Sıcak pres yöntemiyle üretilen PLA–kenevir biyokompozitlerinin karakterizasyonu

Öz

Bu çalışmada, uyumlaştırıcı kullanılmadan sıcak pres yöntemiyle üretilen PLA-kenevir biyokompozitlerinin termal, kimyasal, fiziksel, morfolojik ve mekanik özellikleri incelenmiştir. Boyutu 75 µm’nin altında olan kenevir partikülleri PLA matrisine ağırlıkça %3, %6 ve %9 oranlarında ilave edilerek, saf PLA ise hem granül hem de ekstrüde edilmiş formda değerlendirilmiştir. Karışımlar çift vidalı ekstrüder kullanılarak hazırlanmış ve ardından sıcak presleme yöntemiyle levha formuna dönüştürülmüştür. TGA sonuçları, ekstrüzyon işleminin saf PLA’nın termal kararlılığını sınırlı düzeyde artırdığını, buna karşılık kenevir ilavesinin bozunma sıcaklıklarını düşürdüğünü göstermiştir. DSC analizleri, kenevir liflerinin PLA matrisinde daha erken kristallenmeyi ve kristallenme derecesini artırdığını ortaya koymuştur. FTIR spektrumları, PLA ile kenevir arasındaki etkileşimin temel olarak fiziksel nitelikte olduğunu ve yeni bir kimyasal bağ oluşumuna ilişkin herhangi bir kanıt bulunmadığını göstermiştir. Su alma ve kalınlık artışı değerleri kenevir içeriğinin artmasıyla yükselmiş ve en yüksek değerler PLA-H9 grubunda elde edilmiştir. Yüzey pürüzlülüğü numune türünden istatistiksel olarak etkilenirken, kenevir ilavesinden sonra çekme ve eğilme dayanımları azalmıştır. SEM görüntüleri, lif sıyrılması, arayüzey ayrılması ve mikro boşluk oluşumlarını ortaya koyarak matris–lif etkileşiminin sınırlı olduğunu göstermiştir. Genel olarak, kenevir ilavesi biyobazlı içerik oranını artırmış ama uyumlaştırıcı kullanılmadığında mekanik dayanımı azaltmıştır.

Anahtar Kelimeler

• Biyokompozitler
• Mekanik performans
• Fiziksel özellikler
• Termal özellikler

Characterization of PLA–hemp biocomposites produced by hot-pressing

Öz

This study investigates the thermal, chemical, physical, morphological, and mechanical properties of hot-pressed PLA-hemp biocomposites produced without compatibilizers. Hemp particles below 75 µm were composed of PLA at 3%, 6%, and 9 wt%, and neat PLA was evaluated in both granular and extruded forms. The composition was compounded using a twin-screw extruder and converted into plates by hot pressing. TGA showed that extrusion slightly improved the thermal stability of neat PLA, whereas hemp addition reduced degradation temperatures. DSC results demonstrated that hemp fibers increased earlier crystallization and the crystallinity of the PLA matrix. FTIR spectra showed that the interaction between PLA and hemp was mainly physical but there is no evidence of new chemical bond formation. Water absorption and thickness swelling increased with hemp content, reaching the highest values in PLA-H9. Surface roughness was significantly affected by sample type, while tensile and flexural strengths decreased after hemp incorporation. SEM images depicted fiber pull-out, interfacial debonding, and micro voids, confirming limited matrix–fiber adhesion. Overall, hemp addition improved bio-based content but reduced strength without compatibilization.

Anahtar Kelimeler

• Biocomposites
• Mechanical performance
• Physical properties
• Thermal properties

Etik Beyan

Ethics committee approval is not required

Kaynakça

1. ASTM International. (2017). ASTM D790 – 17: Standard test methods for flexural properties of unreinforced and reinforced plastics and electrical insulating materials. USA: Annual Book of ASTM Standards.
2. ASTM International. (2022a). ASTM D570 – 22:. Standard test method for water absorption of plastics. USA: Annual Book of ASTM Standards.
3. ASTM International. (2022b). ASTM D638 – 22: Standard test method for tensile properties of plastics. USA: Annual Book of ASTM Standards.
4. British Standard Institute (2014). BS EN ISO 11358-1: Plastics. Thermogravimetry (TG) of polymers General principles. UK: International Standard
5. British Standard Institute (2021a). BS EN ISO 11357-3: Plastics — Differential scanning calorimetry (DSC) Part 3: Determination of temperature and enthalpy of melting and crystallization. UK: International Standard
6. British Standard Institute (2021b). BS EN ISO 11357-4: Plastics — Differential scanning calorimetry (DSC) Part 4: Determination of specific heat capacity. UK: International Standard
7. Celik, E., Uysal, M., Gumus, O.Y., & Tasdemir, C. (2025). 3D-printed biocomposites from hemp fibers reinforced polylactic acid: Thermal, morphology, and mechanical performance. Bioresouces, 20(1), 331-356. https://doi.org/10.15376/biores.20.1.331-356
8. Cherney, J. H., & Small, E. (2016). Industrial hemp in North America: Production, politics and potential. Agronomy, 6(4), 58. https://doi.org/10.3390/agronomy6040058

9. Chrysafi, I., Ainali, N. M., Xanthopoulou, E., Zamboulis, A., & Bikiaris, D. N. (2023). Thermal degradation mechanism and decomposition kinetic studies of poly (ethylene succinate)/hemp fiber composites. Journal of Composite Science, 7(6), 216. https://doi.org/10.3390/jcs7060216
10. Hallad, S. A., Ganachari, S. V., Soudagar, M. E. M, Banapurmath, N. R., Hunashyal, A. M., Fattah, I. M. R, Hussain F., Mujtaba M. A., Afzal, A., Kabir, M. S., & Elfasakhany, A. (2022). Investigation of flexural properties of epoxy composite by utilizing graphene nanofillers and natural hemp fibre reinforcement. Polymer and Polymer Composites, 30. https://doi.org/10.1177/09673911221093646
11. Hu, R., & Lim, J. K. (2007). Fabrication and mechanical properties of completely biodegradable hemp fiber reinforced polylactic acid composites. Journal of Composite Materials, 41(13), 1655-1669. https://doi.org/10.1177/0021998306069878
12. Jubinville, D., Sharifi, J., Fayazfar, H., & Mekonnen, T. H. (2023). Hemp hurd filled PLA-PBAT blend biocomposites compatible with additive manufacturing processes: Fabrication, rheology, and material property investigations. Polymer Composites, 44(12), 8946-8961. https://doi.org/10.1002/pc.27749
13. Masirek, R., Kulinski, K., Chionna, D., Piorkowska, E., & Pracella, M. (2007). Composites of poly(l-lactide) with hemp fibers: Morphology and thermal and mechanical properties. Journal of Applied Polymer Science, 105, 255–268. https://doi.org/10.1002/app.26090
14. Namhongsa, M., Mekpothi, T., Yarungsee, K., Daranarong, D., Ross, G. M., Ross, S., & Punyodom, W. (2025). Ternary blends of PLA with ATEC and TMC-200 as medical-grade biodegradable monofilaments for FDM 3D-printing applications. Polymers, 17(21), 2926. https://doi.org/10.3390/polym17212926
15. Pappu, A., Pickering, K. L., & Thakur, V. K. (2019). Manufacturing and characterization of sustainable hybrid composites using sisal and hemp fibres as reinforcement in poly (lactic acid) via injection molding. Industrial Crops and Products, 137, 260-269. https://doi.org/10.1016/j.indcrop.2019.05.040
16. Sanivada, U. K., Marmol, G., Brito, F. P., & Fangueiro, R. (2020). PLA composites reinforced with flax and jute fibers—A review of recent trends, processing parameters and mechanical properties. Polymers, 12(10), 2373. https://doi.org/10.3390/polym12102373
17. Siakeng, R., Jawaid, M., Asim, M., & Saba, N. (2018). Natural fiber reinforced polylactic acid composites: A review. Polymer Composites, 40, 446–463. https://doi.org/10.1002/pc.24747
18. Stevulova, N., Schwarzova, I., Cigasova, J., & Junak, J. (2014). Changes in the properties of biocomposites caused by physical modification of hemp hurds. In International Scientific Conference People, Buildings and Environment (15-17 October, Kroměříž, Czech Republic, pp. 425-431).
19. Stevulova, N., Cigasova, J., Schwarzova, I., Sicakova, A., & Junak, J. (2018). Sustainable bio-aggregate-based composites containing hemp hurds and alternative binder. Buildings, 8(2), 25. https://doi.org/10.3390/buildings8020025
20. Xiao, X., Chevali, V.S., Song, P., He, D., & Wang, H. (2019). Polylactide/hemp hurd biocomposites as sustainable 3D printing feedstock. Composites Science and Technology, 184, 107887. https://doi.org/10.1016/j.compscitech.2019.107887
21. Yang, T. C., & Yeh, C. H. (2020). Morphology and mechanical properties of 3D printed wood fiber/polylactic acid composite parts using. Polymers, 12(6), 1334. https://doi.org/10.3390/polym12061334
22. Yang, Z., Feng, X., Bi, Y., Zhou, Z., Yue, J., & Xu, M. (2016). Bleached extruder chemi‐mechanical pulp fiber‐PLA composites: Comparison of mechanical, thermal, and rheological properties with those of wood flour‐PLA bio‐composites. Journal of Applied Polymer Science, 133, 44241. https://doi.org/10.1002/app.44241