摘要:

AbstractThis series of papers summarizes the results of an experimental research program designed to establish the effects of preexisting orientation and crystallinity on the solvent‐induced crystallization of poly(ethylene terephthalate) films. Dimethylformamide was used as a model for a strongly interacting solvent. This paper deals with the morphological and structural modifications induced by the solvent crystallization process. The effects on the structure and morphology of the solvent crystallization were dominated by surface cavitation, creation of voids, and by changes in the degree of crystallinity. The surface structure varied from a spherulitic cavitated structure for films of low orientations (low draw ratios) to a smooth surface at the higher draw ratios. In addition to the change in the surface morphology, an internal void structure was formed due to crystallization taking place in a swollen state. The formation of voids is dependent on the treatment temperature, draw ratio, and the method of solvent removal. The voids collapse upon annealing at high temperatures. Increases in the degree of crystallinity and changes in orientation were dependent on the treatment temperature. The crystallite size goes through a maximum at an intermediate degree of orientation. The crystalline orientation decreases with increasing treatment temperature. The structures formed during solvent treatments did not show any characteristic premelting endotherms at the low draw ratios. In the case of higher draw ratios, a small premelting endotherm was noticeable at a temperature 70°C greater than that of the solvent treatme

ISSN:0021-8995    

DOI:10.1002/app.1982.070270301

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThe effect of the ionic strength of the solvent on the size‐exclusion chromatography of narrow molecular weight dextrans and monodisperse sodium polystyrene sulfonates has been investigated. In both NaOH and NaCl solutions the elution volume of the sodium polystyrene sulfonates increased as the ionic strength was increased, while the elution volume of the dextrans decreased slightly as the ionic strength was increased. The elution data for various ionic strength solvents could not be described by the traditional universal calibration procedure of plotting the product of the intrinsic viscosity and the molecular weight vs. the elution volume. By using a modified calibration procedure which includes excluded volume effects, the elution data can be described for NaOH solution of moderate and high ionic strength. This modified calibration technique was unable to describe the elution data for very low ionic strength NaOH solutions and for the NaCl solutions. Possible explanations of the inability of straightforward size exclusion chromatographic calibration techniques to quantitatively described all the observed elution behavior are discusse

ISSN:0021-8995    

DOI:10.1002/app.1982.070270302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

Abstractp‐Vinylbenzoylacetone (VBA) was prepared by the condensation ofp‐vinylacetophenone and ethyl acetate. This monomer was homopolymerized and copolymerized with acrylamide or maleic anhydride to produce polymers which would chelate substantial amounts of transition metal ions such as Cu2+, Ni2+, Co2+, Eu3+, and VO2+. In the case of the Cu2+and Ni2+chelates, about 80–90% of the metal ion could be eluted by dilute mineral acids. The resulting eluted products apparently have a somewhat porous structure because they are capable of rechelating these ions from water solution, even though the solid homopolymer which had not been chelated and eluted is too hydrophobic to chelate very much metal ion from water solution. The eluted Cu2+chelate readily reaccepted Cu2+ions from water solution and discriminated against Ni2+almost completely. However, the eluted Ni2+chelate would reaccept both Cu2+and Ni2+ions, but exhibited a strong preference for Cu2+ions in competitive batch experiments. The VO2+chelate was an effective heterogeneous phase catalyst for the epoxidation of allyl alcohols such as geraniol with tert‐butylhyroperoxide. The chelate was stable under these oxidative conditions and could be recovered unchanged and

ISSN:0021-8995    

DOI:10.1002/app.1982.070270303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractElastomers are widely used in drilling and logging applications as static seals such as casing packers and dynamic seals such aso‐rings for drill bits. Static seals often fail in service because of thermochemical degradation due to the combined effects of steam and sour gas at elevated temperatures that are characteristic of deep wells. Dynamic seals frequently fail because of abrasive wear that occurs even at the low temperatures that prevail in shallow wells. We have shown that improved steam–sour gas resistance of a fully formulated ethylene–propylene rubber at elevated temperatures can be achieved by coating the rubber with a thin film of plasma polymerized tetrafluoroethylene. Thus, no change in the mechanical properties of the coated rubber was observed after exposure to steam and sour gas at 275°C for 48 h. In contrast, the shear modulus of the uncoated rubber increased by 96% after the same exposure. While the effectiveness of the fluorocarbon coating decreased at longer exposure times, short‐term protection of elastomers could be beneficial in certain logging operations. It was also found that the coefficient of friction of a nitrile rubber (Buna N) was reduced by 20% after treatment with a carbon tetrafluoride plasma. This enhanced lubricity could lead to better wear characteristics in conventional drill bits where the seal is in contact with a moving metal surface. The surfaces of the plasma treated elastomers were characterized by water contact angle, scanning electron microscopy, and electron spectroscopy for chemical

ISSN:0021-8995    

DOI:10.1002/app.1982.070270304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractBlends of the polyhydroxy ether of bisphenol‐A, Phenoxy, with the polyesters poly(1,4‐butylene adipate), poly(ethylene adipate), poly(2,2‐dimethyl‐1,3‐propylene succinate), poly(2,2‐dimethyl‐1, 3‐propylene adipate), poly(1,4‐cyclohexane‐dimethanol succinate), and poly(ϵ‐caprolactone), are found to exhibit the single, composition‐dependent glass transition temperatures characteristic of miscible systems. Phenoxy blends containing poly(ethylene succinate), poly(hexamethylene succinate), or poly(pivaloactone) were found to be immiscible. Blend interaction parameters, obtained from analysis of the melting‐point depressions observed for miscible blends containing crystallizable polyester components, are found to vary with polyester chemical structure so as to suggest an optimum density of ester groups in the polyester chain for achieving maximum interaction with Phenoxy. Too many or too few ester groups lead to immiscibl

ISSN:0021-8995    

DOI:10.1002/app.1982.070270305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThe recovery of indan derivatives from polystyrene waste for the purpose of efficient utilization of plastic wastes was studied. An attempt was made to construct the apparatus, in which thermal decomposition of polystyrene and catalytic reaction of its decomposition products over silica–alumina catalyst could be controlled continuously at the same time. The reaction temperature for thermal decomposition of polystyrene in the upper part of a reactor tube was 420°C, while that for catalytic reaction of the thermal decomposition products in the bottom of a reactor tube was 300°C. These results indicated that the composition of thermal decomposition products of polystyrene could be controlled by the use of a flow reactor. The indan derivatives recovered were two 1‐methyl‐3‐phenylindans, one 1‐methyl‐1‐phenylindan, and 1‐phenylindan. The yields of these indan derivatives were 20% of the weight of the liquid products recovered. On the basis of the results obtained in the present work, the most suitable reaction conditions to recover indan derivatives from polystyrene w

ISSN:0021-8995    

DOI:10.1002/app.1982.070270306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractCotton fabric was crosslinked with DMDEU by applying the Form D‐Process and Form W‐Process. The cotton and crosslinked cotton were then treated with caustic soda solution of mercerizing strength. The ability of cotton and crosslinked cottons to dyeing with two reactive dyes, viz. Procion Blue MRB and Procion Red HB was examined. It was found that crosslinking reduces significantly the amenability of cotton to reactive dyes particularly when the Form D‐Process was applied. Mercerization enhances dyeability of all substrates, but the enhancement was much greater in the case of noncrosslinked cotton. Based on dyeing and other properties such as tensile strength, elongation at break, and crease recovery, it was shown that crosslinking decreases considerably the affinity of cotton to caustic soda solution. It was further anticipated that different color designs with different patterns and properties can be conferred on a given cotton fabric by making use of local crosslinking and/or mercerizing followed by d

ISSN:0021-8995    

DOI:10.1002/app.1982.070270307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractA thorough study of the shape and size of plastic zones developed around cracks subjected to combined opening‐mode and sliding‐mode loading conditions in glassy polymers under small scale yielding was undertaken. Two pressure‐modified von Mises yield criteria which take into account the characteristic behavior of glassy polymers expressed by the dependence of their yield locus on the hydrostatic stress component and the difference in their tensile and compressive yield stresses were used. The case of an infinite plate subjected to a uniaxial uniform stress at an arbitrary inclination with respect to the axis of the crack was considered. From the whole study useful results concerning the dependence of the shape and size of plastic zones on the crack inclination angle, the Poisson's ratio, and the ratio of the compressive to tensile yield stress of the plate were de

ISSN:0021-8995    

DOI:10.1002/app.1982.070270308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThe curing of novolacs with paraformaldehyde is analyzed with several experimental techniques (DSC, IR, sol fraction) as well as statistical arguments. Results for typical novolacs show that a maximum crosslinking density is attained at a mass ratiomP/mNclose to 0.20. However, atmP/mNgreater than 0.10, hemiformals appear in the cured product, increasing the amount of extractable formaldehyde. The heat of reaction increases linearly frommP/mN= 0 to 0.15, attaining a maximum value of −ΔH= 98 cal/g novolac atmP/mN∼ 0.20. The curing kinetics follows an overall second‐order law with an activation energyE= 32.5 kcal/mol and a preexponential factorA= 1.1 × 1015min−1(both form

ISSN:0021-8995    

DOI:10.1002/app.1982.070270309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractDyeing of synthetic fibers by the heat transfer process of disperse dye vapors is performed by contacting white receptor polyester or polyamide fabric with other dyed polyester fabrics (donor) under the influence of heat. The dye vapours flowing away will diffuse across the very slight air gap enclosed between the inner donor and receptor surfaces under the applied pressure. It is found that the dye uptake by the receptor fabric is dependent on the original dye content of the donor fabric, transfer temperature and dwell time. The released dye from the donor fabric under the influence of heating is found to be dependent on the original dye content of the donor fabric as well as the transfer temperature. The efficiency of the dye transfer is also attributed to the original shading of the donor fabric. Evaluation of the imparted colors on the receptor fabric (polyester, polyamide) obtained by heat contact with the same donor fabric showed visually the same colour level up to the 13th run. Thermodynamic interpretation of the standard affinity (Δu0) and heat of dyeing (ΔH0) as well as the partition coefficient of the dye show that the dyeing process has an exothermic character. The rate controlling step in this dyeing process is found to be dependent on the diffusion of the dye vapors into the fiber phas

ISSN:0021-8995    

DOI:10.1002/app.1982.070270310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY