摘要:

AbstractA photografting method has been developed to surface treat aromatic polyamide fabrics in the presence of fluoroolefin vapors. The new fabrics are more flame resistant in oxygen‐enriched environment than untreated commercial aramid fabrics. The photoaddition reaction of haloolefins has been shown to irreversibly modify the fabrics, which were analyzed by water wettability, scanning electron microscopy, x‐ray analysis, and19F nuclear magnetic resonance spectrosc

ISSN:0021-8995    

DOI:10.1002/app.1977.070211001

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

年代:1977

数据来源: WILEY

摘要:

AbstractIn order to use ligand exchange resins for chromatographic resolution of racemic compounds, two series of asymmetric sorbents were prepared by attachment of various optically active α‐amino acids onto crosslinked polystyrene. Chloromethylated and chlorosulfonated styrene–divinylbenzene copolymers were prepared and then treated with α‐amino acids. Results show that reaction of α‐amino acids with polystyrene could be carried to a substitution of 15% to 40% of the aromatic rings depending on many parameters. Stable copper(II) complexes of the asymmetric resins were prepared. Potentiometric methods were adapted to the case of insoluble materials such as resins. These methods indicate that bis‐chelate complexe

ISSN:0021-8995    

DOI:10.1002/app.1977.070211002

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

年代:1977

数据来源: WILEY

摘要:

AbstractAn improved technique for the precision measurement of dynamic mechanical properties of viscoelastic materials is described. The instrumentation has been adapted for use with commercial device Rheovibron, but can be used with any other similar device. An analysis of the technique, together with typical results, are presented. Analyses of error are included in the appendices.

ISSN:0021-8995    

DOI:10.1002/app.1977.070211003

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

年代:1977

数据来源: WILEY

摘要:

AbstractAcrylic acid anhydride (AAA) and tetreathylene glycol dimethacrylate (TEGDM) were employed as labile and permanent crosslinking monomers for poly(ethyl acrylate), respectively. Upon partial or total hydrolysis of the AAA crosslinks, various states of viscoelastic creep and stress relaxation were brought about. The use of chemically active monomers for crosslinking permits new polymer structures to be synthesized. In this case, decrosslinking converts a thermoset polymer into its thermoplastic counterpart. The relationship between the present decrosslinking study and a new nomenclature theory of grafted and crosslinked polymers is explored.

ISSN:0021-8995    

DOI:10.1002/app.1977.070211004

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe melting temperature of polyethylene was determined at pressures up to 30 kbar. Using these results and the calculated values of the volume change on melting in the Clausius–Clapeyron equation, the enthalpy and entropy of fusion as a function of pressure were also determine

ISSN:0021-8995    

DOI:10.1002/app.1977.070211005

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

年代:1977

数据来源: WILEY

摘要:

AbstractA model that relates to the molecular weight distribution (MWD) of high‐density polyethylene to the steady‐state shear melt viscosity has been applied to polystyrene melts. Relations are developed for predicting the rheological flow curve from the molecular weight distribution. Relationships are also developed to predict the MWD from the flow curve, although practical limitations to this procedure are given. From a consideration of predictions of the model and experimental data, it is concluded that the transition for a given molecular species from Newtonian to non‐Newtonian flow is sharp. Additionally, the calculated empirical parameter that partitions the MWD into molecules that act in a Newtonian fashion and those that do not is shown to be equivalent to the largest molecular weight homolog that can still undergo Newtonian flow at a given shear rate for monodisperse fractions. The temperature dependence of the relaxation times is found to be somewhat higher than that predicted by the Rouse theory. An activation energy of 30 kcal/mole for η0 was used to fit the experimental viscosity data adequately at 190° and 225°C. The terminal relaxation spectrum for a narrow‐MWD polystyrene standard is calculated and found to agree well for long relaxation times with that reported in the

ISSN:0021-8995    

DOI:10.1002/app.1977.070211006

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe thermomechanical behavior of poly(vinyl chloride) (PVC) was investigated during its thermal degradation by using torsional braid analysis. In thermomechanical behavior as a function of temperature, the relative rigidityGrdecreased initially with increasing temperature, then began to increase passing through a minimum at about 200°C, and finally decreased at 340°C. Increase inGrfrom 200°C was caused by formation of a conjugated polyene chain accompanied by dehydrochlorination and by crosslinking reaction, and decrease inGrat 340°C was related to scission reactions of the crosslinking network by oxidation. In the change in logarithmic decrement Δ, three peaks were observed: at 90°C, coinciding with the glass transition of the polymer; at about 200°C, due to the melting transition of crystallites, and at about 300°C, due to a loss of mechanical energy in the rheological transition of the polymer from a liquid state to a glassy state passing through a viscoelastic region. The thermomechanical properties of PVC with different molecular weights were also measured, and the effect of molecular weightGrand Δ are discussed. In isothermal measurements of the relative rigidity in air, exponentially increasing curves were observed as a function of time. These curves were analyzed kinetically as a first‐order reaction, and an activation energy of 22.7 kcal/mole wa

ISSN:0021-8995    

DOI:10.1002/app.1977.070211007

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

年代:1977

数据来源: WILEY

摘要:

AbstractA study has been conducted to determine the effects of flow configuration and reaction conditions on the performance of composite reverse osmosis membranes prepared by plasma polymerization of allylamine over a porous polymer substrate. It was established that superior membranes were obtained by using a gas‐flow configuration avoiding direct monomer flow over the substrate. High rejections of NaCl could be attained when the plasma‐deposited film was sufficiently thick to bridge all of the pores in the substrate. It was observed that in addition to influencing the rate of polymerization, the conditions used to sustain the plasma also affected the reverse osmosis characteristics of the deposited film. The effects of these conditions and other preparation procedures are discussed. Attempts to use infrared spectroscopy and ESCA to identify the relationship between polymer structure and reverse osmosis performance were not successful. ESCA did prove useful, though, in confirming an earlier postulated hypothesis that degradation of reverse osmosis performance is associated with the hydrolysis of nitrogen‐containing structures in the plasma‐deposit

ISSN:0021-8995    

DOI:10.1002/app.1977.070211008

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

年代:1977

数据来源: WILEY

摘要:

AbstractBlends of high‐impact polystyrene with decabromodiphenyl oxide and/or antimony trioxide were characterized by thermogravimetry. The observed weight loss for the blends was compared with a calculated weight loss which was determined from a weighted sum of the weight loss of the individual materials in the blend. This comparison of observed and calculated weight loss provided a method to determine if condensed‐phase reactions occur among the materials in the blend. Definite evidence for condensed‐phase reactions was observed when polybutadiene (impact modifier), decabromodiphenyl oxide, and antimony trioxide were present simultaneously. In that case, the observed weight loss exceeded the calculated weight loss above 330°C. When one of the three materials was absent, the observed weight loss was less than or equal to the calculated weight loss. The condensed‐phase reactions involving polybutadiene, decabromodiphenyl oxide, and antimony trioxide occurred in nitrogen as well a

ISSN:0021-8995    

DOI:10.1002/app.1977.070211009

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

年代:1977

数据来源: WILEY

摘要:

AbstractA kinetic equation was derived for the radiation‐induced polymerization of styrene under the assumption that both radical and cationic polymerizations take place concurrently throughout the whole range of the dose rate of radiation and the water content of the styrene. The equation enables one to calculate rates of the total, radical, and cationic polymerization at a given dose rate and water content and agrees satisfactorily with experimental results, which cover dose rates from 4.2 × 10 to 2.1 × 105rad/sec and water contents from 3.2 × 10−3to 3.5 × 10−2mol/l. Experimental estimation of the contribution of radical and cationic mechanisms was done by GPC curves of polymers obtained under various conditions. When the contribution of ionic mechanism is expressed in weight percent, it changes from 0% to 100% in the range of the experiment; on the other hand, if it is expressed in mole percent, it is independent of the dose rate and remains constant throughout the whole range of the e

ISSN:0021-8995    

DOI:10.1002/app.1977.070211010

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

年代:1977

数据来源: WILEY