Mechanical performance of branched polypropylene foams fabricated via supercritical CO₂ molding

doi:10.19491/j.issn.1001-9278.2025.09.001

Abstract

Abstract:

Polypropylene （PP） with varying degrees of branching was prepared using dicumyl peroxide （DCP） as an initiator and tetramethyl thiuram monosulfide （TMTM） combined with pentaerythritol triacrylate （PETA） as dual monomers. The modified PP was foamed via supercritical CO₂ molding， and the influence of branching degree on molecular weight， molecular weight distribution， melt crystallization， rheological behavior， and foaming performance was systematically investigated. Results indicated that the crystallization temperature of PP gradually increased with higher branching degrees， while crystallinity degree decreased compared to linear PP. Enhanced branching also improved melt viscoelasticity， prolonged relaxation time， and intensified shear thinning and strain hardening effects. Furthermore， the foaming temperature window expanded by 12 ℃. Under optimal conditions （15 MPa CO₂， 152 ℃）， the modified PP achieved a maximum expansion ratio of 30⁃fold， exhibiting a more uniform cell structure. The foam with a 25⁃fold expansion ratio demonstrated superior mechanical properties， with compression and tensile moduli reaching （18.94±0.55）MPa and （3.51±0.06）MPa， respectively， outperforming the E02ES™ foam at the same expansion ratio.

Key words: homopolymer polypropylene, branching, supercritical carbon dioxide, molding foaming, mechanical property

CLC Number:

TQ325.1⁺4

WANG Shuo, YUAN Wenbo, CHENG Yichong, ZANG Yuntao, LENG Dongliang, LI Haiyan, ZHAO Ling, HU Dongdong. Mechanical performance of branched polypropylene foams fabricated via supercritical CO₂ molding[J]. China Plastics, 2025, 39(9): 1-6.

Figures/Tables 11

References 13

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样品	DCP/%	PETA/%	TMTM/%	1010/%	MFR/g·（10 min）^-1	凝胶含量/%
PP⁃0	0	0	0	0.2	3.959	0
PP⁃1	0.1	2	0.025	0.2	1.983	0
PP⁃2	0.1	2	0.050	0.2	1.385	0
PP⁃3	0.1	2	0.100	0.2	2.366	0
PP⁃4	0.1	4	0.050	0.2	0.132	4.1
PP⁃5	0.1	1	0.050	0.2	4.536	0

样品	DCP/%	PETA/%	TMTM/%	1010/%	MFR/g·（10 min）^-1	凝胶含量/%
PP⁃0	0	0	0	0.2	3.959	0
PP⁃1	0.1	2	0.025	0.2	1.983	0
PP⁃2	0.1	2	0.050	0.2	1.385	0
PP⁃3	0.1	2	0.100	0.2	2.366	0
PP⁃4	0.1	4	0.050	0.2	0.132	4.1
PP⁃5	0.1	1	0.050	0.2	4.536	0

样品	M_w/kg·mol^-1	M_n/kg·mol^-1	PDI
PP⁃0	154.71	53.72	2.88
PP⁃1	235.55	71.38	3.30
PP⁃2	241.84	72.19	3.35
PP⁃3	211.66	65.12	3.25

样品	M_w/kg·mol^-1	M_n/kg·mol^-1	PDI
PP⁃0	154.71	53.72	2.88
PP⁃1	235.55	71.38	3.30
PP⁃2	241.84	72.19	3.35
PP⁃3	211.66	65.12	3.25

样品	T_c/℃	T_m/℃	T_c⁃onset⁃T_c⁃peak/℃	ΔH_m/J·g^-1	χ_c/%
PP⁃0	114.5	167.4	6.4	81.38	38.94
PP⁃1	118.7	166.5	18.4	65.38	31.28
PP⁃2	121.2	164.6	21.4	62.14	29.73
PP⁃3	115.6	166.9	15.1	70.93	33.94