Materials and properties

Resins

Polyesters

Unsaturated polyester resins are the most commonly used for the composites industry. Polyester resins have a good balance of mechanical, electrical and chemical properties.

	Unit	Structure = UCU	Structure = U
Glass content	[%-vol]	55-58 %	58-65 %
Tensile strength	[Mpa]	600-900	1000-1200
Tensile modulus	[Gpa]	38-42	42-45
Flexural strength	[Mpa]	700-1000	1000-1300
Flexural modulus	[Gpa]	35-40	40-43
Coefficient of thermal expansion	[10-6/K]	9-11	6-8
Density	[kg/dm3]	1.9-2.0	1.9-2.0

Structure: U = one-way, C = cross coupling

The polyester resins are mainly used in glass fibre profiles. Polyesters resins can be modified so that they are flame-retardant of self-extinguishing. The polyester resins have a good chemical resistance properties. The chemical environment has to to be known before polyester or vinyl ester resin can be chosen. Polyester resins are good in weak alkalis and excellent in weak acid conditions. The maximum recommended operation temperature is 80⁰C for the basic grade polyesters.

Methyl methacrylates

Methacrylic resins have excellent properties and they are commonly used together with high quality reinforcements like carbon fibers. They are flame-retardant of self-extinguishing and bring outstanding solution for fire retardant applications such as La Manche tunnel. They can be used in place of epoxies.

Vinyl esters

Vinyl ester resins combine the best features of polyester and epoxy resins. The strength is good and the resin has a very good chemical resistance in acids and alkalis environments, especially in high temperatures. The glass fibre vinyl ester profile has good electrical and thermal insulation properties. Epoxy based vinyl ester resins have good chemical resistance at elevated temperatures. The maximum recommended operating temperature is 90-150°C.

Epoxies

Epoxies resins have excellent properties and they are commonly used together with high quality reinforcements like carbon fibers and glass fibers, if the conten of reinforcement is high. Different specific properties can be created by changing hardener systems.

Reinforcements

In the pultrusion process all continuous fibres can be used:

Glass fibres
Carbon fibres
Aramid fibres

The most widely used reinforcement material in pultrusion industry is glass fibre.

The mechanical properties of the pultruded composite profile are largely determined by the type of reinforcement (e. g. unidirectional glass fibre roving), its form (mat, multiaxial fabric e. t. c.) and its position and orientation in the cross section, an of course the fibre content has a very remarkable effect. Glass fibre has good tensile, commpression and impact properties.

Glass fibres

Glass fibre has good tensile, commpression and impact properties.

	Density	Tensile strength[Mpa]	Tensile modulus [Gpa]	Coefficient of thermal expansion 10-6/K
E-glass	2.58	3 450	72.5	5.0
ECR-glass	2.62	3 625	72.5	5.0
S-glass	2.48	4 590	86.0	5.6

Glass reinforced profiles and tubes have admirable properties e. g.:

Low weight (about 75% lower then steel and 30% lower then aluminium)
High specific tensile strength
High stiffness
Low coefficient of thermal expansion
Heat insulator
Nemagnetické
Non magnetic
Good chemical resistance
Low maintainance
Good resistance to weathering
Low water absorption (in high fibre content is using)
Cost effectiveness

In our products we are using glass fibres in these forms and their combinations:

Roving
Woven roving
Mats