摘要:

AbstractUV spectroscopic measurements to identify the products of photolysis in polystyrene solutions of CCl4and CHCl3as a function of the atmospheric oxygen concentration are conducted. In polystyrene chains CC bonds are formed, thus changing the absorption properties in the long wave length range. The concentration of induced CC bonds is higher in CCl4solution than in CHCl3solution. The effect of O2is observable for pressuresp≥ 2 · 10−1mmHg; it is of minor importance for the formation of CC bonds, however. On the low‐molecular‐weight side COCl2, Cl2, and HCl are the photolysis products in the presence of O2. Observable changes in the absorption of the solvent at 280 nm were attributed to the electronic n ← π* transition of the carbonyl groups of COCl2, whereas the newly created broad band in the UV spectrum of the solvent was attributed to the electronic1Π1u←1Σg+and3Π+ou←1Σg+transitions in Cl2. The first of these transitions is responsible for the dissociation of Cl2molecules. A hypothesis has been set forth that molecular oxygen affects the probability density of the electronic3Πou+←1Σg+transition. The concentration of O2has a substantial effect on the concentration of the COCl2photoproducts, which is best displayed by the molar absorption

ISSN:0025-116X    

DOI:10.1002/macp.1982.021831221

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractWell‐definded AB and BAB poly(styrene(S)‐b‐4‐vinylpyridine(4VP))s were prepared by anionic polymerization in tetrahydrofuran (THF) at −78°C. Quaternization of these block copolymers was carried out with methyl iodide and P4VP blocks were completely quaternized. The emulsifying effect, viscosity behavior, and binding of methyl orange to the quaternized compounds are discussed in detail from a view‐point of sequential

ISSN:0025-116X    

DOI:10.1002/macp.1982.021831222

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractA technique is described for the measurement of the heat of immersion for polyethylene with a 2 . 10−3J accuracy. For the studied systems, the heat of mixing is positive and due to solubility of the liquid in the amorphous phase of the polymer. The dissolved fraction is estimated from the heat of mixing according to Flory's theory. Measurement of the surface energy from single crystals indicates that this surface constituted of the folds of the chains behaves as an amorphous phase. Last, the heat of immersion is compared to the value calculated from the contact angle. If the solubility of the liquid is very small, the agreement is good. The case of water is studied: the negative value of the heat of immersion ΔHiproceeds from a change in water structure and a decrease of the enthalpy due to the contact with apolar compounds. This value allows to estimate the solubility of water in polyethyle

ISSN:0025-116X    

DOI:10.1002/macp.1982.021831223

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY