9.1 Introduction

Cushionable materials for upholstery, mattresses, etc., have become an indispensable component of everyday life. Such materials are known as cellular materials because they are made by providing tiny air cells in a soft matrix such as rubber or plastic. Rubber-based cellular materials can be made from both dry rubber and rubber latex. Latex-based cellular material known as latex foam is the topic of this chapter. The number of air cells, their average size and whether the cells are intercommunicating, partially intercommunicating or non-intercommunicating determine the properties of latex foam rubber such as density, cushionability, water absorption, etc. In the case of latex foam the cells are mostly intercommunicating.

In 1930 a patent was granted for a process which involved mechanical agitation or whipping of latex into a foam in the presence of additives like soap, gelatin and so on [1] which assist the foaming process. This led to the production of latex foam by the Dunlop process in the early 1930s [2]. The essential feature of the process was that after foaming the latex it could be set using sodium silicofluoride, a delayed action gelling agent. The product after gelling could be vulcanised in a steam chamber [3, 4]. By 1936, several alternative methods had been proposed for the production of latex foam but none of them except the Talalay process [5] was successful. This process originally involved adding hydrogen peroxide or a low boiling organic solvent to the compounded latex and then subjecting the compound...