Insulators and Conductors

Thermal Conductivity is defined as the ability of material to transmit heat through a surface. Thermal Conductivity insulators have low heat conductivity and conductors have a high thermal resistance.

Some foam insulations, such as Styrofoam® and Aerogel®, insulate through the trapping of gases within their structure. This slows down heat transfer because it blocks convection pathways. Fur and feathers are also effective insulators because they trap air in their pores, pockets, or voids.

Metals

Metals conduct thermal energy very well because their particles easily bump into those from cooler matter. The particles of insulators are much further apart, and so don't transfer as much thermal energy.

The thermal conductivity, or k-value is the rate at which heat moves through a material. It's expressed in a number that relates the density of a material to its thickness. Lower numbers indicate better performance. Thermal conductivity does NOT account for convection losses or radiation.

Aerogels can be used as excellent insulators because they are primarily composed of gas. In addition, they are extremely dense which helps prevent thermal bridging. It is for this reason that a good insulator must have both a low thermal conductivity as well as a high density.

Plastics

Plastics are good thermal insulators, as they do not conduct heat well. They are poor conductors because they do not have electrons that can easily pass through them. They are also tightly packed, like the molecules in a glass or ice.

Most plastics are composed of long chains of carbon atoms that are connected together. This structure allows them to stretch a lot without breaking, and then return to their original form when the stretching force has been removed. Rubber, plastic wrap and Plexiglas are all examples.

MIT researchers have discovered a way to alter the molecular structure of some plastics so they can act as conductors, instead of insulators. This could help dissipate any heat generated by electronic devices, such as cell phones and laptops. This would also allow electronics manufacturers to use lighter and more flexible plastics.

Wood

Researchers are converting the wood into a lightweight and strong material which is better than Styrofoam and silica aerogel. The material is hypoallergenic, biodegradable, and should cost less than $7 per square meter to make. It will be expected to help meet energy efficiency and eco-economy goals.

Using waste wood from lumber sawing for constructing heat-insulating mats can benefit society by reducing building thermal load, using biomass waste and sequestering carbon dioxide. The heat conduction, sound absorption, and insulation properties of mats made by thermoforming wood shavings and kenaf fibre were tested.

Wood is a good thermal insulator since it absorbs, rather than transmits, thermal energy. It is slow to transfer thermal energies between adjacent molecules of the lattice. Other factors that affect wood's insulation properties include density and water absorption. These characteristics are crucial when choosing the material for a wall or another structure.

Biological Insulators

Insulators are a class of DNA binding proteins which mediate interactions between genomic sequences, and the nuclear lamina. They have a wide range of effects on chromosomal function such as transcription, DNA recombination and elongation. Insulator mediated interaction is dynamic and controlled by different mechanisms.

Several types of insulators have been identified in Drosophila and vertebrates including the CTCF, Su(Hw), Mod(mdg4)2.2, dTopors, and the SF1 insulator found in the bithorax complex (Belozerov, Majumder et al. 2003). The functions of these proteins differ depending on their interaction with the insulators.

The core of the insulator protein is composed of three domains: a BTB, a Zinc Finger domain and a C terminal domain that interacts directly with the chromatin fibre. Insulator proteins have also been characterized. One example is the GAF, which interacts both with Mod(mdg4)2.2 (modified mdg4) and the insulator sites dTopors. Insulator function is regulated by methylation, poly(ADP-ribosyl)ation and sumoylation. dTopors are required for proper insulator functionality. They act as attachment points for insulators.