What Is a Porous Body?
A porous body is a material with numerous small pores or voids throughout its structure. In nature, examples like pumice, charcoal, shells, plants, and bones demonstrate inherent porous structures. The beehive, known for its honeycomb structure of regular hexagonal columns, is another example of a natural porous body.
Industrially, porous structures are artificially created in metals, resins, glass, and other materials for various applications.
Uses of Porous Bodies
Natural porous bodies have diverse uses, such as:
- Zeolite: Used as a catalyst, soil conditioner, and water purification material.
- Charcoal: Employed as a deodorizer, moisture absorber, and filter material.
- Shells: Utilized in water purification for rivers and lakes.
Artificially created porous bodies also have wide-ranging applications:
- Porous Metals: Used in building structures, industrial machinery, crash mitigation materials, filters for automobiles, and medical applications like artificial bones and implants.
- Porous Glass: Applied in separation membranes and as catalyst carriers.
- Porous Resin: Functions as heat insulators, cushioning materials, and sound-absorbing materials.
Characteristics of Porous Bodies
The characteristics of porous bodies depend on both the material composition and the structure of the pores. The size of the pores significantly influences the properties of the material. For example, in adsorbents or separation materials, the molecular size that can be adsorbed or separated is determined by pore size. In structural materials, smaller pores typically result in higher mechanical strength but increase the weight of the material.
The nature of the pores also plays a crucial role. There are “independent pore structures,” where each pore is isolated, and “continuous pore structures,” where neighboring pores are interconnected. In the case of porous resins like styrene foam and urethane foam, independent pore structures prevent gas or liquid passage, trapping air and providing high heat insulation, buoyancy, and buffering properties. Conversely, continuous pore structures, while less rigid, excel in water and sound absorption.