Part of the family of carbon nanomaterials, graphene and its related functionalized derivates possess a range of characteristics that make them highly suited for use in rubber products.
Graphene can be integrated into rubber polymer networks, significantly influencing the rubber system’s thermal and electrical conductivity. Integration of graphene into rubber polymer networks can also positively impact mechanical properties, for example, wear resistance, grip, compression set and tensile strength.
Properties modified will depend on factors such as layer thickness, surface area, lateral size and functionalization status.
Academic research is ongoing which seeks to demonstrate the benefits of integrating graphene and its related functionalized derivates into rubber products.
This research has drawn the interest of the rubber industry within the last few years; for example, manufacturers of sports shoes have explored the development of shoe soles containing graphene, attracting significant public interest.
A number of industries working with rubber products require consistently high performance; for example, manufacturers of sealings and tires.
The tire industry is constantly looking to enhance abrasion resistance and improve grip, and recent research has prompted Chinese tire companies and their suppliers to focus considerable attention on the potential application of graphene and its related derivates in tire manufacture.
In order to fully exploit the potential of graphene applications in the tire industry, it is important to ensure that only primary particles (and not agglomerates) are present in the polymer. The use of masterbatches is one solution to this challenge – a service that is offered by a small number of specialized companies.
Figure 1. Graphene rubber tires. Image Credit: The Sixth Element (Changzhou) Materials Technology Co.,Ltd.
The Sixth Element worked with Qingdao Lanwan ENE Carbon Material to develop a range of latex-based graphene rubber masterbatches. A special process is employed to disperse the graphene, de-agglomerating this in latex before converting this to a dry natural rubber masterbatch.
Using this approach, it is possible to use different graphene concentrations in the masterbatch.
The addition of a graphene natural rubber masterbatch to a standard tread formulation was found to result in significant improvements in wear resistance, tensile strength and thermal conductivity in the final tire (Figure 2).
Figure 2. Mechanical properties and thermal conductivity of basic tread formulation made with graphene natural rubber masterbatch. Image Credit: The Sixth Element (Changzhou) Materials Technology Co.,Ltd.
Further tests were performed, investigating the use of a complete rubber formulation for semi-steel passenger tyres, both with and without a graphene natural rubber masterbatch. Results of this investigation are provided in Table 1.
In the final series of tests, a GEELY Emgrand GL model was fitted with both graphene enhanced tires and standard tires. Tire size in this test was 205/55R16. Rolling resistance was found to decrease by 10%, while wear resistance was found to increase by 30%. Slightly less noise was also observed.
The enhanced performance of tires using a graphene natural rubber masterbatch in their tread formulation was further confirmed in road testing with passenger car tires and heavy truck tires (Table 1).
Table 1. Semi steel passenger tyres – tread formulation with and without graphene natural rubber masterbatch. Source: The Sixth Element (Changzhou) Materials Technology Co.,Ltd.
|Semi-steel passenger tyre
|Graphene enhanced semi-steel passenger tyre
|Performance increase of graphene enhanced tyre
A similar test was performed on heavy truck tires (Table 2), evaluating all steel tires and comparing these both without and with graphene rubber masterbatch enhanced tread formulations. This test also confirmed a reduction in rolling resistance of 25%, which would result in lower fuel consumption.
Table 2. Heavy truck all steel tyres – tread formulation with and without graphene natural rubber masterbatch. Source: The Sixth Element (Changzhou) Materials Technology Co.,Ltd.
||Average wear of finished tire
|Graphene enhanced all-steel tyres
|Performance increase of graphene enhanced tyre
A further example of a graphene natural rubber masterbatch was employed in formulations for rubber pads fitted under high-speed railway tracks. This was found to increase fatigue resistance of the rubber pads by between 35% and 40%.
This information has been sourced, reviewed and adapted from materials provided by The Sixth Element (Changzhou) Materials Technology Co.,Ltd.
For more information on this source, please visit The Sixth Element (Changzhou) Materials Technology Co.,Ltd.