Physicochemical Changes in UV- Exposed Low- Density Polyethylene Films

M. A. Salem; H. Farouk; I. Kashif

Macromolecular Research, Vol.10, No.3, 168-173, June, 2002

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Physicochemical Changes in UV- Exposed Low- Density Polyethylene Films

M. A. Salem^†, H. Farouk, and I. Kashif

Physics Department, Faculty of Science, Azhar University, Nasr-City, Cairo, Egypt

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Unstabilized low-density polyethylene (LDPE) films and films formulated with hindered amine light stabilizer (HALS) were exposed to UV-radiation; and the physicochemical changes during photooxidation processes have been investigated using tensile, FTIR spectro-photometric and thermal analytical (DSC) techniques. The dependence of tensile properties (elongation- and stress-at-break) , carbonyl index and heat of fusion on UV-irradiation time have been discussed. The use of HALS is found to be effective in maintaining the UV- mechanical properties of the LDPE films. The experimental results showed that there exists no correlation between mechanical properties and carbonyl index, whereas crystallinity correlates well with carbonyl index in unstabilized and stabilized films for irradiation times greater than 100 h. The rate of formation of carbonyl groups is found to be dependent on UV exposure time. Crystallinity of the film samples is strongly influenced by both exposure time and presence of HALS.

Keywords:polyethylene;mechanical properties;carbonyl index;thermal properties

[References]

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[1] Wypych J, Weathering Handbook, Chem. Tec. Publishing, Toronto, Canada, pp 512 (1990)

[2] Rabek JF, Polymer Photodegradation, Chapman and Hall, London, pp 655 (1995)

[3] Hu X, Polym. Degrad. Stabil., 55, 131 (1997)

[4] Andrady AL, Torikai A, Kobatake T, J. Appl. Polym. Sci., 62(9), 1465 (1996)

[5] Olayan HB, Hamid HS, Owen ED, J. Macromol. Sci., C-36, 671 (1996)

[6] Pospisil J, Nespurek S, Polym. Degrad. Stabil., 49, 99 (1995)

[7] Shlyapnikov YA, Kiryushkin SG, Marin AP, Antioxidative Stabilization of Polymers, Taylor and Francis Publishers Ltd., London (1996)

[8] Andrady AL, Adv. Polym. Sci., 128, 49 (1997)

[9] Summers JW, J. Vinyl Tech., 5, 43 (1983)

[10] Pospisil J, Adv. Polym. Sci., 124, 87 (1995)

[11] Pan J, Cui S, Polym. Degrad. Stabil., 40, 375 (1993)

[12] Gugumus F, Polym. Degrad. Stabil., 39, 117 (1993)

[13] Andrady AL, Pegram JE, Tropsha Y, J. Environ. Deg. Polym., 1, 171 (1993)

[14] Hamid SH, Amin MB, Maadhah AG, Handbook of Polymer Degradation, Marcel Dekker Inc. New York (1995)

[15] Mingguang LA, Richard H, Michael EH, Polym. Degrad. Stabil., 49, 151 (1995)

[16] Billingham NC, Prentice P, Walker TJ, J. Polym. Sci. Symp., 57, 287 (1976)

[17] Winslow FH, Matrayek W, Trozzolo AM, Hansen RH, J. Am. Chem. Soc., 9, 377 (1968)

[18] Tanaka A, Miyagawa E, Uno H, Kitamura M, Nitta KH, Polym. Eng. Sci., 40(9), 2007 (2000)

[19] Horrocks AR, Valinejad K, Crighton JS, J. Appl. Polym. Sci., 54(5), 593 (1994)

[20] Scott G, Pure Appl. Chem., 52, 365 (1980)

[21] Gugumus F, Photooxidation of Polymers and Itsinhibition, CRC Press, Ohio, Vol. II, pp 29-262 (1990)

[22] Davidson RS, Meek RR, Eur. Polym. J., 17, 163 (1981)

[23] Gugumus F, Mechanism of Polymer Degradation and Stabilization, G. Scott, Ed., Elsevier Science Ltd., Barking UK, pp 169 (1990)

[24] Brede O, 20th. Intr. Conf. on Advances in Stab. and Deg. of Polym., 10-12 June, Luzern, Switzerland (1998)

[25] Qureshi FS, Amin MB, Madaah AG, Hamid SH, Polym. Plast. Tech. Eng., 28, 649 (1989)