**Acknowledgements**

**Processing Composite Coupling** 

288 Composites from Renewable and Sustainable Materials

LLDPE‐ maple fibers

MAPP was not used in auto‐hybrid composites.

are always important to optimize the general properties.

Compression molding

\*

**6. Conclusion**

**agent**

MAPE (3%)

**Fiber diameter (µm)**

Long fiber: 300–425

Short fibers: 0–45 Medium fibers: 125–250 Long fibers: 355–450

**Table 7.** Overview of the different investigations on auto‐hybrid composites based on natural fibers.

Natural fibers are now interesting alternative to replace synthetic fibers due their good specific properties (per unit weight). They have been used to develop different composites based on thermoset and thermoplastic matrices. As for any composite, their mechanical, thermal and physical properties are function of the properties of the matrix and the reinforcement, as well as fiber loading, fiber source and manufacturing process. Nevertheless, interfacial conditions

The main disadvantages of using natural fibers are water uptake, low thermal stability, as well as low mechanical properties due to fiber agglomeration and poor interfacial adhesion, especially at high concentration. The problem is usually more important in thermoplastics than

**Fiber content (%)**

5, 10, 15, 20

**Crystallinity index (%)**

**Main results References**

long) and 50/50 (short/ long) weight ratio Positive hybridization effect was higher at 20 and 30 wt.% fiber content Impact strength was higher at 20 wt.% with a 30/70 (short/long) weight

Water absorption was not affected by fiber size

RoHM at 30/70 (smaller/ longer) weight ratio, regardless of fiber size 20 wt.% showed higher RoHM positive deviation and auto‐hybridization was more effective Positive deviation of RoHM is affected by fiber size and total fiber content Tensile and flexural modulus increased with fiber content, but not with

[148]

ratio

13–32 Positive deviation of

fiber size

Impact strength and torsion modulus of hybrid composites are affected by fiber weight ratio

The authors would like to thank the financial support of the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Research centre for high performance polymer and composite systems (CREPEC), as well as Centre de recherche sur les matériaux avancés (CERMA) and Centre de recherche sur les matériaux renouvelables (CRMR) of Université Laval for technical help.
