Journal “Scientific Israel ‒ Technological Advantages" Vol.22 № 1 , 2020 82 SUPRAMOLECULAR STRUCTURE OF CELLULOSE IN COTTON FIBERS OF VARIOUS ORIGINS Kh. Aripov 1 , M. Ioelovich 2 1 Namangan Institute of Engineering and Technology, Namangan, Uzbekistan, 2 Designer Energy, Rehovot, Israel, aripov.khsh@gmail.com; ioelovichm@gmail.com ABSTRACT In this article, fifteen varieties of cotton fibers G. hirsutum and ten varieties of cotton fibers G. barbadense of different origins have been studied using WAXS and several other methods. Various characteristics of supramolecular structure of these cellulose fibers were obtained, such as crystallinity, sizes and paracrystallinity degree of crystallites, parameters of a crystalline unit cell, along with microfibrillar angle (MFA) and coefficient of orientation (K o ). From the results, it follows that cotton fibers of G. barbadense have a noticeably more ordered structure than the fibers of G. hirsutum. In particular, cotton fibers of G. barbadense were denser and more crystalline, crystallites in the cellulose of G. barbadense were longer, wider, denser and less disordered than in cellulose of G. hirsutum. Furthermore, measurements of MFA and K o showed that microfibrils in cotton fibers of G. barbadense are better oriented. The revealed structural features of G. barbadense cotton fibers explain their higher density, strength, and elasticity compared to G. hirsutum fibers. Keywords: Cotton fibers, G. hirsutum, G. barbadense, Cellulose, Structure, Orientation of microfibrils, Crystallinity, Sizes of crystallites, Parameters of a crystalline unit cell, Paracrystallinity degree INTRODUCTION Cotton fibers are an important source of natural cellulose. World production of cotton fibers reaches 25 million tons per year [1, 2]. Currently, the largest producers of cotton are India, USA, and China. The main part of the cotton fibers is intended for textile industry, while short fibers and residues (e.g. fuzz) are used for manufacturing of microcrystalline cellulose, nanocellulose, cellulose derivatives, special papers, as well as fillers, reinforcing agents, food additives, medical products, cosmetic ingredients, chemicals, explosives, and other products. Among the Gossypium genus, the species G. hirsutum, G. barbadense, G. arboreum, and G. herbaceum are well known [3]. G. hirsutum, also known as upland cotton or Acala cotton (in the USA) is the most widespread species of cotton in the world. This kind contains medium-quality fibers; nevertheless, these can be produced in a high yield due to good environmental adaptability. G. barbadense has fibers of superior quality - long, fine, silky and strong, which are used to produce the luxury quality fabrics [4]. In the USA, this cotton kind is called Pima, because the Pima Indians helped to grow the long-fiber cotton on experimental farms in Arizona in the early 20 th century. However, G. barbadense cotton is a tropical plant, and therefore for its growth, the special cultivation conditions are required - full sun and high humidity. Due to this limitation, the G. barbadense fibers are rare and expensive. G. arboreum, called also tree cotton, is α species of cotton growing in India and Pakistan. This cotton is relatively cheap, has a high yield of fibers; although these fibers are short and thick, they are strong enough for use in the textile industry. G. herbaceum is a species of cotton native to the semi-arid regions of Africa, Saudi Arabia, and some other Asian regions. Despite very high cellulose content, these cotton fibers are considered short and coarse, which are used mainly in medicine for the production of cotton wool and pads.