Epoxy resin and polypropylene
Recently, the tendency to use nanostructuring additives as modifiers in the production of composite materials for various industries, including aircraft construction, has been dynamically developing. Composite parts made using this process allow the production of lightweight products with improved strength properties. Carbon nanotubes, graphene nanoparticles, and nanofibers also find their way.
Global SO studied the use of various carbon nanomaterials synthesized by us as modifying additives in up-to-date polymeric materials in the following research work: “Development of nanomodified polymer composites with improved strength and process properties.”
Certain positive results were obtained, indicating the promising application of our materials in this area.
The efficiency of CNM application is determined by a number of factors, among which it is necessary to note the nature and properties of the modified polymer materials, the nature of the CNM and methods of their uniform distribution on the surface and throughout the composite material.
Both volume and fine polymers widely used in industry were tested:
- polyethylene and polypropylene of extrusion grades currently used in the production of pipes by extrusion;
- polycarbonate with a complex of high strength and thermophysical characteristics, processed by injection molding;
- epoxy-containing reactive oligomers (epoxy binders) used as polymer matrices to create structural materials used in aviation, automotive industry, as high-strength coatings and other fields.
When using CNM to modify polypropylene, an increase in a number of strength properties was observed: transverse rupture stress by 30-80%, impact resilience by 15-25%, depending on the structural organization and surface properties of the CNM. The amount of injected CNM ranged from 0.01 to 1 wt%. Modification of polypropylene allows expanding the range of products, reducing their weight and, consequently, their cost, which, in the end, will lead to resource savings and will have a large technical and economic effect.
Modified polycarbonate films with increased resistance to shock loads have been obtained. Shrinkage decrease by 20-25% and microhardness increase by 20-30% are observed that can be explained by formation of more regular structures with high degree of crystallinity in the presence of CNM and must lead to increased stability of properties and service life of products.
Since the key factor influencing the properties of epoxy materials is the properties of the formed spatial structures, the influence of CNM on the parameters of the curing processes and the properties of the final products was investigated. The optimal concentration of CNM in the polymer matrix was determined to be 0.01 wt%. The strength and modulus of elasticity of the modified materials increase by 20-25%. Increasing the curing rate of epoxy materials in the presence of CNM will accelerate the production process, and increasing the strength properties will improve the performance of reinforced plastics.
There is also a synergy effect when carbon nanomaterials are introduced into the composition of epoxy oligomers, which contributes to increasing the fire resistance of the final products based on them.
Electrically Conductive Coatings
Currently, transparent electrodes are widely used in making solar cells, displays, touch panels, LEDs and many other devices, including heating elements. These electrodes are a transparent substrate, in particular glass, with a thin film of conductive material on its surface. Today, indium tin-oxide (ITO) is used as such material. It has low surface resistivity (~10-20 Ohm/square) and high transparency (~80% @ λ=550 nm). Significant disadvantages of ITO include the relative high cost of the material due to complex production process, brittleness, low transparency in the IR-spectrum, and limited stocks of indium decreasing due to the rapid development of the electronics industry in the world as a whole. In this regard, researches aimed at developing the process of obtaining transparent electrodes from a more accessible and cheaper raw source seem to be very relevant. CNT thin-film coatings, graphene and metallic nanoparticles are being actively researched as an alternative to ITO.
Global SO carried out research on the topic: “Developing electrically conductive coatings based on carbon nanotubes,” and developed a process for obtaining electrically conductive translucent coatings from carbon nanomaterials, including the ones containing metallic nanoparticles (silver nanofibers).
The process of dispersing nanomaterial powders in aqueous and non-aqueous media, including a chemical functionalization stage, was developed for the application of conductive carbon nanomaterial coatings.
As for combined features (surface resistance, translucency, mechanical strength), the developed electrically conductive coatings are equal or higher to modern world counterparts.
Researches have shown that composite metal-carbon coatings maintained a resistance of <50 Ohm at more than 80% translucency up to a temperature of 400оC.
Dependence of surface resistivity (Rs) and light transmittance at 550 nm (T) vs. temperature: (1) - Ag silver nanofilaments; (2) - CNT/Ag nanofilament