Preparation and properties of all⁃bio⁃based epoxy resin with excellent flame retardancy and degradability

doi:10.19491/j.issn.1001-9278.2024.11.006

Abstract

Abstract:

In this study， an intrinsic flame⁃retardant epoxy resin （TA⁃VAN⁃EP） containing a Schiff⁃base structure was prepared by using vanillin （VAN）， tyramine （TA） and epichlorohydrin （ECH） as raw materials. The chemical structure of the resultant TA⁃VAN⁃EP was characterized by Fourier⁃transform infrared spectroscopy and ¹H nuclear magnetic resonance spectroscopy， and its curing behavior， mechanical performance， thermal stability， flame⁃retardant performance， and other important properties were investigated. The results indicated that the synthesized TA⁃VAN⁃EP exhibited a desired structure. Compared to pure epoxy resin， TA⁃VAN⁃EP obtained a significant improvement in the mechanical properties， in which there is an increase in the tensile strength by 82.0 %. Moreover， it also showed an increase in the glass⁃transition temperature from 152 to 190 ℃. In addition， TA⁃VAN⁃EP achieved a UL94 V⁃1 rating in the vertical burning experiment， along with an increase in the limiting oxygen index value from 24.7 % to 28.4 %. Furthermore， TA⁃VAN⁃EP presented a significant reduction in the total heat release， smoke production rate， and total smoke release. Owing to the presence of a dynamic Schiff⁃base structure in its structure， TA⁃VAN⁃EP exhibited good biodegradation performance under acidic conditions.

Key words: bio?based epoxy resin, Schiff base, flame retardant, degradability

CLC Number:

TQ323.5

CHEN Yuquan, REN Bin, LI Xuemei, RAO Suhan, GUO Zhangyi, HUANG Ying, KANG Ming, LI Xiuyun. Preparation and properties of all⁃bio⁃based epoxy resin with excellent flame retardancy and degradability[J]. China Plastics, 2024, 38(11): 33-40.

Figures/Tables 16

Fig.1. Synthetic routes of TA⁃VAN and TA⁃VAN⁃EP

Fig.2. Structural characterisation of the raw materials and samples

Fig.3. Curing behavior of the EP and TA⁃VAN⁃EP

样品	升温速率/°C·min^-1	T_p/°C	E_a^a/kJ·mol^-1	R²	E_a^b/kJ·mol^-1	R²
EP	5	134.6	51.60	0.999 8	58.65	0.999 8
	10	152.0
	15	162.4
	20	170.1
TA⁃VAN⁃EP	5	123.6	56.74	0.997 9	63.58	0.998 0
	10	138.8
	15	146.7
	20	154.8

Tab.1. Analysis of curing behavior of the EP and TA⁃VAN⁃EP

样品	拉伸强度/MPa	断裂伸长率/%	弯曲强度/MPa
EP	61	8.3	137
TA⁃VAN⁃EP	111	9.4	179

Tab.2. Mechanical properties of the EP and TA⁃VAN⁃EP

Fig.4. Tensile and flexural properties of the EP and TA⁃VAN⁃EP

Fig.5. TG，DTG and DSC curves of the EP and TA⁃VAN⁃EP

样品	LOI/%	UL94
样品	LOI/%	t₁+t₂^a	是否滴落	等级
EP	24.7	BC^b	是	无
TA⁃VAN⁃EP	28.4	11+4	否	V⁃1

Tab.3. LOI and UL⁃94 test results of the EP and TA⁃VAN⁃EP

Fig.6. Results of UL94 vertical combustion test of the EP and TA⁃VAN⁃EP

Fig.7. CCT test results of the EP and TA⁃VAN⁃EP

样品	TTI/s	PHRR/kW·m^-2	COPR/g·s^-1	CO₂PR/g·s^-1	THR/MJ·m^-2	SPR/m²·s^-1	TSR/m²·m^-2
EP	57	1 573.9	0.042	1.04	76.8	0.48	2 438
TA⁃VAN⁃EP	41	1 721.9	0.054	1.16	55.8	0.33	1 231

Tab.4. CCT test data of the EP and TA⁃VAN⁃EP

Fig.8. SEM images of residual char of the EP and TA⁃VAN⁃EP

Fig.9. Raman spectra of residual char of the EP and TA⁃VAN⁃EP

Fig.10. Gas phase product analysis of the EP and TA⁃VAN⁃EP

Fig.11. Schematic diagram of flame retardant mechanism of TA⁃VAN⁃EP

Fig. 12. Degradation behavior of the TA⁃VAN⁃EP under different condition

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