Polypropylene Copolymer versus Homopolymer Impact Resistance
Impact copolymers deliver superior notched and subzero impact resistance over homopolymers by incorporating a dispersed ethylene-propylene rubber phase.
Talc Reinforcement
Meaning
Incorporation of fine mineral particles into a polymer matrix increases the stiffness and heat resistance of the resulting composite. Using talc reinforcement allows for the production of parts that are dimensionally stable and have a higher flexural modulus than the base resin. These platelike particles align themselves during the moulding process, providing a structural framework within the plastic.
The process is limited by the amount of talc that can be loaded before the material becomes too brittle or difficult to process.
Stiffness Gain
Addition of the mineral filler restricts the movement of the polymer chains, making the part much harder to bend. Because talc reinforcement is a cost effective way to improve mechanical properties, it is widely used in automotive and appliance parts. The increase in stiffness is directly proportional to the loading level of the mineral.
These parts can withstand higher loads without deforming.
Processing Effect
Presence of mineral particles changes the flow behavior and the cooling rate of the plastic in the mould. Since talc reinforcement acts as a nucleating agent, the material solidifies faster and can reduce the overall cycle time. However, the high mineral content can also cause increased wear on the injection screw and the tool.
Proper lubrication and hardened steels are often required for these runs.
Component Weight
Balancing the need for stiffness with the desire for a lightweight part is a constant challenge. While talc reinforcement increases the density of the plastic, it also allows for thinner wall designs that can offset the weight gain. Engineers must calculate the total mass of the part to ensure it meets the project targets.
Efficient use of the filler results in a part that is both strong and economical.