electrically resistive organic materials , e . g . silicone rubber , thermoplastic resins , and liquid crystals , are made more electrically conductive by the addition of an effective amount of a compound of the formula : ## str1 ## wherein r 1 is selected from the group consisting of hydrogen , alkyl , and phenyl - substituted alkyl ; r 2 is alkyl with 8 - 20 carbon atoms ; and z is selected from the group consisting of phenyl and alkyl - substituted phenyl . the invention is particularly applicable to silicone rubber light valves and liquid crystals .