Biodegradation and Thermal Properties of Crosslinked Chitosan/Corn Cob Biocomposite Films by Electron Beam Irradiation Ming Yeng Chan , 1 Seong Chun Koay 2 1 HELP College of Arts and Technology (HELP CAT), Centre for Engineering Programmes, Kuala Lumpur 55200, Malaysia 2 School of Engineering, Taylor’s University Lakeside Campus, Subang Jaya, 47500, Selangor, Malaysia Thermal and biodegradation properties of chitosan (CS)/corn cob (CC) biocomposite films and their irradiation-crosslinked were tested. The CS/CC biocomposite films after irradiation showed better thermal stability and lower weight loss in enzy- matic and soil biodegradation in comparison with unirradi- ated CS/CC biocomposite films due to the formation of new bonds (radiation-induced crosslinks). The surface erosion for biodegraded biocomposite films were examined by scanning electron microscope. Furthermore, the formation of new bonds in irradiated biocomposite films were analyzed by Fourier transform infrared spectroscopy. POLYM. ENG. SCI., 00:000–000, 2018. V C 2018 Society of Plastics Engineers INTRODUCTION To date, biopolymer materials have played an important role as a functional polymer materials [1]. This is due to the environ- mental impacts of nonbiodegradable petroleum-based plastic materials wastes that has increased global concerns [2]. Chitosan is widely applied in medical and packaging materials for its bio- compatible, nontoxic, and biodegradable properties [1]. Chitosan (CS) is a well-known biopolymer, which is pre- pared from chitin by deacetylation [3–6]. CS has a higher poten- tial in various applications as compared to chitin because CS contains a greater amount of free NH 2 groups [7]. In general, CS is insoluble in water, but soluble in aqueous organic acids such as formic, acetic, citric, and lactic acid to produce a vis- cous CS solution [8]. Because of these excellent properties (e.g., biocompatible; biodegradable; nontoxic; antimicrobial), CS has potential in the packaging application [9]. Nowadays, many researchers are interested to utilize renew- able resources in their researches [10–13]. These renewable resources such as low value plants, energy crops and product from food crops, sawmills, palm oil production, marine waste, and food waste are new materials to produce composites [14]. Normally, natural fillers, or known as renewable raw materials have unlimited availability. These natural fillers promote several advantages, such as low density, renewability, biodegradability, recyclability, and cost effectiveness [9, 10, 15, 16]. Corn (Zea mays) is a Poaceae (grass family) and one of the top three cereal crops grown worldwide [17]. In 2013, the annual world corn production was about 964 million tons, which gener- ated about 204 million tons of corn residues [18]. Corn cob is a corn residues. To reduce this agricultural waste, the corn cob was utilized as the natural filler in this study. The inclusion of natural fillers into plastics is mainly due to their advantages, such as lower production cost and density, low energy requirements for processing, ease of preparation, and biodegradability. Over the past few decades, radiation processing was used for polymer modification. Accordingly, the irradiation of polymeric materials with ionizing radiations, such as gamma rays, X-rays, ion beam, and accelerated electrons, lead to the formation of reac- tive intermediates, ions, free radicals, and excited states. Conse- quently, these intermediates can follow some reaction paths, resulting in disproportion, hydrogen abstraction, arrangements, and/or the formation of new bonds, to enhance the properties of the polymeric materials [19]. The crosslink by using electron beam irradiation effects on the properties of polymers were inves- tigated by some researchers [20, 21]. This radiation technology is not only for surface grafting, but also for reactive compatibilisa- tion to improve the properties of polymers. There are several ben- efits of radiation application to polymer such as: (i) formation of strong bridges between macromolecules; (ii) compatibilisation of polymer blend by high energy radiation; and (iii) presence of mul- tifunction monomer and inomer to accelerate and increase the crosslinking degree [20, 22]. Normally, the radiation process cov- ers radiation crosslinking, radiation induced polymerization, and degradation of polymers. Many researchers reported that the elec- tron beam irradiation has improved the tensile properties of chito- san biocomposite films, such as konjac glucomannan/chitosan [21], starch/chitosan [23], polyvinyl alcohol (PVA)/carboxylme- thylated chitosan [24], and polyaniline grafted chitosan [25]. Radiation crosslink on chitosan had been widely reported by re- searchers. However, the research on electron beam irradiation crosslink chitosan/corn cob biocomposite films is not found in any literature study. The development of biodegradable polymers from renewable resources has increased in recent years, especially for the packag- ing and disposable applications to maintain the sustainable devel- opment of economical and ecological attractive technology [26]. Biodegradation can be denoted as degradation that occurs in a biological environment [27]. The utilization of a variety of micro- organisms and enzymes to degrade polymers is classified as the biodegradation method of polymers. This research article is focused on two biodegradation methods such as enzymatic hydro- lysis and soil biodegradation. Commonly, enzymatic hydrolysis of biopolymers is a heterogeneous process. The heterogeneous pro- cess is affected by the interaction between enzymes and polymeric chains [27]. In soil degradation method, soil microbes can initiate the depolymerization of biopolymers, such as polysaccharide, cel- lulose, and hemicellulose. These soil microbes secrete different Correspondence to: M. Yeng Chan; e-mail: chan.ming.yeng@helpcat.edu.my DOI 10.1002/pen.24854 Published online in Wiley Online Library (wileyonlinelibrary.com). V C 2018 Society of Plastics Engineers POLYMER ENGINEERING AND SCIENCE—2018