摘要:

AbstractTreatment of 2,7,8‐trioxabicyclo [3.2.1] octane (I) with electrophilic initiators gave polyorthoester composed of five‐ (70‐86%), six‐, and seven‐ (the sum, 14‐30%) membered rings. Treatment of 2,8,9‐trioxabicyclo [3.3.1]nonane (VI) with electrophilic initiators gave mainly oligomers. Trifluoromethane sulfonic acid in dichloromethane was particularly effective for the formation of dimer, 2,8,10,16,17,18‐hexaoxatricyclo[11.3.1.1]hexadecane. The analysis of the structures of poly‐I and oligomer‐VI suggests that I and VI are polymerized thro

ISSN:0360-6376    

DOI:10.1002/pol.1980.170181101

出版商:John Wiley&Sons, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractThe radical grafting of methyl methacrylate (MMA) onto polybutadiene (PBD) in benzene solution at 60°C is more efficiently induced by benzoyl peroxide (BP) than by azoisobutyronitrile (AIBN). PBD exerts a pronounced retardation on the polymerization of MMA and the grafting efficiency is governed by the ratio of rubber to monomer in the system. With BP as initiator, a fairly simple kinetic expression, relating grafting efficiency with reactant concentrations, can be derived by making certain approximations, including the neglect of termination grafting. The experimental data are reasonably consistent with this equation and yield acceptable values of several kinetic parameters. With AIBN, termination grafting is more significant. In consequence the relevant kinetic equation can be only qualitatively validated

ISSN:0360-6376    

DOI:10.1002/pol.1980.170181102

出版商:John Wiley&Sons, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractThe structure of the cellulose solvent ferric sodium tartrate (FeTNa) was studied using a sensitive adiabatic calorimeter. FeTNa was found to be a typical transition metal complex in which three tartrate ligands add in a stepwise fashion to iron. The structure of FeTNa first proposed by Franke is thus confirmed. The equilibrium constant for the addition of the third tartrate ligand to iron is approximately 100, a value typical of those for other cellulose‐dissolving metal complexes. There is no calorimetric evidence for addition of more than three tartrate molecules to iron. The increase in molar heats of reaction with increasing ionic strength is consistent with dilute electrolyte solution theory. Based on these data, the probable reaction between FeTNa and cellulose has been postulate

ISSN:0360-6376    

DOI:10.1002/pol.1980.170181103

出版商:John Wiley&Sons, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractA new telechelic polyisobutylene diol, HOCH2PIBCH2OH, carrying two terminal primary hydroxyl end groups has been prepared from α,ω‐di(isobutenyl)polyisobutylene, CH2C(CH3)‐ CH2PIBCH2C(CH3)CH2, by regioselective hydroboration followed by alkaline hydrogen peroxide oxidation. Infrared (IR) spectra,1H‐NMR analysis of the pure and silylated products, and ultraviolet (UV) spectra of phenylisocyanate‐treated diols indicate quantitative yields and two CH2OH termini per polyisobutylene chain. The viscosity of HOCH2PIBCH2OH is higher than that of the starting α,ω‐diolefin. The telechelic diol prepolymer opens new avenues to the synthesis of

ISSN:0360-6376    

DOI:10.1002/pol.1980.170181104

出版商:John Wiley&Sons, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractThe formation of paramagnetic intermediates following the irradiation of styrene, α‐methylstyrene, and their mixtures at −90°C in the presence of TiCl4and SnCl4in the polycrystalline heptane matrix was investigated. The effect of light on vinyl aromatic monomers leads to the formation of radical cations of styrene and α‐methylstyrene, which subsequently initiate the polymerization. The polymerization of styrene and α‐methylstyrene supposedly proceeds via the cationi

ISSN:0360-6376    

DOI:10.1002/pol.1980.170181105

出版商:John Wiley&Sons, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractThe easily observed autoacceleration of free radical Polymerization is defined as the explosive region and an arbitrary but quantitative definition of it is made. Using this definition it is shown that the explosive regions of solution polymerizations of methyl methacrylate occur at constant values of the product of polymer concentration times (molecular weight)1/2. This upholds the concept that polymer entanglements control the termination reaction in this region. It is also shown that this region does not, as previously suggested, occur at a constant value of free volume, but that free volume does play a role in determining the rate of termination at a given level of chain entanglements.

ISSN:0360-6376    

DOI:10.1002/pol.1980.170181106

出版商:John Wiley&Sons, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractPart I showed that significant differences exist between calcium carbonate and silicate minerals when incorporated into polypropylene (three grades). It showed further that an ultrafine calcium carbonate, when coated with stearic acid, gives significantly better impact properties to the composite than a coated ground whiting but with no significant effect on its tensile properties. This article examines the effect of particle size and surface coating of chalk‐based calcium carbonate on the physical properties of GWE 21 Propathene homopolymer. The effect of variation in filler level was also investigate

ISSN:0360-6376    

DOI:10.1002/pol.1980.170181107

出版商:John Wiley&Sons, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractThe occupied area (Am) of a sodium dodecyl benzene sulfonate molecule adsorbed on particles was measured by the soap titration method. TheAmvalues are 214, 133, and 53 Å2for poly(methyl acrylate) (I), poly(methyl methacrylate) (II), and polystyrene (III), respectively. For methyl metharylate‐styrene copolymer emulsions the additivity was established between theAmvalue and copolymer composition. Composite emulsion particles consisting of I/II, I/III, and II/III were prepared by seeded emulsion polymerization. For these emulsions the relationship between polymer composition at the surface layer calculated from theAmvalue and that in a particle calculated from the polymerization process was investigated. This relationship is remarkably affected by the order of polymerization, the hydrophilicity of polymer, the flexibility of the seed polymer, and the monomer addition method. The models of the morphology of these composite particles explain the results successful

ISSN:0360-6376    

DOI:10.1002/pol.1980.170181108

出版商:John Wiley&Sons, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractA freeze‐dried cellulose acetate membrane fine structure was observed with an ultrathin sectioning electron microscope. The fine structure for the top surface in this membrane could be seen by lead citrate staining ultrathin sectioning. This network structure was observed among pores, which existed in porous substrate. The pore diameter in the top surface was about 50 Å, a value that agrees approximately with the value estimated by gas permeati

ISSN:0360-6376    

DOI:10.1002/pol.1980.170181109

出版商:John Wiley&Sons, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractPolypropylene (PP) and polyethylene (PE) peroxy radicals undergo photoreactions, but under commonly encountered photodegradation conditions these reaction rates are much lower than those of conventional radical reactions; for example, for PP peroxy radicals in noon summer sunlight at 25°C their rate of photolysis to alkyl radicals is less than one‐tenth of their rate of hydrogen abstraction from the polymer. At lower temperatures(<−10°C) or when more intense radiation is used, however, peroxy radical photolysis becomes a proportionately more important source of alkyl radicals. In addition, occurrence of photoinduced radical combination is confirmed but is shown to be important only when photolysis generates an alkyl radical sufficiently close to a peroxy radical that termination can occur before oxygen reconverts the alkyl radical to a peroxy radical. This termination mechanism therefore becomes more important for radicals generated at lower temperatures when the average separation of a radical pair is

ISSN:0360-6376    

DOI:10.1002/pol.1980.170181110

出版商:John Wiley&Sons, Inc.    

年代:1980

数据来源: WILEY