摘要:

AbstractPolymers which are multifunctional in epoxide groups were synthesized by copolymerizing glycidyl methacrylate (GMA) with acrylate and vinyl monomers. The reactivity ratios at 65°C. for the monomer pair styrene (M1)–GMA (M2) arer1= 0.34 ± 0.05 andr2= 0.63 ± 0.01. Glycidyl methacrylate (GMA) is similar to methyl methacrylate in its copolymerization characteristics. The copolymers can be crosslinked by the same classes of materials that are useful with conventional epoxide resins based on epichlorohydrin and bisphenol A. Similar curing conditions and reactant stoichiometry can also be used. Three GMA copolymers are described: (1) a phosphated styrene/GMA (85/15) copolymer which is thermosetting and can be used as an appliance finish vehicle to yield enamels with excellent resistance properties; (2) an ethyl acrylate/GMA (97/3) elastomer which can be vulcanized with amines or diacids; and (3) a methyl methacrylate/GMA (70/30) copolymer which can be crosslinked at room temperature with amines. These polymers have good resistance to yellowing because of their aliphatic hydrocarbon backbone. The molecular weight and epoxide functionality of the polymers can be varied over wide ra

ISSN:0021-8995    

DOI:10.1002/app.1961.070051309

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

年代:1961

数据来源: WILEY

摘要:

AbstractA simple procedure is presented for determining the wavelength or wavelength region principally responsible for the random chain scission of a given polymer film under poorly‐defined polychromatic irradiation condition

ISSN:0021-8995    

DOI:10.1002/app.1961.070051310

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

年代:1961

数据来源: WILEY

摘要:

AbstractStudies were made of the apparent melt viscosity and chain rupture of polyisobutylene melts during high mechanical shear at various temperatures, and for varied times of shearing action. A biconical rheometer was constructed and used for this study. It was observed that the torque developed in such a rheometer by the action of shear on molten polymer shows peculiarities. The initial high torque, or the apparent melt viscosity which may be derived from it, drops rapidly to a pseudo steady state value in about one or two minutes. An interval of shear cessation permits considerable return of the system to the original high value of the apparent melt viscosity, especially if the cessation interval is long (e.g., 10 min. at 45°C.). During the pseudosteadystate period there is a small and continuous drop in the already reduced torque or the apparent melt viscosity. Study of the chain rupture rate, made by examination of dilute solution viscosities, and the viscosity‐average molecular weights determined from them, showed the rate of chain degradation to decrease as the temperature during the shearing operation is raised. The chain rupture rate decreases steadily as shearing is continued, and increases with increase of shear rate at a given temperature and time of shear application. The behavior of the apparent melt viscosity, decreasing sharply to a pseudosteady‐state value shortly after intense shear begins, is presently pictured as due to two mechanisms, one chemical, the other mechanical, acting simultaneously. One process is considered to be the rapid breakdown of the chainlike molecules to smaller fragments forming mainly free radicals or ion pairs at their ends. These reactive ends begin immediately to recombine at a rate which increases with the rise in their concentration until the pseudoequilibrium state is reached. The second process is considered to arise from both chain disentanglement and the preferential migration of holes in the liquid away from the center of gravity of the chains to form regions of low viscosity which may be termed fault lines or reg

ISSN:0021-8995    

DOI:10.1002/app.1961.070051311

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

年代:1961

数据来源: WILEY

摘要:

AbstractThe effect of short arylurethane branches on the physical properties of a linear polyurethane is described. Branches of this type reduce crystallization tendencies of the polymer and alter its bulk and solution viscosity behavior. Vulcanizate properties, such as resilience and modulus, are not affected. The synthesis of polyurethanes containing longchain branches with terminal cure sites is described. Dynamic behavior of these latter polymers, as judged by Yerzley resilience, improves as the proportion of long chain branches in the vulcanizate network is reduced.

ISSN:0021-8995    

DOI:10.1002/app.1961.070051312

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

年代:1961

数据来源: WILEY

摘要:

AbstractA differential thermal analysis apparatus was constructed for the measurement of heats of polymerization. It featured an active cell in which the reacting mixture was contained in expendable thin‐walled, narrow, cylindrical brass, or aluminum cartridges. The cartridges were tightly pressed into holes drilled into the body of the active cell and they, along with the solid reaction product, could be ejected therefrom at the completion of the reaction. A calibration cell was provided with small electric heaters which allowed known amounts of heat to be supplied to the apparatus in calibration runs. With this apparatus the mean value for three determinations of the heat of polymerization of epoxy resins, ca. 22 to 26 kcal./mole, could be measured to within a standard error of 0.37 kcal./mole (i.e., confidence limits of ±0.75 kcal./mole at the 95% confidence level). The heats of polymerization of phenyl glycidyl ether and of an epoxy resin were measured with ten and nine different curing agents, respectively. Primary amine curing agents released about 26 kcal./mole of epoxide reacted, tertiary amines, and boron trifluoride‐ether complex each released about 22 kcal./mole. Mixed‐type curing agents, which could react in part as tertiary amines, or boron trifluoride, and in part as primary amines could liberate intermediate amounts o

ISSN:0021-8995    

DOI:10.1002/app.1961.070051313

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

年代:1961

数据来源: WILEY

摘要:

AbstractA method is described for measuring directly the infrared dichroism spectrum of a film by use of a single‐beam spectrometer. The method involves modulating the beam passing through the sample with a rotating polarizer rather than with a chopper. The a.c. response of a detector is then proportional to the difference between the principal absorbencies of the sampl

ISSN:0021-8995    

DOI:10.1002/app.1961.070051314

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

年代:1961

数据来源: WILEY

摘要:

AbstractNitrile rubbers have often been used together with phenolic resins in molding materials to produce an impactresistant product. These mechanical mixtures may react during final cure. Acrylonitrile–butadiene rubbers containing residual unsaturation can, however, be coreacted with phenolic resins during the early stages of polymerization if appropriate conditions are adopted. The coreaction probably occurs via formation of a chroman from a double bond in the rubber and ano‐methylol phenol. The coreaction products are completely soluble in alcohol, whereas the rubbers are not. Laminates made from these coreaction products are flexibilized to the point at which they lend themselves well to cold punching. Yet the rubber, being tightly bound, cannot be extracted with solvents nor lead to blistering on heat

ISSN:0021-8995    

DOI:10.1002/app.1961.070051315

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

年代:1961

数据来源: WILEY

摘要:

AbstractA tracer study has been made of the polymerization of acrylonitrile in an aqueous solution at 25°C with the use of radioactive K2S352O8and NaHS35O3in a redox catalyst system. Persulfate and bisulfite give sulfate and sulfonate endgroups, respectively. The contents of these endgroups in the polymer were determined and the following empirical equation was derived:\documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{[{\rm Sulfonate endgroups]}}}{{[{\rm Sulfate endgroups]}}} = 1 + 0.27\left\{ {\frac{{[{\rm NaHSO}_{\rm 3} ]}}{{[{\rm AN] [K}_{\rm 2} {\rm S}_{\rm 2} {\rm O}_{\rm 8} ]}}} \right\}^{1.5} $ \end{document}Sulfonate is the major endgroup under every condition of polymerization. A tentative discussion of the polymerization initiation reaction in this redox system is given in order to account for the above experimental results

ISSN:0021-8995    

DOI:10.1002/app.1961.070051316

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

年代:1961

数据来源: WILEY

摘要:

AbstractPolyester–urethane block copolymers were prepared by the block polyaddition reaction of diisocyanate with two kinds of linear polyesters, one of which was polyethylene terephthalate. The melting points of polyester–urethane block copolymers containing more than 30% polyethylene terephthalate are independent of the total molar fraction of the two polyester components, so that the melting point–composition curves are step‐shaped. The relation between the second‐order transition point of the block copolymer and its composition, on the other hand, is the same as that for a random copolymer. It is observed that some polyester–urethane block copolymers containing 15–50% of polyethylene terephthalate have elastic properties. For example, the 15/85 polyethylene terephthalate/polyethylene adipate–tetramethylene diisocyanate block copolymer has a tensile strength of 240 kg./cm.2and an elongation of 700%. It may be supposed that these elastic properties are due to the structure of the block copolymer chains: the flexible polymer chains in the amorphous region may be joined to the crystallites of polyethylene terephthalate, so that a type of network structure similar to crossli

ISSN:0021-8995    

DOI:10.1002/app.1961.070051317

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

年代:1961

数据来源: WILEY

摘要:

AbstractThe molecular weights and molecular weight distribution of a styrene–butadiene rubber produced at 5°C. according to an incrementally modified recipe withtert‐dodecyl mercaptan modifier, do not differ significantly from those of similar conventionally modified rubbers. The limiting effect of diffusion upon the mass transfer of mercaptan in the system provides a consistent explanation of this fin

ISSN:0021-8995    

DOI:10.1002/app.1961.070051318

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

年代:1961

数据来源: WILEY