In order to design particles for particular applications, we need to understand how they affect the functional properties of the product. For example, we need to understand how to control electrical, mechanical, rheological, and optical properties of materials. We have established this expertise in our current businesses.

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Mechanical Properties

We have strong capability in understanding and designing the static and dynamic mechanical properties of particle-polymer composites. This is important in applications such as our plastic masterbatch business or for car tires where mechanical properties are balanced to give the optimum mix of traction, durability, high rigidity, heat buildup, flex resistance, tear strength and stability. In our coatings businesses we utilize knowledge of tribology to design abrasion-resistant coatings. Cabot has an excellent suite of mechanical testing instrumentation and is interested to discuss all potential mechanical applications.

 

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Optical Properties

The ability to design optical performance is key to a wide range of Cabot applications. For example, Emperor carbon blacks are favored in automotive coatings for their highly desirable deep jet black and their blue undertone, while in liquid crystal displays Cabot carbon blacks are used for their high optical density.

We have optics and imaging laboratories for understanding light scattering from materials and the measurement and perception of color. As a result, we understand the links between particle properties, the arrangement of particles in a film and the resulting optical behavior. A good example of this is in our inkjet dispersions. Here we have designed colloids that give an optimized balance of jettability, dispersion stability, optical properties and color fastness. To do this we combine our knowledge of color with an ability to design dispersions that remain stable in the bottle and then bind and spread correctly on the paper for an excellent image.

 

 

Optical properties are also important in matting agents. For example the efficient optical scattering and high transparency from Cabot Nanogel makes it a superior matting agent in polymer coatings, where it gives a matte appearance while maintaining the color of the underlying object. It is even used in cosmetics as a soft focus agent to soften the appearance of imperfections on the skin.

We have extended our knowledge of optical scattering to develop novel signatures for security applications, for example, overt and covert features on bank notes. We have also developed novel silver nanoparticle inks for printing (as well as electronic) applications. We continue to seek all applications to which our ability to manipulate the optical properties of particles and particle-containing matrices can be applied and are keen to discuss any interest areas.

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Electrical Properties

Many of our newer applications involve controlling the electrical properties of materials. For example, Cabot has developed glass-coated silver nanoparticles that form networks with low resistivity at a low-cure temperature. The small particle size and glass coating enable dispersion and the feasibility of non-contact printing. This enables inkjetable conductors for printed electronics and solar cells.

 

 

 

We are also able to control the percolation behavior of carbon black, both through surface treatment and morphology. This enables us to control electrical behavior in sealants, coatings and adhesives.

 

 

We are interested to discuss any applications where controlling the electrical behavior of particle containing media is important to function.

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Rheological Properties

The flow properties of particulate systems are often of great interest to Cabot's customers because fumed metal oxide and carbon black products are often used to modify and control such properties. The fluids used by our customers vary from solvents to low molecular weight to high molecular weight polymers and elastomers of many different chemical compositions. When these fluids become for example adhesives, sealants, laminating resins, and gel coats, a very precise flow profile control during compounding and processing is required. In some instances switching from very high viscosity (solid-like behavior) to very low viscosity is necessary in order to prevent sagging and improve throughput while applying an adhesive, coating or sealant. At Cabot, we use rheology as a tool to measure the specific flow properties required for an application. For example, thickening efficiency, viscosity modification, yield stress, shear thinning, recovery, and aging can be measured by means of a rheology test such as the one exemplified in figure x.

 

 

The level of shear thinning, yield stress and viscosity can be tuned by either changing the surface properties of our particles, their chemical composition or their morphology. As shown below, a highly hydrophobic fumed silica particle such as TS720, can provide the adequate level of yield stress and thinning in a polar fluid like an epoxy resin when compared to an untreated (H5) or less hydrophobic fumed silica particle (TS610, TS530), which can only provide the same level of "thickening" at higher concentrations.

 

The importance of the level of control of the flow profile relies on the fact that each operation during the processing of these materials requires a very specific profile in order to maximize throughput, strength, quality (e.g., bubble release), among others.