bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies of methyl methacrylate‐methyl α‐chloroacrylate, copolymers and poly(methyl α‐chloroactylate) as electron sensitive positive resists
Authors: Lai Juey H. , Shepherd Lloyd T. , Ulmer Robert , Griep Carl 
Published: December 2004

AbstractPoly(methyl α‐chloroacrylate) (PMCA) and the copolymers of methyl methacrylate and methyl α‐chloroacrylate (poly(MMA‐co‐MCA)) have been reported recently to be more susceptible to radiation degradation than poly(methyl methacrylate) (PMMA). In this paper we report our studies of PMCA and poly(MMA‐co‐MCA) as electron‐sensitive positive resists. It has been found that both PMCA and the copolymers are more sensitive than PMMA. Using mixtures of dimethylformamide and 2‐propanol as developers, the sensitivities of PMCA and poly(MMA‐co‐MCA) (38 mole percent MCA) have been found to be 1 × 10−5 and 6 × 10−6 coulomb/cm2, respectively. It has also been found that crosslinking predominates in PMCA when the electron dose exceeds 6 × 10−4 coulomb/cm2.
Surface modification of polymers and practical adhesion
Authors: Schonhorn H. , Frisch H. L. , Gaines G. L. 
Published: December 2004

AbstractThe, nature of polymer surfaces has received increasing attention as the use of these materials, in a variety of forms, increases yearly. Modifications of polymer surfaces for adhesion, friction, and diffusion oriented appiications have necessitated a careful analysis of the surfade region morphology (surface physics) and chemical properties of the surface layer (surface chemistry). The behavior of composite structures has involved the discipline of classical fracture mechanics. The orientation of polymeric species or additives which migrate to the interface may modify the wetting characteristics and, most certainly, the frictional properties in addition to the diffusion of penetrant species beyond the boundary layer. The above topics are discussed within the framework of recent analytical and theoretical developments in surface science. The findings of these recent studies have facilitated many exciting technological advances.
Adhesion at polypropylene‐cellophane interfaces
Authors: Bialski A. , Manley R. St. J. , Schreiber H. P. 
Published: December 2004

AbstractThe shear strength of bonds between isotactic polypropylene and cellophane, formed under standard conditions, has beer studied as a function of cooling rates, following bond formation, and after ageing at temperatures up to 90°C. Rapid cooling produced cohesively failing bonds with shear strengths above 20 kg/em2. Weak, adhesively failing joints were produced under slow‐cooling conditions. Strong bonds deteriorated when joints were aged at temperatures above 50°C, but further improvement in bond strength was observed upon ageing at lower temperatures. Experimental observations were consistent with the development of smectic structure in the polypropylene upon rapid cooling; a tendency for transcrystallization in slow‐cooled joints was offset by the presence of weak boundary layers in the interface. Ageing produced further development of weak boundary layers and a transition from smectic to monoclinic crystallization in polypropylene. At higher ageing temperatures, the former effect seemed dominant; at lower temperatures, the structural change was assumed responsible for the observed improvement in bond strength.
Interface degradation processes and durability
Authors: Kaelble D. H. 
Published: December 2004

AbstractThis paper discusses a recently developed surface energetics criterion for adhesive bonding and fracture and its applications in such diverse areas as structural adhesive bonding, fiber reinforced composites, biomaterials development, and lithographic printing. The theoretical relations describe systematic methods for the surface energy analysis of solid adhesive and adherend surfaces. The surface tension properties for the adhesive and adherend can then be introduced into a modified Griffith fracture mechanics relation to obtain predictions of bond strength under varied conditions of liquid or gas phase immersion such as water and dry air.
Linear dynamic mechanical properties of an SBS block copolymer
Authors: Gouinlock Edward V. , Porter Roger S. 
Published: December 2004

AbstractDynamic viscosity and elastic modulus for a low molecular weight styrene‐butadiene‐styrene (SBS) block copolymer ate measured as a function of temperature (80‐170°C) and frequency using the eccentric rotating disc geometry. These linear properties are superimposed to yield master curves each of which exhibits two branches below different (critical) reduced frequencies. At lower temperatures, the non‐Newtonian behavior characteristic of SBS block copolymers is observed. In contrast, Newtonian response occurs at higher temperatures. As a consequence, plots of the viscoelastic properties vs temperature exhibit discontinuities below the critical frequencies, reflecting a narrow transition at about 142°C. Above this temperature, it is inferred, consistent with the equality of dynamic and steady state viscosities, that the polystyrene (S) blocks, existent in dispersed domains at low temperatures, exceed a critical degree of compatibility with the continuous polybutadiene phase. The activation energies indicate that the S blocks affect the temperature dependence of the dynamic properties in proportion to their presence in an interphase which is assumed to continuously grow in size as temperature is raised to the transition temperature. Below the critical reduced frequencies, it is inferred that S domain disruption may increasingly occur in conjunction with the observed property enhancement due to these domains, relative to the miscible blocks, as reduced frequency is lowered. However, above these frequencies, the presence of frequency‐temperature superposition implies that the S domains and the miscible blocks are equivalent in their effects on properties. At still higher reduced frequencies, the domains present at the low temperatures studied are assumed to remain intact, but plateau behavior similar to the response characteristic of homopolymers is observed.
Deformation behavior of an S‐B‐S copolymer
Authors: Odell J. A. , Keller A. 
Published: December 2004

AbstractIn accordance with previous studies, ‘single crystal’ tyr samples were prepared from the polystyrene‐polybutadien‐ polystyrene (S‐B‐S) three block copolymer Kraton 102 consist ing of a hexagonally packed parallel array of glassy S cylinder within a rubbery B matrix. Following earlier investigations o the pronounced anisotropy of the modulus, the actual deformation mechanism is examined in terms of the microstructures on straining perpendicular and parallel to the cylinder direction up to and beyond yielding. On perpendicular straining, a one to‐one relation is observed between ‘lattice’ and sample stray up to about 10 percent, coupled with complete recovery. For higher strains, the deformation becomes increasingly irreversible dependent on the time of stressing, a behavior which is found to be caused by cracks forming along crys tallographically defined directions of the hexagonal macrolai tice. On parallel straining, the stress‐strain curves display yield behavior at ∼3 percent strain, the yielded material be coming more compliant even at small strains on repeated test ing. However, on storage, the sample rehardens, a proces accelerated by heat treatment. This behavior is explained in terms of a breaking up and reformation of the cylinders and is supported by the subsequent experiments. These includ measurement of birefringence, which in the reversible small strain region corresponds to expectations from uniform strain in both S and B phases, but which beyond the yielded region displays behavior such as expected from deformation of the B phase alone. The postulated break‐up of cylinders on yielding is directly confirmed by electron microscopy on Iongitudinal sections thin enough to contain a single layer of cylinders. The yield behavior itself is treated theoretically using the composite mechanics approach. Two treatments are applied, the trad itional shear lag theory and a new random rod breaking theory In the latter case, in particular, very good agreement with experiment is found in that both the observed stress to yield and the electronmicroscopically seen fractured rod length in the yielded product are predicted.
Small angle X‐ray scattering from block polymers. II. The bulk state
Authors: Legrand A. D. , Vitale G. G. , Legrand D. G. 
Published: December 2004

AbstractThe basic theory of X‐ray scattering is applied to various hypothetical models for the bulk state of block polymers in order to explain the angular dependent scattering. The intensity of scattering is calculated for a rnicellar model, a zone model, and a molecular dumbbell model. The molecular dumbbell model, in contrast to the micellar and zone models, assumes that a block copolymer containing domains may be treated as one giant molecule and that, therefore, the locations of the domains are not random but are governed by the statistics of the segments which interconnect them. Experimental and calculated scattering curves are compared for several different types of block polymers.
Pulsed nuclear magnetic resonance for studying phase separation in block and segmented copolymers
Authors: Assink R. A. , Wilkes G. L. 
Published: December 2004

AbstractPulsed nuclear magnetic resonance measurements have shown that segmented polyurethanes as well as block copolymers segregate into domains with distinct mobilities. The usefulness of this technique for investigating the importance of the domain interface and for studying the mixing/ demixing of domains has been demonstrated. By examining the percent rigid material as a function of temperature, a polystyrene/butadiene block copolymer showed little evidence of domain interface effects, while in a series of segmented polyurethanes, the interface was seen to be important. The domains of a polyester soft segment and diphenylmethane diisocyanate hard segment polyurethane were mixed by annealing at 170°C. Examination of the demixing process as a function of storage temperature enabled an activation energy for domain formation of 36 ± 5 kcal/mole to be calculated. In a series of polyurethanes with varying amounts of hard segments, the material with the least amount of hard segments showed evidence of soft segment crystallinity. The mixing proces in this series was interpreted in terms of shifting correlation frequency distributions.
The influence of diblock copolymers on the structure and properties of polybutadiene‐polyisoprene blends
Authors: Ramos A. R. , Cohen R. E. 
Published: December 2004

AbstractThe structure and properties of a ternary polymer system comprised of 1, 4 polybutadiene, cis 1, 4 polyisoprene, and the corresponding 1, 4 polybutadiene/cis 1, 4 polyisoprene diblock copolymer have been investigated. Dynamic mechanical properties were measured as a function of frequency (3.5 to 110 Hz) and temperature (−135 to 40°C). Thermomechanical analysis and transmission electron microscopy provided additional information on the, phase relationships in the various specimens. The blends studied covered the entire triangular composition diagram; both slow solvent evaporation and rapid spin casting techniques were employed in the sample preparation. Results indicate that the BI diblock is a single phase material whereas binary blends of the two homopolymers are two‐phase in nature. Ternary blends of the two homopolymers with diblock and binary blends of a single homopolymer with diblock can be one or two phase materials depending on the sample composition and the ratio of B to I units in the diblock. All evidence From the dynamic, thermomechanical and microscopic experiments is used to elucidate the influence of the diblock in these polymer blends.
Chiorosulfonated block copolymers
Authors: Rogers C. E. , Covitch M. J. 
Published: December 2004

AbstractRubber‐phase chlorosulforiated polystyrene‐poly‐(ethylene‐butene‐1)‐polystyrene block copolymers were prepared by reaction of the block copolymer in solution with SO2 and C12. Sample compositions ranged up to 7 weight percent sulfur and 29 weight percent chlorine contents as determined by X‐ray fluorescence and infrared spectroscopy. A series of chlorosulfonated derivatives of an analogue of the elastomeric midblock were prepared and analyzed in similar fashion. A comparison of dynamic mechanical and dielectric behavior of solvent cast films of the block copolymer and midblock polymer materials indicates the existence of sulfonyl chloride dipole‐dipole complexes in the solid state. Further evidence for the presence of such aggregates was obtained from analysis by Fourier‐transform infrared spectroscopy. It appears that polystyrene domains in the block copolymer materials hinder this aggregation up to moderate concentrations of the sulfonyl chloride group as compared with the relatively unrestrained aggregate formation in the analogue midblock materials. At high levels of substitution, the formation of dipole aggregates disrupts the integrity of the polystyrene domain structure in the block copolymer materials, resulting in a reduction in mechanical strength.
Effects of coupling agents on the mechanical and rheologica properties and mica‐reinforced polypropylene
Authors: Boaira M. S. , Chaffey C. E. 
Published: December 2004

AbstractDimethylaminoethyl methacrylate (DMAEMA) was investigated as a prospective coupling agent for mica‐reinforced polypropylene. Composites prepared with the widely‐used silane coupling agent, N‐(4‐vinylphenyl) methyl‐N′‐(3‐trimethoxysilylpropyl)ethylenediamine monohydroehloride (Z‐6032), were compared with the amino‐coupled composite. Improvements in the flexural properties at room temperature were observed with the two coupling agents: a 22 percent increase in the strength with the silane compared to a. 16 percent increase with DMAEMA. Cone‐and‐plate viscometry at 220°C showed that the addition of coupling agents greatly, reduces the viscosity of the composite: a 50 percent decease was obtained with the silane‐treated composite and a 20 percent decrease with DMAEMA.
Evaluation of processing factors on turning of thermoplastics
Authors: Roy P. K. , Basu S. K. 
Published: December 2004

AbstractExperiments were carried out to study the effects of cutting speed, feed, depth‐of‐cut and tool‐nose‐radius on the cutting force and surface roughness produced during turning of the thermoplastics Nylon‐6 and Teflon. Generalized equations for the cutting force and surface roughness in terms of processing factors have been established using the statistical technique of multiple regression analysis. The equations have been tested for acceptability by the F‐test and the degree of significance of various factors has been assessed by the t‐test.
Correlations for zero‐shear and shear‐rate dependent viscosity of polymeric solutions
Authors: Chitrangad B. , Osmers H. R. , Middleman S. 
Published: December 2004

AbstractSolution viscosity is known to be sensitive to the nature of solvent and the polymer concentration. The magnitude of such effects, however, is not quantitatively understood. Correlations to predict zero‐shear and shear‐rate dependent viscosity of polymer solutions from polymer solution parameters are presented. Polymer domain volume is found to be the controlling parameter for the zero‐shear viscosity of dilute polymer solutions, that is solutions with insignificant entanglements. At higher concentrations, where polymer‐polymer interactions become significant, it is found that, except for the magnitude of the solvent viscosity, the nature of the solvent is of no consequence. In this region zero‐shear viscosity is correlated as a function of the parameter cM5/8, where C and M represent concentration and molecular weight, respectively. A relaxation time such as Bueche's time constant satisfactorily represents the solvent effects on the non‐Newtonian behavior of polymer solutions by incorporating the measured zero‐shear and solvent viscosities.
Flow and heat transfer in the nozzle of an injection molding machine
Authors: Nunn R. E. , Fenner R. T. 
Published: December 2004

AbstractWhen a polymer melt is forced through the nozzle of an injection molding machine, the material temperature increases significantly. This increase, which is very difficult to measure, is not uniform and local temperature peaks may cause thermal degradation. A method is described for the analysis of timedependent heat transfer and flow in such nozzles. Melts are treated as being inelastic but with viscosities which are nonNewtonian and dependent on both temperature and pressure. Distributions of velocity, temperature and pressure are obtained with the aid of a finite difference method for solving the differential conservation equations' of continuum mechanics. Typical results show that the times required to reach steady flow conditions are small compared with total injection times. Heat transfer is predominantly convective, and flows leaving injection nozzles and entering molds are very far from being thermally fully‐developed.
Effect of cross‐linking on hydrostatic creep of epoxy
Authors: Findley W. N. , Reed R. M. 
Published: December 2004

AbstractSamples of epoxy having three different degrees of crosslinking were subjected to several constant values of hydrostatic pressure ranging from 1000 psi to 80 ksi. Each period of constant pressure was followed by a period at atmospheric pressure. A continuing decrease in volume (creep), as measured by axial strain at constant pressure, was observed for pressures of 10 ksi and greater. The creep strain was recovered immediately upon pressure removal. Reapplication of pressure after a short period at atmospheric pressure resulted in the same creep behavior as that resulting from the first pressure. The least cross‐linked epoxy had the smallest creep rate and the smallest compressibility. These observations are consistent with the view that the leapt cross‐linked epoxy would be the most compact and have the least voids at points of cross‐linking.
Experimental characterization of the alignment of short fibers during flow
Authors: Murty Karra N. , Modlen G. F. 
Published: December 2004

AbstractAn experimental approach has been made to investigate and characterize the alignment of short fibers contained in a suspension, during flow of the suspension through a convergent channel. Flow patterns have been obtained and analyzed for suspensions of various fiber concentrations. The influence of parameters such as fiber length, volume fraction and viscosity of the carrier medium on the degree of fiber alignment, has been examined. In order to minimize jamming, the viscosity of the carrier medium must be larger than a certain critical viscosity that is dependent on fiber length and volume fraction.
Correlation of normal stresses in polystyrene melts and its implications
Authors: Oda Kunio , White James L , Clark Edward S. 
Published: December 2004

AbstractIt is found that the principal normal stress difference, N1, in commercial polystyrene melts is a unique function of shear stress σ12, independent of temperature and molecular weight, An empirical expression representing this relationship is developed. The functional dependence reported does not represent data for narrow molecular weight distribution polystyrenes, generally significantly overpredicting N1 values. The basis for this behavior is discussed. The implications of the N1 − σ12 relationship to some rheological and processing problems are described.
Properties of a polyamide thermoplastic based on 2,2‐bis‐(4‐aminocyclohexyl)propane
Authors: Hill H. Wayne , Campbell Robert W. , Shuk Robert S. 
Published: December 2004

AbstractThe structure and properties of an unusual new polyamide copolymer derived from 2,2‐bis‐(4‐aminoeyclohexyl)propane and a 60/40 molar mixture of azelaic and adipic acids are described. The alicyclic diamine structure, with its cyclohexyl rings and central gem‐dimethyl group, contribute to chain stiffness and amorphous character in the polyamide, and sets it apart from more common polyamides (e.g., nylon 6–6) with their relatively flexible polymer chains, low glass transition temperatures and high levels of crystallinity. The particular combination of dicarboxylic acids employed yields a resin with a high glass transition temperature (185°C). This amorphous, colorless material is exceptionally transparent, with a high luminous transmission (92 percent) and low haze (0.5 percent). The polymer is tough and resistant to scratching and abrasion and to attack by chemicals and solvents. Its high glass transition temperature leads to a high heat deflection temperature (160°C) and excellent retention of its mechanical properties at elevated temperatures. It is an atypical nylon in that its dimensions, mechanical properties and electrical properties are relatively unaffected by changing moisture content.
The effect of glass‐resin interface strength on the impact strength of fiber reinforced plastics
Authors: Yeung Peter , Broutman Lawrence J. 
Published: December 2004

AbstractThe effect of glass‐resin interface strength on the impact energy of glass fabric (style 181) reinforced epoxy and polyester laminates has been determined. The interface strength was altered by surface treatment of the fabrics with silane coupling agents and with a silicone fluid mold release and the interlaminar shear strength was determined as a means to evaluate the interface strength. An instrumented Charpy impact test was used on unnotehed specimens and thus both initiation and propagation energies could be determined as well as dynamic strength. It was found that the initiation energy for both polyester and epoxy laminates increased with increasing interlaminar shear strength, The propagation energy and thus the total energy for polyester laminates displays a minimum at a critical value of interlaminar shear strength (ILSS). Below this critical value, the total impact energy increases with decreasing shear strength and the dominant energy absorption mode appears to be delamination. Above the critical value, the impact energy increases with increasing values of ILSS and the fracture mode is predominantly one of fiber failure. In all cases, even with mold release applied, the shear strength of epoxy laminates was above this critical value and‐thus the total impact energy increases with Increasing values of ILSS. The maximum energy absorbed for the epoxy laminate and the polyester laminate is nearly identical. However, the maximum for the epoxy laminate occurs when the shear strength is maximized while for the polyester laminate the shear strength must be minimized. For the polyester laminate when delamination is predominant, it was found that the glass surface treatment affects the amount of delamination as opposed to the specific value of delamination fracture work.