The effect of thermal history on the properties of polymers

Svojstva polimera uvelike ovise o njihovoj strukturi. Struktura plastomera ovisit će o uvjetima zagrijavanja i hlađenja. Uz pomoć dinamičko-mehaničke analize provedena je usporedba utjecaja toplinske povijesti na svojstva kopolimera etilena i metakrilne kiseline E/MAA. U prvom slučaju u prvom mjerenju materijal je grijan do temperature taljenja i sporo hlađen na sobnu temperaturu, a zatim je s istim ispitnim tijelom ponovljeno mjerenje. U drugom slučaju materijal je u prvom ciklusu mjeren samo do gumastog stanja, hlađen na isti način te je nakon toga također ponovljeno mjerenje. Pokazalo se da uvjeti hlađenja i zagrijavanja imaju utjecaj na stupanj kristalnosti, djelovanje vlage kao omekšavala, oksidaciju i razgradnju makromolekula, te stoga i na temperaturni interval prijelaza iz staklastog u gumasto stanje, kao i temperaturu mekšanja kristala pri početku taljenja. Dobiveni rezultati ukazuju na važnost optimiranja parametara prerade s ciljem dobivanja željene strukture, te redukciju broja ciklusa zagrijavanja i hlađenja materijala.The properties of polymers largely depend on their structure. The structure of the plastomer will depend on the heating and cooling conditions. With the help of dynamic-mechanical analysis, a comparison of the influence of thermal history on the properties of copolymer (ethylene and methacrylic acid, E / MAA) was performed. In the first case in the first measurement the material was heated to the melting temperature and slowly cooled to room temperature, and then the measurement was repeated. In the second case the material was only heaten up to the rubber state in the first heating cycle, cooled to room temperature and after that the measurement was also repeated. Cooling and heating conditions have been shown to affect the degree of crystallinity, the effect of moisture as a plasticizer, the oxidation and decomposition of macromolecules, and therefore the temperature interval of transition from glassy to rubbery state, as well as the softening temperature of crystals. The obtained results indicate the importance of optimizing the processing parameters in order to obtain the desired structure, and reducing the number of heating and cooling cycles of the material