摘要:
A catalytic system to polymerize diolefinic monomers consists of a lanthanide salt, an organometallic compound of a metal belonging to groups I, II and III of the periodic table of elements and an organometallic compound of boron. The polymers obtained are characterized in that they have a high degree of 1,4 chain units and ratio between 1.4-cis/1,4-trans units which can vary as desired, and also a narrow molecular weight distribution.
摘要:
Polymers having a very good combination of chemical, mechanical and process properties, and particularly useable either alone or as mixtures, as high-tenacity thermoplastic polymer and as elastomers or elastomeric modifiers, contain, randomly distributed along their chain, repeating cycloketonic structural units having the following general formula (I): ##STR1## wherein: A represents a tetravalent aliphatic or cycloaliphatic, substituted or non-substituted moiety containing a total number of from 4 to 50, preferably from 4 to 20, carbon atoms.Such polymers can be prepared by means of a process which comprises reacting, in a liquid media, a polydiene containing adjacent structural units derived from the 1,4-cis polymerization of conjugated dienes, with carbon monoxide, in the presence of free radical generating compounds and, optionally, a compound capable of acting as a hydrogen donor.
摘要:
Polyester compositions with a high crystallization rate obtained by mixing, at a high temperature, a polyester resin with at least one organic compound having the general formula:ROOC--Ar--OOC--Ar'--COO--Ar--COOR (I)where R represents a hydrogen atom or a C.sub.1 -C.sub.4 alkyl radical whereare Ar and Ar', either the same or different, represent a simple or condensed aromatic radical containing from 6 to 12 carbon atoms, and cooling the mixture thus obtained to room temperature.
摘要:
A process for coating the surface of bodies fabricated from polymeric materials with inorganic films by depositing on the polymeric bodies a thin layer obtained by thermal evaporation, under vacuum, of glass/silicon mixtures. The process provides for improved control of surface-depending properties, such as wettability, haze resistance, gas and weight barrier properties and selective absorption of ultraviolet light.
摘要:
An active catalyst in the preparation of alternating copolymers of olefins with carbon monoxide (CO) and consisting of: a) a metal salt of the group IB of the periodic table; b) a bidentate binder containing two nitrogen or phosphorous atoms capable of binding themselves to the metal atom by means of co-ordination bonds; c) a Lewis acid; d) optionally an oxidizing agent. The preparation of the catalyst is described together with its use in the alternating copolymerization of ethylene (C2) and/or other olefins with carbon monoxide.
摘要:
A catalyst active in the preparation of alternating olefin/carbon monoxide (CO) copolymers is constituted by:(a) at least one salt of a metal of Group IB of the Periodic System,(b) a mono or bidentate ligand base containing one or two nitrogen or phosphorus atoms capable of linking to the metal atom by means of dative bonds,(c) a mineral or organic oxidizer agent.Also disclosed are the preparation of the catalyst and the use of said catalyst in alternated copolymerization of ethylene (C2) and/or other olefins with carbon monoxide (CO).
摘要:
A catalyst active in the preparation of alternating olefin/carbon monoxide (CO) copolymers is constituted by:(a) Pd(O.sub.2 CNEt.sub.2).sub.2 (NHET.sub.2).sub.2 supported on a solid carrier preferably constituted by hydroxylated silica,(b) an either mono- or bidentate ligand containing one or two nitrogen or phosphorous atoms capable of linking to Pd atom by dative bonds,(c) a mineral or organic acid.Disclosed are the preparation of the catalyst and the use of said catalyst in alternated copolymerization of ethylene (C2) and/or other olefins with carbon monoxide (CO).
摘要:
Polyesters with a high crystallization rate synthesized by the polycondensation of terephthalic acid with at least one C.sub.2 -C.sub.4 alkylenic glycol in the presence of 0.1-1.5 mol % of a copolymerizable reagent having the general formula:ROOC--Ar--OOC--Ar'--COO--Ar--COORwhere Ar and Ar'represent aromatic radicals and R represent a halogen, a hydrogen atom or a C.sub.1- C.sub.4 alkyl radical.
摘要:
Low-crystallization-speed polyesters obtained by means of the polycondensation of 2,6-naphthalene-dicarboxy acid with at least one (C.sub.2 -C.sub.10)-(cyclo)alkylene glycol in the presence of 0.5-50 mol % of a copolymerizable reactant of general formula:ROOC--Ar--OOC--Ar'--COO--Ar--COOR (I)wherein Ar and Ar' stand for aromatic radicals, and R stands for a hydrogen atom or a (C.sub.1 -C.sub.4)-alkyl radical, or the OR group is replaced by a halogen.
摘要:
Process for the polymerization of unsaturated vinyl and/or vinylidene monomers which comprises reacting one or more monomers in the presence of heterocyclic initiators having a nitrogen atom bound to an oxygen atom at a temperature ranging from 100 to 130° C.