摘要:

AbstractThe writer summarises his researches in the field of polymer science. He began with studies of the structures of space‐network and sheet polymers in crystals. Currently he is working on the structures of macro‐ions in silicate and borate crystals and glasses and on the development of a new theory of structures and thermodynamic properties of (polymer and other) soluti

ISSN:0007-1641    

DOI:10.1002/pi.4980040602

出版商:John Wiley&Sons, Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractPorous films of poly(hydroxy ethyl methacrylate) have been made by photo‐polymerisation of solutions of the monomer. The permeability of homogeneous films depends on the cross‐link density and the concentration and composition of the polymerisation solvent. A membrane of minimum water permeability, in which the transport mechanism is principally diffusion, results from a cross‐link concentration of ∼9.4 mol‐% and a monomer concentration of ∼75% in an aqueous ethylene glycol solvent (20% ethylene glycol).More porous (macroporous) films were prepared by first cooling the solution such that the solvent freezes and the monomer occupies the interstices between the solvent crystals. After polymerisation and removal of the solvent, a porous structure results. The rate of freezing, the profile of the thermal gradient, and the solvent and crosslinker concentrations control the permeability of this film. Slow cooling gives random pores (K≃6 × 10−15cm2), but rapid, directional cooling from one face gives oriented pores withK≃10−12cm2. A 6‐order change inKresults from varying the monomer concentration from 40 to 85% in a 4:1 water: ethylene glycol solvent, and a 3‐order change from increasing the ethylene glycol content of the solvent from 0 to 40% at a fix

ISSN:0007-1641    

DOI:10.1002/pi.4980040603

出版商:John Wiley&Sons, Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractAcetylenic compounds have been polymerised by heating at pressures up to 23.5 kbar in the absence of initiators. The products are either low melting or intractable solids. 2‐Butyne copolymerises with tetramethylethylene and trimethylethylene. Propiolic acid gives carbon dioxide and a mixture of aromatic acids as well as an amorphous polymeric aci

ISSN:0007-1641    

DOI:10.1002/pi.4980040604

出版商:John Wiley&Sons, Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThe products of controlled thermal degradation of polyolefins have been examined by gas chromatography. The factors determining the formation of decomposition products in the Curie‐point pyrolyser have been studied and a highly reproducible distribution of products has been obtained at a pyrolysis temperature of 595 °C. The probable degradation mechanisms are discussed and a diagnostic scheme has been derived for determining from the degradation products the nature of the branches and thus identifying the comonomer in an ethylene copolym

ISSN:0007-1641    

DOI:10.1002/pi.4980040605

出版商:John Wiley&Sons, Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThe changes occurring during the heat treatment of polyacrylonitrile polymers in the presence of air up to 350 °C have been examined using both physical and chemical techniques. It is concluded that substantial oxidation does not occur until the polymer has been converted to a ladder structure containing readily oxidisable methylene groups. The development of the highly characteristic physical behaviour of the oxidised polymer, notably absence of melting and hydrophilicity, is associated with the formation of a strongly hydrogen bonded polydihydropyrid‐4‐one structure which acts as an internal restraint to molecular motion and permits the orientation of the parent polymer to be carried through to the higher temperature pyrolysed carbon f

ISSN:0007-1641    

DOI:10.1002/pi.4980040606

出版商:John Wiley&Sons, Ltd    

年代:1972

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980040607

出版商:John Wiley&Sons, Ltd    

年代:1972

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980040608

出版商:John Wiley&Sons, Ltd    

年代:1972

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980040601

出版商:John Wiley&Sons, Ltd    

年代:1972

数据来源: WILEY