Chemistry and Materials Research www.iiste.org ISSN 2224- 3224 (Print) ISSN 2225- 0956 (Online) Vol.6 No.4, 2014 18 Study the Photodegradation of Hydroxypropyl Cellulose in Presence and Absence of Benzophenone and Eosine Dye Zainab Naeif Majeed 1 , Hamid Hashim Mohammed 2 *, and Safana Ahmed Farhan 1 1.Al-Mustansiriya University,College of Science, unit of research polymer P.O. Box 46136, Al-Mustansiriya University, Baghdad, Iraq 2.Al-Mustansiriya University,College of Science, Department of Chemistry P.O. Box 46136, Al-Mustansiriya University, Baghdad, Iraq Corresponding author. E-mail : hammed_sugar@yahoo.com Abstract The induced photodegradation of poly hydroxypropyl cellulose films in air was investigated (for 350 hrs.) in presence and absence of benzophenone and eosine dye (photosensitizer) by accelerated weathering tester. The addition of (0.1wt %) of benzophenone and eosine dye to poly hydroxypropyl cellulose films (25µm in thickness) enhanced the photodegradation of the polymer films. The photodegradation rate was followed by increase in carbonyl absorbance of polymers using infrared (I.R.) and UV-visible. spectra respectively and viscosity. The concluded from this work the eosine dye enhance degradation of polymer more than benzophenone. According to the spectra results, the induced photodegradation mechanisms of polymer films were suggested under the experimental conditions employed using UV-radiation at λ = 313 nm , light intensity 3.49*10 -5 einsteins.dm -3 .S -1 at temperature 45 o C. Key words: photodegradation, hydroxypropyl cellulose Introduction Hydroxypropyl cellulose (HPC) is non-ionic, it is less reactive to active ingredients compared with ionic excipients. This excellent compatibility is the main reason for HPC being the first choice of Japanese pharma companies. For example, aspirin tablets with HPC were stable under high temperature whereas ionic ingredients showed whiskers of salicylic acid formed by hydrolysis (See picture below). Vitamin C tablets formulated with HPC showed no interaction compared with tablets using ionic disintegrants (1) . Photodegradation of polymers is generally accepted as the main factor that limits their use in outdoor applications. It is caused by the ultraviolet (UV) component of solar radiation and is a serious problem in the sunniest climates. Photo-oxidation creates free radicals that start a chain reaction that can progress quite rapidly, causing rapid deterioration of mechanical properties. The chemical and physical mechanisms of degradation and their effects on engineering properties and morphological changes (such as secondary crystallization) are discussed. Photostabilizers that can produce spectacular improvements in polymer lifetime under UV exposure are discussed. Testing for photodegradability is dealt with. It usually involves accelerated laboratory conditioning and this is difficult to calibrate against natural conditions to produce lifetime prediction. Photodegradation products are often prodegradants placing restrictions on the recyclability, which is also discussed (2) . The ageing of plastics, polymers and resins leads to several possibilities. Several oxidation products are formed Free radicals, produced by formation of peroxides, lead to depolymerization, crosslinking, chain termination to polymer leading to chain branching and reversal to monomers in specific cases. Completely new small molecules those were not present at the time of polymerization are formed contributing to volatile organics over the useful life of the product and beyond it. When we have a look at the literature on the subject of photodegradation of polymers the polymer chemist dealing with bulk polymers seem to have worried about it far more than the paint and coatings chemist. The reasons are mainly environmental. The used plastic products are posing a great threat to the environment and efforts have been made to deliberately accelerate the process of photo-degradation of polymers in ordinary sunlight (3) . The degradation of polymer materials on outdoor exposure can often be attributed to photochemical reactions arising from absorption of UV-radiation by polymeric chromophores, impunities like ketone groups, and hydroperoxide groups present on the polymer backbone. Ketones and hydroperoxide groups are more likely to be formed by air oxidation on moulding and synthesis of the polymer. The aim of this work is studying and compared the photodegradation of poly hydroxypropyl cellulose in presence and absence of benzophenone and eosine dye as photosensitizers. Experimental The following materials were used a- Laboratory poly hydroxypropyl cellulose powder ( B.D.H. Ltd A.R.Grade , purity 99%) was used at the test