摘要:

AbstractTwo vinyl chloride polymers with intrinsic viscosities of 0.65 and 1.17 were compounded with four plasticizers. Stress relaxation data were obtained at three temperatures and analyzed by a step function of seven parameters in Maxwell representation. The relaxation times were nearly independent of plasticizer type, plasticizer content, molecular weight, and temperature. The moduli were found to decrease with increasing plasticizer content and/or temperature, the equilibrium moduli being directly dependent on the molecular weight while the delayed moduli were more dependent on plasticizer type. The molecular weight dependence of the equilibrium moduli can be attributed to a participation of the individual chains in several crystalline areas which act as crosslinking points.

ISSN:0449-2951    

DOI:10.1002/pol.1963.100010801

出版商:John Wiley&Sons, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractPlasticized polyvinyl chloride has been found to undergo a permanent deformation when strained past 100%. At the same strains, internal energy effects become pronounced as reflected in the stress‐strain curves. Plasticizer efficiency has been evaluated in several respects, namely rubber‐like behavior, recovery, glass transition, set, and stress‐strain at break. While no single plasticizer stands out, the following sequence has been established with respect to the first four aspects listed above: DOA ≥ TCP>DP

ISSN:0449-2951    

DOI:10.1002/pol.1963.100010802

出版商:John Wiley&Sons, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractTwo monomers, bis(aminomethyl)oxetane (I) and epoxysuccinyl chloride (II)have been prepared and converted to condensation polymers, structurally similar to the epoxides. Both monomers were stable and easy to handle. The polymers crosslinked to insoluble, infusible products.

ISSN:0449-2951    

DOI:10.1002/pol.1963.100010803

出版商:John Wiley&Sons, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractThe effect ofm‐phenylenedimaleimide on the rate of cross linking of synthetic rubbers, polyvinyl acetate, polyvinyl chloride, polyethylene, and other polymers, under the action of ionizing radiation is described. The dose reduction factor for equivalent degrees of crosslinking obtained with and without the maleimide varies from 10 to 25 for the synthetic rubber. Further evidence is given to show that maleimides sensitize the vulcanization of unsaturated polymers, principally by copolymerization, and certain saturated polymers containing labile atoms, by a transfer mechanis

ISSN:0449-2951    

DOI:10.1002/pol.1963.100010804

出版商:John Wiley&Sons, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractThe addition of small amounts of transition metal salts, e.g., CuCl2, to low molecular weight polyoxyalkylenediols results in pronounced autoxidation inhibition. This is in contrast with McGary's findings that this same class of salts accelerates the autoxidative degradation of high molecular weight polyethylene glycols. Inhibition of diethylene glycol is shown to relate to catalyzed hydroperoxide decomposition. With polyoxyethylenediol of molecular weight 600 this inhibition with CuCl2is less pronounced, and with both polyoxyethylene diols and polyoxypropylene diols the inhibitory effect gives way to a net accelerating effect with increasing polymer molecular weight. The inhibitory effect is insensitive to increasing medium polarity and to changes in oxygen pressure, but is markedly sensitive to terminal group capping. Combinations of appropriate metal salts and organic antioxidants produce synergistic stabilization. The results may be explained by postulating a competition between the normal radical‐generating reactions of hydroperoxides with transition metal ions and the formation of specific terminal‐hydroperoxide complexes which decompose heterolytica

ISSN:0449-2951    

DOI:10.1002/pol.1963.100010805

出版商:John Wiley&Sons, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractThe diffusion and solution of propane and of benzene has been studied over a range of temperatures in a series of heterogeneous membranes of natural rubber and zinc oxide filler. The volumes of filler were 0, 5, 10, 20, 30, and 40%. Evidence was obtained of the interaction between rubber and filler, and that some of the membranes involved three phases: polymer, filler, and open gaps between filler particles. No rigorous treatment of diffusion in heterogeneous media exists, but the model of two interdispersed phases was developed and discussed in relation to permeation rates and diffusion coefficients. Differences between steady state and time‐lag diffusion coefficients were ascribed to different structure factors in steady and transient states of flow. Concentration dependences of the interdiffusion and intrinsic diffusion coefficients of benzene were measured. The influence of concentration dependence, filler, and structure factor was combined in one relationship relating the intrinsic diffusion coefficient in the filler rubber with that for diffusion in unfilled rubber, containing the same volume fraction of benzene. The resultant expression appears able to account qualitatively for some of the observed complex diffusion behavio

ISSN:0449-2951    

DOI:10.1002/pol.1963.100010806

出版商:John Wiley&Sons, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractA concept has been developed to explain the kinetic behavior of six transition‐metal catalyst systems for ethylene polymerization: CrO3· SiO2and V2O5· SiO2promoted by (i‐C4H10)3Al; VOCl3promoted by (C2H5)2AlCl; TiCl4promoted by (C2H5)3Al or (i‐C4H10)3Al; and (C5H5)2TiCl2promoted by (CH3)2AlCl. Despite obvious differences in the chemical nature of their active species and known behavioral differences, all of these systems show a second‐order deactivation of active species with time. Production of polymer in batch polymerizations has been shown to obey an equation relating propagation and deactivation constants, monomer concentration, reaction time, and initial number of active sites. This equation has been extended to fit batch runs with continuous catalyst addition. One possible reaction mechanism has been proposed. Qualitative steps are: (1) complex formation between the transition‐metal complex and alkyl, (2) alkylation of the complex, (3) polymerization by the alkylated species, and (4) second‐order decay of a

ISSN:0449-2951    

DOI:10.1002/pol.1963.100010807

出版商:John Wiley&Sons, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractAn attempt has been made to elucidate the nature of the reaction between alkaline hypochlorite and granular wheat starch. With this end in view various analytical determinations were carried out on starch samples oxidized under well‐determined conditions. The reaction was found to be nonspecific, its main results being the formation of functional groups and the scission of glucosidic bounds. The functional groups formed were mainly carboxyls, some carbonyl formation taking place at lower pH values. The consumption of about 0.05 atom of oxygen/AGU resulted in an extensive degradation of both starch components. There are indications to the effect that degradation is random in type. On that assumption, 0.5 to 1 glucosidic bonds in 100 were scinded, each scission being accompanied by the formation of about two carboxyl groups and by an overall consumption of 4–5 oxygen atoms. The reaction apparently took place in the amorphous part of the granule. The amylose‐amylopectin ratio, as well as the granule size remained unchanged. More than one‐quarter of the total oxygen consumed reacted with the dissolved portion of the starch as the result of the ox

ISSN:0449-2951    

DOI:10.1002/pol.1963.100010808

出版商:John Wiley&Sons, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractDeuterated analogs of polyvinyl chloride (PVC) have been prepared and their infrared spectra analyzed as an aid to the more detailed assignment of bands in the spectrum of PVC. The following deuterated polymers were studied: PVC‐αd1, PVC‐βd1, PVC‐αβd2, and PVC‐d3. These, as well as PVC, were polymerized in urea‐complex, at −78°C., and at +50°C. in order to determine which bands are of crystalline origin and which of noncrystalline origin. Polarized spectra of oriented samples were obtained in each case to assist in the analysis. As a result of this study several of the previously uncertain assignments have been clarified. With the help of other studies on model chlorine‐containing compounds it has been possible to identify the various conformations present in the polymer and to associate these with isotactic and syndiotactic pair configurations in the chain. A method is suggested for determining the proportion of each type of pair c

ISSN:0449-2951    

DOI:10.1002/pol.1963.100010809

出版商:John Wiley&Sons, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractA study has been made of the flow behavior at 30°C. of solutions of three samples of polymethyl methacrylate in three solvents in both the Newtonian and non‐Newtonian regions. The concentration range covered was approximately 0–16% by weight. By application of the Ree‐Eyring theory it was found possible to represent the observed data in terms of two flow units, and to obtain from the parameters of the theory the effective hydrodynamic volume occupied by the polymer in solution, ευ2. Here υ2is the volume fraction of the polymer and ε an effective volume factor. The volume factor, ε, was found to be dependent on both solvent and molecular weight only up to ca. υ2= 0.04. Beyond υ2= 0.04, ε is independent of solvent and is a function of molecular weight only. These observations indicate that chain entanglement in solution is not probable. Rather, the polymer chain curls on itself, and compacts to a small mass when the effective concentration ευ2= 1 and the viscosity becomes infinite. The concentration at which this occurs, υ∞, is given by ∞ = 1/ε∞. The quantity ε∞ has been found to be a linear function of molecular weight,M. Further, the value of ε at υ2= 0, ε0, has been found to be an exponential function ofM, and to yield expressions relating intrinsic viscosity to molecular weight in good

ISSN:0449-2951    

DOI:10.1002/pol.1963.100010810

出版商:John Wiley&Sons, Inc.    

年代:1963

数据来源: WILEY