Degradability of Extruded Polyethylene/Chitosan Blends Compatibilized with Polyethylene-Graft-Maleic Anhydride Under Natural Weathering Dora Evelia Rodr  ıguez-F  elix, 1 Jes  us Manuel Quiroz-Castillo, 1 Heriberto Grijalva-Monteverde, 1 Teresa del Castillo-Castro, 1 Silvia Elena Burruel-Ibarra, 1 Francisco Rodr  ıguez-F  elix, 2 Tom  as Madera-Santana, 3 Rafael Enrique Cabanillas, 4 Pedro Jes  us Herrera-Franco 5 1 Departamento de Investigaci  on en Pol  ımeros y Materiales, Universidad de Sonora, P.C. 83000, Hermosillo Sonora, M exico 2 Departamento de Investigaci  on y Posgrado en Alimentos, Universidad de Sonora, P.C. 83000, Hermosillo Sonora, M exico 3 Laboratorio de Envases, CTAOV, Centro de Investigaci  on en Alimentos y Desarrollo A.C. P.C. 83304, Hermosillo Sonora, M exico 4 Departamento de Ingenier  ıa Qu  ımica y Metalurgia, Universidad de Sonora, P.C. 83000, Hermosillo Sonora, M exico 5 Centro de Investigaci  on Cient  ıfica de Yucat an, Unidad de Materiales, P.C. 97200, M erida Yucat an, M exico Correspondence to: J. M. Quiroz-Castillo (E - mail: quiroz51@hotmail.com) ABSTRACT: The impact of chitosan on the natural weathering behavior of two blends obtained by mixing either polyethylene (PE) with chitosan or PE, chitosan and polyethylene-graft-maleic anhydride (PEgMA) as a compatibilizer is analyzed. In order to follow the weathering behavior of both the uncompatibilized and compatibilized systems, the blend films are exposed to outdoor conditions for 6 months. The weathering behavior of the films is monitored by mechanical tests, spectroscopic Fourier transform infrared, and morphological analyses at different weathering periods of time. The presence of chitosan in the blends accelerates significantly the degradation of the films. Apparently, PEgMA also accelerates the photo-oxidation rate of the films. This behavior appears to be related to the photo-oxidative instability of maleic anhydride, and also to the better dispersion of chitosan in the PE matrix, which is due to the interactions in the PE/chitosan interface caused by the addition of the compatibilizer. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41045. KEYWORDS: mechanical properties; polyolefins; polysaccharides; properties and characterization Received 31 January 2014; accepted 13 May 2014 DOI: 10.1002/app.41045 INTRODUCTION Polyolefin-based polymers are the most produced and con- sumed synthetic polymers worldwide; the high stability of these compounds and their significant resistance to degradation has led to their accumulation in the environment. 1 This accumula- tion is a matter of great concern leading to long-term environ- ment, economic, and waste management problems. 2 One promising possible alternative to solve this problem, for the case of plastic waste, is the development of polymers that are degraded by the environment in short periods of time. 3 Natural weathering, which includes solar radiation, wind, and ambient temperature, leads to the formation of free radicals, which may combine with oxygen on the surface and form perox- ides and hydroperoxides, following the known reactions of oxida- tive degradation. 4 Structural defects such as unsaturation, as well as carbonyl or hydroperoxide groups, may be formed in polyolefin-based polymers during polymerization and processing; these defects could enhance their degradation rate, nevertheless, they are present at very low levels. 5,6 A wide variety of synthetic polymers absorbs solar ultraviolet (UV) radiation and undergoes photolytic, thermo-, and photo- oxidative reactions that result in the degradation of these materi- als. 7,8 Photo-oxidative degradation is the process of deterioration of the material by the action of light; this is considered the most important degradation mechanism of synthetic polymers during natural weathering. Normally, the near-UV radiations (290– 400 nm) in the sunlight determine the lifetime of polymeric materials in outdoor applications. 4 Several reports conclude that temperature also plays an important role in degradation rate; when polymers are exposed to the same dose of radiation, 9 the degradation rate is accelerated as temperature increases. 10,11 Polyethylene (PE) films when exposed to UV radiation lose their extensibility, mechanical integrity, and strength along with decrease in their average molecular weight. 12,13 Naturally occur- ring polymers, also known as biopolymers, absorb solar radia- tion and undergo photolytic, photo-oxidative, and thermo- oxidative reactions that result in the degradation of the material. 10 V C 2014 Wiley Periodicals, Inc. WWW.MATERIALSVIEWS.COM J. APPL. POLYM. SCI. 2014, DOI: 10.1002/APP.41045 41045 (1 of 7)