Study on chain⁃extending reaction of PA66 and its supercritical CO2 microcellular foaming behavior

doi:10.19491/j.issn.1001-9278.2023.12.007

Abstract

Abstract:

A multifunctional epoxy chain extender CE and an antioxidant B215 were used to modify linear polyamide 66 （PA66） through melting chain extension， and a series of microporous CEPA66 foams were prepared by supercritical CO₂. The branched PA66 was formed by the introduction of the chain extender CE， and its crystallization behavior， energy⁃storage modulus， and complex viscosity were characterized by using DSC， FTIR and rotary rheometer. The use of CE effectively improved the melt strength of PA66， and its addition amount was optimized to obtain PA66 with a high branching and low crosslinking degrees. The PA66 microcellular foams were successfully obtained at a saturation temperature of 275 ℃. Their cell size and cell density are 23 μm and 3.5×10⁹ cells /cm³， respectively.

Key words: polyamide 66, epoxy chain extender, microcellular foam, foaming, supercritical carbon dioxide

CLC Number:

TQ323.6

SUN Yibo, LIU Yaning, LU Haofan, CHEN Shihong, WANG Xiangdong, WU Lili. Study on chain⁃extending reaction of PA66 and its supercritical CO₂ microcellular foaming behavior[J]. China Plastics, 2023, 37(12): 41-46.

Figures/Tables 13

Fig.1. General chemical structure of PA66 and CE

样品编号	PA66含量/质量份	CE含量/质量份	B215含量/质量份
1^#	100.0	0	0.6
2^#	100.0	2.5	0.6
3^#	100.0	3.0	0.6
4^#	100.0	3.5	0.6
5^#	100.0	4.0	0.6
6^#	100.0	4.5	0.6

Tab.1. Experimental formula

Fig.2. Schematic diagram of CEPA66 sample preparation and its foamed process

Fig.3. Torque curves of the PA66 samples

Fig.4. FTIR spectra of CE， PA66 and CEPA66 and chain extension reaction

Fig.5. Rheological behavior of various CEPA66 samples

Fig.6. Gel content degree of different PA66 samples

Fig.7. DSC curves of CEPA66 composites

样品	T_c/℃	ΔW/J·g^-1	T_m/℃	ΔH_m /J·g^-1	χ/%
1^#	233.35	62.66	264.15	72.88	38.36
2^#	233.11	62.39	263.63	71.41	37.58
3^#	232.85	62.18	263.22	70.07	36.88
4^#	231.87	61.07	263.01	68.35	35.97
5^#	231.34	58.10	262.44	64.21	33.79
6^#	230.19	54.32	263.37	59.01	31.08

Tab.2. Thermal properties of the CEPA66 samples

Fig.8. SEM images of different CEPA66 foams at 275 ℃

Fig.9. The cell density， foaming rate and cell size of CEPA66 samples were calculated at 275 ℃

Fig.10. SEM images of PA66 samples with 4 phr CE content at different soaking temperature

浸泡温度/℃	发泡倍率	平均尺寸/μm	泡孔密度/个∙cm^-3
270.0	7.11	13.13±3.95	2.77×10⁹
272.5	20.44	24.38±3.36	2.32×10⁹
275.0	24.93	21.75±1.90	3.42×10⁹
277.5	24.44	23.22±1.93	3.50×10⁹
280.0	23.11	24.51±1.67	2.33×10⁹

Tab.3. Foam cell statistical parameters of different CEPA66 samples

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Study on chain⁃extending reaction of PA66 and its supercritical CO₂ microcellular foaming behavior

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