Pultruded Profile Properties

Fibre reinforced plastic profiles

The Pultrusion process is a method of continuously manufacturing Fibre Reinforced Plastic profiles of high strength and stiffness. Many different reinforcements and matrix systems can be used, but standard constructions usually consist of glass and polyester resins.

Flexural Properties

The values quoted below have been determined on test coupons cut from profiles produced using glass as reinforcement and an unsaturated polyester resin cured at elevated temperature as the matrix system.

The test method used was a 3-point flexural bend test using a 16 to 1 span to depth ratio corresponding to BS2782-304 and ATSM D-790.

Pultruded profiles normally exhibit a high degree of anisotropy so that the orientation of the test samples is very important.  The angle formed between the test piece geometry and the unidirectional fibre component is referred as the sample orientation.

Standard construction is either all-unidirectional E glass roving at 58% by volume glass content or a unidirectional E glass-roving core with 450 gsm Continuous Filament Mat (CFM) on each face giving a total of 38% by volume glass content.

Table 1 : Variation in flexural strength with angle of test

Construction Thickness
mm
Flexural strength
Orientation Orientation
0 30 60 90 0 30 60 90
MPa MPa MPa MPa 10  psi 10  psi 10  psi 10  psi
Standard profile 4 450 250 200 150 65 36 29 22
Unidirectional profile 4 900 200 50 50 130 29 7 7

Table 2 : Variation in flexural modulus with angle of test

Construction Thickness
mm
Flexural strength
Orientation Orientation
0 30 60 90 0 30 60 90
MPa MPa MPa MPa 10  psi 10  psi 10  psi 10  psi
Standard profile 4 21 12 10 8 3.0 1.7 1.5 1.2
Unidirectional profile 4 40 20 12 9 5.8 2.9 1.7 1.3

Table 3: Variation in flexural properties with thickness
(0  AND 90  ORIENTATION)

Construction Thickness
mm
Flexural strength
Orientation Orientation
0 90 0 90 0 90 0 90
MPa MPa 10  psi 10  psi GPa GPa 10  psi 10  psi
Standard profile 3.5 400 200 58 29 14 12 2.0 1.7
Standard profile 3.5 450 170 65 25 17 11 2.5 1.6
Standard profile 4.0 450 150 65 22 21 8 3.0 1.2
Standard profile 6.5 650 120 94 17 26 8 3.8 1.2
Unidirectional profile 900 50 130 7 40 9 5.8 1.3

Comparison of Properties

TEST Units Glass reinforced Thermoset resins Thermoplastic resins Metals
Pultruded rod (Carbon) Pultruded rod (Glass Pultruded profile (Standard) Sheet moulding compound Nylon PVC Low Carbon Steel Aluminium
Fibre content by volume % 60 60 40 20 15
Specific gravity gm/cm 1.6 1.9 1.7 1.7 1.3 1.35 7.8 2.7
Flexural strength MPa 1200 900 450 150 200 100 190 130
Flexural Modulus GPa 125 44 17 10 10 3 210 70
Tensile strength MPa 1050 800 400 70 90 100 125 165
Tensile Modulus GPa 120 40 16 10 8 3 210 70
Compressive strength MPa 800 450350 250 150 70 450
Thermal conductivity W/M C N/A 0.3 0.3 0.3 0.25 0.1 45 150
Co-efficient of thermal expansion  Cx10 -0.7 6 9 20 30 70 13 23
Dielectric strength KV/mm N/A 12 12 12 16 1 N/A N/A

Specific property comparison

The specific property is defined as the property divided by the density.  It gives a good indication of the frequency of supports required for a suspended structure or the overall weight of a structure to meet defined criteria.

Material Description Density (gms/cm)
Pultruded rod (Carbon fibre) Unidirectional carbon fibre in epoxy resin 1.6
Pultruded rod (Glass) Unidirectional glass in polyester resin matrix 1.9
Pultruded profile Unidirectional roving core with bi-direction reinforcement and polyester resin matrix.Laminate thickness 3.5mm 1.7
Sheet moulding compound A conventional”high glass” product with randomly orientated chopped glass 1.7
Nylon Short fibre glass reinforced engineering thermoplastic 1.3
PVC Unplasticised PVC 1.4

pdf Click Here to download a Pultrex document (PDF) illustrating Standard tolerances for Pultruded Profiles