Preparation and property assessment of eco-friendly composite based on polyvinyl alcohol and lignin extracted from biomass
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| 1. Introduction
In recent years, environmental pollution has become a serious issue of global concern, which causes enormous adverse impacts on ecological balance, including climate change, land degradation, and desertification. As a result, sustainable development of each country has been threatened critically. Consequently, this alarming situation has drawn tremendous attention from society for wide range solutions. A large number of studies related to biodegradable materials which aims at replacing non-degradable plastic by eco-friendly materials have been conducted by numerous researchers. In this context, bio-polymers such as lignin are used as components of biodegradable composites materials due to the diversity of properties and biodegradability. Lignin is a natural polymer playing a key role in the formation of plant cell walls. The chemical structure of lignin is formed by three main components: p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S). The amount of every structural unit varies with plant species [1]. With complicated and diverse chemical structure, various lignin structure models have been proposed [2]. Lignin possesses several advantages such as low cost, low density, and comparable mechanical properties. In addition, lignin is extracted from biomass; therefore, products based on lignin pose no health risk. Due to their biodegradable, renewable, and mechanical properties, composites from lignin are considered prospective candidates to replace glass or carbon fiber-based synthetic composites. Lignin has the potential to be used as composites in construction, sport, packaging, and automotive industries [3], [4]. Lignin has been used with numerous petroleum-based resins to generate composites such as epoxy, unsaturated polyester, and some types of polyolefin. Among synthetic polymers, PVA has superior characteristics including nontoxicity, water-solubility, and hydrophilic with the presence of hydroxyl groups making it compatible with various biopolymer via the formation of hydrogen bonding at the interface [3]. Moreover, PVA possesses other properties such as biodegradability and high mechanical strength [4], [5]. Due to the diversity of its characteristics, PVA is used for many applications as water soluble films in agriculture and additives in textile, paper industries, and a variety of coatings. PVA is also utilized in composites with other polymers, especially natural polymers [6]. Therefore, there is a great amount of research associated with composites based on lignin and poly(vinyl alcohol) (PVA) [7], [8]. Some studies indicate that the linkage between polar polymers such as PVA and lignin is hydrogen bonding, which creates high degree inter-molecular interaction [8]. Besides, both PVA and lignin, and thus their composites are biodegradable, making them eco-friendly materials [9], [10]. Due to the outstanding properties of PVA and lignin, the experiments were conducted to fabricate composite films based on PVA and lignin extracted from bagasse according to previously published work [11]. In this study, the properties of composite films will be investigated, including surface morphology, mechanical properties, optical properties, and ultraviolet-shielding through some analytical methods. tải về 0.53 Mb. Chia sẻ với bạn bè của bạn:
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