Sıcak pres yöntemiyle üretilen PLA–kenevir biyokompozitlerinin karakterizasyonu

Abstract

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.

Keywords

• Biyokompozitler
• Mekanik performans
• Fiziksel özellikler
• Termal özellikler

Characterization of PLA–hemp biocomposites produced by hot-pressing

Abstract

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.

Keywords

• Biocomposites
• Mechanical performance
• Physical properties
• Thermal properties

Ethical Statement

Ethics committee approval is not required

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