20.500.12556/RUL-160047 Degradation of hydroxypropyl methylcellulose (HPMC) by acoustic and hydrodynamic cavitation The present study aims to investigate the degradation of HPMC on a laboratory scale by acoustic and hydrodynamic cavitation. The effects of temperature and the addition of an external oxidizing agent on the effectiveness of HPMC degradation were systematically investigated by SEC/MALS-RI, FTIR and 1H NMR. The results of the experiments without cavitation show that an external oxidizing agent alone reduces the weight-average molar mass at 60 °C in 30 min for 45.1 % (from 335 to 184 kg mol−1). However, the weight-average molar mass of HPMC decreased significantly more in the cavitation treatment, for 98.8 % (from 335 to 4 kg mol−1) in 30 min at optimal operating conditions of hydrodynamic cavitation (i.e. addition of external oxidant and 60 °C) with a concomitant narrowing of the molar mass distribution, as shown by the dispersity value, which decreased from 2.24 to 1.31. Compared to acoustic cavitation, hydrodynamic cavitation also proved to be more energy efficient. The FTIR spectra of the cavitated HPMC samples without the addition of H2O2 show negligible oxidation of the hydroxyl groups and the glycosidic bonds, confirming that mechanical effects predominate in HPMC degradation in these cases. In contrast, when H2O2 was added, FTIR and 1H NMR show typical signals for cellulose oxidation products, especially when the experiments were performed at 60 °C, confirming that chemical as well as mechanical effects are responsible for the extensive HPMC degradation in these cases. Since treatment methods that lead to lower molar masses and narrower molar mass distributions of the polymers are lacking or require longer treatment times (e.g. 24 h), mechanochemical treatment methods such as cavitation have great potential, as they enable faster polymer degradation (in our case 30 min) through a combination of mechanical and/or chemical degradation mechanisms. hydroxypropyl methylcellulose acoustic cavitation hydrodynamic cavitation degradation oxidation hidroksipropil metilceluloza akustična kavitacija hidrodinamska kavitacija degradacija oksidacija true false true Angleški jezik Slovenski jezik Članek v reviji 2024-08-12 07:30:02 2024-08-12 07:30:11 2024-08-14 12:03:21 0000-00-00 00:00:00 2024 0 0 9 str. Vol. 109, art. 107020 Oct. 2024 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 532.528:542.943 1873-2828 10.1016/j.ultsonch.2024.107020 204078851 Zupanc_..._Degradation_of_hydroxypropyl_methylcellulose_(HPMC)_by_acoustic.pdf Zupanc_..._Degradation_of_hydroxypropyl_methylcellulose_(HPMC)_by_acoustic.pdf 1 902F52AAAB9F46EE0EC6EA40EA6BAFA3 11b7a9ba9dade92d89256732bf562f8968797e3fadc0cf05c36080f3e9fd8c8e 1356ff34-5870-11ef-8f74-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=188443 https://www.sciencedirect.com/science/article/pii/S1350417724002682 1 c7aebbe2-586b-11ef-8f74-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=188442 Fakulteta za strojništvo 0 0 0