Reinforced Rubber Sheeting – The Technical Benefits
A wide variety of rubber sheeting is used in applications around the globe. Due to its ability to compress, stretch and resist numerous physical, chemical and environmental degradants, it is obvious why rubber sheeting is chosen in countless sectors. Reinforced rubber sheeting is also commonly used but what is it and what technical benefits does it bring?
What is Reinforced Rubber Sheeting?
Firstly, we are focusing on reinforced rubber sheeting that has been strengthened by another material. Particularly a textile, or alternative substrate or insertion. This is as opposed to straight rubber sheeting made from compound reinforced with high grade fillers. These fillers include special grades of carbon black or silica. This type of reinforced compound is commonly used in many product groups. Here, we’ll discuss the advantages of employing two often dissimilar materials to create a flexible composite material.
So, that provides us with the answer to our first question – reinforced rubber sheeting is a composite material. Like any other composite it is designed to demonstrate a blend of enhanced characteristics that couldn’t be achieved by just one material on its own. The basic properties of rubber are improved by combining it or reinforcing it with another material (most likely another flexible material).
Textile is therefore the most commonly used substrate and is combined with the rubber sheeting during the manufacturing process. This can be spread-coated, calendered or extruded. The end results are very similar; a textile is placed or ‘inserted’ into the middle of the rubber sheet. Multiple textiles can be ‘inserted’ into the rubber sheet to give a range of constructions and thicknesses as required by the end use.
Again, in common with any composite material, care needs to be taken that the rubber and textile combine together or bond. It requires sufficient strength to stand up to the forces the material is subjected to in use. Delamination could lead to failure in the product or system for which the rubber is used.
Textiles Commonly Used in Reinforced Rubber Sheeting
Whilst woven textiles are most commonly used to reinforce rubber sheeting, other ‘substrates’ are also employed:
– Knitted textiles typically offer more stretch
– Unidirectional cord fabrics are used in the tyre industry
– Non-wovens provide cushioning
– ‘Open’ woven and laid scrims are easier to process
– Woven steel wire and expanded aluminium mesh can maintain a shape once bent and are electrically conductive.
Technical Benefits of Reinforced Rubber Sheeting
But what technical benefits does reinforced rubber sheeting exhibit? Examination of a few technical datasheets for rubber sheeting or reinforced rubber sheeting will reveal that they usually contain data on the same parameters. Specific chemical and environmental factors appropriate to the characteristics of that type of sheeting are displayed. For example, EPDM rated for ozone cracking or Nitrile for fuel swell. There are also other more generic types of information regarding physical attributes such as elongation at break, tensile strength, and tear strength. To answer the question let’s consider these two categories in turn.
Chemical and Environmental Factors
With regards to the chemical and environmental characteristics, generally the incorporation of a reinforcement layer doesn’t really extend or enhance the sheeting’s capabilities. It is more a case of ensuring the reinforcement is complementary. Silicone sheeting is commonly utilised for its ability to withstand high temperatures; therefore a high temperature textile should also be used. A good example is glass cloth, as opposed to nylon or polyester which might melt. Similarly, if reinforced Butyl sheeting is used in a wet environment then a synthetic substrate would be needed. This is because a synthetic textile doesn’t absorb moisture like cotton does and would maintain integrity far better.
As seen above, the rubber is typically the material exposed to the surface environment, so primarily responsible for delivering the characteristics the part is designed for. The reinforcement isn’t bringing new properties to the product. The exception to this rule is metal reinforcement. As there are limitations to the electrical and thermal conductivity of rubber sheeting, it can be combined with a steel or aluminium mesh to dramatically bolster its ability to conduct heat or electricity.
However, it is within the second category of enhanced physical characteristics that reinforced rubber sheeting excels. A substrate of most types would provide tensile and tear characteristics far in excess of what rubber on its own could achieve. So, when combined together, a reinforced rubber sheet is much stronger. The reinforcement layer would also typically have the effect of stopping or severely limiting the ability of the sheet to stretch. Therefore, elongation at break would be far lower but the force required to break it would be much higher.
Applications of Reinforced Rubber Sheeting
These enhanced characteristics extend the usage opportunity for rubber. They also allow products like conveyor belts and inflatable dinghies to be made using rubber. The key characteristics of the rubber such as high abrasion, grip and excellent flex properties are bolstered by the strength of the supporting textile. Likewise, the compressive properties of rubber make it an ideal sealing medium. Complemented by textiles, high pressure seals and gaskets can be made. All without fear of the rubber being squeezed out from beneath the plates as the textile offers greater stability.
So, in short, reinforced rubber sheeting is a type of flexible composite material. Its main technical benefit is that it offers far superior physical properties than straight rubber sheeting. When rubber is combined with an appropriate substrate the range of applications can be significantly increased.
White Cross Rubber are experts in such flexible composites and have been manufacturing reinforced rubber sheeting since 1983. Many types are well established but as engineers and designers push the required limits, we have a development capability to help break new ground. We’d be happy to discuss your projects so please call our technical team for more information on 01524 585200 or visit www.wcrp.uk.com.