STARCH-BASED BIONANOCOMPOSITES: PROCESSING AND PROPERTIES Polysaccharide Building Blocks: A Sustainable Approach to the Development of Renewable Biomaterials, First Edition. Edited By (original) (raw)
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Developing Biodegradable Plastics from starch
The diversity and ubiquity of plastic products substantially testify to the versatility of the special class of engineering materials known as polymers. However, the non-biodegradability of these petrochemical-based materials has been a source of environmental concerns and hence, the driving force in the search for 'green' alternatives for which starch remains the frontliner. Starch is a natural biopolymer consisting predominantly of two polymer types of glucose namely amylose and amylopectin. The advantages of starch for plastic production include its renewability, good oxygen barrier in the dry state, abundance, low cost and biodegradability. The longstanding quest of developing starch-based biodegradable plastics has witnessed the use of different starches in many forms such as native granular starch, modified starch, plasticized starch and in blends with many synthetic polymers, both biodegradable and non-biodegradable, for the purpose of achieving cost effectiveness and biodegradation respectively. In this regard, starch has been used as fillers in starch-filled polymer blends, thermoplastic starch (TPS) (produced from the combination of starch, plasticizer and thermomechanical energy), in the production of foamed starch and biodegradable synthetic polymer like polylactic acid (PLA) with varying results. However, most starch-based composites exhibit poor material properties such as tensile strength, yield strength, stiffness and elongation at break, and also poor moisture stability. This therefore warranted scientific inquiries towards improving the properties of these promising starch-based biocomposites through starch modification, use of compatibilizers and reinforcements (both organic and inorganic), processing conditions, all in the hope of realizing renewable biodegradable substitutes for the conventional plastics.
Physical Properties of Thermoplastic Starch Derived from Natural Resources and Its Blends: A Review
Polymers
Thermoplastic starch composites have attracted significant attention due to the rise of environmental pollutions induced by the use of synthetic petroleum-based polymer materials. The degradation of traditional plastics requires an unusually long time, which may lead to high cost and secondary pollution. To solve these difficulties, more petroleum-based plastics should be substituted with sustainable bio-based plastics. Renewable and natural materials that are abundant in nature are potential candidates for a wide range of polymers, which can be used to replace their synthetic counterparts. This paper focuses on some aspects of biopolymers and their classes, providing a description of starch as a main component of biopolymers, composites, and potential applications of thermoplastics starch-based in packaging application. Currently, biopolymer composites blended with other components have exhibited several enhanced qualities. The same behavior is also observed when natural fibre is i...
Physico-Chemical, Rheological, and Viscoelastic Properties of Starch Bio-Based Materials
Journal of Composites Science
This study describes the elaboration and characterization of plasticized starch composites based on lignocellulosic fibers. The transformation of native to plasticized starch (TPS) and the preparation of TPS blends were performed with a new lab-scale mixer based on an original concept. Firstly, the morphology and chemical composition of flax shives were analyzed to better understand the intrinsic properties of these natural fillers. Then, the impact of the processing parameters (temperature, speed screw) on the quality and the structural properties of plasticized starch were examined by SEM and DRX. After that, we focused on the elaboration of various formulations based on plasticized starch matrix by varying TPS formulation and filler content (from 10 to 30%). The viscoelastic and rheological properties of TPS/flax blends have been analyzed by TGA, SEM, and DMTA.
A Preliminary Investigation Of Cassava Starch Potentials As Natural Polymer In Bioplastic Production
The American Journal of Interdisciplinary Innovations and Research, 2020
Starch consists of two types of molecules namely, amylosse and amylopectin .Amylose, a linear chain polymer constitutes about 20% of starch. It is more soluble in water, soluble in hot water but does not form gel while amylopectin is a branched chain polymer that constitutes about 80% of the starch. It is less soluble in water, soluble in hot but forms gel, hence the need for modification. In this study, Cassava starch was modified with distilled water, glycerol and vinegar. The cassava starch, distilled water, vinegar and glycerol were all weighed in required proportions into the beaker. 50g of cassava starch was weighed into a beaker, 10mls of vinegar was added. 20mls of glycerol was also added. The resulting mixture was thoroughly stirred to form a uniform suspension, the suspension was heated, and it was continuously stirred to avoid coagulation with increasing viscosity until gelatinization was achieved at about 100°C. The gel was spread on a smooth, hard surface and mechanically pressed to form sheets. The sheets were air dried to cure for 72hrs to 5% moisture content. The sheet was subjected to tensile test. Water was used as a solvent to first get the biopolymer (starch) into solution. When the solution was heated, the water helped the starch molecules to become disrupted and disordered (denatured). The reduction of starch hydrogen bonding was achieved in the presence of water. Water diffused into the starch granules and hydrogen bonds breaking down the intermolecular bonds of the starch molecules. Water helped the starch molecules to become disrupted and disordered. When the starch was heated with water, water interacted with hydroxyl
Mixed Biopolymer Systems Based on Starch
Molecules, 2012
A binary mixture of starch-starch or starch with other biopolymers such as protein and non-starch polysaccharides could provide a new approach in producing starch-based food products. In the context of food processing, a specific adjustment in the rheological properties plays an important role in regulating production processing and optimizing the applicability, stability, and sensory of the final food products. This review examines various biopolymer mixtures based on starch and the influence of their interaction on physicochemical and rheological properties of the starch-based foods. It is evident that the physicochemical and rheological characteristics of the biopolymers mixture are highly dependent on the type of starch and other biopolymers that make them up mixing ratios, mixing procedure and presence of other food ingredients in the mixture. Understanding these properties will lead to improve the formulation of starch-based foods and minimize the need to resort to chemically modified starch.
The study investigated the physicochemical properties of starches from Caladium bicolor (wild cocoyam), Icacina trichantha (false yam), dioscorea villosa (wild sweet yam) and oyster mushroom. Amylose/amylopectin ratio, gel characteristics, hygroscopicity among other properties were examined. The study revealed that wild yam, sweet yam, false yam and oyster mushroom have total starch content of 86.6%, 82.8%, 58.4& and 49.3% respectively. False yam and oyster mushroom had high percentages of amylose (40.2 and 56.7%) while wild cocoyam and sweet yam had high amylopectin content (88.9% and 84.6%) respectively. The functional properties of the starch samples compared favourably with starches from edible sources. This study revealed that starches from non-edible sources like wild cocoyam, false yam, mushroom and sweet yam can be used in the synthesis of bioplastics with improved quality. This will reduce the amount of plastics littered in landfills and will also replace the use of edible starches in non-food purposes enabling edible starches to be available for human consumption and other food/medical applications.
Influence of plasticizer with different functional groups on thermoplastic starch
Journal of Applied Polymer Science, 2015
Retrogradation of amorphous thermoplastic starch (TPS) films obtained by compression molding of spray dried modified potato starch was investigated. The aim was to investigate the influence of plasticizers with similar molecular weight but different functionality, i.e., isoleucine, asparagine and malic acid, on the properties of plasticized powder and TPS films. Combinations of malic acid with glycerol, urea, and maltodextrin were also evaluated. Except for isoleucine formulated starch, all samples were obtained as amorphous powders and films. Malic acid was identified as a strong antiretrogradation agent as it inhibited recrystallization of starch over the full range of humidity levels. Malic acid was also found to inhibit the retrogradation of formulations containing urea, glycerol and maltodextrin. The converse of the strong inhibition implied strong moisture absorption and high strain at break values, and low tensile strengths. Malic acid was also identified as a potential crosslinking agent to control swelling of starchbased products.