Application in polystyrene resin (PS)
Unmodified general-purpose polystyrene is an amorphous polymer. It is hard and brittle, but it has good electrical properties, aging resistance and high dimensional stability. The disadvantage is high brittleness and sensitivity to environmental stress cracking. Adding ultrafine talcum powder can improve impact toughness, adjust rheology, significantly improve flexural modulus, and also improve tensile yield strength. For example: adding 40% ultrafine talcum powder or talcum powder masterbatch, the flexural modulus increases from 23800kg/cm2 to 58800kg/cm2. and the tensile strength increases from 336kg/cm2 to 385kg/cm2.
Application in nylon resin (PA)
For nylon (polyamide), special attention is paid to the use of the toughness and wear resistance of this plastic in industry. Nylon is generally hard, similar to keratin, with good wear resistance and high dimensional stability. These properties can be further improved by fillers or reinforcing agents. PA66 has the best hardness, stiffness, wear resistance and heat deformation temperature among nylons; PA6 is known for its high toughness; PA610 has low water absorption, so its dimensional stability is also high; PA11 has the highest impact strength among nylons.
Among various fillers, talcum powder with a layered structure can improve the original good properties of nylon and improve wear resistance. Compared with metal, unfilled modified nylon has a low elastic modulus, low tensile and creep strength, and its mechanical properties are significantly dependent on temperature. The molecule contains water-absorbing amino groups and has a high water absorption rate. The product is easy to absorb water, swell and deform during use. During processing and molding, the cooling is fast and the crystallization is incomplete. It is still crystallizing during use, which causes the product to deform or even crack.
The above shortcomings of nylon can be greatly improved by adding ultrafine talcum powder. Talc powder has the function of nucleating agent. After adding, it can increase the crystallization rate of nylon and increase the crystallinity. Therefore, it can especially improve the toughness, mechanical strength, hardness, thermal stability, dimensional stability of nylon, improve the surface quality and deformation behavior of products, and also have a good effect on moisture absorption, electrical properties and chemical properties.
Application in polyvinyl chloride resin (PVC)
Filling polyvinyl chloride with ordinary powder has been very commonly used. For example, in the manufacture of rigid polyvinyl chloride pipes, the amount of calcium carbonate filled can reach 40%, but the tensile strength and impact strength of polyvinyl chloride are reduced; if talcum powder with an average particle size of 5 microns, i.e. 2000 mesh, is added to 40-45% by volume, it can be found that the yield strength of the material is even higher than the original fracture strength, which has a significant enhancement effect on the polyvinyl chloride system.
For impact strength, adding ultrafine talcum powder, the unnotched impact strength is basically not reduced within 15% by weight, the notched impact strength is reduced, and the flexural modulus can be significantly increased. Ultrafine powder has a very significant reinforcing effect on polyvinyl chloride systems with added toughening agents, such as PVC/CPE and PVC/ABS systems.
