Hello,

The elastic modulus is higher for fibers used in composites in general. The differences are in order of one or two magnitudes. 

Below is a list of some synthetic and natural fibers with their corresponding tensile characteristics:

Fiber                     Tensile strength              Elastic modulus

                               (MPa)                                  (GPa)

E-glass                  2000                                      80

S-glass                  4890                                      93

Carbon                 5670                                      276

Kevlar                   3620                                      112

Cotton                  300-700                               6-12

Flax                        345-1100                               28-80

Jute                       200-700                               10-55

data taken from

https://www.azom.com/properties.aspx?ArticleID=764

Zhang, D. (2014). Progressive Damage and Failure Analysis of 3D Textile Composites Subjected to Flexural Loading. The University of Michigan.

Yılmaz, N.D. “Agro-Residual Fibers as Potential Reinforcement Elements for Biocomposites”, Chapter 11, in “Lignocellulosic Polymer Composites: Processing, Characterization and Properties”, Ed. Thakur, V.K., Wiley -Scrivener, USA, ISBN 978-1-118-77357-4, s. 233-270. ,2015

Best Regards

Not always true. Ceramic matrix composites are the exceptions.

NO 

The elastic modulus of fibre normally depends on the type of fibre used in the laminate( i.e GFRP, CFRP). Also it depends on the orientation of fibre plies included in the laminate.

In order to calculate elastic modulus of the laminate we need to calculate the equivalent  modulus which can be estimated based on number of plies, thickness and elastic modulus in each direction.

You seside.

A man design composite in dependence of the specific needs.

Now, the most designs use fibers with hirg elastic modulus and strength limit.

Mechanical properties of polypropylene-fiber reinforced concrete after gamma irradiation

By Gonzalo Martínez-Barrera,  Fernando Ureña-Nuñez, Osman Gencel and Witold Brostow

abstract

Fiber reinforced concretes (FRCs) exhibit property improvement caused by the fibers. By using gamma radiation we have further improved mechanical properties of hydraulic concretes elaborated with Portland cement, water, silica sand, marble and polypropylene (PP) fibers. Compression strength, compression modulus, impact strength and dynamic elastic modulus were determined. Impact fatigue testing is a convenient way to evaluate non-irradiated concretes. We find improvement of the strength and elastic modulus – dependent on PP fiber concentration, marble particle sizes and the applied dose. Both the compressive strength and the elastic modulus are the highest for concrete with 1.5 vol% of PP fibers. The compressive strength value at that PP fibers concentration, the average marble size of 1.4 mm and irradiated at 50 kGy is higher by 19% with respect to non-irradiated concrete. For 9.5 mm marbles the analogous improvement amounts to 25% but for the dose of 10 kGy.

.....

https://lapom.unt.edu/publications/pdf%20articles/Lisa/Mechanical%20properties%20of%20polypropylene-fiber.pdf

Physically the module the module and strength can only decrease when processing fiber in material, with one exception - aramid. In this case strength in material can be 20-30% higher than in fiber. But there are methodical questions of measurement of the module and strength, especially for high-strength and high-modulus fibers - the module depends on a testing length and a method (stretching or ultrasound), strength depends on a testing length.