bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dipole moments and molecular structure of copolymers IV: Study of methyl acrylate‐methyl methacrylate copolymers
Authors: Kotera Akira , Shimomura Kazuko , Shima Mikiko 
Published: June 2010

AbstractThe dielectric properties of methyl acrylate‐methyl methacrylate copolymers in benzene solutation have been measured, and it was found that the value of the average orientation polarization, Po, Av. of a monomer unit in the copolymers increases with an increase in the methyl acrylate content of the copolymers, e.g. from 37.4 cc. (for the copolymer in which the mole fraction of methyl acrylate, x, is 0.0605) to 40.9 cc. (for the copolymer in which x is 0.788) at 20°C. A theoretical treatment concerning the relation between the average orientation polarization and the detailed structure of a polar‐polar copolymer has been developed, and the variation in value of PoAv. of the copolymer has been discussed in view of the detailed arrangement of monomer units in the copolymer molecule.
Supermolecular organization of as‐spun fibers form melts of crystalline polyolefines
Authors: Baranov V. G. , Volkov T. I. , Farshyan G. S. , Frenkel Ya 
Published: June 2010

AbstractWhen polymers are converted into films or fibers, the crystallizing melt is subject to considerable jet stretching and the cooling of the melt proceeds under complex temperature conditions. The occurrence of the temperature and the rate gradients can profoundly affect the tupermolecular organization of the final polymer system. The investigation of the supermolecular organization of polyethylene and polypropylene fibers and films shows that practically in all cases the polymer contains spherulites elongated transversally to the direction of the stretching of the crystallizing melt. The value of the spherulite radius and the degree of its flattening are definitely associated with quite different components of the formation process. Thus, the value of the spherulite radius is inversely porportional to jet stretching, while the change in temperature conditions (e.g. the melt temperature or the cooling conditions) shift the hyperbolae R = f(ϕ) downwards or upwards. The factors Musing the formation of flattened spherulites are analyzed. Probably in the case of thin fibers the major factor is the occurrence of the two temperature gradients while in the case of films it is the mechanical field of the longitudinal rate gradient.
Steady‐state flow properties of poly(ethylene terephthalate) melts
Authors: Gregory D. R. , Watson M. T. 
Published: June 2010

AbstractSteady‐state flow properties of poly(ethylene terephthalate) melts as a function of Temperature (T), shear rate (γ), and inherent viscosity (I.V.) were determined. An Instron capillary rheometer was used to obtain data on wall shear stress (τW) vs. γ for poly(ethylene terephthalate) (PET) at temperatures of 265 to 295°C. The polymer samples investigated covered an inherent viscosity range of 0.35 to 0.82, corresponding to a weight‐average molecular weight range of 23,000 to 70,000. Capillaries used in this investigation covered the range of 10 to 67.5 in length/diameter (L/D) values. End‐effect corrections (n) estimated by Bagley's method were small with n < 1 over the entire shear rate range covered (50–24,000 sec.−1). Flow curves showed (1) that over the shear rate range of about 50 to 1000 sec.−1, the flow behavior of PET was nearly Newtonian, i.e., log‐log plots of τW vs. γ were linear with slopes of about 1, and (2) that over the shear rate range of 1000 to 24,000 sec.−1, the flow behavior of the polymer was slightly pseudoplastic. Using Mendelson's shear rate‐temperature superposition scheme with an additional shifting to a single reference I.V. level, we were able to shift all the data to a single master curve of log (aTb τ γ), where aT and b are the shift factors for temperature and molecular weight, respectively.
Specific volume and viscosity of polyolefin melts
Authors: Rudin A. , Chee K. K. , Shaw J. H. 
Published: June 2010

AbstractA simple, inexpensive method is described for the measurement of specific volumes of thermoplastic melts during extrusion at low shear stresses. Data for several polyolefins agree closely with specific volumes obtained by dilatometry or compression measurements on static melts. Data can be obtained at a variety of temperatures more rapidly than by dilatometry. The method described yields specific volumes essentially at atmospheric pressure, but extension to higher pressures and the measurement of compressibilities is possible, with more complicated apparatus. Simultaneous measurements can be also made of apparent shear rates, and these can be converted to absolute shear rates, and viscosities, by application of standard techniques. The simple procedure described does not permit the concurrent measurement of useful apparent shear and volume viscosities because the initial state of the system reflects operational as well as polymer properties. It is suggested that an extension of the present method would provide such data.
Untersuchung von vinylpyridinium‐verbindungen. I. IR‐ und nmr‐spektroskopische untersuchung
Authors: Mielke I. , Ringsdorf H. 
Published: June 2010

Abstract3‐ and 4‐vinylpyridinium compounds were prepared and investigated by infrared and NMR‐spectroscopy. The spectroscopic data can be used to explain the polymerization behavior of the monomers.
Distribution of ultraviolet stabilizers in crystalline polypropylene
Authors: Frank H. P. , Lehner H. 
Published: June 2010

AbstractThe distribution of Tinuvin 328 [2‐(2′‐hydroxy‐3,5′‐di‐tert‐amyl phenyl)benzo‐triazole] in isotactic polypropylene was studied by means of ultraviolet microscopy. Whereas Tinuvin 328 is uniformly dispersed in noncrystalline polypropylene (atactic or molten isotactic polymer) a certain distribution pattern is generated in the course of crystallization; the details of this pattern depend on a number of factors such as rate of cooling, fraction of noncrystalline polymer, etc. The main feature of the distribution pattern is that Tinuvin 328 is accumulated in the noncrystalline regions within and between polypropylene spherulites and rejected by crystalline regions.
The influence of structure and other factors on molecular motions in solid polymers from 4°K TO 300°K
Authors: Sauer J. A. 
Published: June 2010

AbstractSemicrystalline, as well as amorphous, polymers frequently develop some measure of molecular mobility at temperatures well below their melting temperature, Tm, or their glass transition temperature, Tg. In these polymers, one or more damping or internal friction peaks are usually found to occur in the low temperature region from 4°K to 300°K. The magnitude, and temperature position, of these maxima are dependent upon the structure of the polymer, its mode of preparation and past history, and the local environment of the moving units. For purposes of discussion, the observed relaxation processes may be classified, on the basis of their temperature location at low measuring frequencies (∼1 Hz) as δ‐processes, those occurring below 80°K; γ‐processes, those occurring in the temperature range from 80°K to about 240°K; and β‐processes, those occurring from about 200°K to above 300°K. Various examples will be given of polymers that show significant δ, γ, and β‐processes and the influence of structure, structural substitution, crystallinity and low molecular weight diluents will be illustrated.The extent to which relaxation behavior can be correlated to macroscopic ductility and fracture toughness is discussed. It is noted that the lowest temperature δ‐relaxations arise primarily from reorientational and/or wagging motions of pendant methyl, ethyl, and phenyl side chains and, as such, have little bearing on macroscopic impact strength. The intermediate temperature γ‐processes arise from reorientational motions, of short side chain sequences or from local motion of main chain sequences. Some degree of main chain mobility. appears to be an essential requisite if ductility and toughness are to be realized. The higher temperature β‐processes in the 200°K t o 300°K range arise from motion of polar side groups, from motion of short chain sequences involving water complexes, or from large‐scale motions associated with the Tg of the amorphous regions. In the latter instance, the β‐process i s accompanied by a large increase in ductility and impact strength and this feature is utilized in polyblends and copolymers to raise the fracture toughness of otherwise brittle polymers.
Effect of tension and temperature on crystalline polymer texture
Authors: Station W. O. 
Published: June 2010

AbstractA variety of annealing treatments at elevated temperatures have been characterized by a specific infrared absorption assigned to the folded chain segments in polyethylene terephthalate fibers. The higher the annealing temperature, the more regular is the chain folding introduced into the fiber. When a fiber is free to contract, it will have a much larger amount of refolding than one which is held at constant length. Stretching is able to prevent refolding at low temperatures but in these experiments stretching was not able to prevent refolding at the highest temperature.By comparing the above infrared results with small angle X‐ray diffraction and broadline nuclear magnetic resonance techniques, it is now possible to give validity to the interpretation that chain folds are major contributors to the long period.The external tension applied to a fiber during an annealing treatment will determine the internal shrinkage tension caused by the molecules during subsequent reheating. If chain refolding is allowed to occur during annealing, the potential for subsequent shrinkage and the amount of internal shrinkage tension are lowered, and higher temperatures are required to activate additional shrinkage. It thus appears that a major contributor to shrinkage and shrinkage tension in an oriented fiber is the refolding of molecules during thermal activation.
Thermodynamic properties of liquids, including solutions. III. Solutions of polymers, especially poly(viny chloride)
Authors: Huggins Maurice L. 
Published: June 2010

AbstractA new theory of solution thermodynamics is outlined. The energy and enthalpy are related to the contacting areas of the chemically different kinds of molecular segments, the energy per unit contact area for each kind of contact, and an equilibrium constant. Departures of the entropy of mixing from the classical Raoult's law relationship result from differences in the volumes of solvent and solute molecules, from departures from perfect randomness of mixing, and from the concentration dependence of the orientational randomness of the bonds in the molecules. Simple equations for these relationships have been tested. Quantitative agreement is usually obtained.Examples are given of applications of the theory to polymer solutions. Application to poly(vinyl chloride) solutions has not yet been made, but the appropriate procedures and methods for determining the parameters are discussed.
Studies on the initiation of the emulsion polymerization of vinyl chloride
Authors: Liegeois J. M. 
Published: June 2010

AbstractIn another paper it was shown that the decomposition reaction of persulphate is equilibrated, and the initial rate of decomposition in a borax buffered solution was determined. Here we have measured the decomposition rate of persulphate in the presence of vinyl chloride at a pressure lower than the vapor pressure. It is found that the initiation which takes place in the aqueous phase proceeds at a rate equal to the initial rate of decomposition found without vinyl chloride. Experiments were done at two different pH and we found an increase of both the decomposition rate and the rate of reaction of vinyl chloride from pH 13 to pH 9.
Effect of initiator end groups and trichlorethylene units on the dehydrochlorination of solution polymerized poly(vinyl chloride)
Authors: Park G. S. , Skene C. L. 
Published: June 2010

AbstractHigh proportions of initiator end groups are incorporated into poly(vinyl chloride) when the monomer is polymerized in solution. The rate of thermal dehydrochlorination of these polymers increases linearly with the number of initiator end groups and varies with the type of initiator. The effectiveness of the end groups for causing dehydrochlorination is in the ratio, lauroyl peroxide: isopropyl peroxydicarbonate: benzoyl peroxide: azoisobutyronitrile: 9.7:5.8:4.4:1.6. It is suggested that the low stability of the benzoyl peroxide polymer could be due to the incorporation of phenyl groups while primary radical transfer might decrease the stability in the lauroyl peroxide and isopropyl peroxydicarbonate initiated polymers. High conversion polymers have greater stability than low conversion ones. Transfer polymers produced in the presence of trichloroethylene have much lower stability and this is attributed to both copolymerized CHClCCl2 groups and unsaturated end groups.
Branching structure and thermal stability of poly(vinyl chloride)
Authors: Suzuki T. , Nakamura M. , Yasuda M. , Tatsumi J. 
Published: June 2010

AbstractLow molecular‐weight model compounds structurally related to polyvinyl chloride undergo thermal changes in considerably different manners depending on their molecular structures. For example, 3‐chloro‐4‐ethyl‐n‐hexane is far more stable than 3‐chloro‐3‐ethyl‐n‐pentane when heated under nitrogen. This suggests that the type of atom attached to the tertiary carbon at the sites of branching in polyvinyl chloride would play an important role in the thermal degradation of the polymer. Results of the present study using polyvinyl chloride and varieties of model compounds indicate that most, if not all, of the tertiary carbons in the polyvinyl chloride molecules carry hydrogen atoms rather than chlorine atoms. It is furthermore shown that the number of branchings does not affect the thermal stability to any significant extent. It thus seems conceivable that the branching structures of polyvinyl chloride do not contribute to the initiation of the thermal decomposition, at least under the ordinary processing conditions.
New plasticizers for poly(vinyl chloride)
Authors: Zeinalov B. K. , Radzhabov D. T. , Mekhtieva F. A. 
Published: June 2010

AbstractThe results of the research of the synthesis and plasticizing properties of symmetrical and mixed esters of ethyleneglycol (“Plastiazans‐1, 25, and 30”), obtained on the basis of various fractions of synthetic fatty and natural naphthenic acids, and their application in the production of polymeric materials are reported.
Polymerization of vinyl chloride in the presence of chain transfer agents. Ii. Polymerization in the presence of small quantities of propionaldehyde
Authors: Ryska M. , Kolinsky M. , Lim D. 
Published: June 2010

AbstractThe influence of additions of propionaldehyde (0.001–0.1 mole/liter) on the kinetics of a homogeneous polymerization of vinyl chloride in solution at temperatures of 25, 30, and 35°C was investigated. The additions cause an increase of the polymerization rate and an anomalous dependence of the polymerization degrees on the quantity of the transfer agent. The phenomena in question are discussed from the point of view of the capability of propionaldehyde to reactivate the less active types of radicals. Besides the reactivation of primary and monomer radicals, a reactivation of polymer radicals is also considered.
Adsorption characteristics of water‐soluble polymers at aqueous‐organic liquid interfaces
Authors: Glass J. E. 
Published: June 2010

AbstractAdsorption characteristics of water‐soluble polymers, as denoted by interfacial tension measurements, were investigated at aqueous‐organic liquid interfaces via the volume ‐drop and pendant‐drop techniques. Interfacial results obtained from both studies parallel the alkanol adsorption data of Bartell and Davis. If surface tension data are included in the comparison, discrepancies with respect to the alkanol data are observed; macromolecular aqueous solution surface pressures are substantially lower than corresponding interfacial pressures at aqueous‐hexane boundaries. Minute amounts of organic impurities in the air phase effect surface pressures approximate with aqueous‐hexane boundary data. The observations reflect a lesser degree of unfolding and surface occupation at the aqueous‐air interface than at high energy aqueous‐organic boundaries.Poly(ethylene oxide) possesses a random conformation in bulk benzene solutions and a highly ordered structure in aqueous solutions. An inquiry into boundary conformational effects was undertaken via pendant‐drop studies of PEO adsorption at the common interface from both benzene and aqueous phases. Despite different conformations in two media with different solvating characteristics equivalent interfacial pressures were obtained. Interfacial pressure equilibrium attainment was achieved more rapidly from the aqueous phase. Additional hexane‐water and aqueous‐air boundary studies show the faster equilibrium attainment rate to be related more to the ability of the benzene phase to rapidly orient interfacial polymer segments than to conformational effects.
Extrusion degradation of a high molecular weight polystyrene
Authors: Goetze K. Peter , Porter Roger S. 
Published: June 2010

AbstractMechanochemical research has been extended to the study of the magnitude and mechanism for the capillary shear degradation of a narrow distribution and high molecular weight polystyrene (Mw 1,800,000). An Instron Capillary Rheometer was used to perform the experiments over the temperature ranges from 164° to 250°C. The change in molecular weight distribution was evaluated by calibrated gel permeation chromatography. The maximum shear stress employed was 8.8 × 106 dynes/cm2. It was confirmed‐as previously found with a lower molecular weight polystyrene‐that degradation could be induced at high stress at temperatures where it would not occur inclusively due to thermal forces. The activation energy of the shear degradation was +27 kcal/mole with a sign and magnitude consistent with degradation induced principally by thermal forces but distinctly augmented by mechanical energy. For the first time the effect on degradation of capillary entrance angle and reservoir conditions has been examined.
Application of gpc to studies of the viscose process. III. Effect of various treatments of rayon print cloth on the molecular weight distribution of cellulose
Authors: Dyer John , Phifer Lyle H. 
Published: June 2010

AbstractGel permeation chromatography (GPC) has been used to determine the molecular weight distribution of cellulose in rayon print cloths. The fabrics were made from a regular and a high wet modulus rayon with staple length of 1 9/16 inches in an 80 × 80, 31 × 41 singles construction. The effects of various treatments of the print cloths including bleaching exposure to UV and abrading on the yarn properties and the molecular weight distribution were determined.With chemical treatments, the changes in the molecular weight distribution in both warp and fill were similar. The chemical reactions with the fabric immersed in solution were fairly uniform throughout the yarn and in the filaments. In this group, bleaching drastically reduced the average molecular weight.Degradation due to abrasion and flexing was severe. Results indicate that the larger molecules are particularly susceptible to mechanical degradation. The detritus from abrasion of the high wet modulus and the regular rayons had similar, relatively narrow molecular weight distribution.The changes in yarn properties and distribution on washing were primarily the result of mechanical damage. Heating at 400°F for 30 min substantially changed the staining characteristic of cross sections of the yarns. The molecular weight distribution width increased on heating and for these samples, the weight average molecular weight determined from GPC was significantly greater than the value determined viscosimetrically.
Chemi‐mechanical pulping of hardwoods using ammonia vapor
Authors: Peterson R. C. , Strauss R. W. 
Published: June 2010

AbstractPrevious investigations have shown that treatment with gaseous ammonia makes wood into an easily deformable material while in a plasticized condition. In many ways the action of ammonia is similar to water or steam except that it is a more efficient plasticizer. Thus at sufficiently high pressures (100‐150 psig) ammonia not only solvates the lignin, hemi‐cellulose, and amorphous cellulose but enters the crystalline cellulose region as well. Much effort has been devoted to studying the overall plasticization of wood and treated wood properties for whole wood forming applications. The concept of defibering wood while in an ammonia plasticized condition has not been investigated.Conventional wood chips treated with ammonia vapor were fiberized in an Asplund pressurized refiner to produce chemi‐mechanical pulps with properties similar to the conven‐tional cold soda process. When ammonia is used alone the pulps are relatively dark colored. Pretreatment with SO2 vapor improves both the brightness and physical properties of the pulp.The possible implications of this novel processing technique to both high yield and conventional pulping are discussed.
The separation of oligosaccharides on cellulose gels
Authors: Chitumbo K. , Brown W. 
Published: June 2010

AbstractThe synthesis of tightly cross‐linked cellulose gels in bead form is described. Their ability to separate low molecular weight polyethylene oxides as a function of molecular size is demonstrated.With cellulose‐80 and water as eluant, chemisorption was found with the cellodextrins at chain lengths greater than three units. Weak adsorption was found for the xylodextrins and mannodextrins in the comparable size interval. The results suggest that an exact structural correspondence between adsorbent and adsorbate is necessary for the adsorption of oligosaccharides to cellulose.With DMSO as eluant, the separations are determined by a partitioning bearing a direct relationship to the liquid‐liquid partitioning coefficient in thin layer chromatography.
Viscosity and the prolate ellipsoid model applied to low molecular weight cellulose triacetate fractions
Authors: Swenson Harold A. , Carlson John A. , Kaustinen Hilkka M. 
Published: June 2010

AbstractCellulose triacetate of molecular weight 5,600, obtained by acetolysis, and separated into 15 fractions by preparative permeation chromatography, was analyzed for intrinsic viscosity, number average, and weight average molecular weight. Glucose pentaacetate, cel‐lobiose octaacetate, and cellotriose hendecaacetate are also included in the analysis. The axial ratios of a prolate ellipsoid calculated from the viscosity of the low DP CT A fractions, when compared to a molecular model and to the fully extended contour length, confirm the persistence length found by viscosity theory at high molecular weight levels. A long plateau region of slope 0.28 to ca. DP 8, is found in the log‐log [n] versus DPn plot. The curve then rises sharply to slope ca. 2.0 at DPn 10 and declines again to slope ca. 0.9 above DP 30. A close correspondence is found with the hydrodynamic predictions of Peterlin [5, 16] for short‐chain wormlike or inflexible polymers. Plots of R2/DPn versus DPn for CTA and CA show that coil randomness is apparently not achieved before DP 400. No change in viscosity was detectable for CTA of DP 50, when increasing amounts of nonsolvent isopropyl alcohol were added to 1,2‐dichloroethane, short of the precipitation point.
Distribution of substituents in partially acetylated cellulose
Authors: Björndal Håkan , Lindberg Bengt , Rosell Karl‐Gunnar 
Published: June 2010

AbstractThe distribution of substituents in a partially acetylated cellulose (DS 2.4) has been determined. 0‐Acetyl groups were replaced by 0‐methyl groups by using methylsulphinyl sodium and methyl iodide on a product, in which the original free hydroxyl groups had been protected by reaction with methyl vinyl ether. The methylated sugars obtained on acid hydrolysis of this product were converted into alditol acetates and analyzed by GLC‐mass spectrometry.