Frequent Doubts

Most of the doubts related to polyurethane, its uses, advantages and other issues that we frequently receive from our customers can easily be answered here, in our page of “Frequent Doubts”.

Here you will find several examples of application of certain types of PUs. There are uncountable other combinations of material for the most diverse applications. The most important point for definition of PU of your project is that you have the technical advice from a company which processes the widest possible range of polyurethanes. Thus, your chances of choosing the correct PU, with cost and performance advantages, increase.

Do your research and if you need any assistance, contact our technical team.

What Is The Best Polyurethane For The Coating Of Rollers For Application Of Paints And Varnishes?

TDI Esther
This PU will operate because it offers:
– High resistance to solvents and oils
– Good properties and low hardnesses

What Are The Advantages Of Polyurethane Over The Metal?

It is lighter;
Less noise in service;
Resistance to corrosion;
Manufacture with lower cost;
Non-conductive;
Resistance to impacts;
It does not generates sparks due to friction.

What Are The Main Limitations When Using Polyurethane?

– Work in high temperature (It could generate Hysteresis);
– Humid and warm environments (It could cause Hydrolysis);

What Are The Advantages Of Polyurethane Over The Rubber?

Resistance to the abrasion;
Resistance to cut and tearing;
Resistance to oils/non-absorption;
High dynamic characteristics;
Wide range of hardnesses;
Clarity and translucency;
It does not leave marks or blots;
Versatility

What Are The Advantages Of Polyurethane Over The Plastic?

 

Not breakable (including in high hardnesses);
Elastomeric Memory (after suffering great torsion, they return to its initial condition);
High resistance to the Abrasion.

 

Why Use Pu?

– Reduction of costs
– Resistance to the abrasion
– It reduces the number of machine downtime for maintenance.
– It supports heavy loads
– Resistance to tearing

The PUs are being a great alternative in many applications, substituting Metal, Plastic and Rubber.

What Is Polyol?

A wide range of polyols is associated to TDI, MDI and NDI in the manufacture of PU’s. The polyether polyol is the most frequently used and is obtained through the polymerization of propylene, ethylene and butylene oxides. The most used are polyglycol (propylene oxide) and copolymers of polyglicols ((PPG’s) (propylene/ethylene oxides). The polyether polyols, such as polyglycol (tetramethylene oxide), are used in high performance PU fibers and elastomers. In addition to these, we have the polyol polyesters, which are used in high performance applications.

What Is Mdi – Diphenyl Methane Di-Isocyanate?

MDI is the abbreviation of Diphenyl Methane Di-isocyanate

Obtained from reaction of aniline with the formaldehyde, it produces mixed isomers of functionality 2.0 to 3.0. The attainment of MDI of ideal productivity implies extra processes, influencing the cost of material. This explains the different offers found in the market, as well classifications of low, medium and high cost – directly related to the quality.

What Is Tdi – Toluene Diisocynate

TDI is the abbreviation of Toluene Diisocynate
It is manufactured through the nitration of Toluene, getting a mixture of ortho, meta and para-nitrotoluene isomers. The separation of these isomers is accomplished by fractional distillation causing 80/20, 65/35 and pure mixtures. The market offers then TDI’s of different reactivity and costs, with implication in the quality of the product.

What Is Ndi – Naphthalene Diisocyanate?

NDI is the abbreviation of Naphthalene Diisocyanate
It is one of the Raw Materials used for the manufacture of Vulkollan.

What Are Additives?

Additives are loads which can be added to polyurethanes in order to adjust its properties as required.

What Is Thermal Contraction Or Expansion?

What Are Shore Hardnesses?

The hardnesses of Elastomers (polyurethanes) are measured in “Shore A” and “Shore D”.

Shore Hardness is the measure which measures the resistance of the material according to the penetration of the needle of a durometer over a defined force. It is determined by numbers from 0 to 100 in scales A or D. The higher the number, the greater the hardness. The letter A is used for flexible types and the letter D for rigid types.

What Is Hydrolysis?

It is the aging of certain types of polyurethanes to the time, attack of fungi and microbes.
(there are correct manners for the storage of polyurethane parts and minimization of this problem. For more information contact our Technical Department).

What Is Hysteresis?

It is the phenomenon where the development and accumulation of heat generated by action of mechanical work, excess of load or high speed, cause the build-up of a bubble concentrated inside the polyurethane layer.

What Are The Physical Properties Of Polyurethane?

They are the characteristic properties of each material, determined by its: Hardness, compression/traction module, tensile strength, elongation at break and the resistance to tearing.

What Are The Dynamic Properties Of Polyurethane?

Resilience, elasticity, resistance to the abrasion, low deformation, resistance to aging and others.

What Is Aging – Fluids?

It is the resistance to oils and solvents, observed after immersion periods, calculating the loss of original properties and the variations of volume related to the initial properties.

What Is Thermal Aging?

It is the capacity of a test specimen or artifact to withstand the action of the temperature during a certain time with the retention of the original physical properties.

What Is Compression Module?

It demonstrates the response of the material, in force, when submitted to deformation by linear compression.

What Is Resilience (Memory)?

It is the capacity of the test specimen or artifact of developing the energy absorbed during its mechanical deformation. The resilience is expressed in percentage.

What Is Resistance To Abrasion?

It is the capacity of a material to withstand the wear through the contact against an abrasive surface. Usually, it is measured under defined conditions of load and speed. Expressed in mm³ (volume of loss).

What Is Permanent Deformation By Compression?

It is a dimensional alteration of the test specimen or artifact, when submitted to the compression.

What Is Resistance To Tearing?

It defines the tension supported by material until the beginning of the tearing, guided in a point of the test specimen.

What Is Elongation?

It determines the extension which the material extends until breaking. It is expressed as a percentage related to the measure of original length.

WHAT IS HARDNESS?

It is the resistance offered by the surface of a test specimen or artifact, to the penetration of an object of specified dimensions and under a certain load.

What is tensile strength?

Defined as the force per unit of area required for the break of the test specimen. It is calculated by dividing the break force by section area of the test specimen. The units expressed are MPa, Kgf / cm2 or Psi ( pounds per square inch).

Fale conosco

@ Send us an e-mail

To get in touch with our team quickly, you can send us an email directly.

Call us

If you prefer to talk to us, you can call us whenever you need to. We are ready to serve you!

Fill in the form

Please tell us your needs or send us your project and we will get back to you as soon as possible. "