1. © Effects Of Increased Solar Ultraviolet Radiation On Materials Andrady, AL; Hamid, SH; Hu, X; Torikai, A ELSEVIER SCIENCE SA, JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY; pp: 96-103; Vol: 46 King Fahd University of Petroleum & Minerals http://www.kfupm.edu.sa Summary Synthetic polymers such as plastics, as well as naturally occurring polymer materials such as wood, are extensively used in building construction and other outdoor applications where they are routinely exposed to sunlight. The W-B content in sunlight is well known to affect adversely the mechanical properties of these materials, limiting their useful life. Presently their outdoor Lifetimes depend on the use of photostabilizers in the case of plastics and on protective surface coatings in the case of wood. Any increase in the solar UV-B content due to a partial ozone depletion would therefore tend to decrease the outdoor service life of these materials. It is the synergistic effect of increased UV radiation with other factors such as the temperature that would determine the extent of such reduction in service Life. The increased cost associated with such a change would be felt unevenly across the globe. Those developing countries that depend on plastics as a prime material of construction and experience high ambient temperatures are likely to be particularly affected in spite of the relatively small fractional decrease in ozone at those locations. Assessment of the damage to materials, associated with ozone depletion, requires a knowledge of the wavelength dependence as well as the dose-response characteristics of the polymer degradation processes of interest. While the recent literature includes some reliable spectral sensitivity data, little dose-response information has been reported, so it is difficult to make such assessments reliably at the present time. This is particularly true for the naturally occurring materials popularly used in construction applications. To maintain polymers at the same useful Lifetime in spite of increased solar W-B content, the amount of photostabilizers used in the formulations might be increased. This strategy assumes that conventional stabilizers will continue to be effective with Copyright: King Fahd University of Petroleum & Minerals; http://www.kfupm.edu.sa

2. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. © the spectrally altered W-B-enhanced solar radiation. While the present understanding of the degradation chemistry suggests the strategy to have merit, its effectiveness, in an altered solar radiation environment, has not been demonstrated for common polymers. The availability of these data is crucial for reliably estimating the cost of mitigating the increased damage to materials as a result of a possible partial depletion of the ozone layer using this approach. (C) 1998 UNEP. Published by Elsevier Science S.A. All rights reserved. References: ALLEN NS, 1983, DEGRADATION STABILIZ, P373 ANDRADY AL, UNPUB ANDRADY AL, 1989, J APPL POLYM SCI, V37, P935 ANDRADY AL, 1990, J APPL POLYM SCI, V39, P363 ANDRADY AL, 1991, J APPL POLYM SCI, V42, P2105 ANDRADY AL, 1992, POLYM DEGRAD STABIL, V35, P235 ANDRADY AL, 1993, J ENV POLYM DEG, V1, P171 ANDRADY AL, 1996, J APPL POLYM SCI, V62, P1465 ANDRADY AL, 1997, ADV POLYM SCI, V128, P49 BURN LS, 1994, PLAST RUB COMPOS PRO, V21, P99 DECKER C, 1984, DEGRADATION STABILIZ, P81 FACTOR A, 1987, ADV STABILIZATION CO, V2, P45 FACTOR A, 1995, ANGEW MAKROMOL CHEM, V232, P27 FORSSKAHL I, 1993, ACS SYM SER, V531, P45 FUKUDA Y, 1991, POLYM DEGRAD STABIL, V34, P75 GAPPERT G, 1996, VINYL 2020 PROGR CHA GARDETTE JL, 1991, POLYM DEGRAD STABIL, V34, P135 GHAFFAR A, 1976, EUR POLYM J, V11, P271 GUGUMUS F, 1993, POLYM DEGRAD STABIL, V39, P117 HAMID H, 1998, COMMUNICATION HAMID SH, 1991, J APPL POLYM SCI, V43, P651 HAMID SH, 1995, HDB POLYM DEGRADATIO HEITNER C, 1993, ACS SYM SER, V531, P3 HIRT RC, 1967, APPL POLYMER S, V4, P61 HO BYK, 1984, J VINYL TECHNOL, V6, P162 HON DNS, 1991, WOOD CELLULOSIC CHEM, P525 HU X, 1998, IN PRESS POLYM DEGRA HU XZ, 1997, POLYM DEGRAD STABIL, V55, P131 HUSSAIN I, 1995, J VINYL ADDIT TECHN, V1, P137 JAHAN MS, 1987, PHOTOCHEM PHOTOBIOL, V45, P543 LAUNER HF, 1965, TEXT RES J, V35, P395 LENNOX FG, 1971, APPL POLYM S, V18, P353 MADER FW, 1992, MAKROMOL CHEM-M SYMP, V57, P15 Copyright: King Fahd University of Petroleum & Minerals; http://www.kfupm.edu.sa

3. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. © MATSUMOTO S, 1984, J POLYM SCI POL CHEM, V22, P869 MITSUOKA T, 1993, J APPL POLYM SCI, V47, P1027 MOORE S, 1994, MODERN PLASTICS APR, P46 OWEN ED, 1984, DEGRADATION STABILIZ, P320 PAN JQ, 1993, POLYM DEGRAD STABIL, V40, P375 PYRDE CA, 1985, ACS SYM SER, V280, P329 RABEK JF, 1995, POLYM PHOTODEGRADATI, P655 RABONAVITCH EB, 1983, J VINYL TECHNOL, V5, P110 RIVATON A, 1988, POLYM DEGRADATION ST, V23, P51 SCOTT G, 1985, NEW TRNEDS PHOTOCHEM SCOTT G, 1990, POLYM DEGRADATION ST SHLYAPNIKOV YA, 1996, ANTIOXIDATIVE STABIL SUMMERS JW, 1983, J VINYL TECHNOL, V5, P43 TITOW WV, 1984, PVC TECHNOLOGY, P1233 TORIKAI A, 1993, J APPL POLYM SCI, V50, P2185 TORIKAI A, 1993, J POLYM SCI POL CHEM, V31, P2785 TORIKAI A, 1993, POLYM PREPR-JAPAN, V42, P2045 TORIKAI A, 1998, J APPL POLYM SCI, V67, P1293 WARNER WC, 1966, I EC P RES DEV, V5, P219 WYPYCH J, 1990, WEATHERING HDB, P512 ZHANG ZF, 1996, POLYM DEGRAD STABIL, V51, P93 For pre-prints please write to: abstracts@kfupm.edu.sa Copyright: King Fahd University of Petroleum & Minerals; http://www.kfupm.edu.sa