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Synergistic Effect of Hollow Glass Microspheres and Polymer Processing Additives in Wire and Cables

IP.com Disclosure Number: IPCOM000244880D
Publication Date: 2016-Jan-26

Publishing Venue

The IP.com Prior Art Database

Abstract

The current article outlines the method of using hollow glass microspheres in thermoplastics for reducing polymeric insulation failure. Typical failure of polymeric insulation, including for example, improper polymer fusion, voids and air bubble generation were overcome by usage of polymer processing additives (PPA) in cable extrusion. In addition, the synergistic presence of PPA's along with glass microspheres improved the dielectric strength and arcing resistance across a carbonized path in low voltage cables. Tracking was reduced in insulators by combining one or two polymers with an anti-tracking filler comprising alumina trihyrdrate (ATH) and soda lime borosilicate based light weight filler synergistically combined with fluoroelastomer based PPA's for improved the surface finish of the insulation. The composition also provided improved dielectric resistance and arc resistance against control sample formulation in high voltage heat shrink cable terminations.

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Synergistic Effect of Hollow Glass Microspheres and Polymer Processing Additives in Wire and Cables

Abstract:

     The current article outlines the method of using hollow glass microspheres in thermoplastics for reducing polymeric insulation failure. Typical failure of polymeric insulation, including for example, improper polymer fusion, voids and air bubble generation were overcome by usage of polymer processing additives (PPA) in cable extrusion. In addition, the synergistic presence of PPA's along with glass microspheres improved the dielectric strength and arcing resistance across a carbonized path in low voltage cables. Tracking was reduced in insulators by combining one or two polymers with an anti- tracking filler comprising alumina trihyrdrate (ATH) and soda lime borosilicate based light weight filler synergistically combined with fluoroelastomer based PPA's for improved the surface finish of the insulation. The composition also provided improved dielectric resistance and arc resistance against control sample formulation in high voltage heat shrink cable terminations.

Introduction:

     Polymeric materials are used for insulating electrical apparatus. They are not suitable for contaminated atmospheres such as moisture, fog, with salts and dust particles, which causes leakage current to flow across the surface of the insulation. This current causes a rise in temperature and consequent moisture evaporation and ultimately dry substrate formation. The electrical stress across the dry bands often exceeds the breakdown stress of air-insulation interface so spark scintillation takes place. Spark temperature is extremely high (about 2000◦C). The carbon formation occurs in dendritic fashion and the organic insulation fails by progressive creepage tracking.

     Manufacturing defects may fail to be detected and emerge as a cause of fire in appliance cable cords. There has been little published on this topic and there is only a single statistical study. In that study, Hirschler tested a number of products purchased from retail channels which were manufactured in Asia, but containing listing labels claiming compliance to UL standards. Of 6 sets of Christmas tree lights, he found that 50% did not meet the 105ºC requirement, while 33% of 9 appliance cords tested also failed to comply as per UL 62 and UL 1581.

     In high voltage cable the amount of alumina trihydrate required is usually 60-90wt% of entire insulation. Higher filler content is undesirable due to higher temperature used in molding or extrusion and/or radiation employed in crosslinking causes loss of hydrated water with development of voids and porosity leading to failure of the insulation. Also, the presence of tensile stress promote Christmas tree


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effect while the compression stress reduce generation of Christmas tree effect due to electrical stress. Presences of glass microspheres improved the compression strength and reduce the tensile stress by improving the rigidity o...