Process for crosslinking thermoplastic polymers with silanes employing peroxide blends, the resulting crosslinked thermoplastic polymer composition and articles made therefrom

Abstract

In one embodiment herein there is provided a composition comprising (i) one or more unsaturated silane compounds according to the Formula (1): G 1 R 1 SiX 1 X 2   (1) wherein G 1 is an olefinically unsaturated hydrocarbon group optionally heteroatom-substituted with one or more oxygen and/or nitrogen atoms; R 1 is selected from the group consisting of alkyl, aryl, aralkyl and arenyl; each of X 1 and X 2 is independently a hydrolyzable group or alternatively each of X 1 and X 2 is a hydrolyzable group having a direct bond to the silicon atom and also simultaneously a direct bond to each other to form a ring with the silicon atom of the unsaturated silane of Formula (1); and (ii) a system of at least two peroxides comprising a first peroxide having a first 0.1 hour half-life temperature and a second peroxide having a second 0.1 hour half-life temperature, the first and second 0.1 hour half-life temperatures in said composition having a temperature differential of at least about 5° C. In another embodiment herein there is provided a process for producing a silane-grafted thermoplastic polymer. In yet a further embodiment herein there is provided a process for producing a crosslinked thermoplastic polymer. In yet an even further embodiment there is provided an article.

1 . A composition comprising:
 (i) one or more unsaturated silane compounds according to the Formula (1):
   G 1 R 1 SiX 1 X 2    (1) 
   
       wherein G 1  is an olefinically unsaturated hydrocarbon group, optionally heteroatom-substituted with one or more oxygen and/or nitrogen atoms; R 1  is selected from the group consisting of alkyl, aryl, aralkyl and arenyl; each of X 1  and X 2  is independently a hydrolyzable group or alternatively each of X 1  and X 2  is a hydrolysable group having a direct bond to the silicon atom and also simultaneously a direct bond to each other to form a ring with the silicon atom of the unsaturated silane of Formula (1); and
 (ii) a system of at least two peroxides comprising a first peroxide having a first 0.1 hour half-life temperature and a second peroxide having a second 0.1 hour half-life temperature, the first and second 0.1 hour half-life temperatures in said composition having a temperature differential of at least about 5° C. 
 
     
     
         2 . The composition of  claim 1 , wherein the unsaturated silane compound is characterized in that G 1  is vinyl or allyl, R 1  is a straight alkyl group having from one to six carbon atoms, a branched alkyl having from 3 to 6 carbon atoms, an unbranched cycloalkyl group of from 6 to 8 carbon atoms or a branched cycloalkyl of from about 6 to 8 carbon atoms, and each of X 1  and X 2  is independently an alkoxy group having one to six carbon atoms. 
     
     
         3 . The composition of  claim 1 , wherein the unsaturated silane compound is selected from the group consisting of vinylmethyldimethoxysilane vinylethyldimethoxysilane, vinylmethyldiethoxysilane, vinylethyldiethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, N-(3-methyldimethoxysilylpropyl)methacrylamide and combinations thereof. 
     
     
         4 . The composition of  claim 1 , wherein one or more of the unsaturated silane compounds are according to the Formula (2):
   G 1 R 1 SiZ   (2)   
       wherein G 1  is an olefinically unsaturated hydrocarbon group, optionally heteroatom-substituted with one or more oxygen and/or nitrogen atoms; R 1  is selected from the group consisting of alkyl, aryl, aralkyl and arenyl; and Z is a divalent hydrolyzable alkanedioxy group that forms a cyclic structure with the silicon atom of Formula (2). 
     
     
         5 . The composition of  claim 4 , wherein the unsaturated silane compound of formula (2) is characterized in that G 1  is vinyl or allyl, R 1  is a straight alkyl group having from one to six carbon atoms, a branched alkyl having from 3 to 6 carbon atoms, an unbranched cycloalkyl group of from 6 to 8 carbon atoms, or a branched cycloalkyl of from 6 to 8 carbon atoms and Z is a divalent hydrolyzable alkanedioxy group having two to about 30 carbon atoms. 
     
     
         6 . The composition of  claim 4 , wherein the crosslinkable unsaturated silane compound of Formula (2) is 2,4,4,6-tetramethyl-2-vinyl-[1,3,2]dioxasilinane; 2-methyl-5,5-diethyl-2-vinyl-[1,3,2]dioxasilinane, 2-phethyl-5,5-diethyl-2-vinyl-[1,3,2]dioxasilinane, 2-methyl-5-ethyl-2-vinyl-[1,3,2]dioxasilinane, 2,4,4,6-tetramethyl-2-(3-methacryloxypropyl)-[1,3,2]dioxasilinane, 2-methyl-5,5-diethyl-2-(3-methacryloxypropyl)-[1,3,2]dioxasilinane, 2-phethyl-5,5-diethyl-2-(1-methacryloxymethyl)-[1,3,2]dioxasilinane, 2-methyl-5-ethyl-2-(2-methacryloxyethyl)-[1,3,2]dioxasilinane and combinations thereof. 
     
     
         7 . The composition of  claim 1 , wherein the temperature differential between the first and second 0.1 hour half-life temperatures of the first and second peroxides is in the range of about 5° C. to about 110° C. 
     
     
         8 . The composition of  claim 1 , wherein the temperature differential between the first and second 0.1 hour half-life temperatures of the first and second peroxides is in the range of about 30° C. to about 90° C. 
     
     
         9 . The composition of  claim 1 , wherein the temperature differential between the first and second 0.1 hour half-life temperatures of the first and second peroxides is in the range of about 45° C. to about 70° C. 
     
     
         10 . The composition of  claim 1 , wherein the first peroxide is selected from the group consisting of bis-(2,4-dichlorobenzoyl)peroxide, tert-butylperoxypivalate, dilauroyl peroxide, dibenzoyl peroxide, tert-butylperoxy-2-ethylhexanoate, 1,1-bis-(tert-butylperoxy)-3,3,5-trimethylcyclohexane, bis-(tert-butylperoxy)cyclohexane, tert-butyl peroxy-3,5,5-trimethylhexanoate, tert-butylperoxyacetate, tert-butylperoxybenzoate, di-tert-amyl peroxide, dicumylperoxide, bis-(tert-butyl peroxyisopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and combinations thereof; and the second peroxide is selected from the group consisting of tert-butylperoxyacetate, tert-butylperoxybenzoate, di-tert-amyl peroxide, dicumylperoxide, bis(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-bis-(t-butylperoxy)hexane, tert-butylcumyl peroxide, 2,5-dimethyl-2,5-bis-(t-butylperoxy)-3-hexyne, di-tert-butylperoxide and combinations thereof; wherein at least one first peroxide is different from at least one second peroxide. 
     
     
         11 . The composition of  claim 1 , wherein the first peroxide is selected from the group consisting of bis-(2,4-dichlorobenzoyl)peroxide, dilauroyl peroxide, dibenzoyl peroxide, 1,1-bis-(tert-butylperoxy)-3,3,5-trimethylcyclohexane, tert-butylperoxybenzoate, dicumyl peroxide and combinations thereof; and the second peroxide is selected from the group consisting of tert-butylcumyl peroxide, 2,5-dimethyl-2,5-bis-(t-butylperoxy)-3-hexyne and combinations thereof; wherein at least one first peroxide is different from at least one second peroxide. 
     
     
         12 . A composition comprising:
 (i) one or more unsaturated silane compounds according to the Formula (1):
   G 1 R 1 SiX 1 X 2    (1) 
   
       wherein G 1  is an olefinically unsaturated hydrocarbon group, optionally heteroatom-substituted with one or more oxygen and/or nitrogen atoms; R 1  is selected from the group consisting of alkyl, aryl, aralkyl and arenyl; each of X 1  and X 2  is independently a hydrolyzable group or alternatively each of X 1  and X 2  is a hydrolyzable group having a direct bond to the silicon atom and also simultaneously a direct bond to each other to form a ring with the silicon atom of the silane;
 (ii) a system of at least two peroxides comprising a first peroxide having a first 0.1 hour half-life temperature and a second peroxide having a second 0.1 hour half-life temperature, the first and second 0.1 hour half-life temperatures having a temperature differential in said composition of at least about 5° C.; and 
 (iii) one or more thermoplastic polymers; 
 
       the composition optionally containing one or more additional components capable of inhibiting silane grafting and/or crosslinking during storage. 
     
     
         13 . The composition of  claim 12 , wherein the thermoplastic polymer comprises one or more polyolefins. 
     
     
         14 . The composition of  claim 13 , wherein the one or more polyolefins are polyethylene polymers or copolymers. 
     
     
         15 . The composition of  claim 13 , wherein the one or more polyolefins are selected from the group consisting of high-pressure low-density polyethylene, medium- or low-pressure high-density polyethylene, low-pressure low-density polyethylene, medium-density polyethylene, ethylene-α-olefin copolymers, polypropylene, ethylene-ethyl acrylate copolymers, ethylene-vinyl acetate copolymers, ethylene-propylene copolymers, ethylene-propylene-diene terpolymers, ethylene-butene copolymers, polymethylpentene, polybutenes, chlorinated polyethylenes, chlorinated ethylene-vinyl acetate terpolymers, and combinations thereof. 
     
     
         16 . A composition comprising:
 (i) one or more unsaturated silane compounds according to the Formula (1):
   G 1 R 1 SiX 1 X 2    (1) 
   
       wherein G 1  is an olefinically unsaturated hydrocarbon group, optionally heteroatom-substituted with one or more oxygen and/or nitrogen atoms; R 1  is selected from the group consisting of alkyl, aryl, aralkyl and arenyl; each of X 1  and X 2  is independently a hydrolyzable group or alternatively each of X 1  and X 2  is a hydrolyzable group having a direct bond to the silicon atom and also simultaneously a direct bond to each other to form a ring with the silicon atom of the unsaturated silane of Formula (1);
 (ii) a system of at least two peroxides comprising a first peroxide having a first 0.1 hour half-life temperature and a second peroxide having a second 0.1 hour half-life temperature, the first and second 0.1 hour half-life temperatures in said composition having a temperature differential of at least about 5° C.; 
 (iii) one or more thermoplastic polymers; and 
 (iv) one or more crosslinking catalysts; 
 
       the composition optionally containing one or more additional components capable of inhibiting silane grafting and/or crosslinking during storage and/or optionally at least one additive. 
     
     
         17 . A silane-grafted thermoplastic polymer comprising a thermoplastic polymer grafted to one or more unsaturated silane compounds according to a process comprising subjecting a composition comprising (i) one or more unsaturated silane compounds, (ii) a system of at least two peroxides, and (iii) one or more thermoplastic polymers, to conditions suitable for grafting of the unsaturated silane compound to the thermoplastic polymer to form a silane-grafted thermoplastic polymer, wherein: 
       the one or more unsaturated silane compounds are according to the Formula (1):
   G 1 R 1 SiX 1 X 2    (1) 
 
       wherein G 1  is an olefinically unsaturated hydrocarbon group optionally heteroatom-substituted with one or more oxygen and/or nitrogen atoms; R 1  is selected from the group consisting of alkyl, aryl, aralkyl and arenyl; each of X 1  and X 2  is independently a hydrolyzable group or alternatively each of X 1  and X 2  is a hydrolyzable group having a direct bond to the silicon atom and also simultaneously a direct bond to each other to form a ring with the silicon atom of the unsaturated silane of Formula (1); and the system of at least two peroxides comprises a first peroxide having a first 0.1 hour half-life temperature and a second peroxide having a second 0.1 hour half-life temperature, the first and second 0.1 hour half-life temperatures in said composition having a temperature differential of at least about 5° C. 
     
     
         18 . A process for producing a silane-grafted thermoplastic polymer, the process comprising subjecting a composition comprising (i) one or more unsaturated silane compounds, (ii) a system of at least two peroxides, and (iii) one or more thermoplastic polymers, to conditions suitable for grafting of the unsaturated silane compound to the thermoplastic polymer to form a silane-grafted thermoplastic polymer, wherein: 
       the one or more unsaturated silane compounds are according to the formula
   G 1 R 1 SiX 1 X 2    (1) 
 
       wherein G 1  is an olefinically unsaturated hydrocarbon group, optionally heteroatom-substituted with one or more oxygen and/or nitrogen atoms; R 1  is selected from the group consisting of alkyl, aryl, aralkyl and arenyl; each of X 1  and X 2  is independently a hydrolyzable group or alternatively each of X 1  and X 2  is a hydrolyzable group having a direct bond to the silicon atom and also simultaneously a direct bond to each other to form a ring with the silicon atom of the unsaturated silane of Formula (1); and the system of at least two peroxides comprising a first peroxide having a first 0.1 hour half-life temperature and a second peroxide having a second 0.1 hour half-life temperature, the first and second 0.1 hour half-life temperatures in said composition having a temperature differential of at least about 5° C. 
     
     
         19 . The process of  claim 18 , further comprising subjecting the silane-grafted thermoplastic polymer to conditions suitable for crosslinking of the silane-grafted thermoplastic polymer to produce a crosslinked thermoplastic polymer. 
     
     
         20 . The process of  claim 18 , wherein conditions suitable for grafting of the unsaturated silane compound to the thermoplastic polymer comprise subjecting the composition to a reaction temperature between about a melting temperature and about a degradation temperature of the thermoplastic polymer for a period of time suitable for the at least partial grafting of the unsaturated silane compound to the thermoplastic polymer. 
     
     
         21 . The process of  claim 20 , wherein said reaction temperature is in a range of about 140° C. to about 260° C. and said period of time is about 0.5 to about 10 minutes. 
     
     
         22 . The process of  claim 19 , wherein conditions suitable for crosslinking of the silane-grafted thermoplastic polymer comprise subjecting the silane-grafted thermoplastic polymer to moisture and a crosslinking catalyst. 
     
     
         23 . The process of  claim 18 , wherein the thermoplastic polymer comprises one or more polyolefins. 
     
     
         24 . The process of  claim 23 , wherein the one or more polyolefins are polyethylene polymers or copolymers. 
     
     
         25 . The process of  claim 23 , wherein the one or more polyolefins are selected from the group consisting of high-pressure low-density polyethylene, medium- or low-pressure high-density polyethylene, low-pressure low-density polyethylene, medium-density polyethylene, ethylene-a-olefin copolymers, polypropylene, ethylene-ethyl acrylate copolymers, ethylene-vinyl acetate copolymers, ethylene-propylene copolymers, ethylene-propylene-diene terpolymers, ethylene-butene copolymers, polymethylpentene, polybutenes, chlorinated polyethylenes, chlorinated ethylene-vinyl acetate terpolymers, and combinations thereof. 
     
     
         26 . The process of  claim 18 , wherein the unsaturated silane compound is characterized in that G 1  is vinyl or allyl, R 1  is a straight alkyl group having from one to six carbon atoms, a branched alkyl having from 3 to 6 carbon atoms, an unbranched cycloalkyl group of from 6 to 8 carbon atoms, or a branched cycloalkyl of from 6 to 8 carbon atoms and each of X 1  and X 2  is independently an alkoxy group having one to six carbon atoms. 
     
     
         27 . The process of  claim 18 , wherein the unsaturated silane compound is selected from the group consisting of vinylmethyldimethoxysilane vinylethyldimethoxysilane, vinylmethyldiethoxysilane, vinylethyldiethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, N-(3-methyldimethoxysilylpropyl)methacrylamide and combinations thereof. 
     
     
         28 . The process of  claim 18 , wherein one or more of the unsaturated silane compounds are according to the Formula (2):
   G 1 R 1 SiZ   (2)   
       wherein G 1  is an olefinically unsaturated hydrocarbon group, optionally heteroatom-substituted with one or more oxygen and/or nitrogen atoms; R 1  is selected from the group consisting of alkyl, aryl, aralkyl and arenyl; and Z is a divalent hydrolyzable alkanedioxy group that forms a cyclic structure with the silicon atom of Formula (2). 
     
     
         29 . The process of  claim 28 , wherein the unsaturated silane compound of Formula (2) is characterized in that G 1  is vinyl or allyl, R 1  is a straight alkyl group having from one to six carbon atoms, a branched alkyl having from 3 to 6 carbon atoms, an unbranched cycloalkyl group of from 6 to 8 carbon atoms, or a branched cycloalkyl of from 6 to 8 carbon atoms and Z is an alkanedioxy group having from 2 to about 12 carbon atoms. 
     
     
         30 . The process of  claim 28 , wherein the unsaturated silane compound of Formula (2) is 2,4,4,6-tetramethyl-2-vinyl-[1,3,2]dioxasilinane; 2-methyl-5,5-diethyl-2-vinyl-[1,3,2]dioxasilinane, 2-phethyl-5,5-diethyl-2-vinyl-[1,3,2]dioxasilinane, 2-methyl-5-ethyl-2-vinyl-[1,3,2]dioxasilinane, 2,4,4,6-tetramethyl-2-(3-methacryloxypropyl)-[1,3,2]dioxasilinane, 2-methyl-5,5-diethyl-2-(3-methacryloxypropyl)-[1,3,2]dioxasilinane, 2-phethyl-5,5-diethyl-2-(1-methacryloxymethyl)-[1,3,2]dioxasilinane, 2-methyl-5-ethyl-2-(2-methacryloxyethyl)-[1,3,2]dioxasilinane and combinations thereof. 
     
     
         31 . The process of  claim 18 , wherein the temperature differential between the first and second 0.1 hour half-life temperatures of the first and second peroxides is in the range of about 5° C. to about 110° C. 
     
     
         32 . The process of  claim 18 , wherein the temperature differential between the first and second 0.1 hour half-life temperatures of the first and second peroxides is in the range of about 30° C. to about 90° C. 
     
     
         33 . The process of  claim 18 , wherein the temperature differential between the first and second 0.1 hour half-life temperatures of the first and second peroxides is in the range of about 45° C. to about 70° C. 
     
     
         34 . The process of  claim 18 , wherein the first peroxide is selected from the group consisting of bis-(2,4-dichlorobenzoyl)peroxide, tert-butylperoxypivalate, dilauroyl peroxide, dibenzoyl peroxide, tert-butylperoxy-2-ethylhexanoate, 1,1-bis-(tert-butylperoxy)-3,3,5-trimethylcyclohexane, bis-(tert-butylperoxy)cyclohexane, tert-butyl peroxy-3,5,5-trimethylhexanoate, tert-butylperoxyacetate, tert-butylperoxybenzoate, di-tert-amyl peroxide, dicumylperoxide, bis-(tert-butyl peroxyisopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and combinations thereof; and the second peroxide is selected from the group consisting of tert-butylperoxyacetate, tert-butylperoxybenzoate, di-tert-amyl peroxide, dicumylperoxide, bis(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-bis-(t-butylperoxy)hexane, tert-butylcumyl peroxide, 2,5-dimethyl-2,5-bis-(t-butylperoxy)-3-hexyne, di-tert-butylperoxide and combinations thereof; wherein at least one first peroxide is different from at least one second peroxide. 
     
     
         35 . The process of  claim 18 , wherein the first peroxide is selected from the group consisting of bis-(2,4-dichlorobenzoyl)peroxide, dilauroyl peroxide, dibenzoyl peroxide, 1,1-bis-(tert-butylperoxy)-3,3,5-trimethylcyclohexane, tert-butylperoxybenzoate, dicumyl peroxide and combinations thereof; and the second peroxide is selected from the group consisting of tert-butylcumyl peroxide, 2,5-dimethyl-2,5-bis-(t-butylperoxy)-3-hexyne and combinations thereof; wherein at least one first peroxide is different from at least one second peroxide. 
     
     
         36 . A process for producing a crosslinked thermoplastic polymer, the process comprising:
 a) subjecting a composition comprising (i) one or more unsaturated silane compounds, (ii) a system of at least two peroxides, and (iii) one or more thermoplastic polymers, to conditions suitable for grafting of the unsaturated silane compound to the thermoplastic polymer to form a silane-grafted thermoplastic polymer; and   b) subjecting the silane-grafted thermoplastic polymer of step (a) to conditions suitable for crosslinking of the silane-grafted thermoplastic polymer to form a crosslinked thermoplastic polymer;   
       wherein: 
       the one or more unsaturated silane compounds are according to the Formula (1):
   G 1 R 1 SiX 1 X 2    (1) 
 
       wherein G 1  is an olefinically unsaturated hydrocarbon group, optionally heteroatom-substituted with one or more oxygen and/or nitrogen atoms; R 1  is selected from the group consisting of alkyl, aryl, aralkyl and arenyl; each of X 1  and X 2  is independently a hydrolyzable group or alternatively each of X 1  and X 2  is a hydrolyzable group having a direct bond to the silicon atom and also simultaneously a direct bond to each other to form a ring with the silicon atom of the unsaturated silane of Formula (1); 
       and wherein the system of at least two peroxides comprise a first peroxide having a first 0.1 hour half-life temperature and a second peroxide having a second 0.1 hour half-life temperature, the first and second 0.1 hour half-life temperatures in said composition having a temperature differential of at least about 5° C.; 
       the conditions for silane grafting according to step (a) and for crosslinking according to step (b) are the same or different, and wherein steps (a) and (b) are conducted simultaneously or consecutively. 
     
     
         37 . The process of  claim 36 , wherein the thermoplastic polymer comprises one or more polyolefins. 
     
     
         38 . The process of  claim 37 , wherein the one or more polyolefins are selected from the group consisting of high-pressure low-density polyethylene, medium- or low-pressure high-density polyethylene, low-pressure low-density polyethylene, medium-density polyethylene, ethylene-α-olefin copolymers, polypropylene, ethylene-ethyl acrylate copolymers, ethylene-vinyl acetate copolymers, ethylene-propylene copolymers, ethylene-propylene-diene terpolymers, ethylene-butene copolymers, polymethylpentene, polybutenes, chlorinated polyethylenes, chlorinated ethylene-vinyl acetate terpolymers, and combinations thereof. 
     
     
         39 . The process of  claim 36 , wherein the unsaturated silane compound is selected from the group consisting of vinylmethyldimethoxysilane vinylethyldimethoxysilane, vinylmethyldiethoxysilane, vinylethyldiethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, N-(3-methyldimethoxysilylpropyl)methacrylamide and combinations thereof. 
     
     
         40 . The process of  claim 36 , wherein the unsaturated silane compound is 2,4,4,6-tetramethyl-2-vinyl-[1,3,2]dioxasilinane; 2-methyl-5,5-diethyl-2-vinyl-[1,3,2]dioxasilinane, 2-phethyl-5,5-diethyl-2-vinyl-[1,3,2]dioxasilinane, 2-methyl-5-ethyl-2-vinyl-[1,3,2]dioxasilinane, 2,4,4,6-tetramethyl-2-(3-methacryloxypropyl)-[1,3,2]dioxasilinane, 2-methyl-5,5-diethyl-2-(3-methacryloxypropyl)-[1,3,2]dioxasilinane, 2-phethyl-5,5-diethyl-2-(1-methacryloxymethyl)-[1,3,2]dioxasilinane, 2-methyl-5-ethyl-2-(2-methacryloxyethyl)-[1,3,2]dioxasilinane and combinations thereof. 
     
     
         41 . An article produced by a process comprising:
 a) providing a composition comprising:
 (i) one or more unsaturated silane compounds according to the Formula (1):
   G 1 R 1 SiX 1 X 2    (1) 
 
    wherein G 1  is an olefinically unsaturated hydrocarbon group, optionally heteroatom-substituted with one or more oxygen and/or nitrogen atoms; R 1  is selected from the group consisting of alkyl, aryl, aralkyl and arenyl; each of X 1  and X 2  is independently a hydrolyzable group or alternatively each of X 1  and X 2  is a hydrolyzable group having a direct bond to the silicon atom and also simultaneously a direct bond to each other to form a ring with the silicon atom of the unsaturated silane of Formula (1);
 (ii) a system of at least two peroxides comprising a first peroxide having a first 0.1 hour half-life temperature and a second peroxide having a second 0.1 hour half-life temperature, the first and second 0.1 hour half-life temperatures in said composition having a temperature differential of at least about 5° C.; and 
 (iii) one or more thermoplastic polymers; 
   b) subjecting the composition of step (a) to conditions suitable for grafting of the unsaturated silane compound to the thermoplastic polymer to form a silane-grafted thermoplastic polymer;   c) subjecting the silane-grafted thermoplastic polymer of step (b) to conditions suitable for crosslinking of the silane-grafted thermoplastic polymer to form a crosslinked thermoplastic polymer; and,   d) producing the article therefrom before, and/or during and/or after conducting step (c),   
       wherein the conditions for silane grafting according to step (b) and for crosslinking according to step (c) are the same or different, and wherein steps (b) and (c) are conducted simultaneously or consecutively.