Which of the following belt materials can withstand acidic and wet conditions?

Explanation:

The belt material should have a high coefficient of friction to generate enough frictional force to overcome the slipping, strong enough to withstand the tensions, and flexible to withstand the deformations.

The following are commonly used material for the belts.

Leather:

• The most commonly used material for the belt is leather. The leather may be either oak-tanned or mineral salt tanned. The belts are specified according to the number of layers. The belts must be periodically cleaned and dressed so that the belt remains soft and flexible in service.
• Tanning is a process is a progressive immersion of the leather in solutions known as "tan liquors".
• Belt dressing is done to lubricate the internal fibers and to maintain the coefficient of friction on the pulley side of the belt by keeping it in soft condition.
• Advantages:
  • Leather does not easily become frayed by wear
  • Leather material can be used again and again
  • coefficient of friction can be increased by proper use
  • Higher overload capacity than other materials

Balata

• It is a vegetable gum, extrude as sap from trees.
• These are 20% stronger than rubber belts but not be used at a temperature above 45°C because at this temperature the balata begins to soften and sticky.
• Properties
  • Having great toughness
  • Less elastic than a rubber belt
  • Fully acid and waterproof

Rubber Belt

• These are made of layers of fabric impregnated with rubber and have a thin layer of rubber on the faces.
• These are flexible, sensitive to heat, oiled, or greased. 
• Properties
  • Water or  atmospheric moisture will cause rubber belts to shrink
  • They are highly elastic with a little stretch
  • Protect against acids, alkalis, oil by appropriate compounding
  • Uniformity in quality and dimensions.