Composite materials starch/polymer

Extrusion is a cost effective manufacturing process. Extrusion is popularly used in large scale production of food, plastics and composite materials. Most widely used thermoplastics are processed by extrusion method. Many biopolymers and their composite materials with petroleum-based polymers can also be extruded. These include pectin/starch/poly(vinyl alcohol) (Fishman et al. 2004), poly(lactic acid)/sugar beet pulp (Liu et al. 2005c), and starch/poly(hydroxyl ester ether) (Otey et al. 1980), etc. In this study, composite films of pectin, soybean flour protein and an edible synthetic hydrocolloid, poly(ethylene oxide), were extruded using a twin-screw extruder, palletized and then processed into films by compression molding process or blown film extrusion. The films were analyzed for mechanical and structural properties, as well as antimicrobial activity. 

The solid phase of bread crumb can be viewed as a composite material where amylose, amylopectin and protein form separated phases due to poor thermodynamic miscibility of the different polymers. Composites are characterized by exhibiting mechanical properties that cannot be achieved with the individual constituents alone, but are dependent on the interface between the components. A sharp interface as found between starch and protein provides strong evidence of little polymer interdiffusion and weak interfacial adhesion.14 The present results suggest that starch forms a continuous phase in bread which has also been confirmed with confocal scanning laser microscopy.15 The presence of a protein phase reduces the continuity of the starch phase and, thus, reduces the cohesion of the material as revealed by a comparison of the breaking stresses of aged flour and starch gels (data not shown).16... 

U.S. Pat. No. 6,274,652 [127] discloses a biodegradable composite material comprising bacterial cellulose in a powdery state and a polymeric material such as poly-hydroxybutyrate, polyhydroxyvalerate, polycaprolactone, polybutylenesuccinate, polyethylenesuccinate, polylactic acid, polyvinylalcohol, cellulose acetate, starch, and other biodegradable polymers. 

Four main types of polymer are currently accepted as being environmentally degradable. They are the photolytic polymers, peroxidisable polymers, photo-biodegradable polymers and hydro-biodegradable polymers. Commercial products may be composite materials in which hydrolysable and peroxidisable polymers are combined (e.g. starch-polyethylene composites containing prooxidants). The application, advantages and limitations of each group will be briefly discussed. 

Blending and compositing have been successfully used in starch-based materials. Starch was initially used a fillers blended with various polymers, especially with polyolefin. Blending starch with biodegradable polymers has attracted more and more attention. The interest in new nanoscale fillers has rapidly grown since it was discovered that a nanostructure could be built from a polymer and a layered nanoclay. These new nanocomposites show dramatic improvement in mechanical properties with low filler content. Cellulose is the major substance obtained from vegetable fibers, and applications for cellulose fiber-reinforced polymers have again come to the forefront with the focus on renewable feedstocks. Hydrophilic cellulose fibers are very compatible with most natural polymers. 

Ljungberg N, Cavaille J-Y, Heux L (2006) Nanocomposites of isotactic polypropylene reinforced with rod-like cellulose whiskers. Polymer 47 6285-6292 Lu Y, Weng L, Cao X (2005) Biocomposites of plasticized starch reinforced with cellulose crystallites from cottonseed linter. Macromol Biosci 5 1101-1107 Lu J, Wang T, Drzal LT (2008) Preparation and properties of microfibrillated cellulose polyvinyl alcohol composite materials. Compos Part A 39A 738-746 Magalhaes WLE, Cao X, Lucia LA (2009) Cellulose nanocrystals/cellulose core-in-shell nanocomposite assemblies. Langmuir. doi 10.1021Aa901928j Malainine ME, Mahrouz M, Dufresne A (2005) Thermoplastic nanocomposites based on cellulose microfibrils from Opuntiaficus-indica parenchyma cell. Compos Sci Technol 65 1520-1526 Marchessault RH, Sundararajan PR (1983) Cellulose. In Aspinall GO (ed) The polysaccharides. Academic, New York... 

Shogren RL (1995) Poly(ethylene oxide)-coated granular starch-poly(hydroxybutyrate-co-hydroxyvalerate) composite materials. J Environ Polym Degrad 3 75-80 Shogren R (1997) Water vapm pmneability of biodegradable polymers. J Environ Polym Degrad... 

For composite materials applications, the main useful polysaccharides are cellulose and starch, but more complex carbohydrate polymers originated from bacteria and fungi (e.g., exo-polysaccharides such as xanthan, curdlan, puUulan, levan and hyaluronic acid) have attracted increased interest in the last years due to their outstanding potential for various industrial areas [10-14]. 

High performance composite materials can be obtained with a good level of dispersion, mainly when the hierarchical structure of cellulose and use of a water soluble polymer to form the matrix are considered. For most materials applications, the main biopolymers of interest are cellixlose and starch. The ease of adhesion that occurs in cellulose has contributed to its use in paper and other fiber-based composite materials. 

F. Vilaseca, 1.A. Mendez, A. Pelach, M. Llop, N. Canigueral, J. Girones, X. Turon, and P. Mutje, Composite materials derived from biodegradable starch polymer and jute strands. Process Biochem. 42,329-334 (2007). 

Eco-friendly biodegradable polymers and biocomposites are relatively novel materials that can contribute to reduce the dependence on fossil sources. Because of their renewable nature and biodegradability, environmentally benign composite materials with properties comparable to those of some widely used commodities can be produced. Py-GC/MS has developed as a useful tool for the study of thermal degradation of such polymers and composites, and many studies have recently been published for biodegradable polymers, such as polycaprolactone (PCL), polyhydroxyalcanoates (PHAs) and their copolymers,poly(lactic acid) (PLA), and carbohydrates, including starch and cellulose. 

That is, if some enzymes can be immobilized by the above mentioned method, a composite enzyme-immobilized polymer membrane of the laminate type can be easily prepared as shown in Fig. 22.10, in which Ej, Ej and E3 represent different enzymes. When such a composite enzyme-immobilized polymer membrane is apphed to a chemical reaction and the resulting product is permeated through Ej immobilized layer and becomes a substrate for the next enzyme (Ej) immobilized layer, then the synthesis of materials due to multistage reactions will become possible. For example, a laminated polyion complex membrane in which amylase, maltose and yeast are immobilized in each polyion complex layer, respectively, was applied to the ethanol production using starch as a first substrate. ... 

Starch is a natural biopolymer and was obtained from the roots, piths and seeds of the plants (Bhattachaiya, 1995). It is a cheap and readily available raw material that is relatively easy to produce from sustainable sources. Starch is a precursor for a veiy large number of ingredients used in food, textile, paper, pharmaceutical, and adhesive industries. The presence of amorphous and ciystalline regions and a large number of Itydroxyl groups in starch offer better opportunities for starch modification to develop tailor-made products. Starch has vast scope for exploitation in the development of composite materials due to its biocompatibility with other polymer systems (Gomes and Reis, 2004 Murthy et al., 2006). 

Blends or composites materials have been produced by the processing of starch with biodegradable polymers such as poly(s-caprolactone), pofy(lactic acid), pofy(virtyl alcohol), pofy(ltydroxybutyrate-co-valerate), and polyesteramide. The most common are Mater-Bi from Novamorrt arrd Ecostar from Natiortal Starch. 

One of the most abundant poljmieric materials from renewable resources is starch. While abundant and inexpensive, however, starch alone as a material does not offer satisfactory properties for many applications. Meanwhile, the synthetic biodegradable pol5miers with satisfactory properties are prohibitively expensive when compared to commodity non-biodegradable polymers. A common approach is to make blends/composites of starch and other biodegradable synthetic polymers to produce materials of satisfactory properties and a low overall cost. 

A brief overview of composite materials based on cellulose fibers (vegetal cellulose, bacterial cellulose and nanofibrillated cellulose) with other natural polymers such as chitosan and starch will be presented. 

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