Rubber Technology

- Dec 03, 2019-

  1. Accelerator Activators

  • Inorganic compounds – mainly metal oxides-zinc oxide, hydrated lime

  • Organic Acids – Normally in combination with metal oxides

    • Stearic, oleic

  • Alkaline substances – will increase ph of rubber

    • Usually increases cure rate

  1. Age Resistors (Antidegredants) – All rubbers are affected by aging

    • Prevent or slow polymer breakdown caused by

      • Ozone, oxygen, heat, light, weather

  • Chemical Protectants – 3 types

    • Amines – tend to discolor, “staining”

    • Phenolics – nonstaining

    • Phosphites – used as stabilizers for SBR

  • Physical Protectants – waxy materials that bloom to surface forming a protective coat

    • Shields the part from ozone, oxygen etc.

  • Effects of oxygen on elastomers

    • Softens (or usually softens) – NR, IR, IIr

    • Hardens ( or usually hardens)- CR, SBR, NBR, BR, EPDM, CSM, FKM

  • PHR – usually 2-3 phr

  • Amines are about 65% of the age resistors