Lichen-Derived Mineral Residue as a Renewable Particulate Filler in Polylactic Acid Biocomposites: Structure, Melt Rheology, Viscoelastic, and Flexural Behavior
Polymer Composites, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Basım Tarihi: 2026
- Doi Numarası: 10.1002/pc.71612
- Dergi Adı: Polymer Composites
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Aerospace Database, Chemical Abstracts Core, Chimica, Compendex, INSPEC, Academic Search Ultimate (EBSCO), Materials Science & Engineering Collection (ProQuest), Pharma Collection (ProQuest), Technology Collection (ProQuest)
- Anahtar Kelimeler: bacteriostatic activity, biodegradable polyester, cold crystallization, oxygen permeability, sustainable
- Kocaeli Üniversitesi Adresli: Evet
Özet
A lichen-derived natural material, known as “höllük” in southeastern Turkey, is introduced as a renewable filler for polylactic acid (PLA). X-ray diffraction and scanning electron microscope analysis of höllük identified quartz and calcite as the major crystalline phases within a silicate-organic matrix, and thermogravimetric analysis indicated that the decomposition of filler began at 325°C, well above the melt-compounding window of PLA. PLA-lichen composites, containing 5, 10, and 15 wt% of filler were prepared in a twin-screw extruder with 3 phr of triacetin. Rheological measurements in the melt state revealed that höllük addition slightly improves storage modulus (G′) and viscosity of PLA and acted as antioxidant. In dynamic mechanical analysis, 5 wt% filler increased the storage modulus (E′) from 3.37 to 3.54 GPa and the flexural strength from 114 to 160 MPa, whereas 15 wt% lowered E′ to 2.19 GPa, consistent with filler agglomeration and interfacial micro-cavities observed by scanning electron microscopy. Differential scanning calorimetry analysis implied that filler addition restricted cold crystallization and yielded slightly higher crystallinity. Oxygen permeability improved about 37% with introducing 15 wt% of filler, and a dose-dependent inhibition of Escherichia coli was recorded. The results identify that 5 wt% of loading balances stiffness, melt processability, and thermal stability in this biocomposite system.