Curing Kinetics of Flame Retardant Epoxy Resin Promoted by Imidazole Grafting Graphene Oxide†

doi:10.7503/cjcu20170059

Abstract

Abstract:

The curing kinetics of a flame-retardant epoxy resin(1.5P-D-U-EMI) containing 9,10-dihydro-9-oxa-10-phosphaphenantrene-10-oxide(DOPO) with imidazole grafting graphene oxide(GO-IPDI-MZ) was investigated by differential scanning calorimetry. The non-isothermal autocatalysis curing mechanism of 1.5P-D-U-EMI was not changed by adding 1% of GO-IPDI-MZ. T_onset and T_p of the flame-retardant epoxy resin with 1 Phr of GO-IPDI-MZ(1.5P-D-GOM-1) were decreased compared with those of 1.5P-D-U-EMI, and the total curing heat ΔH of 1.5P-D-GOM-1 was higher than that of 1.5P-D-U-EMI. 1% of GO-IPDI-MZ plays a catalytic and co-curing action on the epoxy system. The phenomenon of diffusion control was observed at the later stage of isothermal curing, especially at low temperatures. The Kamal-Sourour model modified with diffusion expressed the observed reaction rate curves fairly well. The curing reaction became steady and uniform by introducing GO-IPDI-MZ.

Key words: Imidazole grafting graphene oxide, Flame retardant epoxy, Curing kinetics, Catalytic and co-curing action, Differential scanning calorimetry

CLC Number:

O631
O643.1

TrendMD:

HU Jianhua, SHAN Jiye, TONG Zhen. Curing Kinetics of Flame Retardant Epoxy Resin Promoted by Imidazole Grafting Graphene Oxide^†[J]. Chem. J. Chinese Universities, 2017, 38(10): 1906.

Figures/Tables 12

Scheme 1 Structures of DGEBA, 11DB07, DICY, U-52 and EMI-2,4

Fig.1 TG and DTG thermograms of 1.5P-D-GOM-x with indicated x(A) and non-isothermal DSC thermograms of curing reaction for 1.5P-D-GOM-x systems(B)

Table 1 Parameters from the non-isothermal curing reaction thermograms of 1.5P-D-U-GOM-x(10 ℃/min)

Sample	T_onset/℃	T_p/℃	T_end/℃	ΔH/(J·g^-1)	ΔH/(kJ·mol^-1 epoxide)
1.5P-D-U-EMI	133.3	148.9	179.7	327.9	87.7
1.5P-D-GOM-0.25	130.3	146.0	176.8	331.2	88.8
1.5P-D-GOM-0.5	128.9	143.8	174.5	364.1	97.9
1.5P-D-GOM-0.75	126.9	142.6	173.4	374.0	100.7
1.5P-D-GOM-1	120.2	140.7	167.0	397.7	107.4
1.5P-D-GOM-1.25	124.7	141.5	167.5	390.2	105.5

Fig.2 Non-isothermal DSC thermograms at indicated heating rates for the curing reaction of 1.5P-D-GOM-1(a) compared with that of 1.5P-D-U-EMI(b) Heating rate/(℃·min-1): (A) 2.5; (B) 5; (C) 10; (D) 15.

Fig.3 Conversion α of 1.5P-D-GOM-1(a—d) and 1.5P-D-U-EMI(e—h) systems plotted as a function of temperature during the non-isothermal curing at indicated heating ratesHeating rate/(℃·min-1): a,e. 2.5; b,f. 5; c,g. 10; d,h. 15.

Fig.4 Kissinger plot of -ln(β/Tp2) vs. l/Tpa. 1.5P-D-U-EMI; b. 1.5P-D-GOM-1.

Table 2 Parameters for the non-isothermal curing reaction thermograms of 1.5P-D-GOM-1 and 1.5P-D-U-EMI systems*

System	β/(℃·min^-1)	T_onset/℃	T_p/℃	ΔH/(J·g^-1)
1.5P-D-U-EMI	2.5	119.5	130.9	327.2
	5	125.7	140.2	327.7
	10	133.3	148.9	327.9
	15	142.1	158.6	328.3
1.5P-D-GOM-1	2.5	114.1	128.8	397.5
	5	120.2	135.7	392.2
	10	132.0	147.9	397.7
	15	140.7	157.2	398.4

Fig.5 Conversion α for 1.5P-D-GOM-1 as a function of curing time at different isothermal temperaturesTemperature/℃: a. 110; b. 120; c. 130; d. 140; e. 150.

Table 3 Maximum conversion αT of the isothermal curing for the 1.5P-D-GOM-1 and 1.5P-D-U-EMI systems

System	α_T
System	110 ℃	120 ℃	130 ℃	140 ℃	150 ℃
1.5P-D-U-EMI	0.727	0.845	0.906	0.958	0.981
1.5P-D-GOM-1	0.790	0.846	0.907	0.980	0.998

Fig.6 Comparison of Kamal model(a), the diffusion factor modified Kamal model(b) and experimental data(c) for the isothermal curing of 1.5P-D-GOM-1 Temperature of curing/℃: (A)110; (B) 120; (C) 130; (D) 140; (E) 150.

Table 4 Kinetic parameters of the autocatalytic model for isothermal curing

T/℃	10⁴k₁/s^-1	10³k₂/s^-1	m	n	α_c	C
110	0.84	2.79	0.918	2.18	0.66	68.2
120	1.65	4.72	0.766	2.04	0.74	76.4
130	2.78	6.65	0.733	1.81	0.82	84.6
140	4.29	11.00	0.658	1.68	0.90	92.3
150	8.10	17.40	0.625	1.49	0.98	104.8

Fig.7 Arrhenius plots of lnk1(a) and lnk2(b) vs. 1/T

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