| Abstract [eng] |
Plastics are an integral part of modern life, due to their very wide use. Since it is an important material for many products and plastic is the main demand, the raw materials and plastic problems need to be solved. In solving these problems, starch is a very popular material for research to obtain new plastics that would replace the current ones. Natural starch is non-thermoplastic, which is why it is modified by physical and chemical methods. At this time, the starch was esterified with two organic acid anhydrides - dodecenyl succinic anhydride and acetic anhydride. The obtained esters were analysed to find out how the thermal and hydrophobic properties of the starch were changed. The modification of starch with dodecenyl succinic anhydride gave very good hydrophobic properties: the best result was obtained when the degree of substitution was 0.02 and the contact angle was 127.8 degrees. Thermal properties did not get changed by dodecenyl succinic anhydride. After further modification of these compounds with acetic anhydride, the hydrophobic properties worsened, but compared to natural starch, these properties were still better. Starch modified by acetic anhydride with a substitution degree of more than 0.40 acquires a glass transition temperature, and the destruction temperature becomes worse until the substitution degree does not reach at least 2. Starch of 0.05 dodecenyl succinic anhydride and 1.4 acetic anhydride degree of substitution was blended with triacetin and polyethylene glycol 200 plasticizers to extrudate the synthesized material and find their mechanical properties. The polyethylene glycol 200 plasticizer gave thermoplastic properties for the modified starch, but mechanically the material had poor strength as it became hard and brittle, with an average mechanical resistance of 2.04 MPa during tension and an average elongation of only 4.52% before breaking. Meanwhile, triacetin plasticizer gave properties similar to elastomer for the modified starch - the compound became soft, flexible and had an average elongation of 65.37% during stretching, and an average mechanical resistance during stretching was 1.26 MPa. |
