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Introduction to Thermoplastic Composites
Published in R. Alagirusamy, Flexible Towpregs and Their Thermoplastic Composites, 2022
Starch is a biodegradable and biocompatible polysaccharide derived from renewable resources. It mainly consists of two dissimilar macromolecules named amylose and amylopectin. The amylose is a straight-chain polymer while amylopectin is a branch polymer. Figure 1.11 shows the chemical structure of amylose and amylopectin. Starch is obtained from various plant resources such as wheat, maize, rice, potatoes, peas etc. where its composition, i.e. the amylose and amylopectin content, varied from one source to another. The decomposition temperature of native starch is below its melting point. Hence on heating, the native starch tends to degrade thermally before melting. However, native starch can be transformed into a thermoplastic starch by adding a suitable plasticizer. A plasticizer enhances the mobility of the starch molecules and brings down the melting temperature of the starch below its degradation temperature. Glycerol, glycol, sorbitol, sugar and ethanolamine are some examples of plasticizers which are generally mixed with native starch to produce thermoplastic starch (Wang, Yang, and Wang 2003).
Integrated Bioremediation and Beneficiation of Biobased Waste Streams
Published in Linda Godfrey, Johann F Görgens, Henry Roman, Opportunities for Biomass and Organic Waste Valorisation, 2020
SH Rose, L Warburg, M Le Roes-Hill, N Khan, B Pletschke, WH van Zyl
Potatoes are a versatile vegetable with more than 50% of the potato crop being processed into food products, animal feed, starch and seed tubers for the next season’s crop (Potato processing and uses, 2013). The dry matter and starch content of South African potato varieties range from 12 to 24% and 8 to 16%, respectively (Leighton et al., 2009). Starch is composed of two related polymers in different proportions according to its source, amylose (16–30%) and amylopectin (65–85%). Amylose is a linear polymer consisting of α-1,4 linked glucose units. Amylopectin is a large highly branched polymer of glucose with α-1,6 bonds at the branch points (Hashem & Darwish, 2010). Potato pulp is reported to contain 55% galactose, 9% arabinose, 17% galacturonic acid and 1.4% rhamnose – no fucose, xylose or mannose (Thomassen et al., 2011; Van Dyk et al., 2013).
Starch based Polymers for Drug Delivery Applications
Published in Akhilesh Vikram Singh, Bang-Jing Li, Polysaccharides in Advanced Drug Delivery, 2020
Fernando G. Torres, Omar P. Troncoso
In this paper we have reviewed the use of starch in drug delivery systems. In most cases, starch is not used in its native state but has undergone modification treatments such as self-association, complexation with salts and covalent crosslinking. Other approaches include the use of starch to prepare blends and composites. The drug delivery systems reviewed include gels and hydrogels, micelles, capsules, microparticles and nanoparticles. Most of such systems are environmentally responsive. Typical stimuli include temperature, pH, electric field, light, magnetic field and concentration of electrolytes and glucose. Starch is a biomaterial with different applications in the biomedical field. Future prospects include the use of starch to produce amylopectin nanocrystals that could be used in different biomedical application such as wound dressings, scaffolds for tissue engineering and drug delivery systems.
A Review on the Application of Starch as Depressant in Iron Ore Flotation
Published in Mineral Processing and Extractive Metallurgy Review, 2022
Swagat S. Rath, Hrushikesh Sahoo
Starch is an energetic vegetative reserve photosynthesized by plants and stored in the cereals, fruits, roots tubers, and legumes in the range of 25–90% (De Ojogbo, Blanchard and Mekonnen 2018; Sousa et al. 2017). It is a natural semicrystalline polymer under the class of homopolysaccharides. Its simple chemical representation is (C6H10O5)n, where “n” represents the units of aldo-hexose, a monosaccharide. Starch is composed of two types of α-D-glucan chains, namely amylose and amylopectin. The other minor components are proteins, fatty acids, phosphorus, and some inorganic contaminants. Amylose is a linear glucose chain attached by α-1,4 glucosidase bond, whereas amylopectin is a branched glucose chain with branching at α-1,6 position (De Sousa et al. 2017). The polymerization index “n,” and hence, the molecular weight of starch and the ratio between the number of amylopectin and amylose species vary in a wide range. Figure 1 presents the structures of amylopectin and amylose chains.
Industrial production and applications of α/β linear and branched glucans
Published in Indian Chemical Engineer, 2021
Geetha Venkatachalam, Senthilkumar Arumugam, Mukesh Doble
α-glucans are glucose monomers linked by α-glucosidic bonds. The structure of α-glucans varies on different microbial strain. Dextran (Figure 1A) is produced by Lactobacillus hilgardii, Leuconostoc, mesenteroides, Leuconostoc dextranicum and Streptococcus. Amylopectin (Figure 1B) are highly branched glucans (main component 70–85% in common starches) which are found in higher plants (corn, rice and sorghum) and animals. Glycogen (Figure 1C) are highly branched α-glucans (contains 60,000 glucose residues) which are major carbohydrate forms (liver 6–8% wet weight), and are found in animals and higher plants (starch analog) [5]. Pullulan (Figure 1D), the water-soluble gum-like glucans are produced by strains of Aureobasidium pullulans [4,6,7]. Pea starch (Figure 1E) are highly branched glucans with rich amylose content and are derived from plant sources. An overview of some of the important α glucans, their manufacturers and applications are listed in Table 1 [8–12].
Enhanced solidification/stabilization of lead in MSWI fly ash treatment and disposal by gelatinized sticky rice
Published in Environmental Technology, 2021
Yitian Wang, Hongyong Xu, Cheng Chen, Xiong Wang, Han Zhang, Xiangyu Wu, Lankun Cai
Rice starch consists of two types of polysaccharides: amylose and amylopectin, while sticky or waxy rice contains a higher proportion of amylopectin than amylose [25]. Amylopectin, a branched polymer comprised of α-1,4-linked glucose units with α-1,6 branching links, has high molecular weight and highly branched structures [25–27]. As inorganic–organic composite material, the organic substrate can restrict overgrowth of inorganic minerals and optimize the property of inorganic materials, which is called as the fundamental aspect of biomineralization [28–30]. Schmidt et al. [31] used polysaccharides as modifying admixtures in mineral binder systems, and observed that amylopectin strongly influenced the dispersion and stabilization of inorganic particles, and affected the dynamic yield stress of dispersions. Yang et al. [30] investigated the growth of hydration products in amylopectin modified cement pastes and found that amylopectin made material denser and microstructure more refined than the unmodified cement paste, and heavily branched structure of amylopectin was critical for the control of microstructure of hydration products.