Find out which is the most effective insulating material out of a range of different materials.

G.C.S.E science coursework

Coursework: Insulator

Aim:

My aim is to find out which is the most effective insulating material out of a range of different materials.

Introduction

The choice of an insulation material is usually made depending on the application. Polyethylene and polystyrene are usually used in high-frequency applications. Insulators must also be selected according to the maximum temperature they will encounter.

I.E. Teflon is used in the high-temperature range of 175° to 230° C. Other materials may need to be used in awkward mechanical or chemical conditions. Nylon has an excellent abrasion resistance, also neoprene, silicone rubber, epoxy polyesters, and polyurethane's usually provide protection against chemicals and moisture.

Thermal insulating materials are used to reduce the flow of heat between hot and cold regions. The sheathing often placed around steam and hot-water pipes, for instance, reduces heat loss to the surroundings, and insulation placed in the walls of a refrigerator reduces heat flow into the unit and permits it to stay cold.

Thermal insulation may have to for fill one or more of three functions:

1. To reduce thermal conduction in the material, in which heat is transferred by electrons.

2. To reduce thermal convection currents, which can be set up in air- or liquid-filled spaces

3. To reduce radiation heats transfer, where thermal energy is transported by electro-magnetic waves.

Conduction and convection are suppressed in a vacuum, which radiation is the only method of transferring heat. Radiation maybe reduced if the surfaces are made highly reflective. So why thin aluminium foil can be used in building walls, and reflecting metal on roofs minimizes the heating effect of the Sun. Thermos bottles or Dewar flasks retain or exclude heat because they have double walls that have reflective silver or aluminium coatings and are separated by a vacuum. .

Air offers around 15,000 times as much resistance to heat flow compared to a good thermal conductor such as silver, but only about 30 times as much as compared to glass. Insulating materials are usually made of non-metallic materials and are filled with small air pockets. Magnesium carbonate, cork, felt, cotton batting, rock or glass wool, and diatomaceous earth. Asbestos was once widely used for insulation, but has since been found to be a health hazard and has now been banned in new construction in many countries.

Home-heating and air-conditioning costs can be reduced by proper building insulation. In cold climates about 8 cm of wall insulation and about 15 to 23 cm, of ceiling insulation are recommended.

In building materials, air pockets provide more insulation in hollow glass bricks or double-glazed windows (consisting of two or three sealed glass panes with a thin air space between them), and partially hollow concrete tile. Insulating properties become poorer if the air space becomes large enough to allow thermal convection, or if moisture seeps in and acts as a conductor. The insulating property of dry clothing, for example, is the result of air trapped between the fibres, this can be significantly reduced by moisture.

There has recently been the development of ‘the super insulator‘ . Super insulation fabric consists ...