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Frequently Asked Questions



Q. What are the main benefits of hybrid cords?

A. Hybrid cords are the combination of different kinds of fibers (Nylon 6.6, Polyester, Aramid, Rayon etc.) By means of combining different materials, hybrid cords can
deliver superior performance and cost structure which cannot be achieved with a single material.


Q. In hybrid constructions different materials are physically combined together. As this is not a chemical process, is there any risk that hybrids will not show a single
behavior?


A. Hybrid cords are made with the proper combination of different synthetic yarns and adhesive treatment to produce a single tensile and thermal shrinkage behavior.
To produce a single behavior, the cord forming parameters have to be properly adjusted so that the components will support each other to act as a single body.
These parameters are:

   • twist levels of the plies
   • cable twist levels
   • linear densities of the plies
   • percentage of the yarn ply components
   • heat treatment conditions

For instance, Aramid - Nylon 6.6 hybrids are made of two different components. Aramid is a hard material with high tenacity and with a load-elongation curve that is
almost a straight line. Nylon 6.6 has a typical viscoelastic material load-elongation curve. In an Aramid - Nylon 6.6 hybrid, the high twist level of Aramid shifts the
load - elongation curve to the Nylon 6.6 side and decreases the gap between these two materials. Low twisting of Nylon 6.6 shifts the load - elongation curve to the lower side. Therefore, the optimization of the twist levels of both these components is important. In addition, twisting the plies creates a mechanical interlocking for
these components.

However, the material properties of the components remain the same. For instance; in Aramid - Nylon 6.6 hybrids, Aramid is a thermally stable material and
ecomposes at above 500oC, whereas Nylon 6.6 is a semi-crystalline material with a melting point of approximately 260oC. Treatment of these two materials as a
hybrid cord does not change their material properties.


Q. How can the optimum hybrid construction be determined for a specific application?

A. There are several hybrid constructions available to serve the different needs of customers. For instance, Polyester - Nylon (PET-NY) hybrids offer better modulus
and modulus retention compared to %100 NY products and better adhesion retention compared to %100 PET product. Polyester - Polyethelene napthalate (PET-PEN)
hybrids can be used as a carcass material due to their better modulus and breaking strength properties compared to %100 PET products. Naturally, the final price of
the hybrid also is an important criteria for decision making.

Q. Is it possible to use more than 2 different materials in hybrid cords?

A. Yes, based on the end use requirements, hybrid cords can be produced using more than 2 types of materials.

Q. How can the adhesion performance of hybrids be ensured compared to single material products?

A. The right solution to achieve the desired adhesion performance in a hybrid can be determined based on the properties of the low adhesion performing material
used in the particular hybrid. For example, in PET-NY hybrids, the optimum dip solution for best adhesion performance can be determined based on the adhesion
performance of PET.


Q. Are there any concerns regarding the manufacturing process of hybrid cords?

A. As hybrid cords are the combination of different kinds of fibers, it is critical to select the right dipping conditions and dip chemicals to achieve high performance
cords. Therefore, the manufacturing process of hybrid cords requires high levels of technical expertise and know-how.


Q. In Aramid-Nylon hybrids, what is the main benefit of the final product compared to %100 Aramid or %100 Nylon products?

A. Aramid- Nylon hybrids show improved fatigue resistance and dual modulus behavior, which is high modulus at high elongation and low modulus at low elongation,
compared to products made of 100% Aramid. In addition, they have reduced flat spotting behavior, lower shrinkage and better property retention at elevated
temperatures compared to %100 Nylon products.


Q. Aramid is known as an inferior material in the tire industry in terms of fatigue performance. Can fatigue be a problem when Aramid is used in hybrid constructions?

A
. Fatigue in Aramid-Nylon hybrid constructions can be improved by using high twist levels of Aramid in the cord and with the compact construction of the plies.


Q. Can different stress-stain curves be achieved by utilizing the same materials?

A. Yes, this is the main attribute of hybrid constructions. Depending on the final application need, by changing the twist number, ply number or linear density,
different end products can be produced.


Q. Are there any limitations in terms of ply number in hybrid constructions compared to regular tire cord fabric ?

A. By definition, a hybrid must have at least 2 plies . Hybrid constructions can have as many as 6 plies but the most common style consists of 3 plies.


Q. Are there any dtex limitations when producing hybrids?


A. Hybrids can be produced in the linear density range of 670 to 3300 dtex.


Q. Is there any rule of thumb in terms of preferring the right hybrid combinations?

A. Obviously, there is no right tool to determine the right product for each and every tire application. However, there is a tendency of using heavy dtex hybrids in
aircraft or OTR tires, and lower dtex hybrids in mainly UHP tires.


Q. Are there any unusual hybrid constructions beyond standard multi-ply constructions ?

A. Yes, there are some niche hybrid applications such as core insertion type of products. Core insertion cord has a core yarn in the center of the cord and is
surrounded by a different type of yarn.


Q. What is the advantage of core insertion?

A
. Through core insertion products, better breaking strength can be delivered for applications that require high ply strength. Better fatigue performance is also
achieved with this product.