This study investigates the effect of processing strategy on the structure–property relationships of bio-based epoxy composites reinforced with pine rosin powder extracted from Pinus halepensis trees in Algeria's Green Dam. Two processing protocols were employed:
(fixed epoxy-to-curing-agent ratio) and
(fixed curing-agent proportion). Composites containing
rosin were fabricated and characterized using Fourier Transform Infrared Spectroscopy (
),
Diffraction (
), Thermogravimetric Analysis (
), Scanning Electron Microscopy (
), tensile and flexural tests.
confirmed hydrogen-bonding interactions between rosin and epoxy without new chemical bonds, while
patterns revealed an increase in amorphous character.
indicated reduced thermal stability compared to neat epoxy, attributed to the low-molecular-weight fractions of Pine rosin.
showed more uniform particle dispersion and stronger interfacial adhesion in
, correlating with improved mechanical retention. Tensile and flexural tests revealed that rosin acts as a natural plasticizer: strength and modulus decreased gradually with increasing rosin content, while ductility improved. Optimal performance was achieved at
rosin under
, maintaining about
tensile and
flexural strength. At higher loadings
, agglomeration caused embrittlement. These findings demonstrate that the processing route critically governs the microstructure and mechanical behavior of bio-based epoxy composites. Algerian pine rosin thus provides a sustainable and cost-effective bio-filler for developing flexible, partially bio-based epoxy materials suited for coatings, adhesives, and structural applications.
