Naslov
Hydrolytic degradation of poly(lactic acid)/hydroxyapatite composites

Autori
Ivanković, Hrvoje ; Bauer, Leonard ; Milovac Lerga, Dajana ; Ivanković, Marica

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Book of Abstracts / - , 2023, 191-191

Skup
28th Croatian Meeting of Chemists and Chemical Engineers

Mjesto i datum
Rovinj, Hrvatska, 28.03.2023. - 31.03.2023

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
poly (lactic acid) ; hydroxyapatite ; composite ; degradation

Sažetak
Poly(lactic acid) (PLA), one of the mostly used biodegradable polymers for tissue engineering, is a thermoplastic polymer well suited for additive manufacturing of bone scaffolds due to low melting temperature for melt extrusion. PLA for additive manufacturing usually is a technical-grade filament which is cost-effective ; however, this material contains additives that greatly influence biological and degradation properties. We compared technical- and medical-grade polymer properties at accelerated hydrolytic degradation in phosphate- buffered saline (PBS) at 50 °C for 28 days. Technical-grade PLA (4043D, NatureWorks) samples preserved mass and shape throughout the degradation test. Medical-grade PLA (FP158009, Carbosynth) samples went through significant weight loss during simulated degradation, which directed our research towards significantly more expensive medical-grade PLA. The addition of bioactive ceramics, such as hydroxyapatite (HAp), is one way to tailor the degradation properties of PLA-based scaffolds. Composites of medical-grade PLA with 0, 10 and 20 wt% of hydroxyapatite (PLA-0-HAp, PLA-10-HAp and PLA-20-HAp) were prepared in the form of circular films. The hydrolytic degradation test on prepared composites was carried out according to ISO 13781:2017 (E) norm for 10 weeks in PBS at 37 °C. The results show that PLA-0-HAp weight loss exponentially grows up after 6 weeks, while the addition of HAp stabilises it through the whole degradation process. The visible non-uniform degradation region appears in the thicker middle part of the film, where autocatalytic “bulk erosion” is favoured, and results in the transition of PLA into a rubbery state. Determined glass transition temperatures (Tg) confirmed mentioned composite degradation. Tg of composite with the highest amount of HAp remains stable at around 50 °C through 10 weeks. PLA-10- HAp’s Tg is stable until week 8, while Tg of PLA- 0-HAp starts to decrease towards 30 °C just after 2 weeks. The thicker sample region in the middle of each film is characterized by lower Tg than the thinner outer part. Although the poor distribution of HAp particles, observed by SEM in PLA-20-HAp, can induce sample degradation, it is obvious that a higher amount of HAp slows down sample mass loss and polymer degradation. HAp dissolution process is simultaneous with precipitation and polymer hydrolysis. The results lead to the conclusion that PLA and HAp form good molecular interactions that can inhibit composite degradation.

Izvorni jezik
Engleski

Znanstvena područja
Kemijsko inženjerstvo, Temeljne tehničke znanosti

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