---

---

---

---

Science Current Events and Science News RSS Feeds

---

---

Email a Friend Printer Friendly

Better composites through right shape of particles

November 08, 2001

The shape of the small clay particles in polymer-clay composite materials can determine the stiffness, strength and oxygen permeability of the material. The size of the particles determines the sheen and transparency. These are conclusions from the PhD research project of Martin van Es. He will receive his degree at TU Delft on 12 November. “Until now, it was thought that the collective surface area of the particles was the important factor.” The results of the project are important for the mass use of, for example, plastic foils, but also for very small composite products.

Composite synthetics have become indispensable in daily use. In the automobile industry, metal parts are increasingly being replaced by parts made from such materials. They are light, strong and less expensive. Van Es: “The problem is that these materials often have less sheen than metals do. However, by adding nano-sized particles to the material, it can shine just like metal.” These composites are also used in the food industry. “The packaging of cheese for example, must be strong, impermeable for oxygen and transparent,” says Van Es. Polymer-clay composites have these characteristics.

Literature on these materials says that that these characteristics are achieved by having a large collective surface area of nano-particles. One must think in terms of 700 square meters per gram of the composite. Van Es: “My opinion however, based on my previous research of fibre reinforced composites, was that the shape of the particles is the most important factor. During my PhD research project, using electron microscopy and NMR techniques, I proved that this idea was correct. The slenderness and length of the clay particles are the most influential on the characteristics of the material.”
Van Es also constructed a computer model that is able to predict the characteristics of polymer-clay compositions. Van Es: “This greatly reduces the time needed in product development.”

These developments make it possible to, for example, produce tiny, but very strong cogs. “If a product becomes smaller than the fibre used as reinforcement in the material, a large problem arises,” says Van Es. “The use of nano-particles could prove to be an excellent solution, but, as I have shown, the particles need to be the right size and shape to be effective.”

Delft University of Technology