Faq

1. What is a composite?
2. What technology is the composite produced? 
3. What are a strength properties?
4. What are a thermal and electrical insulative properties?
5. What is a thermal durability?
6. What is a fire-resistance?
7. What is a corrosive, chemical resistance and what is a life span?
8. Is it possible to colour the composites profiles?
9. What are the composite materials joined?
10. How much is it?
11. Do some limitations exist in the course of produce?

1. What is a composite?

As a composite is called material, in which two or more components are combined by specific way. These components differ in physical and chemical properties markedly. Reinforced plastics have as compared with particular components, i.e. fibres and resins, variant unique properties. Unreinforced resin has got a low density and it is easy workable, but it has a low strength properties. The fibres have required stiffness and strength though, but they are very breakable, subject to damage and in addition it is very difficult to keep them in required steric arrangement. If the composite material is produced so that fibres are distributed in the resin spatialy suitably, a new material with properties unavailable by particular components will be obtained.

2. What technology is the composite produced?

Our company specializes in continual highvolume technologies such as pressing and pultrusion. Pultrusion is a process for continual production of composite profiles with constant cross section and material properties which are manufactured for specific purposes. This technology is done by reinforced material being pulled through a quide where the fibres are impregnated with the matrix, which can contain other additives as dyes, filler or flame retardant. The combinated mixture of fibres and matrix is pulled on through the heated equipment where the profile is cured in its final geometry. The fully curred profile is then pulled forward to a floating suspended saw which cuts the profiles into defined lengths.

3. What are a strength properties?

The big advantage of fibre-reinforced composites is a possibility to change their elastic properties and strength by "mere" variance of steric arrangement of reinforcement, its type (rovings, mats, textiles), rate between content of reinforcement and matrix and technology of producing. One cam produce a wide range of different materials by using of same raw components (fibres, resins). That´s why it is necessary to know basic relationships, which allow to quality a dependence of Young modulus of composites on content of reinforcement, its steric arrangement and type. From above-mentioned results a wide range of strength, which is between 250 and 900 MPa.

4. What are a thermal and electrical insulative properties?

 Thermal and electrical insulative properties depend on the kind of used resin. Generally, composite materials have good thermal and electrical characteristics in the course of keeping electromagnetic transparency. Dielectric constant is 6 - 12 kV/mm.

5. What is a thermal durability?

As well as insulative properties also thermal durability depend on the kind of used resin. Composite profiles can be used without restriction between -20 ^oC a +80 ^oC, in the case of special resins       -20 ^oC a +150 ^oC. The coefficient of linear expansion is 8 - 10.10^-6K^-1.

6. What is a fire-resistance?

Fire-stopping requirements differ along using and national legislation, and so special requirements on special structure could be given for every one case. Pultruded profiles reach to finite or acceptable dues to fire in dependence on the used resin, rate of reinforcement in the product, its thickness and other parametres.

7. What is a corrosive, chemical resistance and what is a life span?

The composite materials are highly water, wheater and chemicla resistant. This resistance is also the most influenced by type of used resin. A representative choice of chemicals is given in the table.

A veil is added into the profiles under their surface. This veil protects within UV inhibitors degradation of materials.

8. Is it possible to colour the composite profiles?

The pultruded profiles are coloured in the mass by default, so that other painting is needless. For customer´s request it is possible to make a profile in any colour from our RAL colour card. The profiles can be painted by special colour for achieving of extremely smooth surface or in case of request of other colour than RAL. It´s possible to carry on various imitations (e.g. wood) by means of surface veils.

9. What are the composite materials joined?

The profiles are bolted joints or they are glued. A bolted joint transfers the shear forces between the profiles in a structure. Bolted joints transfer the shear force by friction through regions of concentrated local compression of the profiles around the bolts. In static calculations for bolted joints, it is necessary to ensure that the profile and bolts can withstand this concentrated local compression. It is also necessary to ensure that the region surronding a group of bolts will not be torn out of profile i.e. that the region around the bolted joint has sufficient capacity to transfer the load to the rest of the structure. Using of special glue has many advantages e.g.: it is easy to make aesthetic joints, glued joints between profiles are typically more rigid than traditional bolted joints, glued joints subjected to dynamic loads are good. However, it is necessary to consider a number of conditions in using a glued joint e.g.: a number of adhesive agents have properties that depend on time and are influenced by enviromental factors, failure in glued joints takes place suddenly in contrast to bolted joints. On this account, joints in load-bearing structures are normally secured with bolts. In many cases, an adhesive is applied to the contact surfaces between the joined profiles, thus increasing the rigidity of the joint in operation.

10. How much is it?

A price of pultruded profiles or stamped products depends on many factors. The price of profiles, which are produced by default, is given by demand quantity. A complications of profile and consenquently the complications of form play and important role in the price of customer profile.

11. Do some limitations exist in the course of produce?

A cross section of pultruded profiles must be constant, whereas the transverse properties are less low, but with the systems under development one can clearly improve them, e.g.: addition of filament device of rolling up. The minimal thickness of profile wall 1,5 mm is other limit. Possible but not recommended are variations thickness by one profile.