Study on Chain Extension and Foaming Behaviors of Thermoplastic Polyamide Elastomer

doi:10.19491/j.issn.1001-9278.2021.10.003

Abstract

Abstract:

In this study， an epoxy?type chain extender （KL-E4370） was used to modify the thermoplastic polyamide elastomer （TPAE）. The rheological， crystalline， and foaming properties of TPAE before and after the chain extension were investigated using a rotating rheometer， differential scanning calorimeter and scanning electron microscope， and the corresponding chain extension reaction was studied， too. The results indicated that the molten TPAE has poor thermal and foaming properties. The introduction of chain extender can effectively increase the branching level of TPAE. After modification， the complex viscosity of TPAE was increased by more than one order of magnitude， the foaming rate was increased， the foaming temperature zone was widened， and the bubble rupture and merging problems were effectively overcome. However， the crystallization performance of TPAE decreased， and the initial crystallization temperature decreased by about 20 °C， resulting in obvious shrinkage of the bubble. When the content of chain extender was 1 wt%， the foaming rate of TPAE increased from 5.5 times to approximately 9 times， and the diameter of the bubble reached 50 μm.

Key words: thermoplastic, polyamide, elastomer, chain extension, foaming

CLC Number:

TQ323.6

WEN Hui, MA Yufei, XIN Chunling, HE Yadong. Study on Chain Extension and Foaming Behaviors of Thermoplastic Polyamide Elastomer[J]. China Plastics, 2021, 35(10): 14-20.

Figures/Tables 19

Fig.1. Rheological behavior of TPAE

Fig.2. DSC curves of TPAE

Fig.3. Foaming rate and apparent density of TPAE

Fig.4. SEM image of foamed samples

Fig.5. Torque?processing time curve

样品名称	反应峰面积	反应峰斜率
TPAE?0.5	18.4	0.065
TPAE?1	42.0	0.092
TPAE?1.5	77.7	0.088

Tab.1. Parameters of chain extension

Fig.6. Reaction mechanism for TPAE and KL?E4370

Fig.7. Complex viscosity?angle frequency curves

扩链剂含量/%	复数黏度/Pa·s
0	1 116
0.5	1 853
1.0	2 453
1.5	7 083

Tab.2. Complex viscosity of different samples at an angular frequency of 0.628 rad/s

Fig.8. Storage modulus?angle frequency curves

Fig.9. tanδ?angle frequency curves

Fig.10. Cole?cole curves

Fig.11. Crystallization curve during cooling

Fig.12. Melting curve during heating

样品名称	熔点温度/℃	熔融焓/J·g^-1	起始结晶温度/℃
TPAE	185	18.32	83
TPAE?0.5	183	15.81	84
TPAE?1	182	13.82	79
TPAE?1.5	181	12.74	57

Tab.3. Crystallization performance of the sample

Fig.13. Foaming rate of the sample

Fig.14. Picture of foamed samples before and after shrinkage

Fig.15. SEM images of different TPAE samples

Fig.16. Diameter and density curve of the cells of different TPAE samples

References 10

1	YOON P J， HAN C D. Effect of Thermal History on the Rheological Behavior of Thermoplastic Polyurethanes［J］. American Chemical Society， 2000， 33（6）： 2 171⁃2 183.
2	NICHETTI D， GRIZZUTI N. Determination of the Phase Transition Behavior of Thermoplastic Polyurethanes from Coupled Rheology/DSC Measurements［J］. Polymer Engineering & Science， 2004， 44（8）： 1 514⁃1 521.
3	XU M L， CHEN Y C， LIU T， et al. Determination of Modified Polyamide 6’s Foaming Windows by Bubble Growth Simulations Based on Rheological Measurements［J］. Journal Of Applied Polymer Science， 2019， 136（42）： 48138.
4	XU M L， LU J W， QIAO Y N， et al. Toughening Mechanism of Long Chain Branched Polyamide 6［J］. Materials and Design， 2020， 196： 109173.
5	舒梦莹，翁云宣，张彩丽. 多元环氧扩链剂（ADR）对PBAT的扩链改性及其耐老化性能的影响［J］. 中国塑料， 2020，34（3）：33⁃39.
	SHU M Y， WENG Y X， ZHANG C L. Influence of Multi⁃component Epoxy Chain⁃Extension Agent on Aging Resistance of Chain⁃Extension Modified PBAT［J］. China Plastics， 2020，34（3）： 33⁃39.
6	XU M L， YAN H C， HE Q J， et al. Chain Extension of Polyamide 6 using Multifunctional Chain Extenders and Reactive Extrusion for Melt Foaming［J］. European Polymer Journal， 2017， 96：210⁃220.
7	NAM G J， YOO J H， LEE J W. Effect of Long⁃Chain Branches of Polypropylene on Rheological Properties and Foam⁃extrusion Performances［J］. Journal of Applied Polymer Science， 2005， 96（5）： 1 793⁃1 800.
8	HAN C D， JHON M S. Correlations of the First Normal Stress Difference with Shear Stress And of the Storage Modulus with Loss Modulus for Homopolymers［J］. Journal of Applied Polymer Science， 1986， 32（3）： 3 809⁃3 840.
9	VALLES E M， CARELLA J M， WINTER H H. Gelation of A Radiation Crosslinked Model Polyethylene［J］. Rheological Acta， 1990， 29（6）： 535⁃542.
10	TIAN J， YU W， ZHOU C. The Preparation and Rheology Characterization of Long Chain Branching Polypropylene［J］. Polymer， 2006， 47（23）： 7 962⁃7 969.

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