Nitrogen Containing Polymers

Boron- and Nitrogen-Containing Polymers for Advanced Materials 103... 

Boron-containing nonoxide amorphous or crystalline advanced ceramics, including boron nitride (BN), boron carbide (B4C), boron carbonitride (B/C/N), and boron silicon carbonitride Si/B/C/N, can be prepared via the preceramic polymers route called the polymer-derived ceramics (PDCs) route, using convenient thermal and chemical processes. Because the preparation of BN has been the most in demand and widespread boron-based material during the past two decades, this chapter provides an overview of the conversion of boron- and nitrogen-containing polymers into advanced BN materials. 

Unfortunately, most fatalities in fires occur by inhalation of toxic vapours. These can be carbon monoxide (which arises from incomplete combustion), cyanides (from nitrogen-containing polymers) and chlorides (from chloropoly-mers). These are the adverse consequences of flammable polymer combustion. They can be overcome by using breathing apparatus, face masks, etc. 

It is well known that hydrogen cyanide can be liberated during combustion of nitrogen containing polymers such as wool, silk, polyacrylonitrile, or nylons (1, 2). Several investigators have reported cyanide levels in smoke from a variety of fires (3, 4, 5). The levels reported are much below the lethal levels. Thus the role of cyanide in fire deaths would seem to be quite low. However, as early as 1966 the occurence of cyanide in the blood (above normal values) of fire victims was reported (6). Since then many investigators have reported elevated cyanide levels in fire victims (7-13). However, it has been difficult to arrive at a cyanide blood level which can be considered lethal in humans. In this report the results of cyanide analysis in blood of fire victims are reported as well as the possibility that cyanide may, in some cases, be more important than carbon monoxide as the principal toxicant in fire smoke. 

Nitrogen containing polymers have the potential to release cyanide when thermally decomposed. This study demonstrates that cyanide plays an important role in fire deaths. 

The release of semivolatile compounds from a variety of nitrogen containing polymers, including ABS, PA 6 PU and melamine/urea formaldehyde resins can be found in the literature (52). The temperature of treatment runs from 70°C to 300°C, i.e., low temperature pyrolysis, if pyrolysis at all. 

Among the most frequently used nitrogen containing polymers in electrical, electronic, and automotive applications are PA and ABS. Pyrolysis proved to be a suitable method for recycling plastic waste. 

Pyrolyzed N4 chelates and nitrogen-containing polymers on porous carbons and soots might become an option as electrocatalysts for 02... 

A lingering limitation with the present generation of reverse osmosis membranes is their limited resistance to chemical attack. In particular, membranes derived from polyamides, polyureas, and other nitrogen-containing polymers are susceptible to oxidative degradation by chlorine—the most widely used disinfectant to pretreat feed waters. Dissolved oxygen can also damage reverse osmosis membranes when catalyzed by trace heavy metals. Successful development of oxidation-resistant membranes will help reduce the complexity and costs associated with the elaborate pretreatment now required. 

Phosphorus and nitrogen containing polymers were synthesized according to literature data (14-16). The chemical structure and some physical and chemical properties of these polymers together with the modifications occurring in cold plasma are presented in Table I. 

Physical and chemical properties of the phosphorus and nitrogen containing polymers used In the grafting plasma processes ... 

X HE USE OF CHEMICAL APPROACHES to improve the processing, properties, and performance of advanced ceramic materials is a rapidly growing area of research and development. One approach involves the preparation of organometallic polymer precursors and their controlled pyrolysis to ceramic materials. This chapter will review the preparation and application of silicon-, carbon-, and nitrogen-containing polymer systems. However, the discussion is not exhaustive the focus is on systems with historical significance or that demonstrate key technological advances. 

Photosensitive polymers Heterochain polymers, nitrogen-containing polymers, polyesters Vinyl polymers Aliphatic polymers with quaternary carbon atoms... 

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