Prysmian S.p.a.

Politecnico Di Milano

Vito Scrima

Luigi Caimi

Fabio Tosi

Attilio Citterio

Franco Galletti

Flavio Casiraghi

Massimo Gola

Sergio Gutierrez

Marco Andreoletti

Carlo Castelli

Pauline Audebet

Serge Colombier

Disclosed herein are flame-retardant electric cables () having a core containing an electric conductor () and an electrically insulating layer () made from a flame-retardant polyolefin-based composition including a) a cross-linked polyolefin as base polymer, b) silica, and c) carbon nanotubes, wherein the amount of silica is from 5 wt % to 10 wt % of the polyolefin-based composition, and the amount of carbon nanotubes is from 0.5 wt % to 2 wt % of the polyolefin-based composition. Such cables have improved flame retardant performances, especially regarding a lower occurrence of droplets during burning, which render them capable of being certified in higher classes of the current international standards, for example of the standard EN 50399:2011/A1 (2016).

Flame retardant electrical cable

A flame-retardant cable having a core is disclosed. The cable contains at least one conductor and a coating made from a low smoke zero halogen flame-retardant polymer composition. The polymer composition contains a halogen free base polymer added with a) less than 170 phr of at least one metal hydroxide; b) from 1 to 10 phr of a phyllosilicate clay; c) at least 1 phr and less than 10 phr of melamine or a derivative thereof; and d) an alkali or alkaline-earth metal carbonate. The cable has improved reaction to fire performances especially in that no dripping occurs during burning, which renders it compliant with the requirements of the more recent international standards.

Flame-retardant cable with self-extinguishing coating layer

A fire resistant cable comprising: a conducting element (); a layer, surrounding the conducting element, made of a ceramifiable composition comprising: &#x2014;a thermoplastic polymer mixture comprising: (a) a copolymer of ethylene with a C-Calpha-olefin, having a density of from 0.860 to 0.910 g/cm, a melt flow index not higher than 3 g/10 min and a melting point of 105&#xb0; C. at most; (b) an ethylene homopolymer or copolymer of ethylene with a C-Calpha-olefin, having a density of from 0.900 to 0.985 g/cm, a melt flow index not higher than 5 g/10 min and a melting point of at least 110&#xb0; C.; and (c) a polyethylene grafted with an ethylenically unsaturated monomer; &#x2014;at least 25 wt % of silica; &#x2014;a fluxing agent selected from alkaline metal oxides or precursors thereof; &#x2014;an inorganic hydroxide compound selected from magnesium hydroxide, aluminium hydroxide and mixtures thereof; &#x2014;a stabilizing agent comprising a hydrated magnesium silicate in an amount of at least 5 wt %; weight percentages being based on the total weight of the ceramifiable composition. Upon exposure to elevated temperatures such as those encountered in case of fire, the ceramifiable composition is transformed into a ceramic material capable of protecting the conducting element from fire and mechanical stresses. The fire resistant cable of the present invention can continue operating under fire conditions for a certain period of time.

Fire resistant cable with ceramifiable layer

A fire resistant cable comprising: at least one conducting element; at least one layer, surrounding said conducting element, made of a ceramifiable composition comprising: a polymeric material comprising an ethylene/vinyl acetate copolymer as main polymer; at least 25 wt % of silica; a fluxing agent selected from alkaline metal oxides or precursors thereof; a stabilizing agent comprising at least one of MgO, CaO, PbO, B2O3, or a precursor thereof; from 0.1 wt % to 5 wt % of a hydroxide selected from magnesium hydroxide, aluminum hydroxide and mixtures thereof; the above percentages being expressed with respect to the weight of the ceramifiable composition. Upon exposure to elevated temperatures such as those encountered in case of fire, the ceramifiable composition is transformed into a ceramic material capable of protecting the conducting element from fire and mechanical stresses. The fire resistant cable of the present invention can continue operating under fire conditions for a certain period of time.

A process for recovering wastes of a polymeric composition including at least one peroxide-curable polymer and at least one peroxidic crosslinking agent, which includes compounding the wastes with at least one antioxidant agent suitable for sulfur-vulcanized elastomeric compositions, at a temperature lower than the decomposition temperature of the at least one peroxide crosslinking agent. The compounding of the polymeric wastes with the antioxidant agent is carried out at a temperature lower than the decomposition temperature of the peroxide crosslinking agent, so as to avoid any premature activation of the crosslinking agent. The process is particularly suitable for compositions based on elastomeric polyolefins, more preferably for elastomeric ethylene copolymers such as ethylene-propylene copolymers (EPR) and ethylene-propylene-diene terpolymers (EPDM), which can be processed at relatively low temperatures, much lower than the decomposition temperatures of the most common peroxide crosslinking agents.

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