The necessity of toughening PC/PBT/talc powder materials
The PC has good dimensional stability and high rigidity, but has poor wear resistance, low impact toughness, poor workability, and excellent PBT processability.
PC/PBT blended materials have excellent performance, high heat-resistant temperature and notched impact strength, good processability and chemical resistance, and can be widely used in automotive, electronic and electrical fields.
The addition of talc (talc) as a reinforcement to PC/PBT increases the rigidity of the material and further broadens the range of applications. However, the PC/PBT/talc system has poor interfacial adhesion, which makes the material impact toughness difficult and difficult to use as a structural material. Therefore, Juwei Engineering Plastics (Shanghai) Co., Ltd. Wang Jing and others toughened and modified it.
Why use E–MA–GMA as a toughener?
Some scholars have used ethylene-butyl acrylate copolymer, ethylene-acrylate-glycidyl methacrylate copolymer (E-MA-GMA) and ethylene-acrylate-maleic anhydride copolymer to increase PC/PBT materials. Tough contrast, E–MA–GMA was found to have the best toughening effect on PC/PBT materials.
This is because the polyethylene segment of E-MA-GMA has good flexibility and toughening effect; on the other hand, GMA epoxy group has higher reactivity and can react with the end group of PBT to improve compatibility. Sex.
How to determine the PC/PBT ratio?
With the increase of PBT content, the MFR of the material is gradually increasing, and the flow performance is getting better and better. When the PBT content is 10-40 parts, the impact strength of the material does not change much, but the impact strength decreases after the PBT content exceeds 40 parts. The hybrid system more reflects the characteristics of the PC, and the mechanical properties of the material are better. Thus, the PC/PBT ratio range is determined to be 6/4 to 8/2.
What is the toughening effect of E–MA–GMA?
Determine the PC/PBT/talc ratio of 70:30:10 and change the amount of E-MA–GMA in the PC/PBT/talc system (2, 4, 6, 10) to study the PC/PBT/talc system. Toughening effect.
It can be seen from the above figure that the elongation at break of the material increases gradually and when the content of E-MA-GMA exceeds 6 parts, the elongation at break of the material increases more obviously.
The flexural strength and flexural modulus of the PC/PBT/talc material decreased in a nearly linear trend.
When the E-MA–GMA is added in an amount of 6 to 10 parts, the impact properties of the PC/PBT/talc material are significantly improved, and the material achieves a brittle-ductile transition.
It can be seen from the above figure that the increase of E-MA–GMA increases the melting peak of the blend material to the low temperature direction, and the crystallization temperature Tc of PC/PBT/talc/E–MA–GMA decreases continuously, and the degree of subcooling (ΔTmc) =Tm-Tc) is also increasing. This aspect indicates that the entanglement of the amorphous PC molecular chain with PBT hinders the activity of the PBT molecular chain, and on the other hand, the addition of the toughening agent E-MA-GMA improves the compatibility of PC and PBT.
in conclusion
1. Toughener E-MA–GMA can significantly improve the compatibility of PC and PBT.
2. The ideal ratio of PC/PBT in PC/PBT/talc material ranges from 6/4 to 8/2. At this time, the comprehensive performance of the material is good.
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