rubber latex, so the competition between the two choices here is mostly economical. Polymer choices for variation in properties Other kinds of polymers were chosen for their properties and how they affect the properties of the foam in turn. For example, polychloroprene foam rubber is more difficult to burn and provides a less flammable alternative to traditional latex foam. Acrylonitrile-butadienelatex foam rubber is resistant to swelling in hydrocarbon oils. Fillers Structural fillers These are fillers meant to increase the stability and load bearing capabilities of the foam latex while increasing expansion and therefore lowering the coast of materials. However, adding fillers also affects the desirable properties of the latex foam, such as by decreasing extension at break and resistance to repeated occurrences of stress and relaxation. Mineral fillers like kaolinite clays and calcium carbonates can be added during the whipping phase (in the batch process) or mixing phase (in the continuous process) to the latex foam. Wet-ground micas can similarly be added into the latex during foaming, and they tend to have a lower impact on tensile strength and extension at break. However, micas tend to cause more shrinking to the product at the unmolding phase. Flame Retardants Since latex foams are a fire hazard, there are efforts to incorporate fillers into the foams to decrease their flammability. Such fillers include chlorinated paraffin hydrocarbons, antimony trioxide, zinc borate, and hydrated aluminum oxide. Naturally Sourced Fillers 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. Eggshell powder is an example of such a filler which can be added into the latex foam to manipulate the properties of the product and increase its environmental friendliness. Similarly to mineral fillers, eggshell powder increases compression stress, compression set, hardness, and density of the foam while decreasing tensile strength and extension at break. This filler also decreases the thermal stability of the material produced, but adding resin, another possible organic filler, was found to increase the tensile strength of eggshell powder filled natural rubber polymer foam. Another proposed filler with similar properties was rice husk powder, which increases load bearing properties of the foam while decreasing tensile strength and extension at break. This was also found to increase the biodegradability of the foam for improved control over post-consumer waste of these