Isotropic properties of Glass fibres

[izax1]

Can anyone help me.

Is it so that Glass fibres (not the composite, only pure fibres) exibit isotropic properties, whereas carbon fibres and Aramid fibres do not? If so, is the properties of a GFRP along the fibre direction and across for GFRP anisotropic only because of the resin?

Thankful for any help.

izax1

 

[clocklight]

the anisotropic is due to the geometry

 

[rnd2]

If you study in depth the general physical properties of each fiber it will help you reach a better understanding of what you ask. For example, GRP will have less tensile strength and lower stiffness, but better impact resistance than CRP all other things being equal.

 

[Compositepro]

Carbon fibers have a graphitic crystal structure and molecular orientation than is aligned with the fiber axis. Aramid fibers are also highly oriented. The properties in the axial direction are very different from the the properties in the radial direction within a single filament. This is a large part of the difference in composite properties between the axial and transverse directions. A major example is the coefficient of thermal expansion. Axial CTE of carbon and aramid is slightly negative. Radial CTE is positive but still low for carbon. Aramid radial CTE is greater than most polymers.

As far as I'm aware glass fibers do not have any significant internal orientation.

 

[TVP]

Glass fibers do not have any significant orientation, because the composition and processing of the glass results in an amorphous (non-crystalline) structure. This is why it can be said that glass fibers are isotropic.

 

[RvL04]

izax1;

I would suggest you get the glass fibers tested; I've seen several cases in the past that were clearly orthotropic, oddly enough... I'm no materials guy, so I'm hesitant to make any type of generalization, but rather, get the results to look at...

Ron