There are many advantages of adding nucleating agent in polypropylene modification. Nucleating agent can promote the crystallization rate of melt, obviously improve the mechanical properties and processing properties of polypropylene products, and benefit the aging resistance and optical properties of products. The functions of these nucleating agents are summarized into 5 points and introduced in 2 articles. This paper introduces three of them, which are the effect on crystallization rate, mechanical properties and aging resistance.
Effect of Physical Foaming Nucleating Agent point 1: promote crystallization rate
After adding proper amount of nucleating agent to the blank polypropylene, the nucleating agent, as the heterogeneous crystal nucleus of crystallization, can promote the nucleation and increase the crystallization temperature. The crystallization temperature of blank homopolymer polypropylene is generally around 115 ℃, and the crystallization temperature rises obviously after adding nucleating agent. On the one hand, even if the state of supercooling is not reached in the process of processing and molding, polypropylene resin begins to crystallize; on the other hand, it is possible to process at a relatively high temperature, which shortens the molding cycle of products and improves the processing efficiency.
The effect of Physical Foaming Nucleating Agent point 2: obviously improve the mechanical properties of polypropylene
The addition of nucleating agent can obviously improve the mechanical properties of polypropylene, and the general change trend of its mechanical properties is as follows: tensile strength, tensile modulus, full strength, bending modulus, thermal deformation temperature and elongation at break all increase with the increase of nucleating agent dosage, but because there is a saturated concentration of nucleating agent in polypropylene, the dosage of nucleating agent increases to a certain extent The mechanical properties tend to be stable. Therefore, the more the nucleating agent is added, the better.
Function of Physical Foaming Nucleating Agent point 3: it is beneficial to improve the aging resistance of polypropylene
The results show that the addition of nucleating agent has little effect on the aging resistance of PP. However, due to the increase of crystallinity, more perfect crystallization and more regular crystal structure of polypropylene after adding nucleating agent, it is not easy to be aged by oxygen or ultraviolet, so the overall trend of adding nucleating agent is to improve the aging resistance of materials.
