Biopolymer Foil Materials Examination with DSC and TSD methods
Abstract
Ther mally Simulated Depolarization Current measurement is an excellent but not widely used method for identifying relaxation processes in polymers. The TSDC method is used here to analyze the molecular movements in biopolymers. Differential Scanning Calorimetr y is a technique used to measure thermal properties of polymers based on the rate at which they absorb heat energy compared to a reference material. The two techniques take advantage of the energy changes involved in the various phase transitions of certai n polymer molecules. This allows for several properties of the material to be ascertained; melting points, enthalpies of melting, crystallization temperatures, glass transition temperature s and degradation temperatures. The examined biopolymer films are ma de from biological materials such as proteins and polysaccharides. These materials have gained wide usage in pharmaceutical, medical and food areas. The uses of biopolymer films depend on their structure and mechanical properties. This work is based on thr ee types of alginate, and gelatin films. The films were prepared by casting. The casting technique used aqueous solutions in each case of sample preparation. The manufacturing process of the sodium alginate and gelatin films was a single stage solving proc ess, and for the calcium alginate and alginic acid have a chemical reaction process.
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Introduction
The past few years have witnessed rapidly expanding interest in food additives as sources of biomolecules with potential to replace synthetic polymers in medical materials with biocompatibility, bioactivity, biodegradability for unique applications.
Due to biomolecules having become more available, ever increasing demand for high-performance "natural" matrices for biomedical and pharmaceutical applications such as organ regeneration and tissue engineering, gel like bandages, wound dressing, medical suture lines, artifical limbs, controlled drug delivery systems, films, contact lenses and capsules for oral ingestion.[1]
Biopolymer films and biofoils are formed from natural polymers, of animal or plant origin, such as polysaccharides, lipids and proteins. The biopolymers are neutral and always renewable, because they are made from plant materials which can be grown indefinitely.
Alginic acid forms water-soluble salts with monovalent cations, but these are precipitated upon acidification. Alginates of many bivalent cations, particularly of Ca2+, Mg2+ are insoluble in water and can be prepared when sodium ions of water soluble Na- alginate are replaced by di- and trivalent cations. The alginate extracted from various species of algae (Phaeophyceae), are natural polymers, which have low cost, high stability, good gelling properties, biocompatibility. Thus, these materials have great potential for use in the preparation of biopolymer films, gelling agents, drug coatings for vegetarians (instead of gelatin) or for dental applications. Toxicological data showed that alginates are safe when used in food. The Na-alginate acts as stabilizer and thickener facilitating the dissolution and improving viscosity of the ingredients preventing the formation of crystals that will determine the appearance and homogeneity, mainly in frozen products [1]
Gelatin is a mixture of peptides and proteins produced by partial hydrolysis of collagen extracted from the bovine, pork fish or poultry skin, bones, and connective tissues of animals. Gelatin is a typical material used in the medical or pharmaceutical fields [2].