Journal of Applied Polymer Science Research Papers (original) (raw)

Radical polymerization of limonene (limonene) using benzoyl peroxide (BPO) as an initiator at 85 C 6 1 C under an inert atmosphere of nitrogen in xylene as solvent was carried out. The system follows nonideal kinetics: R p a [I] 0.3 [M] 1.4 , due to both primary radical termination and degradative chain transfer reaction. The activation energy of the polymerization was estimated to be 22.97 kJ mol À1 . 1 H-NMR spectrum of polymer shows the presence of a triplet between 2 and 2.5 d, which reveals that b-carbon of limonene is the active site in the polymerization of limonene. The FTIR spectrum of the polymer shows band at 1645 cm À1 due to gem disubstituted C¼ ¼C stretching vibrations. The glass transition temperature (T g ) of the polylimonene of the polylimonene is 116 C.

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- Engineering, Kinetics, Mechanism, Controlled/living Radical Polymerization

Polymeric curing agent modified with hexamethyldisilazane (PCA-D), or with hexamethylcyclotrisilazane (PCA-T), was used to improve the mechanical properties of hydroxyl-teminated polydimethylsiloxane (PDMS) rubber. The structure and the gel time of PCA were characterized by 29Si NMR and shear viscosity measurement, respectively. The PCA modified with silazanes was more stable in storage than that without treatment (PCA-0). Chemical bonds were formed during the reaction of silazanes and PCA according to 29Si NMR results. The crosslink density (γe) and the mechanical properties of PCA/PDMS rubber were determined by swelling equilibrium and stress–strain tests. It was found that PCA treated with both silazanes could better enhance the mechanical properties of PCA/PDMS rubber compared with PCA-0. PCA-T/PDMS rubber, with additional crosslinks, was the best among the three types of PCA/PDMS rubber on the mechanical properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

- by Lina Dai
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- Engineering, CHEMICAL SCIENCES, Journal of Applied Polymer Science

Linear poly(dimethylsi1oxane diol) of about 650 D.P. was synthesized by hydrolytic condensation of dimethyldichlorosilane in a saturated solution of sodium chloride. The polymer was then compounded with various fillers, Cab-O-Sil, Dicalite, and titanium dioxide, and cured at room temperature in the presence of tin salt and tri-or tetrafunctional s h e . The tensile strength and elongation of the unfilled rubber were found to be 0.8 kg/cm2 and 320%, respectively. However, Dicalite White (100 phr)-reinforced elastomer showed a tensile strength of 40 kg/cm2. Crosslink density was determined from the swelling studies. Thermal aging at 150,200, and 25OOC was also studied.

The processing of hard and liquid silicone rubbers (LSR) are compared by means of modeling and simulation. The curing process for both, hard and liquid silicone, are modeled using the auto-catalytic Kamal-Sourour model and a nonlinear regression method is used to find the kinetic parameters. The fitted kinetic model is then combined with the heat balance equations to simulate real processing conditions. Both resins are compared in terms of process perform-ance and consistency of the final part. The results show that even though hard silicone rubbers are less expensive resins, its processing conditions present several issues of consistency and quality control when compared with LSR.

- by Juan Hernández-ortiz
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- Engineering, Kinetics, Modeling, Heat Transfer

Experimental performance evaluation of heat pump-based steam supply system T Kaida, I Sakuraba, K Hashimoto et al. -Fluid-Structure interaction analysis and performance evaluation of a membrane blade M. Saeedi, R. Wüchner and K.-U. Bletzinger -Optimization and performance evaluation for nutrient removal from palm oil mill effluent wastewater using microalgae Raheek I Ibrahim, Z H Wong and A W Mohammad -This content was downloaded from IP address 168.151.1.23 on 24/09

- by Lisa Shriver-Lake
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- Engineering, Materials Engineering, Mechanical Engineering, Genetics

Epoxidized natural rubber–alumina nanoparticle composites were prepared by melt compounding with an internal mixer for a constant filler loading of 10 phr. Mixer parameters such as the mixing temperature, mixing time, and rotor speed were screened and optimized with response surface methodology to maximize the impact strength. The parameters were selected as three independent variables and the impact strength (J/m) was selected as the response in a screening factor study. The mixing temperature and its interaction terms were identified as insignificant factors with a P value greater than 0.0500. The optimum calculated values of the tested variables (rotor speed and mixing time) for the maximum impact strength were found to be a rotor speed of 60 rpm and a mixing time of 6 min with a predicted impact strength of 208.88 J/m. These predicted optimum parameters were tested in real experiments. The final impact strength was found to be close to the predicted value of 215.84 J/m, with only a 3.33% deviation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

- by mariyam ghazali
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- Engineering, Response Surface Methodology, Nanocomposites, Mixing

The electrical resistivity of crosslinked high-density polyethylene loaded with conductive blacks and carbon fibers was studied as a function of filler concentration and temperature. A thermoelectric switching phenomenon (a sudden resistivity increase in the vicinity of the polyethylene melting point) in such semicrystalline conductive systems was investigated. Significant switching properties were found only in compounds useful in the medium conductivity range. A significant switching behavior was exhibited by compounds containing very low concentrations of carbon fibers. Some crosslinked compounds filled with mixtures of carbon black and carbon fibers were also studied. EXPERIMENTAL Compounds of polyethylene, carbon black, or carbon fibers, and peroxide were compression-molded at 190-200°C giving about 3 mm thick plaques. Radiation crosslinking was done by irradiating thermoplastic plaques with a Co60 source

- by Anita Vaxman
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- Engineering, Materials Science, Polyethylene, CHEMICAL SCIENCES

A number of cellulose samples was submitted to homogeneous phase carbanilation in dimethylacetamide/LiCL The process is quantitative and leads to a completely substituted product, as verified by elemental analysis and UV spectroscopy. Tricarbanilated samples were characterized by viscometric and light-scattering measurements in tetrahydrofuran. Our results are in good agreement with those reported in the literature, concerning products obtained in the heterogeneous phase. Gel permeation chromatography was performed for evaluating the molecular weight distribution of the parent cellulose, using both universal and linear calibration. The chromatographic technique is not adequate for samples exhibiting a high degree of polymerization. 0 1995 John Wiley & Sons, Inc.

As an alternative to petroleum-based polyol, hydroxyl containing material was prepared from linseed oil for polyurethane synthesis. Hexamethylene di-isocyanate (HMDI) and/or 4, 4 0-methylene diphenyl di-isocyanate (MDI) were used as isocyanate source. The polymerization reaction was carried out without catalyst. Polymer films were prepared by casting-evaporation technique. The MDI/ HMDI-based polyurethane and its films had higher T g and better thermal property than that of the HMDI-based one because of the existence of benzene ring in the polymer chain. Static water contact angle was determined to be 74 and 77.5 for HMDI and MDI/HMDI-based films, respectively. Water adsorption was found to be around 2.6-3.6% for both films. In vitro degradation of polyurethanes in phosphate buffered saline at 37 C was investigated by gravimetric method. Fourier transform infrared spectros-copy and scanning electron microscopy were used for confirmation of degradation on the polymer surface. The degradation rate of the HMDI-based polyurethane film was found higher than that of the MDI/HMDI-based film. Both the direct contact method and the MMT test were applied for determination of cytotoxicity of polymer films, and the polyurethane films investigated here was not cytotoxic. Silver-containing films were prepared using Biocera A V R as filler and were screened for their antibacterial performance against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and/or Bacillus subtilis. The films prepared with and without Biocera A V R exhibited antibacterial activity.

- by Fikret Sahin
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- Engineering, Applied, CHEMICAL SCIENCES, Journal of Applied Polymer Science

Amorphous and crystallized poly(L-lactic acid) (PLLA) films were prepared and the hydrolytic degradation of the ultraviolet (UV)-treated and UV-nontreated films was investigated. This study reveals that the combination of UV and thermal treatments can produce the PLLA materials having different hydrolytic degradation profiles and that the UV-irradiation in the environment will affect the design of recycling process for PLLA articles. In an early stage, the degrees of hydrolytic degradation monitored by weight loss (W loss ), number-average molecular weight (M n ), and melting temperature (T m ) were higher for the UV-treated films than for the UV-nontreated films. In a late stage, the trend traced by W loss was reversed, and the difference in the degrees of hydrolytic degradation between the UV-treated and UV-nontreated films monitored by M n and T m became smaller, with the exception of the degrees of hydrolytic degradation of the amorphous films traced by T m . Also, in the early stage, the degrees of hydrolytic degradation monitored by W loss and M n were higher for the crystallized films than for the amorphous films. In the late stage, this trend was reversed, with the exception of the degrees of hydrolytic degradation of the UV-treated films monitored by M n . The main factors that determined the W loss and T m were the molecular weight and initial crystallinty but not the molecular structures such as terminal C¼ ¼C double bonds and crosslinks.

- by Hideto Tsuji
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- Engineering, Biodegradable, CHEMICAL SCIENCES, Journal of Applied Polymer Science

Nano-Mg(OH) 2 was synthesized with an in situ deposition technique, and its size was confirmed by X-ray diffraction. A polypropylene-Mg(OH) 2 composite was prepared by melt-extrusion processing. The addition of a small quantity of a nanofiller (up to 10 wt %) increased Young's modulus up to 433% with respect to the modulus of virgin polypropylene. The addition of up to 4 wt % Mg(OH) 2 produced the maximum increase, and a further decrease in the tensile strength was observed with an increase in the concentration of nano-Mg(OH) 2 . Increases in the hardness and other properties were due to higher nu-cleation and the intercalation of polymer chains in the nanolayer galleries. The flame-retarding property was demonstrated by the rate of burning. The time required to burn the nanofilled composite was greater than the time required for virgin polypropylene.

- by Raman Singh
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- Engineering, Applied, Polypropylene, CHEMICAL SCIENCES

The viscoelastic behavior of semi-crystalline polyamide 6,6 fiber is exploited in viscoelastically prestressed polymeric matrix composites. To understand better the underlying prestress mechanisms, strain-time performance of the fiber material is investigated in this work, under high creep stress values (330-665 MPa). A latch-based Weibull model enables prediction of the 'true' elastic modulus through instantaneous deformation from the creep-recovery data, giving 4.6 ± 0.4 GPa. The fiber shows approximate linear viscoelastic characteristics, so that the time-stress superposition principle (TSSP) can be implemented, with a linear relationship between the stress shift factor and applied stress. The resulting master creep curve enables creep behavior at 330 MPa to be predicted over a large timescale, thus creep at 590 MPa for 24 h would be equivalent to a 330 MPa creep stress for ~5200 years. Similarly, the TSSP is applied to the resulting recovery data, to obtain a master recovery curve. This is equivalent to load removal in the master creep curve, in which the yarns would have been subjected to 330 MPa creep stress for ~4.56 × 10 7 h. Since our work involves high stress values, the findings may be of interest to those involved with long-term load-bearing applications using polyamide materials.

A mathematical model for a continuous direct esterification reactor has been developed. The solid-liquid equilibrium of terephthalic acid (TPA) was considered in our modeling, and the characteristic dissolution time, an adjustable parameter, was introduced to account for the mass-transfer effect in the dissolution of TPA. The effects of the characteristic dissolution time, monomer feed ratio, temperature, and pressure on the reactor performance at different residence times were investigated through simulation. It was observed that the behavior of the first reactor strongly depends on whether the solid TPA is completely dissolved in the reaction mixtures. From the dynamic simulations, it was found that a sudden change in the operating conditions affects the ethylene glycol (EC) vapor flow rate instantly. For the esterification process having two reactors in series, the strategy for time distribution and recycling of EG is also discussed. 01997 John Wiley & Sons, Inc.

- by David Tremblay
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- Engineering, Modeling, Applied, CHEMICAL SCIENCES

The rheological and morphological properties and in vitro theophylline release of tertiary aminebased microgels were evaluated. The testing of such a formulation through in vitro diffusion experiments revealed that the release of theophylline from the microgels was pH-dependent and differs significantly with respect to a nonresponsive gel like scleroglucan (Scl). The microgels were obtained from 2-(diethyl amino) ethylmethacrylate (DEA) in the presence of a bifunctional crosslinker at pH 8-9. As the resulting microgels are pH-responsive and an increase in viscosity from high to low pH range is exhibited, the in vitro release of theophylline as model drug was studied at different pHs of both the matrix and the receptor medium. The release behaviors of PDEA-based microgels were compared to nonresponsive natural gel Scl, studied previously. For microgels, diverse release patterns were found at different acidity conditions. This observation seems to be related to complex diffusion phenomena and the different gel structure obtained for samples prepared at dissimilar pH.

- by Oscar Pardini
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- Engineering, Kinetics, Morphology, Drug delivery

Smart polymer recycling: Synthesis of novel rigid polyurethanes using phosphorus-containing oligomers formed by controlled degradation of microporous polyurethane elastomer-Grancharov-2007-Journal of Applied Polymer Science-Wiley Online... more

- by Ivan Gitsov
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- Engineering, Phosphorus, Applied, CHEMICAL SCIENCES

Ethylene was copolymerized with 10undecen-1-ol and 5-hexen-1-ol using stereorigid [rac-ethylene(Ind) 2 ZrCl 2 ], [rac-ethylene(H 4 Ind) 2 ZrCl 2 ], and the new catalyst systems [rac-norbornane(Ind) 2 TiCl 2 ] and [mesonorbornane(Ind) 2 TiCl 2 ], activated with methylaluminoxane. The characterization of the copolymers by 13 C NMR spectroscopy revealed that the polymerization products were copolymers and that the conversion of the polar comonomer was strongly favored in the case of the zirconocene precursors. Very high catalytic activity values, nearly independent on the amount of comonomer in the feed, and comonomer incorporations up to 25.4%weight have been found for 10-undencen-1-ol comonomer.

The curing reaction kinetics of an epoxy based on the diglycidyl ether of bisphenol A (DGEBA) with an inorganic complex based on nickel(II) chelate with ethylenediamine (en) as a ligand were studied using DSC in dynamic mode. The complex curing agent was synthesized and characterized by the elemental analysis, FT-IR, and ICP-Plasma techniques. Thermal dissociation behavior of curing agent was also studied using thermogravimetric (TG) analysis in isolated form. Three kinetic models, Kissinger, Ozawa-Flynn-Wall, and Expanded Freeman-Carrole, were used to determine the kinetic parameters. The effect of hardener concentration on the kinetic parameters and the shape of DSC thermograms of the DGEBA/Ni(en) 3 Br 2 system were investigated. Finally, the previous proposed mechanism by another researcher was used to explain the DSC data in detail.

- by Mousa Ghaemy
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- Engineering, Kinetics, Nickel, CHEMICAL SCIENCES

Dynamic mechanical properties of poly(methyl methacrylate) (PMMA) reinforced with glass fibers were investigated. The composite used as dental base material contained other additives for different purposes to give the same appearance as natural dentals. The fiber-polymer bonding and orientation of fibers in polymer matrix are very important in the application of the product. To see that, the fibers were treated with silane and compared with untreated fibers. The commercial polymer and monomer used were the heat-cured type. However, in addition to heat curing, ␥-radiation was also used in curing. This gives much improved material in terms of mechanical properties. The voids, which cause mechanical failure in the material, will be minimal in number with irradiation curing. The results showed that the orientation of all fibers were not regular. This could be observed from the micrographs and DMA behaviors of samples.

- by Arife Dogan
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- Engineering, Applied, CHEMICAL SCIENCES, DMA

A novel copolymer, poly(N-isopropylacrylamide-co-hydroxypropyl methacrylate-co-3-trimethoxysilypropyl methacrylate) has been synthesized and the hydrodynamic diameters in various aqueous solutions under different temperatures are determined by dynamic light scattering. The results show that the hydrodynamic diameters of copolymers have no obvious change in each working solution below lower critical solution temperature (LCST); across LCST, the diameters increased suddenly at different initial temperature in various aqueous solutions; above LCST, they decreased slightly as the temperature increased in UHQ water, and increased continuously with increasing temperature or salt concentration in saline solutions, and reduced with the rising of pH value in pH buffer. These are attributed to different intermolecular and intramolecular forces leading to disparity in dimension, conformation, and LCST of copolymers. The hydrogen bonding between water molecules and copolymer chains could maintain size and conformation of copolymer single chain; the hydrogen bonding between amide linkages and hydrophobic interactions between isopropyl groups result in intramolecular collapse and intermolecular aggregation; the electrostatic repulsion weakens aggregation extent of copolymers. V C 2012

The aim of this work was to study the effect of the degree of substitution (DS) and the purity of sodium carboxymethyl cellulose (CMCNa) prepared from Tunisian vine stem on the absorption and retention of water. Vine stem was first delignified using souda-anthraquione, then bleached and finally chemically modified, in order to synthesize different CMCNa derivatives. The carboxymethylation reaction was carried out in presence of NaOH (40 %) and monochloroacetic acid (ClCH 2 COOH), in n-butanol as a reaction solvent. The obtained CMCNa derivatives were characterized using different tools such as the DS, Fourier transforms IR techniques, CP-MAS 13 C-NMR, the exchange capacity as well as the determination of modification reaction yield. The performance of the prepared derivatives in term of absorption capacities and retention capacities was established. The performance of CMCNa derivatives was compared with that achieved by commercial counterparts and it was concluded that the prepared ones exerted higher efficiency.

- by Angel Cortés
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- Engineering, Environmental Engineering, Materials Engineering, Bioinformatics

The preparation of the new w-epoxide and 1,2-dihydroxy tri¯uorovinyl monomers useful as comonomers in the copolymerization of commercially available alkenes is presented. The addition of 1-iodo-1,2-dichloro-1,2,2-tri¯uoroethane to allyl acetate led quantitatively to the expected chlorotri¯uorinated-2-iodo-1-acetate which underwent a thermal rearrangement yielding R F,Cl CH 2 CH(OAc)CH 2 I even in the presence of a radical initiator that started to decompose at mild temperature. Whatever the amount of rearranged product, both these iodoacetates formed epoxides in alkali media giving two new compounds in high yields. Dechlorination yielded the tri¯uorovinyl epoxide (in 40% yield) and side products from the ring opening of the oxirane group. The mixture of halogenated epoxides was quantitatively hydrolysed into the halogenated -1,2-diol which was dechlorinated into F 2 CCFCH 2 CH(OH)CH 2 OH in 58% yield. All these products and intermediates were characterized by 1 HY 19 F and 13 C NMR spectroscopy. # 1999 Elsevier Science S.A. All rights reserved.

- by petya petrova
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- Engineering, Inorganic Chemistry, Organic Chemistry, Nuclear Magnetic Resonance

Hybrid organic inorganic coatings can be extremely beneficial to improve the performance of steel substrates as their outstanding adhesion strength, scratch resistance and chemical endurance. However, the design and manufacture of the appropriate coating systems on the different metal alloys can be troublesome. Defective coatings can cause the deterioration of their performance, especially the resistance to aggressive chemicals. In this manuscript, the direct deposition of functionalized methyl phenyl polysiloxane resins on hot rolled and high strength Fe 430 B steel substrates is comparatively evaluated with a double-layered coating that also involves an intermediate layer based on a hybrid organic inorganic grafting polymer (VTEOS) and the functionalized methyl phenyl polysiloxane as topcoat. Visual appearance, scratch and wear resistance of the coatings as well as their attitude to act as chemical proof barriers are investigated. Proper functionalization of methyl phenyl polysiloxane resins with hydroxyl and alkoxy groups can lead to coatings that are well adhered to the underlying substrates, thus exploiting all the performance they were designed for. In this case, the use of an organo-silane interlayer can further increment the final properties of the overall coating systems.

- by Massimiliano Barletta and +1
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- Engineering, CHEMICAL SCIENCES, Journal of Applied Polymer Science

Influence of spinning velocities on the mechanical and structural properties of polyethylene terephthalate (PET)/nylon 6 blend fibers have been reported. Fibers of PET/nylon 6 containing a small percentage of nylon (5% by weight) have been melt-spun at 3 different spinning velocities (2,900; 3,200; 3,600 m/min). The fibers have been characterized by thermal, morphological, structural, and mechanical analysis. Various techniques such as SEM, DSC, X-ray diffraction, hot water shrinkage (HWS), viscosity, and birefringence have been used. SEM analysis revealed that in the blend, nylon 6 is well-dispersed as spheres in the PET matrix. The blend shows a marked decrease in the melt-flow index, which in turn leads to a beneficial effect on the rheological properties of the PET without negatively influencing its mechanical characteristics. This finding results in a saving on energetical requirements of the processing, as both temperature and pressure of spinning can be decreased. 0 1995 John Wiley & Sons, Inc.

- by Riccardo Bianchi
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- Engineering, CHEMICAL SCIENCES, Journal of Applied Polymer Science

Using the principle of geochemistry of fluoride, green and cost effective anion adsorbents were developed for the removal of F 2 from water systems. The scheme was further applied for the removal of NO 3 2 also. Carboxymethylated starch functionalized through network formation with acrylamide was used as adsorbent, and the resultant hydrogels were loaded with Fe 21 ions to generate anchorage for the anions. Sorption of Fe 21 was studied as a function of different factors such as time, temperature, pH, and ion strength. The network having the highest Fe 21 uptake was loaded with the Fe 21 ions under optimum conditions and used for the sorption of F 2 and NO 3 2. High efficiency has been observed for F 2 , as even up to 100% uptake has been observed within just 10 minutes. The support shows high selectivity for NO 3 2 , which was used as anion reference. Thermodynamics of sorption confirms low order and low energy processes.

- by Ghanshyam Chauhan
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- Engineering, Grafting, CHEMICAL SCIENCES, Journal of Applied Polymer Science

Epoxidized natural rubbers (ENR) with various levels of epoxide groups were prepared. Thermoplastic vulcanizates based on 75/25 ENRs/PP blends with Ph-PP compatibilizer were later prepared by dynamic vulcanization using sulfur curing system. Influence of various levels of epoxide groups on rheological, mechanical morphological properties, and swelling resistance of the TPVs was investigated. It was found that the mixing torque, apparent shear stress, apparent shear viscosity, tensile strength, and hardness properties increased with increasing levels of epoxide groups in the ENR molecules. This may be attributed to increasing level of chemical interaction between the methylol groups of the Ph-PP molecules and polar functional groups of the ENR molecules. Also, the PP segments in the Ph-PP molecules are capable of compatibilizing with the PP molecules used as a blend composition. In SEM micrographs, we observed finer dispersion of vulcanized rubber domains as increasing levels of epoxide contents. This corresponds to increasing trend of strength and hardness properties of the TPVs. An increasing trend of tension set and a decreasing trend of elongation at break were observed as increasing levels of epoxide groups in the ENR molecules. This is because of higher rigidity of the vulcanized ENR phase with higher epoxide groups.

- by Charoen Nakason
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- Engineering, Morphology, Polymer Blends, Mixing
- by Pornsawan Amornsakchai
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- Engineering, Morphology, Composite Material, Fractography

The rheological properties of hydrophilic fumed silica dispersed in polyethylene glycol (PEG) were investigated. The dispersion was prepared by dispersing the fumed silica in PEG with various concentrations. The reversible sol-gel transition was observed over 5 wt % of silica concentration as a function of temperature. The gelation temperature was found to depend on the applied shear stress and silica concentration, and the high shear stress was found to lead to the decrease of sol-gel transition temperature of the dispersion with the same silica concentration. As the silica concentration increases, the sol-gel transition shifts to the lower temperature.

- by Dong-hee Han
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- Engineering, Silica, CHEMICAL SCIENCES, Polyethylene Glycol
- by Christian Roy
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- Engineering, Kinetics, Modeling, Rheology

Natural starches obtained by fruit seeds have been a subject of studies because of their applications, as a consequence of their chemical properties. As it is known, the fruits depend on the geographic region. Because of this, several factors affect the seed starches nature, such as granules size, morphology, components, and composition. Thus, to better understand starch properties, it is necessary to investigate the chemical behavior of these factors. This work focused on the chemical components and molecular dynamic behavior of the Dipterxy Alata Vogel (cumbaru) starch, because this fruit is very popular and is used in abundance for people because they think that it is good for some kinds of diseases. The main chemical components and the molecular dynamics of starch from the Dipterxy Alata Vogel were studied by applying solid-state 13C nuclear magnetic resonance spectroscopy (NMR). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2151–2154, 2004

- by Emerson Silva
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- Engineering, Applied, Nmr, CHEMICAL SCIENCES

In preparation for studying the hydrolytic degradation of Estane® 5703 and related poly(ester urethane) elastomers, the absorption (solubility) and diffusion of water in these polymers have been examined experimentally and modeled theoretically. Weight gain and loss experiments have been carried out. The amount of water absorbed per gram of sample was linear at low relative humidities (RHs) but curved upward at higher RHs. This curvature was not fit by Henry's law or the Flory–Huggins equation but was easily fit by a water-cluster model. Diffusion coefficients were determined by fitting the time dependence of the sample weights, and the diffusion appeared Fickian to within experimental uncertainty. The similarity of related polymers was used to determine the approximate temperature dependence of the absorption. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 181–191, 2002

- by Michael Salazar
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- Engineering, Materials Engineering, Kinetics, Modeling

A new hydrogel that combines poly(ethylene glycol) and β-cyclodextrin has been synthesized. Both components are linked by using a diisocyanate (HDMI), first by end-capping the poly(ethylene glycol) with isocyanate groups an then reacting it with β-cyclodextrin, forming urethane links. Hydrogels of molar compositions (β-cyclodextrin/poly(ethylene glycol)) ranging from 1/4 to 1/14 have been synthesized. These hydrogels swell quickly and their water contents depend upon temperature. The gels are temperature resistant and show an elastomeric behavior. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1162–1166, 2006

- by Camilo Ramirez
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- Engineering, Hydrogels, Applied, CHEMICAL SCIENCES

This work describes the properties of plastics made from partially denatured proteins produced by the animal coproduct (rendering) industry and these plastics' fabrication. Specifically, plastic samples from partially denatured feathermeal protein were successfully produced by a compression-molding process. The modulus (stiffness) of the material obtained was found to be comparable with that of commercial synthetic materials, such as polystyrene, but was found to have lower toughness characteristics, which is a common phenomenon among plastics produced from animal and plant proteins. A reversible stress-strain property was observed over the yield region. Plastic-forming conditions for undenatured animal proteins, such as albumen and whey proteins, were also formulated for fabricating plastics out of these proteins' blends with feathermeal proteins. The resultant plastic samples that were developed of biomacromolecular blends, such as feathermeal/whey and feathermeal/ albumen, demonstrated improved mechanical properties, specifically tensile strength, when compared with neat plastics from feathermeal proteins. The values for the stiffness of the feathermeal/whey blends deviated from simple mixing rule and showed a synergistic effect.

- by Suraj Sharma
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- Engineering, Rendering, CHEMICAL SCIENCES, Denaturation

An in-depth wettability and interfacial phenomena investigation was carried out to study interactions between high density polyethylene (HDPE) and petroleum coke. The aim is to investigate the effect of temperature and contact times on possible interactions and adhesion characteristics for partially substituting coal-tar pitch binder with waste polymers. Using a sessile drop arrangement, experimental assemblies consisting of ground HDPE and a petroleum coke substrate were heat treated in the temperature range of 150-350 C for 15-60 min. Contact angles between molten HDPE and petroleum coke surface and depth of penetration of HDPE into petroleum coke substrate were measured. The highest contact angle (131.5 ) was observed at 250 C after 15 min. and lowest contact angle (30.9 ) was observed at 350 C after 60 min. Highest penetration depth (75 lm) was observed at 350 C after 60 min and lowest penetration (13 lm) at 200 C after 15 min. Analysis of results showed that increasing time and temperature of heat treatment had a significant impact on the interactions of molten HDPE with petroleum coke. Longer residence time and higher temperatures increased the extent of melting of HDPE, which in turn resulted in improved wettability and deeper penetration into petroleum coke substrate. HDPE was found to bind and adhere strongly with petroleum coke.

- by Sharifah Shahnaz
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- Engineering, Wettability, CHEMICAL SCIENCES, Petroleum Coke
- by Tinh Nguyen
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- Engineering, Water, Kinetics, Brackish Water

A series of novel copolymer superabsorbents based on the monomers acrylamide (AM), acrylic acid (AA), acrylonitrile, methacrylic acid, sodium acrylate (SA), and 2-hydroxyethyl methacrylate (HEMA) were prepared by copolymerization using ammonium persulfate as an initiator and N,N-methylenebisacrylamide as a crosslinking agent. The experimental results of superabsorbent polymers (SAPs) show that the absorbency in water and NaCl solutions is maximum for AM, SA, HEMA and AM, AA, SA combinations. The copolymers were characterized by IR spectroscopy. The water retention of soil was also enhanced using the above superabsorbents. Use of SAPs for the growth of the croton plant was also investigated.

- by km raju
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- Engineering, CHEMICAL SCIENCES, Journal of Applied Polymer Science

Graft copolymerization of glycidyl methacrylate (GMA) onto cellulose filter paper (CFP) was carried out by a free-radical initiating process using ceric ammonium nitrate (CAN) as an initiator. Optimum conditions pertaining to different grafting percentages were evaluated as a function of monomer and initiator concentrations, polymerization time and temperature. CFP with various graft levels of GMA was characterized by fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis (TGA). Surface morphology of ungrafted and grafted CFP was evaluated by scanning electron microscopy (SEM). Attenuated total reflectance (ATR)-FTIR spectral analysis provided the evidence of grafting of GMA onto CFP. The maximum grafting of 102% was achieved by using 4 Â 10 À3 molL À1 CAN and 5% of GMA (w/v) monomer at 60 C in 25 min. The CFP-g-GMA surfaces with different graft levels were evaluated as a support for immobilization of biomolecules. Urease was selected as the model enzyme to be covalently coupled through the surface epoxy groups of the CFP-g-GMA discs. Immobilized discs were further studied for urea estimation and their reusability. Although the highest degree of urease immobilization was observed at 100% (162-lg urease/disc) graft level, the urease immobilized on discs with 70% (105-lg urease/disc) graft level gave the maximum activity of the enzyme.

The determination of the effectiveness of lead (Pb) and mercaptotin (MT) stabilizers on the useful service life of poly(viny1 chloride) PVC in outdoor applications, necessitates testing the mechanical properties of the polymer before and after weathering, to learn its behavior in the outdoor environment. Artificial weathering was used, and four mechanical tests were carried out, namely tensile, flexure, impact, and fracture toughness tests. The Pb stabilizer system used gave better fracture toughness and impact strength after exposure. The tensile strength and modulus of elasticity of MT-stabilized specimens increased significantly after exposure, unlike Pb-stabilized specimens. Brittleness in unplastisized PVC can be attributed to a number of fadors, such as unsaturation, carbonyl group concentration, stabilizer concentration, crystallinity, and extent of dehydrochlorination. The tensile strength and modulus of elasticity increase in tin mercaptide stabilizers significantly with increased UV exposure, while the increase in Pb specimens is less significant. There is a continuous diminution of the percent of elongation at break in both types of Pb or MT specimens, with increased exposure. The ductility of Pb may be accounted for by PbO and Pb stearate (C17H3SCOO)2Pb. One of the possible causes for the brittleness of tin mercaptide stabilized specimens is antiplasticization.

- by Maher Younan
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- Engineering, CHEMICAL SCIENCES, Journal of Applied Polymer Science

The curing kinetics of a liquid melamineformaldehyde impregnation resin were analyzed with differential scanning calorimetry, and the conversion-dependent activation energy for melamine-formaldehyde curing was estimated with the isoconversional model-free kinetic approach developed by Vyazovkin. The conversion-dependent activation energy was used to extend the predictive power of a response surface model describing the influence of some processing factors (press time and resin composition) in the manufacturing of particleboards coated with melamine-formaldehyde-impregnated papers. By substituting the factor ''press time'' in an RSM established for a press temperature of 170 C by the factor ''conversion'' which is accessible from thermo-chemical analysis, additional information on temperature was incorporated into the model. Model applicability for additional temperatures was evaluated with 12 validation experi-ments. Although chemical resistance was difficult to model, cleanability was sufficiently well described by only one factor (conversion). Surface gloss depended on both the conversion and catalyst amount and was predicted by a two-factor interaction model (R 2 ¼ 0.95). This study demonstrates that parameters derived from the isoconversional kinetic analysis of liquid resins not only are theoretical descriptors but also have direct practical relevance in the modeling of product properties derived from these liquid resins when used to supplement technological databases.

- by Duane Priddy
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- Engineering, CHEMICAL SCIENCES, Journal of Applied Polymer Science

Binary blend films from lactide-rich poly (D-lactide-co-glycolide) (PDLG) and poly ( Llactide-co-glycolide) (PLLG ) were obtained by casting methylene chloride solutions of the two mixed copolymers with different D-and L-lactide contents... more

- by Hideto Tsuji
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- Structure, Kinetics, Morphology, Poly (lactic acid)

The purpose of this study was to examine the influence of some swelling agents with reduced water content on final properties of cotton fabrics. A single-step swelling of cotton in the reagent was used. There were selected properties generally used to characterize mercerized cotton that are technologically important, such as water retention, shrinkage, stiffness, crease recovery angle, and hand. Water retention method and dyeing with CI Direct Red 81 have been used to compare the degree of swelling for different samples. Correlations have been established between structural changes induced by the swelling agents and final properties of cotton fabric. The mixtures of an alkali solution and an additive produced similar or better end-use properties as compared with classical sodium hydroxide or ammonia treatments, combining the action of a diluted alkali solution (3.13 mol/L NaOH or KOH) and a nonalkali reagent. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 2848–2855, 2006

- by Christian Schimper
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- Engineering, Cotton, Crosslinking, Additives

Organosolv lignin from olive tree pruning was subjected to liquefaction under microwave heating and modifying the experimental conditions (time, temperature, and concentration of catalyst) according to an experimental design. The organosolv lignin and obtained polyols were characterized using attenuated-total reflection infrared spectroscopy (ATR-IR), thermogravimetric analysis (TGA), gel permeation chromatography, and another parameter such as the hydroxyl number (I OH ). The ATR-IR and the TGA results showed that the solvents (polyethylene glycol #400 and glycerol) reacted with the lignin being present in the final product. The optimal polyol showed a liquefaction yield of 99.07% that was obtained in 5 min of reaction at 155 C with 1% of sulphuric acid. The liquefaction product showed a hydroxyl number of 811.8 mg KOH/g, suitable to be used as a precursor in polyurethane foam synthesis.

- by Jalel Labidi
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- Engineering, CHEMICAL SCIENCES, Journal of Applied Polymer Science

The purpose of this study was to investigate the effects of reaction media, composition, and temperature on the rate of the alkaline depolymerization of poly(trimethylene terephthalate) (PTT). The alkaline depolymerization of PTT was carried out at 160 -190°C in ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TEG), ethylene glycol monobutyl ether (EGMBE), diethylene glycol monoethyl ether (DEGMEE), and a mixture of these solvents. During the reaction, PTT was quantitatively converted to disodium terephthalate and 1,3-propanediol. The alkaline depolymerization reaction rate constants were calculated based on the concentration of sodium carboxylate, which was equivalent to the molar amount of sodium hydroxide. The depolymerization rate of PTT was increased by increasing the reaction temperature and by adding ethereal solvents. Moreover, the depolymerization rate was significantly accelerated in the order of EG Ͻ DEG Ͻ TEG Ͻ EGMBE Ͻ DEGMEE.

- by Richard Kotek
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- Engineering, CHEMICAL SCIENCES, Journal of Applied Polymer Science

The objective of this investigation is to characterize various room temperature (RT)-curable epoxies for vacuum-assisted resin transfer molding (VARTM) of large structure manufacturing. Six epoxy candidate resins: X-40, 780-33, 780-35, 8601/8602, 8602, 8603, and two vinyl ester resins (VE), 411-350 and 411-510A, are physically and thermochemically characterized. All the resins are cured at RT with extended period of time. The degree of cure for 24-h RT-cured samples ranges from 70 to 85% for epoxies and is comparable with the baseline VE systems (75%). After 1 year at RT, the degree of cure increases from 90 to 98%. Most of the epoxies show a single transition in dynamic mechanical analysis and differential scanning calorimetry. However, two heterogeneous transitions are observed for the VE systems. The glass transition temperature increases monotonically with exposure time, except X-40, that rapidly achieves a plateau and remains constant. The degree of cure for the majority of the systems increases logarithmically with RT curing time with excellent fitting (R 2 varies from 0.92 to 1). Consistent with the increase in degree of cure, the storage modulus increases and (tan d) max decreases with time of exposure. A negative correlation between the curing temperature range and the total heat of reaction is observed among the epoxy systems. However, the VE systems show the reverse trend. RT curing epoxy resin (X-40) shows promising overall result to VE system and can be a viable alternative to VE for VARTM processing. V

- by John Gillespie
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- Engineering, Viscoelasticity, Kinetics, CHEMICAL SCIENCES

Impact modification was studied for a variety of engineering thermoplastics to determine if notched Izod data obtained at various temperatures and modifier concentrations could be correlated with particle size or surface-to-surface interparticle distance of the modifier. Elastomers evaluated were characteristic of those used in commercial blend systems for those polymers, and both functionalized and nonfunctionalized materials were studied. For the single matrix polymer/elastomer-modified blend systems studied [ poly (phenylene sulfide) (PPS) , polyoxymethylene (POM) , poly(butylene terephthalate) (PBT) 1, elastomer interparticle distance provides a better correlation to brittle-tough transition temperature than does particle size, as predicted by the Wu model. In POM, the dispersion morphology of the samples used was not adequate to achieve the critical interparticle distance required for supertoughening a t room temperature. In this study, the critical interparticle distance has been shown to depend on the degree of crystallinity (PPS) and the modulus of the impact modifier relative to the matrix (PBT). Actual adhesion of the polymer to the matrix (variation of functionality levels) was not found to have a strong influence (PBT). In POM, the increase in impact at the brittle-tough transition was dependent on the molecular weight of the base resin. This is examined with respect to the ratio of the molecular weight (M ,) to the entanglement molecular weight (M e) , which determines the critical molecular weight necessary to achieve useful physical properties. In polyester (PET) /polycarbonate (PC)/elastomer blends, the molecular weight of the primary matrix resin (PET) determined impact properties within the molecular weight range of the resin studied. This was again related to the M J M , ratio for PET and PC. 0 1994 John Wiley & Sons, Inc.

- by Vincent Sullivan
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- Engineering, CHEMICAL SCIENCES, Journal of Applied Polymer Science

This research studied the characteristics of poly(acrylamide) and methylcellulose (PAAm-MC) hydrogels as a novel adsorbent material for removal of pesticide paraquat, from aqueous solution, with potential applications in curbing environmental risk from such herbicides. PAAm-MC hydrogels with different acrylamide (AAm) and MC concentrations were prepared by a free-radical polymerization method. The capability of the hydrogels in removing paraquat dichloride from aqueous solution was determined using UV-Vis analysis. The scanning electron microscopy method was used to study the morphological properties of the hydrogels, and swelling degree (Q) of the hydrogels was also measured. The entrapped MC in PAAm chains provoked significant changes in morphological, hydrophilic, and adsorption properties of the PAAm-MC hydrogels. The adsorption capacity of hydrogels was strongly influenced by AAm, MC, and paraquat concentrations with the highest adsorption capacity (q eq ¼ 14.3 mg g À1) was observed for hydrogels synthesized with 6.0% AAm with 0.75% MC swollen in 45.7 mg L À1 of paraquat solution. Freundlich model performed better than Langmuir model in describing the adsorption isotherm of PAAm-MC/paraquat system, implying a heterogeneous surface. These results suggest that PAAm-MC hydrogels are potentially viable absorbents for removal of paraquat pesticide from aqueous solution and cleaning water contaminated with dyes, heavy metals, and others pesticides. V

- by William Orts
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- Engineering, Morphology, Hydrogels, Polymer Blends

The aim of the present study is to clarify some problems concerning the synthesis of additional quantities of ethyl-2-cyanoacrylate monomer ( ECA) utilizing the waste residue (WR) from the large-scale depolymerization of ECA oligomers. The composition of WR was established by GPC and IR spectroscopy. WR was found to consist mostly of diethyl dicyanoglutarate (DEDCG) and low molecular weight products of its condensation with paraformaldehyde (pFA) . The DEDCG-pFA interaction was studied as a model, and the influence of DEDCG conversion on the average degree of polymerization (X, and Fw) of the oligomers formed was also followed. On this basis, it was found that oligomer formation in condensation of WR with pFA is consistent with a stepgrowth mechanism, the polymer chain length being determined by steric hindrance and destructive reactions.

- by Zlatan Denchev
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- Engineering, CHEMICAL SCIENCES, Journal of Applied Polymer Science