bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interaction of poly(methyl methacrylate) and manganese chloride
Authors: Wilkie Charles A. , Leone Joseph T. , Mittleman Martin L. 
Published: April 2003

AbstractThe thermal degradation of poly(methyl methacrylate) (PMMA), in the presence of manganese chloride has been studied by sealed tube reactions and thermogravimetric analysis coupled to FT‐IR spectroscopy. From sealed tube reactions it was found that the degree of mixing of the MnCl2 and PMMA has an important effect on monomer formation. In systems where the two components are simply poured together, the amount of monomer is about half that observed for the thermolysis of PMMA alone; when the two components are thoroughly mixed by dissolution in solvent, the monomer yield fails to zero. The TGA–FT‐IR experiment on solvent mixed material does show the presence of monomer. In sealed tubes, monomer may not escape and must repolymerize, while in the TGA experiment the monomer is swept out before reaction may occur. Monomer production also commences at temperatures lower than those for degradation of PMMA alone. It is apparent that manganese chloride catalyzes both the degradation of polymer to monomer and the reoligomerization of this monomer. The gases that are produced include CO, CO2, CH3Cl, HCl, and CH4. A mechanism is proposed to account for all of these products and a manganese ionomer is the final product of the reaction.
Photochemistry and photopolymerization activity of perester derivatives of benzophenone
Authors: Allen N. S. , Hardy S. J. , Jacobine A. F. , Glaser D. M. , Yang B. , Wolf D. , Catalina F. , Navaratnam S. , Parsons B. J. 
Published: April 2003

AbstractThe spectroscopic properties and photopolymerization activities of a mono‐ and tetraperester derivative of benzophenone are examined and compared with those of benzophenone. Their photopolymerization activity in methyl methacrylate (MMA) and an ethoxylated bis‐phenol‐A diacrylate have been studied using a combination of gel permeation chromatography (GPC), and real time Fourier transform infrared spectroscopy (RTFTIR) as well as the commercial pendulum hardness test. Using GPC analysis on the poly(methyl methacrylate) samples the tetra‐‐t‐butyl perester derivative of benzophenone is found to give a higher weight average (Mw) and number average (Mn) molecular weight polymer than that produced using the mono perester. For the two peresters of benzophenone photopolymerization efficiency using real time FTIR increases with increasing initiator concentration, and no self‐termination is observed up to 0.75% w/w concentration with the mono perester derivative being the more efficient initiator. Similar results were obtained using the commercial pendulum hardness tester with a triacrylate/epoxyurethane acrylate resin with benzophenone exhibiting the lowest activity. Photopolymerization activities of the initiators correlate well with their spectroscopic properties. The phosphorescence quantum yield is higher for the monoperester than the tetraperester derivative and is consistent with a shorter lifetime and lower photolysis quantum yields in 2‐propanol. Compared with benzophenone, phosphorescence analysis indicates that the perester groups impart a degree of charge‐transfer content to the molecule which is consistent with the degree of substitution. Ketyl radical formation on microsecond flash photolysis follows the order benzophenone > mono‐ > tetraperester derivative and is consistent with the phosphorescence quantum yields. On nanosecond laser flash photolysis in nitrogen‐saturated acetonitrile, triplettriplet absorption is extremely weak for both the perester derivatives, being stronger for the monoperester.
Kinetics of emulsion copolymerization with acrylic acids
Authors: Shoaf Glenn L. , Poehlein Gary W. 
Published: April 2003

AbstractA kinetic model is presented that describes the reaction behavior of emulsion copolymerization systems where significant polymerization occurs in both the particle and aqueous phases. Equations for predicting aqueous‐phase free‐radical concentrations and aqueous‐phase and particle‐phase reaction rates are developed. A method for estimating the radical entry rate coefficient is also presented. The model is applied to two seeded carboxylated emulsion copolymerization systems, acrylic acid‐styrene and methacrylic acid‐styrene. Both experimental and predicted results reveal that the reaction behavior is greatly affected by the type of acid monomer, partition of monomer between the various phases, and locus of polymerization. The mechanism for the acrylic acid‐styrene system is more complicated than that for the methacrylic acid‐styrene system. Evidence suggests that the primary reaction locus in the acrylic acid‐styrene system shifts from the particles to the aqueous phase after the hydrophobic monomer, styrene, has been consumed.
Solution and emulsion polymerization with partially neutralized methacrylic acid
Authors: Shoaf Glenn L. , Poehlein Gary W. 
Published: April 2003

AbstractPolymerizations of partially neutralized methacrylic acid (MAA) were performed in both solution and emulsion systems. Polymerizations of MAA in solution were performed at an overall degree of neutralization ranging between 0 and 1. The rate of polymerization of the acid is found to decrease as the degree of neutralization increases due to increased electrostatic repulsion of the dissociated acid species (anions). The degree of neutralization of the unreacted monomer increases as the conversion increases. A kinetic model based on a copolymerization mechanism is used to describe the reaction behavior. Partially neutralized methacrylic acid was also polymerized with styrene in a seeded emulsion system. The reaction rates of both the acid and styrene decrease as the overall degree of neutralization increases. A previously developed emulsion copolymerization kinetic model is extended to account for reaction of the anions and used to investigate the overall “terpolymerization” of the acid, anions, and styrene.
A study of the response of open end and ring spun yarns to zinc chloride and sodium hydroxide
Authors: Subramaniam V. , Selvamurugan U. , Thambidurai S. , Krishnasamy V. 
Published: April 2003

AbstractAn investigation of the swelling behavior of open end and ring spun yarns in slack condition in 64.5% (w/w) aqueous zinc chloride and sodium hydroxide 22% (w/w) for different intervals ranging from 30 to 90 min is reported. The results show that the response of the yarns to the swelling agents is different in that the products treated with zinc chloride are found to possess higher strength and higher bending rigidities but low elongation. Swelling of yarns with sodium hydroxide has resulted in large increase in elongation. The other properties, namely, coefficient of friction and abrasion resistance, are found to be slightly higher than that of the yarns treated with sodium hydroxide. Degree of set of open end yarns is significantly higher than that of the ring spun yarns. Coefficient of friction and abrasion resistance of the zinc chloride treated yarn samples are found to be slightly higher than that of the sodium hydroxide treated samples.
Epoxy–lignin polyblends: Correlation between polymer interaction and curing temperature
Authors: Feldman D. , Banu D. , Luchian C. , Wang J. 
Published: April 2003

AbstractA bisphenol A–polyamine hardener based epoxy adhesive (EP) was modified by polyblending with Kraft lignin (L). EP–L polyblends with an L content up to 40% by weight were cured at room temperature or above their glass transition temperature (Tg). Previous data have shown that the thermal and viscoelastic properties, as well as adhesive performance of the EP–L polyblends, are influenced by the curing temperature and by the L content in thermally cured polyblends. A reasonable explanation for the different behavior of EP–L polyblends as function of the curing temperature and their L content could be the enhanced degree of bonding between L and the EP network taking place at elevated temperature. This bonding was specifically considered to take place between L and possible unreacted amine groups of the hardener. Characterization of the EP–L polyblends was performed to search for evidence of irreversible chemical bonding between L and the EP network in thermally cured EP–L polyblends. FTIR studies, L extractibility from the crosslinked, polyblends, and quantitative data concerning the reactivity of L toward the polyamine hardener are discussed.
A FT‐IR analysis method for simple unsaturated polyesters
Authors: Paauw M. , Pizzi A. 
Published: April 2003

AbstractA simple and reliable FT‐IR method enabling almost complete qualitative and quantitative identification of the components of unsaturated polyester resins for glass‐reinforced laminates is presented. This method is based on percentage transmission ratios of characteristic bands in a single IR spectrum. Coupled with simple chemical tests, such as resin acid number and, when needed, UV‐VIS determination of Co (II) curing accelerators, this FT‐IR method allows the qualitative and quantitative determination of the various reacted and unreacted components of the resin. Some critical discussion of the advantages of such a method over some conventional tests is presented.
Phase behavior of ternary PBT–PC/phenoxy blends
Authors: Remiro P. M. , Nazábal J. 
Published: April 2003

AbstractTernary polymer blends were obtained by melt mixing, mixing up to 30% poly(butylene terephthalate) (PBT) with polycarbonate (PC) and phenoxy in an attempt to improve the miscibility of the PC/phenoxy binary blend. Although most of the blends with a PBT content higher than 10% appear as transparent, two Tg's appeared at all the blend compositions. These Tg's correspond to PC‐rich and phenoxy‐rich phases where a low amount of the main component of the other phase and all PBT are dissolved in amounts that are a function of the PC/phenoxy ratio of the blend. Increasing the PBT contents in the blends closes to linearity the torque versus composition plot, so that a relationship between miscibility level and viscosity exists in these blends.
Miscible blends of styrene‐acrylic acid copolymers with aliphatic, crystalline polyamides
Authors: Kuphal J. A. , Sperling L. H. , Robeson L. M. 
Published: April 2003

AbstractStyrene‐acrylic acid copolymers exhibit miscibility with various aliphatic, crystalline polyamides (e.g., nylon 6, 11, and 12) at 20% acrylic acid content in the copolymer. At 8% acrylic acid, phase separation is observed with the crystalline polyamides. At 14% acrylic acid, partial miscibility is observed with each polyamide, resulting in the Tg's of the constituents shifted toward the other constituent. The miscibility of the styrene‐acrylic acid copolymers ( > 14 wt % AA) can be ascribed to hydrogen bonding interactions with the polyamides. Styrene‐acrylic acid (20% AA) copolymers are miscible with other nylons with alternating amide orientation along the chain (e.g., nylon 6,6 and nylon 6,9). These samples tend to crosslink upon exposure to temperatures above the polyamide melting point unlike the nylon 6, 11, and 12 blends in which branching may only occur. Nylon 11/styrene‐acrylic acid blends were chosen for crystallization rate studies. A melting point depression of nylon 11 occurs with addition of the styrene‐acrylic acid (20% AA). The Flory‐Huggins interaction parameter from the melting point depression is calculated to be ‐0.27. The crystallization rate of nylon 11 is significantly reduced with the addition of the miscible SAA copolymers (20% AA). The spherulitic growth rate equation predicts this behavior based on a Tg increase with SAA addition.
Na+ and Cl− transport across polyimide films
Authors: Schussler A. , Bellucci F. , Senturia S. D. , Latanision R. M. 
Published: April 2003

AbstractNa+ and Cl‐ transport across 2.4‐ and 5.2‐μm‐thick polyimide (PI) PMDA/ODA and 7.5‐μm‐thick du Pont Kapton films was studied in a diffusion cell using ion‐selective electrodes. The temperature was 30°C. Diffusion coefficients Dm (in cm2/s), permeability coefficients P (in cm2/s), and distribution coefficients K were obtained by applying the time lag analysis on the ion uptake transient in the acceptor compartment of the diffusion cell. Both Na+ and Cl‐ were observed to diffuse across PI. Diffusion coefficients varied in the range 10‐12‐10‐13 cm2/s whereas ionic permeability results showed more scatter ranging from 1 X 10‐11 to 8 X 10‐14 cm2/s. The latter discrepancy was ascribed to diffuse heterogeneities on the order of 0.5 μm. No significant ionic selectivity between Na+ and Cl‐ was observed. This result indicates the absence of ionic fixed charge (unreacted polyamic acid) in the polymeric matrix. An attempt is made to determine the effect of water sorption mode and contaminants in the film on the ionic permeabilities data.
Solute and penetrant diffusion in swellable polymers. XI. The dynamic swelling behavior of hydrophilic copolymers containing multiethylene glycol dimethacrylates
Authors: Shieh Lisa Y. , Peppas Nikolaos A. 
Published: April 2003

AbstractCopolymers of 2‐hydroxyethyl methacrylate with a number of multiethylene glycol dimethacrylates were prepared by bulk copolymerization in the presence of AIBN s an initiator. The content of the dimethacrylate varied between 30 and 50 mol %. Additional copolymers were prepared by solution polymerization in the presence of water or ethanol. All samples were swollen in water up to thermodynamic equilibrium, and their dynamic swelling behavior was studied as a function of time. It was concluded that the mechanism of water transport in these moderately and highly crosslinked polymers was a coupled relaxation and diffusion and that the relaxational contribution to the overall transport depended on the chain length of the multiethylene glycol dimethacrylate.
Development of interchange reactions in ternary PBT‐PC/phenoxy blends
Authors: Remiro P. M. , Nazábal J. 
Published: April 2003

AbstractTernary PBT‐PC/phenoxy blends were melt mixed for periods of time up to 110 min to determine the development of interchange reactions among the blend components. This development was evaluated by means of solvent extraction and DSC measurements on blends obtained after characteristic blending times shown in the torque vs. blending time curve. PBT reacts, after very short blending times and, probably due to residual catalyst, mainly with phenoxy. Although at high phenoxy contents a single torque peak is observed, at low phenoxy contents two peaks are observed that correspond to the two stages in which the reaction takes place: at the beginning in the phenoxy‐rich phase and later in the overall blend.
Radioluminescent polymers: Preparation of deutero‐ and tritopolystyrene
Authors: Nelson David A. , Molton Peter M. , Jensen George A. 
Published: April 2003

AbstractDeuterium and tritium exchanges were performed on the aromatic groups of polystyrene using DCl or TCl and TiCl4. Up to 5 deuterium atoms per monomer unit could be placed on the aromatic groups depending upon time, DCI pressure, and TiCl4 concentration. Tritiated polystyrene mixed with zinc sulfide phosphor produced 1.06 Cd/m2 of luminance.
Thermal degradation of epoxy novolac‐phenol formaldehyde novolac resin systems
Authors: Sullivan Eileen A. 
Published: April 2003

AbstractThe evolution of organic vapors from encapsulants at elevated temperatures has been implicated as the source of the degradation of the gold–aluminum intermetallic of the wire that connects the bond pad to the leadframe in an integrated circuit. Gas chromatography/infrared spectroscopy/mass spectrometry were used to study the decomposition of three commercial epoxy‐novolac thermosetting compounds. Outgassing products have been identified and their origins discussed. Insight into the types of initiators used in encapsulants and their possible influence upon ball bond failure rates has been gained.
Dynamic mechanical properties of binary blends of different polyethylenes. I. Nonisothermal treatment
Authors: Orozco Jose A. Gonzalez , Rego Jose M. , Katime Issa 
Published: April 2003

AbstractThe relaxation processes and thermal properties of a series of blends of a highly linear high‐density polyethylene (HDPE) with several branched high‐density, linear low‐density (LLDPE) and low‐density polyethylenes (LDPE) have been measured. For the sake of comparison, all the samples were subjected to the same thermal treatment, that is, a rapid quenching from the molten state. The mechanical properties have been analyzed, taking into consideration the crystallization behavior of each sample. The existance of cocrystallization provides a bigger change in the dynamic mechanical properties than when segregation takes place. The observed changes in the end‐corrected storage modulus supports this conclusion as well as those associated with the α, β, and γ relaxation temperatures.
Microstructure, mechanical properties, and fracture behavior of liquid rubber toughened thermosets
Authors: Zeng Yi‐Bing , Zhang Lian‐Zheng , Peng Wei‐Zhou , Yu Qiao 
Published: April 2003

AbstractPhenolic epoxy resin was toughened by carboxyl‐randomized butadiene acrylonitrile copolymer (CRBN) for use as composite matrix. By adding different parts of butadiene acrylonitrile copolymer (BN‐26, without carboxyl contained) to CRBN, different sizes of rubber domains and different numbers of chemical bondings between the resin matrix and the rubber phase were obtained. It is found that small rubber particles (less than 0.1 μm) are cavitated during the crack development. The interaction between secondary crack zones caused by the cavitation makes the fracture toughness KIC of the materials high; by comparison, a local stress‐whitened zone is produced in the material with large rubber particles (more than 0.1 μm) when it is subjected to tensile stress. In this case, the flexure strength σf of the material is great. Using ultrasection and TEM techniques, the stress‐whitened zone was shown to be caused by the special multiple‐phase structure of the material, in which many caves and “macrocrazes” coexist.
Crosslinking and scission in radical‐promoted functionalization of polyethylene
Authors: Kwei T. K. , Pearce E. M. , Schlecht M. F. , Cheung W. 
Published: April 2003

AbstractWe reported earlier on grafting hexafluoroisopropanol groups onto polyethylene through the reaction of polyethylene with hexafluoroacetone and di‐t‐butyl peroxide. The modified polyethylene was partially crosslinked. In this work, we adapted the Charlesby–Pinner Equation to estimate the ratio of chain scission to crosslinking in the reaction.
Dynamic mechanical properties of binary blends of different polyethylenes. II. Isothermal treatment
Authors: Orozco Jose A. Gonzalez , Rego Jose M. , Katime Issa 
Published: April 2003

AbstractThe relaxation processes and thermal properties of a series of blends of a highly linear high‐density polyethylene (HDPE) with several branched high‐density, linear low‐density (LLDPE), and low‐density polyethylenes (LDPE) have been measured as a function of crystallization temperature, Tc, and content of branched polyethylene (BPE). The influence of composition on the dynamic mechanical spectrum of the HDPE has been rationalized taking into account the dilution with increasing content of BPE of those crystals formed during the isothermal crystallization. The influence of the type of second constituent (HDPE, LLDPE or LDPE) on the relaxation process of the HDPE has been explained in terms of segregation material data.
Peroxydiphosphate/bisulfite‐initiated polymerization of acrylamide and its retardation kinetics
Authors: Bajpai U. D. N. , Bajpai A. K. , Bajpai J. 
Published: April 2003

AbstractThe kinetics of aqueous polymerization of acrylamide with peroxydiphosphate/bisulfite redox pair was studied at 35 ± 0.2°C under atmospheric oxygen. The rate of polymerization was found to be of first power to monomer, half‐power to catalyst, and 0.75 power to activator concentration. The overall energy of activation was calculated to be 11.0 kcal/deg mol between 25 and 45°C. The effect of addition of organic solvents and dinitrobenzenes as retarders on the rate of polymerization were studied kinetically and retardation constants for nitro compounds were evaluated by a newly proposed method (intercept method), when two retarders act simultaneously.
Polymers for information storage systems. II. Polymerization kinetics for preparation of highly crosslinked polydimethacrylates
Authors: Bowman Christopher N. , Peppas Nikolaos A. 
Published: April 2003

AbstractPolymers of ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and tetraethylene glycol dimethacrylate were prepared by photoinitiated polymerizations in the presence of 2,2‐dimethoxy‐2‐phenyl‐acetophenone at 27°C. The reactions led to highly crosslinked polymeric networks. The volume shrinkage observed during polymerization was a function of the number of ethylene glycol units in the dimethacrylate monomer. The kinetic rate constants of polymerization, as determined from the photopolymerization characteristics using a dilatometric technique, were again dependent on the number of ethylene glycol units in the monomer. The importance of these results on the crosslinked structure of the prepared networks is discussed.
Effect of hydroquinone on location of methacrylic acid‐grafted chains introduced into polyethylene film by photografting
Authors: Kubota Hitoshi , Hata Yasuo 
Published: April 2003

AbstractEffect of hydroquinone (HQ) on photografting of methacrylic acid (MAA) on low‐density polyethylene film (thickness = 30 μm) sensitized with xanthone was investigated at 60°C in water medium. Both the formation of grafted polymer and homopolymer were retarded by HQ. The contact angle of water on the MAA‐grafted polyethylene films (sample with HQ) prepared in the system with HQ was larger than that of the grafted films (sample without HQ) prepared in the system without HQ. Based on electron probe microanalysis of the grafted films, it was found that distribution of grafted chains in the direction of film thickness is different between the both grafted films. Namely, the grafted chains of the sample with HQ distributed in the inside of the film compared with those of the sample without HQ. The difference in the distribution of grafted chains between the grafting systems with and without HQ was discussed in terms of effect of HQ on the photodecomposition of MAA‐grafted chains and the subsequent initiation of polymerization by radicals due to the photodecomposition.
Optical rotation of dilute aqueous xanthan solutions at elevated hydrostatic pressure
Authors: Stokke B. T. , Knudsen K. D. , Smidsrød O. , Elgsaeter A. 
Published: April 2003

AbstractThe optical rotation of dilute aqueous xanthan solutions of ultrasonically depolymerized xanthan have been measured in the pressure range from 0.1 to 50 MPa. This was achieved using a high‐pressure cell in a spectropolarimeter of original design. The conformational melting temperature Tm of xanthan was found to decrease with increasing pressure. The pressure coefficients of the melting temperature at constant ionic strengths, I, was found to be (ΔTm/Δp)I = −(9.5 ± 4.0) 10−8 K Pa−1 and (ΔTm/Δp)I = −(20 ± 10) 10−8 K Pa−1 for solution ionic strengths of 10 mM NaCl and 25mM NaCl, respectively. The largest shift in Tm of xanthan for an increase in hydrostatic pressure from 0.1 to 50 MPa is less than −10 K. The observed decrease in conformational transition temperature can have significant implications when xanthan is used in polymer or micellar flooding processes in high‐salinity, high‐temperature oil reservoirs where the reservoir temperature is close to the structural transition temperature at ambient pressure.