In general, frying in sunflower oil is not recommended.
During frying, chemical reactions including oxidation, polymerization, splitting, etc would occur in high temperature and brings chemical compounds such as carbonyl, carboxyl, etc. These compounds are high in polarity, called polar compounds. Longer high temperature last, more polar compounds are created.
Polar compounds during frying in sunflower oil
Sunflower oil consists of plenty of unstaurated fatty acid, poor stability in high temperature. Thus, sunflower oil is not suitable for frying.
But sunflower oil is frangant oil, we can use sunflower oil as seasoning oil to enhace frangance of food.