Influence of compatibilizing system on morphology, thermal and mechanical properties of high flow polypropylene reinforced with short hemp fibers

What is it about?

Simultaneous influence of polypropylene-graft-maleic anhydride (MAPP) and silane-treated hemp fibers (HF) on morphology, thermal and mechanical properties of high-flow polypropylene (PP) modified with poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) was studied in this paper. The addition of SEBS reduced the efficiency of MAPP in PP composites with HF, thus silane-treated fibers (HFs) were used to improve polymer – fiber interface. Thermal stability of HF was improved after silane treatment and less than 2% weight loss was observed at 240 ºC in composites with 30 wt% HF. Better dispersion of fibers and better efficiency in enhancing static and dynamic mechanical properties of PP, doubling its strength and stiffness were observed in composites with treated fibers compared to untreated ones. These composites were studied as an alternative to conventional PP/glass fibers composites for injection molding of small to medium auto parts.

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Why is it important?

The simultaneous influence of maleated polypropylene and silane treated hemp fibers (HF) on morphology, thermal and mechanical properties of high-flow polypropylene (PP) modified with SEBS was studied. Great improvement of HF thermal stability was observed after silane treatment and minor change of the thermal stability of composites at low concentration of fibers (10 wt%). Treated hemp fibers showed good efficiency in enhancing static and dynamic mechanical properties of PP, doubling its strength and stiffness. Good correlation was found between static and dynamic modulus, which highlights the stiffening effect of fibers, proportional with their concentration in composites. Likewise, good balance between strength and stiffness was found for PP modified with SEBS and MAPP containing 30 wt% HFs, which is emerging as a viable alternative to conventional PP/GF composites for injection molding of auto parts.