Additives chemical blowing agents

Polypropylene, solid additives, (chemical blowing agent)... 

Several more recent variations of the film-to-fiber approach result in direct conversion of film to fabric. The film may be embossed in a controlled pattern and subsequently drawn uniaxiaHy or biaxiaHy to produce a variety of nonwoven products (47). Addition of chemical blowing agents to the film causes fibrillation upon extmsion. Nonwovens can be formed directly from blown film using a unique radial die and control of the biaxial draw ratio (48)... 

Chemical blowing agents (CBAs). These are solids that decompose to give a gas at the processing temperature. In addition to the demands above, the CBA must possess the following ... 

Hurnik H (1990) Chemical blowing agents, In Plastics additives handbook, Gachter R and Muller H (Eds), Hanser Publishers Munich, pp 811-8321. 

The proper balance between viscosity and gas evolution can be controlled by a number of factors such as a suitable type and concentration of catalyst and surfactant, the presence of a nucleating agent (not always necessary) (17,18) and control of reaction temperature (or exotherm). Additional factors that must be considered are the use of a suitable chemical blowing agent, which is especially important for the production of thermoplastic foams, and the formation of oligomers (prepolymers) which exhibit higher viscosities than monomers in the preparation of thermoset foams (e.g. polyurethane foams). 

Additives and Fillers for Structural Foam Chemical Blowing Agents Processing Structural Foam Tooling... 

Still, in physical blowing processes, chemical additives do serve as nucleating agents to produce finer cells, or to reduce the amount of physical blowing agent that is needed. Chemical blowing agents (discussed below), especially... 

H. Hurnik, Chemical Blowing Agents in Plastics Additives, 4th ed., R. Gachter and H. Muller, Eds., Carl Hanser Verlag, Munich, 1993. 

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