TRIBOLOGICAL PROPERTIES OF LUBRICANTS DERIVED FROM RENEWABLE RESOURCES

Sažetak Biljna ulja i životinjske masti već se godinama koriste kao maziva. Otkrićem nafte i dostupnošću jeftinih ulja, alternative su postale neprivlačne te su ostavljene po strani. Posljednjih godina povećana pozornost javnosti i ekološka svijest potakle su razvoj velikog broja maziva koja su lako biološki razgradljiva s obzirom na više međunarodno priznatih metoda ispitivanja, te koja se odlikuju niskim stupnjem otrovnosti s obzirom na vodne organizme. Najvažnija osnovna sirovina za formulacije ekološki prilagođenih maziva su biljna ulja, kao i njihovi modificirani esteri. U radu su ispitana dva tipična estera i dvije formulacije napravljene iz esterne uljne baze, zajedno s odabranom mješavinom aditiva, i to s obzirom na oksidacijsku stabilnost i tribološko ponašanje. Čak i mineralno ulje i sintetički ester koji sadržava potpuno zasićene masne kiseline pokazali su se stabilniji glede oksidacijske razgradnje. Formulacija s nezasićenim esterom pokazala je bolje tribološko ponašanje kod umjerenih opterećenja. Rezultati upućuju na zaključak da je moguće povezati dugi vijek primjene s visokom razinom radnih svojstava, što je korisno za okoliš, poljoprivredu i potrošače.TRIBOLOGICAL PROPERTIES OF LUBRICANTS DERIVED FROM RENEWABLE RESOURCES Abstract Vegetable oils and animal fats have been used as lubricants for many years. With the discovery of petroleum and the availability of inexpensive oils, alternatives became unattractive and were left by the wayside. In recent years, the increased public attention and the awareness of environment protection have stimulated the development of a vide variety of lubricants that are readily biodegradable in terms of one of the several internationally recognized test methods, and that have a low toxicity toward water organisms. The most important base stocks for environmentally adapted lubricants formulations are vegetable oils as well as modified vegetable oil esters. In the present work, two typical esters and two formulations made from ester oil base along with a unique blend of additives were investigated with respect to their oxidative stability, and tribological behavior. Even mineral oil and synthetic ester containing fully saturated fatty acids have proven to be more stable against oxidative attack, unsaturated ester formulation exhibit better tribology performance at moderate loads. Results suggest that it is possible to combine high renewability and high technical performance, which should benefit the world’s environment, the agricultural community and the consumer