Weathering, polymer materials

XPS is able to answer the question of how the weathering at a polymer surface differs from that in the bulk material and is able to detect changes in the surface chemistry of weathered polymers at a stage where the degree of bulk oxidation is small. 

New experimental results on specific polymer material problems are presented in the last nine chapters. Several cases involve the study of polymers from commercial sources. The topics include (1) surface chemistry as induced by (a) outdoor weathering, (b) chemical reactions, and (c) plasma exposure (2) chemical bond formation at the polymer -metal interface and (3)biomaterials characterization and relationship to blood compatibility. 

FIGURE 5.3 Accelerated and real-time weathering of polymer materials obtained at NREL. PET, polyethyleneteraphthalate PVDF, polyvinylidenedifluoride PE, polyethylene PC, polycarbonate PMMA, polymethylmethacrylate. 

The dispersed polymer phase throughout the concrete causes considerable reduction in porosity and microcracks in the Portland cement matrix as well as serving as an additional binding material [11, 19]. Thus, PPCC is a more durable and weather resistant material for deck coverings and parking lot overlays. 

There are two major producers of SAN for the merchant market in the United States, Bayer Corp. and the Dow Chemical Co., which market these materials under the names of Lustran and Tyril, respectively. Bayer became a U.S. producer when it purchased Monsanto s styrenics business in December 1995 (332). Some typical physical properties of these SAN resins have been shown in Table 11. These two companies also captively consume the SAN for the production of ABS as well as SAN-containing weatherable polymers. The other two U.S. SAN producers, either mainly consume the resin captively for ABS and ASA polymers (GE Plastics) or toll produce for a single client (Zeon Chemicals). BASF is expected to become a more aggressive SAN supplier in the United States since its Altamira, Mexico, stryenics plant came on-line in early 1999. Overall, U.S. SAN consumption has been relatively stable for the last few years, ranging from 43 x 10 to 44.5 x 10 t (95-98 million poimds) between 1994 and 1996. Most markets for SAN are growing at only GDP rates. Consumption growth for SAN in 1996-2001 is expected... 

Table 3 is composed based on technical data for over 180 commercial blends. Producers of blends included in Table 3, rated their products as weather resistant materials for reasons included in the last column. Analysis of this information shows that most blends included in the table have at least one polymer which belongs to group A defined in Table 1. It means that weatherstable blend is more likely to be obtained from combination of durable material. In fact, a more thorough analysis of information in Table 3 shows that UV stability of a mixture is at best an average of composition. Only in two cases, blend stability was better than expected from component pol5aners. At the same time, literature on the subject contains numerous examples of compostions which are less durable than component polymers. ...

J. Lemaire in Long-term Forecasting of the Behavior of Polymer Materials in Outdoor Weathering Conditions, Report PB90-2002482, NTIS, 1989. 

Searle, N.D., McGreer, M., Zielnik, A. Weathering of polymer materials. Encycl. Polym. Sci. Technol. (2010). doi 10.1002/0471440264.pst401.pub2... 

The photochemical reactivity of polymers is of considerable interest because photodegradable plastics have a number of applications. Additional interest in polymer photoreactivity stems from the need to limit and control weathering in polymer materials. Photodegradation is an important component of polymer weather, and a proper understanding of degradation processes and of the experimental factors that affect degradation is necessary for the accurate estimation of polymer lifetime and for the development of stabilizing systems. 

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