摘要:

AbstractHigh molecular weight polysilane copolymers which contain the units in the title were prepared in high yield by sodium coupling the corresponding organodichlorosilanes in toluene. These copolymers are highly soluble in common solvents and can be drawn into fibers or formed into films by molding or casting. They are also photoactive.

ISSN:0360-6376    

DOI:10.1002/pol.1984.170220121

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractPhotomicrographys of concentrated lyotropic hydroxypropylcellulose solutions confirm the cholesteric nature of the anisotropic phases in acetic acid and water. They reveal the existence of biphasic separation. Typical liquid‐crystal solvent‐dependent textures are observed. The behavior of liquid‐crystalline phases in mixed solvents is also studied, and the cholesteric pitch of the twist structure is measured for various relative concentrations of solvents. Spherical droplets, or “spherulites,” in well‐defined relative concentrations of solvents have be

ISSN:0360-6376    

DOI:10.1002/pol.1984.170220122

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractHigh‐molecular‐weight branched‐addition polymers made from oligomeric solid epoxy resins and amines carrying two active hydrogen atoms are described. The reaction with aliphatic amines like ethanolamine, 2‐ethylhexylamine, or piperazine can easily be controlled carrying out the polymerization in about 15% solutions of boiling 2‐methoxyethanol. Less basic derivatives of aniline and epoxy resins are processed at 200°C in the molten state. Polymers withMnup to 33,000 andMwto 720,000 are obtained. Properties of films and injection moldings are described. The tertiary nitrogen atoms present in the polymer chain can be quaternized with alkylating agents, like dimethylsulfate, methyliodide, or trimethyl phosphate. Thin membranes cast from the polyquats thus obtained exhibit a good flow rate for water and a high salt rejection under reverse osmosis

ISSN:0360-6376    

DOI:10.1002/pol.1984.170220123

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe ignition of slabs of high‐impact polystyrene by a lean hydrogen–oxygen flat flame was studied. The ignition delays and inital rates of flame development after ignition are reported as functions of gas temperature and the separation between flame and polymer surface. The delays follow an Arrhenius‐type expression with an activation energy of 98 ± 18 kJ mol−1. The rates of flame development drop as the gas temperature increases. During long ignition delays the apparent heat transfer coefficient at the sample surface dropped from about 100 W m−2K−1to values close to that expected for a hot gas impinging at right angles on a cold surface. For short delays it was higher and more constant at about 100 W m−2K−1. Although the surface temperature reached before ignition exceeded that required for nonoxidative pyrolysis, the polymer surface charred only when oxygen was present. It is concluded that both oxidative and nonoxidative pyrolysis contribute to the ignitio

ISSN:0360-6376    

DOI:10.1002/pol.1984.170220124

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe chlorometylation of linear and crosslinked polystyrene with 1,4‐bis(chloromethoxy) butane was studied, and the behavior of 1,4‐bis(chloromethoxy)butane in the presence of chloromethylation catalysts was also established by1H‐NMR spectro

ISSN:0360-6376    

DOI:10.1002/pol.1984.170220125

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

ISSN:0360-6376    

DOI:10.1002/pol.1984.170220126

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY