Studies on structure and properties of high⁃impact copolymerized polypropylene with high melt flow rate

doi:10.19491/j.issn.1001-9278.2024.05.002

Abstract

Abstract:

To improve the rigidity⁃toughness balance of high⁃impact copolymerized polypropylene with high melt flow rate （IPC⁃J）， the ethylene content and the ethylene content in ethylene propylene rubber （EPR） were increased to 12.4 wt% and 54 wt%， respectively， by combination with the high⁃impact copolymerized polypropylene （IPC⁃H） technology. Meanwhile， the molecular segment structures and aggregation morphologies of IPC⁃J， IPC⁃H， IPC⁃1， and IPC⁃2 were investigated. The results indicated that the EPR content of IPC⁃J increased from 19.4 wt% to 22.8 wt%， its weight average molecular weight （M_w） decreased from 2.0×10⁵ to 1.9×10⁵ g/mol， its intrinsic viscosity increased from 1.80 to 1.86 dL/g， its molecular weight distribution index increased from 8.9 to 10.7， and the maximum M_w of EPR increased from 1.1×10⁶ to 1.2×10⁶ g/mol， compared to those of IPC⁃H. The relatively longer ethylene crystalline chains with a greater amount were beneficial to enlarging the dispersed particle size. This resulted in a transformation of the maximum proportion region from 0.3~0.6 to 0.6~0.9 μm， which promoted higher impact strength of 11.0 kJ/m² at 20 ℃ and 5.7 kJ/m² at -20 ℃. The rigidity⁃toughness balance of the IPC with a high melt index were fully optimized through increasing the ethylene content and the ethylene content of EPR， according to the production technology for 300⁃kt/a polypropylene without changing the Ziegler⁃Natta⁃type catalyst system.

Key words: impact copolymer polypropylene, impact strength, crystallization, successive self?nucleation and annealing

CLC Number:

TQ325.1⁺4

GUO Minghai. Studies on structure and properties of high⁃impact copolymerized polypropylene with high melt flow rate[J]. China Plastics, 2024, 38(5): 7-13.

Figures/Tables 15

References 19

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试样	MFR/ g·（10 min）^-1	乙烯含量/ %	EPR/ %	EPR中乙烯含量/ %
IPC⁃J	29.2	12.4	22.8	54
IPC⁃H	29.7	9.4	19.4	48
IPC⁃1	29.3	10.7	20.4	52
IPC⁃2	29.6	9.2	17.8	52

试样	MFR/ g·（10 min）^-1	乙烯含量/ %	EPR/ %	EPR中乙烯含量/ %
IPC⁃J	29.2	12.4	22.8	54
IPC⁃H	29.7	9.4	19.4	48
IPC⁃1	29.3	10.7	20.4	52
IPC⁃2	29.6	9.2	17.8	52

试样	M_w/g·mol^-1	M_n/g·mol^-1	M_w/M_n	IV/dL·g^-1
IPC⁃J	186 000	17 400	10.7	1.86
IPC⁃H	197 500	22 300	8.9	1.80
IPC⁃1	197 900	21 800	9.1	1.80
IPC⁃2	193 200	24 000	8.0	1.71

试样	M_w/g·mol^-1	M_n/g·mol^-1	M_w/M_n	IV/dL·g^-1
IPC⁃J	186 000	17 400	10.7	1.86
IPC⁃H	197 500	22 300	8.9	1.80
IPC⁃1	197 900	21 800	9.1	1.80
IPC⁃2	193 200	24 000	8.0	1.71

试样	熔融温度/℃	熔融焓/J·g^-1	结晶温度/℃	结晶焓/J·g^-1	结晶度/%	EPR/%
IPC⁃J	165.1	75.7	130.4	74.7	36.2	22.8
IPC⁃H	165.0	78.7	131.2	77.7	37.7	19.4
IPC⁃1	166.7	79.2	131.2	79.8	37.9	20.4
IPC⁃2	165.8	80.0	129.4	81.9	38.3	17.8