tensile testing showed improvements in both the tensile modulus and yield strength for all the prepared nanocomposites. The results from the dynamic mechanical thermal analysis showed an improvement in the storage modulus over the entire temperature range for both layered silicates together with a shift in the tan δ peak to higher temperatures. The effect of using PLA–MA differed between the two layered silicates because of a difference in the organic treatment. The bentonite layered silicate showed a more distinct improvement in exfoliation and an increase in the mechanical properties because of the addition of PLA–MA in comparison with the hectorite layered silicate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1852–1862, 2006
Adsorption and antibacterial activity of silver‐dispersed carbon aerogels
Authors: Zhang Shuting , Wu Dingcai , Wan Lin , Tan Haibing , Fu Ruowen
Published: July 2006

Silver‐dispersed carbon aerogels (Ag/CAs) were obtained by the direct immersion of organic aerogels in aqueous AgNO3 solutions and then carbonization of the resulting material under a nitrogen atmosphere. The adsorption and antibacterial activity of Escherichia coli and Staphylococcus aureus on Ag/CAs were studied by the measurement of the amount of viable bacteria in suspensions and scanning electron microscopy (SEM) observations. The adsorbed amount of bacteria on samples without silver increased with an increase in the carbonization temperature and contact time. SEM studies showed that the adsorption capacity of Ag/CAs decreased with an increase in the silver content; this was considered to be mainly due to the dissolution behavior of bacteria by silver ions. The antibacterial test showed that 2.5 mg of Ag/CAs with more than 3.6% Ag could inhibit the growth of 105 cfu/mL E. coli in 10 mL of a Mueller–Hinton broth culture, but in the case of S. aureus, 10‐mg samples just got the same antibacterial effect. An antibacterial persistency test showed that 25 mg of Ag/CAs with 6.5% Ag could kill 50 mL of 105 cfu/mL E. coli eight times. These results indicate that Ag/CAs possess strong and long‐term antibacterial activity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1030–1037, 2006
Oscillatory measurements for salad dressings stabilized with modified starch, xanthan gum, and locust bean gum
Authors: Dolz M. , Hernández M. J. , Delegido J.
Published: July 2006

The rheological properties of low‐oil‐content food emulsions were analyzed with oscillatory tests within the linear viscoelastic region. The formulations of these salad dressings usually include modified starch because of its low cost and the special creamy texture that it affords. The combination of starch with other natural gums may improve the quality of the product. A reference emulsion containing 4% modified starch and four other formulations in which the starch was partially replaced by xanthan gum (0.4%), locust bean gum (0.4%), and synergistic blends of these gums (0.03 + 0.03% or 0.1 + 0.1%) were formulated. Gels before emulsification were studied for comparative purposes. All systems showed weak gel behavior. An empirical equation fitting the storage and loss modulus dependence on the frequency was applied. The loss tangent allowed us to compare the viscoelastic character of all the systems. The complex viscosity followed the power law in all cases, and the generalized Cox–Merz rule was applied. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 102: 897–903, 2006
Effect of the processing molding temperature on the crystalline structure and properties of acrylonitrile‐butadiene rubber/trinylon thermoplastic vulcanizates
Authors: He Chunjiang , Zou Hua , Zhao Suhe
Published: July 2006

The effect of the processing molding temperature on the properties and crystalline structure of acrylonitile‐butadiene rubber (NBR)/nylon 6,66,1010 (trinylon) thermoplastic vulcanizates (TPV) was studied. With decreasing molding temperature, the stress at 100% and elongation at break of TPV changed slightly, and the solvent resistance of TPV improved. The best conditions for processing molding were 170°C and 12 min. The crystalline structure of the nylon continuous phase in TPV was investigated by X‐ray diffraction, polarized optical microscopy, and differential scanning calorimetry. The results show that the crystalline structure of the nylon phase in TPV was more perfect/orderly and formed α‐crystalline structure at a processing molding temperature of 170°C. Therefore, the oil resistance of NBR/trinylon TPV clearly improved. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1374–1379, 2006
Characterization of 25 tropical hardwoods with Fourier transform infrared, ultraviolet resonance Raman, and 13C‐NMR cross‐polarization/magic‐angle spinning spectroscopy
Authors: Nuopponen Mari H. , Wikberg Hanne I. , Birch Gillian M. , Jääskeläinen Anna‐Stiina , Maunu Sirkka L. , Vuorinen Tapani , Stewart Derek
Published: July 2006

Twenty‐five tropical hardwoods from Ghana were examined with Fourier transform infrared (FTIR), ultraviolet resonance Raman (UVRR), and 13C‐NMR cross‐polarization/magic‐angle spinning spectroscopy. FTIR and UVRR spectral data were subjected to principal component analysis, whereas four selected samples exhibiting large structural and compositional variation were investigated in more detail by NMR spectroscopy. The acetyl bromide lignin and α‐cellulose contents of the samples and the amount of acetone‐soluble substances were also determined. The most prominent principal components of the FTIR spectral model separated samples mainly due to the variations in lignin structures and carbohydrate contents and the amount and type of carbonyl structures, whereas UVRR spectral data distinguished between various aromatic and other unsaturated structures. The presence of condensed lignin/tannin‐type structures were detected from UVRR and FTIR loading line plots of the minor principal components. Condensed tannins were also observed in the dipolar dephasing NMR spectra. Furthermore, the NMR results showed variations in the amount of crystalline cellulose and hemicelluloses and in the syringyl/guaiacyl proportions in lignin. Both NMR and FTIR data suggest that in most cases, a higher amount of guaiacyl units correlated with higher levels of acetyl bromide lignin and better bioresistance of the samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 810–819, 2006
Electrochemical copolymerization of carbazole and 3‐methylthiophene
Authors: Nie Guangming , Xu Jingkun , Zhang Shusheng , Cai Tao , Han Xuejun
Published: July 2006

The copolymerization of carbazole (CZ) and 3‐methylthiophene (3MeT) was successfully performed electrochemically in freshly distilled boron trifluoride diethyl etherate by direct anodic oxidation of the monomer mixtures, although the oxidation potentials of CZ and 3MeT were quite different. The electrochemical properties of the copolymers were studied with cyclic voltammetry. The influence of the applied polymerization potential on the synthesis of the copolymers was investigated. The higher potential favored the incorporation of 3MeT units into the copolymers. The insertion of 3MeT units into polycarbazole (PCZ) was helpful in improving the conductivity of PCZ. The novel copolymers had the advantages of both PCZ and poly(3‐methylthiophene), that is, good redox activity, good thermal stability, and high conductivity. The structure and morphology of the copolymers were investigated with ultraviolet–visible, infrared spectroscopy, thermal analysis, and scanning electron microscopy. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1877–1885, 2006
In vitro comparative hemostatic studies of chitin, chitosan, and their derivatives
Authors: Janvikul Wanida , Uppanan Paweena , Thavornyutikarn Boonlom , Krewraing Jirawat , Prateepasen Rujiporn
Published: July 2006

The effects of chitin, chitosan, and their derivatives on in vitro human blood coagulation and platelet activation were comparatively studied. The coagulation was assessed by the measure of the whole blood clotting time (WHBCT) and plasma recalcification time (PRT). The tested materials were chitin, chitosan, partially N‐acetylated chitosan (PNAC), N,O‐carboxymethylchitosan (NOCC), N‐sulfated chitosan, N‐(2‐hydroxy)propyl‐3‐trimethylammonium chitosan chloride, and SPONGOSTAN® standard (a positive control). The results revealed that the WHBCTs of whole blood mixed with chitin, chitosan, NOCC, or SPONGOSTAN® standard were significantly decreased with respect to that of the pure whole blood (a blank control) (P < 0.05), while the WHBCT value of whole blood mixed with PNAC was not significantly reduced. However, the presence of PNAC significantly lowered the PRT value, similar to the addition of chitin, NOCC, or SPONGOSTAN® standard. Chitosan was found to reduce PRT, but not significantly. In the platelet adhesion and activation studies, the morphology of platelets adherent to the film surfaces of tested materials was examined using a scanning electron microscopic technique. Because of their effective coagulation activites, chitosan, PNAC, and NOCC were further evaluated to determine how platelets behaved when in contact with these film samples for given periods. It was found that NOCC activated platelets most effectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 445–451, 2006
Polymer blends of epoxy resin and epoxidized natural rubber
Authors: Chuayjuljit S. , Soatthiyanon N. , Potiyaraj P.
Published: July 2006

The aim of this research was to investigate the behaviors of epoxy resin blended with epoxidized natural rubber (ENR). ENRs were prepared via in situ epoxidation method so that the obtained ENRs contained epoxide groups 25, 40, 50, 60, 70, and 80 mol %. The amounts of ENRs in the blends were 2, 5, 7, and 10 parts per hundred of epoxy resin (phr). From the results, it was found that the impact strength of epoxy resin can be improved by blending with ENRs. Tensile strength and Young's modulus were found to be decreased with an increasing amount of epoxide groups in ENR and also with an increasing amount of ENR in the blends. Meanwhile, percent elongation at break slightly increased when ENR content was not over 5 phr. In addition, flexural strength and flexural modulus of the blends were mostly lower than the epoxy resin. Scanning electron microscope micrograph of fracture surface suggested that the toughening of epoxy resin was induced by the presence of ENR globular nodules attached to the epoxy matrix. TGA and DSC analysis revealed that thermal decomposition temperature and glass transition temperature of the samples were slightly different. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 452–459, 2006
Degradation characteristics of poly(ϵ‐caprolactone)‐based copolymers and blends
Authors: Huang Ming‐Hsi , Li Suming , Hutmacher Dietmar W. , Coudane Jean , Vert Michel
Published: July 2006

The hydrolytic degradation of various bioresorbable copolymers and blends derived from ϵ‐caprolatcone, D,L‐lactide and poly(ethylene glycol) (PEG) was investigated at 37°C in a pH 7.4 phosphate buffer. Poly(ϵ‐caprolatcone) (PCL) followed a slow degradation profile due to its hydrophobicity and crystallinity. The hydrophilicity and degradability of the materials can be improved by copolymerization with PEG and/or poly‐(D,L‐lactide) (PLA). Homogenous degradation was shown in the cases of PCL, PCL/PEG copolymers and their blends, whereas PLA‐containing copolymers followed a heterogenous degradation due to internal autocatalysis. It was also shown that PCL‐based materials gradually turned to PCL‐enriched residues during degradation due to preferential hydrolysis of PLA segments and to diffusion of soluble species such as PLA oligomers and detached PEG blocks bearing short PLA segments. The results are discussed in comparison with literature data. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1681–1687, 2006
Dissolution enhancement of flavonoids by solid dispersion in PVP and PEG matrixes: A comparative study
Authors: Kanaze F. I. , Kokkalou E. , Niopas I. , Georgarakis M. , Stergiou A. , Bikiaris D.
Published: July 2006

Polyvinylpyrrolidone (PVP) and poly(ethylene glycol) (PEG) solid dispersion systems with flavanone glycosides, naringin and hesperidin, and their aglycones, naringenin and hesperetin, were prepared, using solvent evaporation method, to enhance their dissolution rates that may affect their bioavailability. Drug release of both flavanone glycosides and their aglycones was directly affected by the physical state of solid dispersions. Powder‐XRD technique in combination with scanning and transmission electron microscopy revealed that PVP polymer formed amorphous nanodispersion systems with flavanone aglycones, while such systems could not be formed with their glycosides, which are bulkier molecules. Fourier transform infrared spectra suggest the presence of hydrogen bonds between PVP carbonyl groups and hydroxyl groups of both flavanone aglycones. These interactions prevent the crystallization of naringenin and hesperetin aglycones in PVP matrix. On the other hand, the ability of PEG carrier to form hydrogen bonds with flavanone glycosides or aglycones was limited, and as a result both flavanone glycosides and their aglycones remain in the crystalline form. For this reason, the solubility enhancement of PEG solid dispersions was lower than when PVP was used as drug carrier. At pH 6.8, the % release of naringenin and hesperetin from PVP/naringenin–hesperetin (80/20 w/w) solid dispersion was 100% while in PEG solid dispersions, it was not higher than 60–70%. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 460–471, 2006
Colored rubber vulcanizates with some magnetic properties
Authors: El‐Sabbagh S. H. , Ahmed N. M. , Daoush W. M.
Published: July 2006

A new composite based on natural rubber vulcanizates loaded with the newly prepared iron oxide–aluminum oxide (Fe2O3·Al2O3) fillers were prepared and their physical and magnetic studies were investigated. The prepared fillers were evaluated as reinforcing fillers with some magnetic properties; these properties were dependent on the ratio of iron oxide to aluminum oxide in each prepared ratio of these fillers. Rheological properties of rubber mixes containing (1Fe2O3:3Al2O3) and (1Fe2O3:1Al2O3) fillers exhibited better properties than mixes containing (3Fe2O3:1Al2O3) and (α‐Fe2O3), which showed almost the same behavior. Physical properties such as tensile strength, stress at 100 and 200% strain, Young's modulus, and hardness were increased by increasing the volume fraction of the investigated fillers concentration in the mixed vulcanizates. Measured rheological and physical results were inversely related to the magnetic properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:494–505, 2006
Investigating polypropylene–green coconut fiber composites in the molten and solid states through various techniques
Authors: Leblanc Jean L. , Furtado Cristina R. G. , Leite Marcia C. A. M. , Visconte Leila L. Y. , Ishizaki Marina H.
Published: July 2006

A series of polypropylene (PP)–green coconut fiber (GCF) composites were prepared by melt mixing and their properties studied in the molten state using an advanced nonlinear harmonic testing technique, and in the solid state using standard mechanical testing and scanning electron microscopy (SEM). The effect of fiber loading as well as the role of maleated polypropylene as compatibilizing agent was investigated. PP–GCF composites are heterogeneous materials that, in the molten state, are found to exhibit essentially a nonlinear viscoelastic character, in contrast with the pure PP, which has a linear viscoelastic region up to 50–60% strain. Complex modulus increases with GCF content but in such a manner that the observed reinforcement is at best of hydrodynamic origin, without any specific chemical interaction occurring between the polymer matrix and the fibers. The addition of maleated polypropylene improves the wetting of fibers by the molten polymer but the effect is so small that specific chemical reactions could hardly be considered as occurring. Flexural modulus data confirm the reinforcing effects of the fiber and an improvement is noted when some maleated polypropylene is used, with an optimum level of around 1% (or the PP content). SEM microphotographs clearly show that maleated polypropylene imparts a better wetting of GC fibers by PP, but chemical interactions are unlikely to occur between the polymer and GCF. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1922–1936, 2006
Comparison between microwave and thermal curing of glass fiber–epoxy composites: Effect of microwave‐heating cycle on mechanical properties
Authors: Tanrattanakul Varaporn , Jaroendee Dumrong
Published: July 2006

The objective of this study was to compare the mechanical properties between epoxy composites cured by thermal heating and microwave heating. Epoxy‐anhydride resins reinforced with glass fiber were cured in a domestic microwave oven and in a thermal oven. Hardening agents included methyl tetrahydrophthalic anhydride and methyl hexahydrophthalic anhydride. Microwave curing was carried out at various conditions, including 1‐, 2‐, and 3‐step heating cycle, whereby each cycle employed different power level and time. Mechanical properties were tested according to ASTM standards. It is found that the microwave‐cured composites produced mechanical properties as good as the thermally cured composites. The 2‐ and 3‐step heating cycle used in the microwave curing process produced better mechanical properties higher than those obtained from the microwaved 1‐step and thermally curing process. This is attributed to the slow increase in temperature during the beginning of the microwave curing process whereby the very low power level was applied in the first cycle of the multistep heating process. This affected the slower rate of viscosity increment, resulting in better wettability of the glass fiber with enhanced interfacial adhesion between the fibers and the resins. The viscosity of resins affected the homogeneity of the crosslinked structure. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1059–1070, 2006
Electrical behavior of high impact polystyrene/liquid crystalline polymer blends containing low content of carbon black
Authors: Shemesh R. , Siegmann A. , Tchoudakov R. , Narkis M.
Published: July 2006

This article presents a study of the structure and electrical behavior of carbon black (CB) containing immiscible polymer blends. A series of electrically conductive blends of high impact polystyrene (HIPS), liquid crystalline polymer (LCP), and CB was compounded and followed by a capillary rheometer extrusion process or by injection molding. In these immiscible blends, HIPS serves as a low surface tension matrix and LCP as a polar dispersed phase. Shear and elongational flow result in blend morphology consisting of highly elongated and oriented LCP particles dispersed in the HIPS matrix. The enhancement of conductivity in these blends is due to the affinity of CB to LCP and the formation of cocontinuous phase morphology, giving rise to conductive networks. Blends of various compositions were prepared using various processing conditions, emphasizing the relationship between morphology, rheology, and electrical properties. The presence of at least 20 wt % LCP and 2 phr CB under certain processing conditions (mixing sequence and temperature) is necessary to obtain stable resistivity, independent of the studied extrusion shear rate, and low resistivity values. In addition, the processing mode significantly affects the blends' structure and the resultant electrical properties. Hence, injection molding due to high shear rates, elongational flow, and fast cooling results in high structural and electrical anisotropy. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1688–1696, 2006
Synthesis of asymmetric star‐branched block copolymers based on PS, PTHF, and PMMA by combination of cationic ring opening polymerization and redox polymerization methods
Authors: Arslan Hülya , Hazer Baki , Higashihara Tomoya , Hirao Akira
Published: July 2006

Asymmetric star‐branched block copolymers based on polystyrene (PS), polytetrahydrofuran (PTHF), and poly(methyl methacrylate) (PMMA) were synthesized by a combination of cationic ring opening polymerization and redox polymerization methods in two steps. At first, cationic ring opening polymerization of THF was initiated by using chain‐end‐multifunctionalized polystyrenes with 2, 4, and 8 benzyl bromide moieties as initiators in the presence of AgSbF6 at 30°C to obtain 3‐, 5‐, and 9‐arm AB2, AB4, and AB8 type asymmetric star‐branched polymers consisting of PS (A) and PTHF‐OH (B) segments. Polymers obtained in this way were characterized by gel permeation chromatography, FTIR, 1H NMR, and thermal analysis (DSC and TGA). At second step, redox polymerization of methyl methacrylate was initiated by using these characterized asymmetric star‐branched polymers as macroinitiators in the presence of Ce(IV) salt at 40°C to obtain PS‐s‐(PTHF‐b‐PMMA)n (n = 2, 4, and 8) asymmetric star‐branched block copolymers. PS‐s‐(PTHF‐b‐PMMA)n (n = 2, 4, and 8) asymmetric star‐branched block copolymers obtained were purified by fractional precipitation method before characterization. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 516–522, 2006
Mechanical and tribological properties of PA66/PPS blend. III. Reinforced with GF
Authors: Chen Zhaobin , Liu Xujun , Lü Renguo , Li Tongsheng
Published: July 2006

Based on previous work, 70 vol % PA66/30 vol % PPS blend was selected as a matrix, and the PA66/PPS blend reinforced with different content of glass fiber (GF) was prepared in this study. The mechanical properties of PA66/PPS/GF composites were studied, and the tribological behaviors were tested on block‐on‐ring sliding wear tester. The results showed that 20–30 vol % GF greatly increases the mechanical properties of PA66/PPS blend. When GF content is 20 vol %, the friction coefficient of composite is the lowest (0.35), which is decreased by 47% in comparison with the unfilled blend. The wear volume of the GF‐reinforced PA66/PPS blend composite decreases with the increase of GF content. However, the wear‐resistance is not apparently improved by the addition of GF in the experimental range for comparison with unfilled PA66/PPS blend. The worn surface and the transfer film on the counterface were examined by scanning electron microscopy (SEM). The observations revealed that the friction coefficient of composite depends on the formation and development of a transfer film. The wear mechanism involves polymer matrix wear and fiber wear. The former consists of melting wear and plastic deformation of the matrix, while the latter includes fiber sliding wear, cracking, rupturing, and pulverizing. The contributions of the matrix wear and the fiber wear determine the ultimate wear volume of PA66/PPS/GF composite. In addition, the abrasive action caused by the ruptured glass fiber is also a very important factor. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 523–529, 2006
Effect of physical aging on the microstructure and dynamic mechanical properties of poly(ether sulfone) copolymer
Authors: Zhou Xiao‐Ming , Jiang Zhen‐Hua
Published: July 2006

Effects of physical aging on the submicroscopic structure and dynamic mechanical properties of amorphous poly(ether sulfone) copolymer film were studied by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and electron‐microscopy measurements. Heat flow responses were measured after annealing the amorphous samples obtained, by quenching the melt into an ice‐water bath close to but below the glass transition temperature. The extent of aging is related to the supercooling from the glass transition temperature and to the aging time. The activation energy of the aging process was estimated by the Williams–Watt expression (Williams and Watts, Trans Faraday Soc 1970, 66, 80). A systematic study of the influence of aging on the dynamic mechanical properties of poly(ether sulfone) copolymer has also been made. During isothermal annealing, the increase of the temperature of tan δ peak for the α and β′ relaxation with aging time has been observed. The aging in the zone of the β peak has also been investigated and an interpretation of the results was proposed on the basis of foregone theories. The result of electron‐microscopy investigation indicates that poly(ether sulfone) copolymer has formed a local order structure during the physical aging. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 530–534, 2006
The importance of interfacial design at the carbon nanotube/polymer composite interface
Authors: Gorga Russell E. , Lau Kenneth K. S. , Gleason Karen K. , Cohen Robert E.
Published: July 2006

This research focuses on the need for interfacial engineering at the carbon nanotube/polymer composite interface in the effort to obtain enhanced mechanical properties. The mechanical properties of multiwall carbon nanotubes (MWNTs)/poly (methyl methacrylate) (PMMA) nanocomposites were studied as a function of both nanotube concentration and surface treatment. One method, plasma enhanced chemical vapor deposition (PECVD), was successfully used to produce a PMMA conformal coating (using methyl methacrylate monomer) on multiwall carbon nanotubes. Excellent suspensions of MWNTs in organic solvents were achieved via the PMMA coating. The coated‐MWNTs were dispersed into PMMA via melt mixing and orientation was achieved by melt drawing. The overall set of mechanical properties indicates that while the conformal polymer coating had a significant effect on the mechanical properties at a 1% concentration of nanotubes as compared to the uncoated nanotube composites, suggesting improved interfacial adhesion between the nanotube and the matrix material. However, the mechanical properties of the 1% coated nanotube composite were not significantly better than those for pure PMMA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:1413–1418, 2006
Synthesis and characterization of flame retarding UV‐curable organic–inorganic hybrid coatings
Authors: Karataş Sevim , Hoşgör Zuhal , Menceloğlu Yusuf , Kayaman‐Apohan Nilhan , Güngör Atilla
Published: July 2006

UV‐curable, organic–inorganic hybrid materials were synthesized via sol–gel reactions for tetraethylorthosilicate, and methacryloxypropyl trimethoxysilane in the presence of the acrylated phenylphosphine oxide resin (APPO) and a bisphenol‐A‐based epoxy acrylate resin. The sol–gel precursor content in the hybrid coatings was varied from 0 to 30 wt %. The adhesion, flexibility, and hardness of the coatings were characterized. The influences of the amounts of inorganic component incorporated into the coatings were studied. Results from the mechanical measurements show that the properties of hybrid coatings improve with the increase in sol–gel precursor content. In addition, thermal properties of the hybrids were studied by thermogravimetric analysis in air atmosphere. The char yield of pure organic coating was 32% and that of 30 wt % silicate containing hybrid coating was 30% at 500°C in air atmosphere. This result demonstrates the pronounced effect of APPO on the flame retardance of coatings. Gas chromatography/mass spectrometry analyses showed that the initial weight loss obtained in thermogravimetric analysis is due to the degradation products of the photoinitator and the reactive diluent. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1906–1914, 2006
Analysis of spinning process parameters on development of spun‐dyed PET yarn using the Taguchi method
Authors: Cho Dae Hwan , Jeong Youngjin
Published: July 2006

The yarn tenacity of a spun‐dyed yarn is predicted from the spinning conditions and other properties of the yarn are analyzed through the defined parameters using the Taguchi method. To develop a spun‐dyed yarn using the Taguchi method, four factors that can largely influence the yarn properties are selected. From the experimental design based on four factors, the processes are executed to produce the specific yarns whose properties are measured to analyze the relationship between the process conditions and their results. The target properties of a spun‐dyed yarn may be obtained through adjusting the spinning parameters that are related to the yarn properties by the Taguchi tool. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:1419–1427, 2006
In situ polymerization of aniline in the presence of carbon black
Authors: Souza Fernando G. , Sirelli Lys , Michel Ricardo C. , Soares Bluma G. , Herbst Marcelo H.
Published: July 2006

A hybrid material of polyaniline doped with dodecylbenzenesulfonic acid and conductive carbon black (PaniDBSA/CB) was prepared by in situ polymerization. The presence of low amount of CB (up to 25 wt %) resulted in a decrease in resistivity as compared to pure PaniDBSA. Composite with 25 wt % of CB presented the lowest resistivity and a tubular morphology characterized by microtubules with high aspect ratio evidenced by SEM examination. Higher amount of CB give rise to materials with higher resistivity values and a granular morphology, similar to pure carbon black. Ultraviolet–visible and electron paramagnetic resonance analyses were employed to evaluate the polaron concentration. X‐ray diffraction was used to characterize the molecular structure of these composites. It was observed a decrease in the crystallinity degree and a shift of the polaron band transition toward lower wavelength as the amount of CB in the composite increases. From the EPR measurements, one can suggest that the higher chain order and polaron mobility is observed in hybrid with 25% of CB. This behavior is in agreement to the electrical resistivity values and SEM microscopy. The effect of CB on thermal stability of the composites was also investigated. The effect of the PaniDBSA/CB hybrid material on the processability and resistivity of the composites based on styrene‐butadiene‐styrene (SBS) block copolymer as the insulating matrix have been also evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 535–541, 2006