G. Vitarelli's research while affiliated with CYTEC Industries and other places

Chlorine chemistry is complex. Under certain common conditions, chlorinated compounds can react with polyethylene pipes causing premature failures (bursts/leaks). It is important to understand this degradation mechanism in order to prevent future premature pipe failure. Recently, a specific additive system, when incorporated into polyethylene pipe resin was demonstrated to significantly improve the pipe's resistance to degradation caused by chlorine exposure. BACKGROUND Disinfected drinking water is critical for maintaining the healthy and sanitary conditions we enjoy today. Before 1915, unsafe drinking water caused a significant number of deaths due to cholera, dysentery, hepatitis A and typhoid fever. Abel Wolman, as the Chief Engineer of the Maryland State Department of Health from 1922-1939 (1) , made the important contribution of chlorinating the Baltimore drinking water supply. The cities of New York, Detroit and Columbus (OH) quickly followed in chlorinating their drinking water supplies. By the late 1920's, this practice was widely accepted nationwide and an 85% drop in typhoid fever death was reported.

Geomembrane has been used successfully over the past 20 years in many different applications from reservoir liners to fish ponds to landfill liners. Increasing usage in new applications areas leads to higher performance demands on geomembrane. This paper will study the effects of various traditional and new environmental stresses on geomembrane and how to formulate the stabilization package to meet these performance requirements for new applications.

Chlorine chemistry is complex. Under certain common conditions, chlorinated compounds can react with polyethylene pipes causing premature failures (bursts/leaks). It is important to understand this degradation mechanism in order to prevent future premature pipe failure. Recently, a specific additive system, when incorporated into polyethylene pipe resin was demonstrated to significantly improve the pipe's resistance todegradation caused by chlorine exposure.

Hindered amine light stabilizers (HALS) are the primary means of stabilizing many polymers against the effects of light. Over the past two decades new and improved variations of this chemistry have made it possible to use plastics in an increasing number of critical applications. However, there is a vast array of plastic applications that are not technically demanding but do need some level of light stabilization. These applications generally use first generation HALS systems. Though these early HALS typically suffers from poor compatibility with polyolefins, their low cost ensures continued use. Now there is a cost-effective alternative that provides improved performance without the shortcomings of first generation HALS. In natural and pigmented polyolefins improvements in both aesthetic and physical property retention can be achieved. This is largely due to the increased compatibility of this HALS with non-polar substrates.

Antioxidants can be divided into two broad classes, primary and secondary, depending upon their mode of action. The most broadly used primary antioxidants are hindered phenolics. Phenolic antioxidants have traditionally been based on 2,6-di-t-butyl-4-methylphenol (BHT). This functional moiety has been incorporated into larger molecules affording products with lower volatility or greater polymer compatibility. More recently, molecules have been introduced which vary in steric hindrance about the phenol and also the way in which multiple phenol functional groups are linked to form larger molecules. This has led to structures which have lower colour contribution. Surprisingly, in some cases these molecules have shown higher levels of efficiency relative to other antioxidants with similar phenol/molecular weight ratios. This has included enhanced levels of synergism with secondary antioxidants. An attempt is made to correlate structural features of these molecules to the enhanced performance and/or lower colour.

Antioxidants can be divided into two broad classes, primary and secondary, depending upon their mode of action. The most broadly used primary antioxidants are hindered phenols. Phenolic antioxidants have traditionally been based on 2,6-di-t-butyl-4-methylphenol (BHT). This functional moiety has been incorporated into larger molecules affording products with lower volatility or greater polymer compatibility. More recently, molecules have been introduced which vary in steric hindrance about the phenol and also the way in which multiple phenol functional groups are linked to form larger molecules. This has led to structures which have lower color contribution. Surprisingly, in some cases these molecules have shown higher levels of efficacy relative to other antioxidants with similar phenol/molecular weight ratios. This has included enhanced levels of synergism with secondary antioxidants. An attempt is made to correlate structural features of these molecules to the enhanced performance and/or lower color.