Foam latex

Foam latex or latex foam rubber is a lightweight form of latex containing bubbles known as cells, created from liquid latex. The foam is generally created though the Dunlop or Talalay process in which a liquid latex is foamed and then cured in a mold to extract the foam. Structural enhancements are applied to a foam by making different choices of polymers used for the foam or through the use of fillers in the foam. Historically, natural rubber latex is used for the foam, but a similar commercial contender is styrene butadiene latex, which is especially designed for use in latex foams. Mineral fillers may also be used for the enhancement of properties like stability, load bearing, or flame resistance, but these fillers often come at the cost of lowered tensile strength and extension at break, which are generally desirable properties in the product. Latex foam has properties of energy absorption, thermal conductivity, and compression that make them suitable for many commercial applications like upholstery, soundproofing, thermal insulation (especially in construction), and transportation of goods. Foam latex is also used in masks and facial prosthetics to change a person's outward appearance. The Wizard of Oz was one of the first films to make extensive use of foam latex prosthetics in the 1930s. Since then, it has been a staple of film, television, and stage productions, in addition to use in a number of other fields. Single use plastics and polymer foams are often disposed of in landfills, and there is a growing concern about the amount of space this waste takes up. In an effort to make the foams more environmentally friendly, research is being done into fillers than can achieve the same enhancements as mineral while also increasing biodegradability of the product. Examples of such fillers include eggshell powders and rice husk powders. While the density of the foam can be measured, a more important property is relative density of the foam to the density of the original latex base This is expressed as Polymer foams will also have some ratio of closed cells to open cells (air bubbles which have been burst open), which can be measured through the water permeability of the foam.

The Dunlop process can be performed in batch form and in a continuous form. The following is a description for the batch process. The disuse of a gelling agent in preference for carbon dioxide makes the process more environmentally friendly, but the Talalay process is still not widely used for specialized latex foams industrially.

Relating to the longevity of the material, the resistance to dynamic fatigue is tested by recursively compressing a foam and allowing it to relax. The resistance of the foam to dynamic fatigue can then be measured either by visually observing the structure of the cells to note what proportion of cell walls has broken or ruptured, or by measuring the change in physical properties like the thickness of the material.]] Historically, natural rubber latex was used, and foams were produced using the Dunlop processes. Styrene butadiene rubber latex rose to prominence once high solids concentrates, which were designed specifically for foaming, began to be sold on the market. Properties of this polymer were fairly similar to natural rubber latex, so the competition between the two choices here is mostly economical.

These are materials that improve the structural properties of latex foam while also making it more environmentally friendly through increased biodegradability. A particular interest is using organic waste products to create these fillers.

Foam latex is used in masks and facial prosthetics to change a person's outward appearance. The Wizard of Oz was one of the first films to make extensive use of foam latex prosthetics in the 1930s. Theatrical latex foam is a specialized latex foam which is softer than commercial latex foam. It can be used in various arts and crafts including puppetry and costumes because of its ability to pick up small details of painting as well as its strength. Miss Piggy, Statler and Waldorf in Jim Henson's The Muppet Show as well as characters in Henson's next production, The Dark Crystal, were some of the first puppets created from latex foams used on a large scale. Artists such as Lordi and GWAR wear costumes that include this material. Latex foam is also widespread in the manufacture of modern soccer goalkeeper gloves. The material has proven to be the most effective way of allowing players to grip the football in wet and dry playing conditions, as well as providing damping properties which help in catching. A variety of treatments are applied to latex foam to produce different types of foam with varying properties to assist performance. Some, for example, are designed to offer a high level of grip; whereas others are designed to offer maximum durability.