摘要:

AbstractA method which empolys the linearization of DTA traces is presented for the estimation of kinetic parameters during polymer pyrolysis. By this method, two DTA traces are used, changes in mechanism with conversion may be detected, and it is not necessary to measure areas prior to evaluating activation energy and reaction order. The method is applied to polyethylene, polypropylene, and polystyrene. The agreement between observed and reported values of kinetic parameters is good. Advantages and disadvantages of the method are discussed.

ISSN:0021-8995    

DOI:10.1002/app.1967.070110201

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

年代:1967

数据来源: WILEY

摘要:

AbstractArbitrary cure times and glass transition temperatures are reported for an epoxy resin cocrosslinked by various weight fractions of hexamethylenediamine (HMDA) andm‐phenylenediamine (m‐PLDA). The glass transition temperatures of the epoxy resin systems studied yielded an excellent fit to an empirical equation developed by Dyvik for copolymers. The cure time parameters were found to be a linear function of the weight fractions of each crosslinking agent present. The mechanical properties of the epoxy resins were measured by anin situdynamic modulus technique which employed the use of a resin‐coated metallic subs

ISSN:0021-8995    

DOI:10.1002/app.1967.070110202

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

年代:1967

数据来源: WILEY

摘要:

AbstractData obtained from gaseous sorption isotherms of CO2on eight organic films at three temperatures and three pressures were evaluated for evidences of chemisorption and physical adsorption. The rates of sorption, affected by both temperature and pressure, were analyzed by calculating the perameters of the Elovich equation and those of Barrer's solution of Fick's law for diffusion. Through a consideration of the Elovich parameters, the sorption coefficients, the limiting diffusion coefficients, and the activation energies for diffusion it appears that the rate of interaction of CO2with these organic films is primarily a diffusion‐controlled proces

ISSN:0021-8995    

DOI:10.1002/app.1967.070110203

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

年代:1967

数据来源: WILEY

摘要:

AbstractDifferential thermal analysis has been used to examine the process of dry blending of plasticizer and PVC. The rate of transformation of the glass transition from that of the polymer initially in the cold mix to the glass transition of the blend (blendTg) has been examined at various temperatures from room temperature to above the polymerTg. The dependence on temperature of this rate of transformation of the observedTgis similar to the temperature dependence of the diffusion of plasticizer into PVC. It is concluded that diffusion of plasticizer into polymer particles is the rate‐determining step in the dry blending of PVC. It also appears that a single mechanism of diffusion is involved both below and above the glass transition of the polyme

ISSN:0021-8995    

DOI:10.1002/app.1967.070110204

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

年代:1967

数据来源: WILEY

摘要:

AbstractBy the incorporation of certain types of additives in bisphenol A polycarbonate, the modulus and tensile strength of the films are increased and the elongation is decreased. This effect is called antiplasticization, because the opposite results are obtained on plasticization—decreased modulus and tensile strength and increased elongation. A study of these additives indicated that antiplasticizers are compounds which are comptiable with the polymer and which (1) contain polar atoms such as halogen, nitrogen, oxygen, or sulfur, (2) contain at least two nonbridged rings, (3) have a glass transition temperature greater than −50°C., and (4) have one dimension less than about 5.5 A. in at least 65% of the length of the molec

ISSN:0021-8995    

DOI:10.1002/app.1967.070110205

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

年代:1967

数据来源: WILEY

摘要:

AbstractAntiplasticization is applicable to polymers which contain rigid, polar groups and stiff chains, such as many bisphenol polycarbonates and polyesters, 2,2,4,4‐tetramethyl‐1,3‐cyclobutanediol polycarbonates and polyesters, cellulose triacetate, and a commercial poly(sulfone ether). The stiffness, hardness, and tensile strength of these polymers are increased by antiplasticizers, and the elongation, impact strength, and heat‐distortion temperature are decreased. The stiffness of antiplasticized polymers can be further increased by crystallization. A clear, hard, stiff, tough, self‐extinguishing molding plastic with good electrical properties and improved resistance to stress cracking is obtained by antiplasticizing bisphenol A polycarbonate with 20% Aro

ISSN:0021-8995    

DOI:10.1002/app.1967.070110206

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

年代:1967

数据来源: WILEY

摘要:

AbstractThe extent of photolysis of the surface of an elastomer may be characterized semiquantitatively by utilizing the physical model of a two‐ply stressed beam. A brief mathematical exposition is given. This permits a numerical estimate of the degree of chain scission and crosslinking occurring in the surface during photolysi

ISSN:0021-8995    

DOI:10.1002/app.1967.070110207

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

年代:1967

数据来源: WILEY

摘要:

AbstractIn the part installment of the present paper, the authors formulated the dynamics of melt spinning by introducing a set of fundamental equations that consist of the equations of heat, force, and material balances. Some steady‐state solutions were also given. Additional steady‐state solutions corresponding to many different spinning conditions for polyester and polypropylene filament yarns consistently show good agreement with experimental results. These steady‐state solutions that give filament cross‐sectionA(x) and filament temperaturet(x) as functions of positionxare correlated with yarn qualities: yarn density and birefringence, crystallinity and molecular orientation, are correlated respectively with the speed of Polymer cooling at 100°C. and the maximum tensile stress (F/A)wacting on the filament. A transient solution of the fundamental equations computed on an IBM 1401 machine shows that the filament cross‐sectionAat the take‐up roll forms a large transient peak after a stepwise increase in the speedvyof cooling air. This agrees with experiments fairly well. The fundamental equations, therefore, clarify the dynamic relations between cooling air speed and yarn weigh

ISSN:0021-8995    

DOI:10.1002/app.1967.070110208

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

年代:1967

数据来源: WILEY

摘要:

AbstractThe mercerization behavior at 20°C. ofValonia macrophysacellulose of Japanese origin was investigated by x‐ray, moisture regain, and infrared spectrographic methods. The NaOH concentration range necessary for mercerization was 16–20%, which is higher than those required for wood pulp (8–11%), ramie or cotton (11–14%), and even the animal cellulose, Tunicin (14–16%). Treatment with the alkaline solution of the ordinary concentration (17.5%) for 4 days could not mercerize it, and even mercerization with a 19% solution brought about the presence of the reflection from (101)IIalong with those from (101)Iand (101)Iafter regeneration. Such a high resistance to mercerization of theValoniacellulose may be due to its larger crystallite size rather than the crystalli

ISSN:0021-8995    

DOI:10.1002/app.1967.070110209

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

年代:1967

数据来源: WILEY

摘要:

AbstractThe advancing contact angle of water on plastic film coatings on metal was measured against both the air and the metal side surfaces after their being peeled off from the metal substrate. The plastic used was a methacrylate copolymer, and it was baked on cadmium, aluminum, nickel, iron, and gold. Contact angle for the air side was about 74° at 25°C. for all metals, but the values on the metal side differed considerably, ranging from 76° for gold to 50° for cadmium. At the same time the static breaking strengths of the same films were investigated by applying a knife‐edge vertically to the film with increasing load and measuring the weight at which the electric resistance through the film became zero. Increasing film thickness gave increasing strength, but further thickening made the film weaker with a tendency for crack formation. The film–metal combinations of larger contact angle difference generally also showed the higher breaking s

ISSN:0021-8995    

DOI:10.1002/app.1967.070110210

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

年代:1967

数据来源: WILEY