AUTHOR
Merilä, Ann-Jeanette

DATE
2000-09-10

DEPARTMENT
Materials and Manufacturing Engineering / Polymer Engineering

SUMMARY
The main purpose with this master thesis project was to investigate the mechanical properties of nettle fiber reinforced epoxy and phenolic composites.

The nettle fiber composites were manufactured using the resin transfer molding (RTM) process. The nettle fibers were unidirectional and epoxy (E) and phenolic (P) resins were used. Afterwards the composites were tested and their mechanical properties were studied. The adhesion between fiber and matrix, and the morphology of the fibers were studied using scanning electron microscope (SEM) and optical microscope (OM). Water uptake measurement was also made. Finally, the results from the literature study and experimental part were analyzed and compared with a flax reinforced epoxy composite (FE). The flax/epoxy composite came from an earlier project done at SICOMP AB.

The tensile strength and stiffness of nettle/epoxy (24 v% fibers) composites were 91 MPa and 9 GPa, respectively, compared with flax/epoxy (21 v% fibers) composite where strength and stiffness are more than twice as high. Further, the nettle/phenol (23 v% fibers) composite showed a strength and stiffness of 13 MPa and 5 GPa, which was lower than for pure epoxy resin.

The microscopic study indicates that the adhesion between fiber and matrix was better with phenol than with epoxy. The water uptake measurements showed that the nettle fiber composites absorbed a high amount of water with an increase in thickness as result.

ISSN 1402-1617 / ISRN LTU-EX--00/235--SE / NR 2000:235