Characterization of Linear Low-Density Polyethylene/ Poly(vinyl alcohol) Blends and Their Biodegradability by Vibrio sp. Isolated from Marine Benthic Environment Vidya Francis, 1 S. Raghul Subin, 2 Sarita G. Bhat, 2 Eby Thomas Thachil 1 1 Department of Polymer Science & Rubber Technology, Cochin University of Science and Technology, Kochi 682 022, Kerala, India 2 Department of Biotechnology, Cochin University of Science and Technology, Kochi 682 022, Kerala, India Received 14 September 2010; accepted 14 January 2011 DOI 10.1002/app.34155 Published online 4 October 2011 in Wiley Online Library (wileyonlinelibrary.com). ABSTRACT: Increasing amounts of plastic waste in the environment have become a problem of gigantic propor- tions. The case of linear low-density polyethylene (LLDPE) is especially significant as it is widely used for packaging and other applications. This synthetic polymer is normally not biodegradable until it is degraded into low molecular mass fragments that can be assimilated by microorgan- isms. Blends of nonbiodegradable polymers and biode- gradable commercial polymers such as poly (vinyl alcohol) (PVA) can facilitate a reduction in the volume of plastic waste when they undergo partial degradation. Further, the remaining fragments stand a greater chance of undergoing biodegradation in a much shorter span of time. In this investigation, LLDPE was blended with different propor- tions of PVA (5–30%) in a torque rheometer. Mechanical, thermal, and biodegradation studies were carried out on the blends. The biodegradability of LLDPE/PVA blends has been studied in two environments: (1) in a culture me- dium containing Vibrio sp. and (2) soil environment, both over a period of 15 weeks. Blends exposed to culture me- dium degraded more than that exposed to soil environ- ment. Changes in various properties of LLDPE/PVA blends before and after degradation were monitored using Fourier transform infrared spectroscopy, a differential scanning calorimeter (DSC) for crystallinity, and scanning electron microscope (SEM) for surface morphology among other things. Percentage crystallinity decreased as the PVA content increased and biodegradation resulted in an increase of crystallinity in LLDPE/PVA blends. The results prove that partial biodegradation of the blends has occurred holding promise for an eventual biodegradable product. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 124: 257–265, 2012 Key words: biodegradable; vibrio sp; poly(vinyl alcohol); morphology; differential scanning calorimetry INTRODUCTION Conventional polymers such as polyethylene (PE) and polypropylene (PP) persist for many years in the environment after disposal. It has been estimated that polyethylene biodegrades less than 0.5% in 100 years and about 1% if pre-exposed to sunlight for 2 years. 1 Since polyolefines such as PE constitute the vast majority of plastic materials used, especially for packaging applications (Fig. 1), it is important to devise ways to improve their biodegradability. Attempts to produce environmentally degradable, low cost, plastic materials from polyolefines date back to the second half of the 20th century. 2 Syn- thetic polymers like polyolefins are not degraded by microorganisms in the environment which property is responsible for their long life and an ever increas- ing volume of plastic waste. 3 These polymers are characterized by high molecular weight, chemical inertness, hydrophobicity, reduced surface area, rela- tive impermeability to oxygen etc. which make them resistant to microbial attack and at the same time impose enormous restrictions on the design and de- velopment of biodegradable polymers. 4,5 Therefore, recycling and degradation of plastics is an important issue for environmental and economic reasons. 6,7 Griffin 8,9 introduced the idea of increasing the bio- degradability by adding a biodegradable ingredient to the polymer material. When a biodegradable com- ponent is present, microorganisms can readily attack it thereby increasing the porosity of the material and resulting in a mechanically weakened film. The sur- face area will increase making it more susceptible than the original material to all degradation pro- cesses including biodegradation. 10 Partially biode- gradable polymers obtained by blending biodegrad- able and nonbiodegradable polymers undergo considerable loss of volume over a period of time thus effectively reducing the environmental hazards. Correspondence to: E. T. Thachil (ethachil@cusat.ac.in). Journal of Applied Polymer Science, Vol. 124, 257–265 (2012) V C 2011 Wiley Periodicals, Inc.