Effect of the hardener to epoxy monomer ratio on the water absorption behavior of the DGEBA/TETA epoxy system

Pereira, Ayrton Alef Castanheira; d’Almeida, José Roberto Moraes

doi:10.1590/0104-1428.2106

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Seção Técnica • Polímeros 26 (1) • Jan-Mar 2016 • https://doi.org/10.1590/0104-1428.2106 copy

Effect of the hardener to epoxy monomer ratio on the water absorption behavior of the DGEBA/TETA epoxy system

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

The water absorption behavior of the DGEBA/TETA epoxy system was evaluated as a function of the epoxy monomer to amine hardener ratio. Weight gain versus immersion time curves were obtained and the experimental points were fitted using Fickian and Non-Fickian diffusion models. The results obtained showed that for all epoxy monomer to hardener ratios analyzed water diffusion followed non-Fickian behavior. It was possible to correlate the water absorption behavior to the macromolecular structure developed when the epoxy/ hardener ratio was varied. All epoxy/hardener ratios present a two-phase macromolecular structure, composed of regions with high crosslink density and regions with lower crosslinking. Epoxy rich systems have a more open macromolecular structure with a lower fraction of the dense phase than the amine rich systems, which present a more compact two-phase structure.

Keywords:
water absorption; epoxy resins; hardener to epoxy monomer ratio

	Fick Model			McKague Model
PHR	M∞ (%)	D x 10^–7 (mm²/s)	r²	M∞ (%)	D x 10^–7 (mm²/s)	r²
7	2.78	3.94	0.90	3.08	4.07	0.95
9	3.41	2.46	0.93	4.16	1.92	0.97
11	3.39	3.52	0.92	4.33	3.46	0.96
13	4.01	2.61	0.93	4.81	2.29	0.97
15	5.11	1.67	0.92	7.18	0.94	0.97
17	5.26	2.02	0.91	6.82	1.36	0.96
19	5.83	2.01	0.93	7.41	1.43	0.97
21	6.56	1.70	0.94	9.01	1.01	0.98

	Berens and Hopfenberg Model
PHR	M∞,_F (%)	M∞,_R (%)	*M∞ (%)**	k × 10^–12 (s^–2)	D × 10^–7 (mm²/s)	r²
7	2.47	0.60	3.07	5.69	1.64	0.96
9	3.01	0.53	3.54	1.06	1.52	0.95
11	3.06	0.74	3.80	1.18	1.49	0.96
13	3.81	0.90	4.71	0.29	1.13	0.96
15	4.49	0.87	5.37	0.11	1.11	0.95
17	4.79	0.92	5.71	0.24	1.09	0.94
19	5.27	1.00	6.27	0.20	1.15	0.96
21	5.56	1.25	6.81	0.12	1.10	0.96

	Jacobs-Jones Model						Modified Jacobs-Jones Model
PHR	M∞ (%)	V_d	D × 10^–7 (mm²/s)	D_d × 10^–8 (mm²/s)	D_l × 10^–5 (mm²/s)	r²	M₁ (%)	M₂ (%)	M∞ (%)	D₁ × 10^–7 (mm²/s)	D₂ × 10^–9 (mm²/s)	r²
7	5.05	0.8	2.39	3.03	0.50	0.98	0.98	3.57	4.55	0.53	39.60	0.98
9	4.97	0.8	1.28	4.54	0.27	0.98	1.00	10.49	11.49	0.32	9.20	0.98
11	6.37	0.8	0.90	2.65	0.26	0.97	1.45	16.03	17.48	0.21	3.90	0.97
13	4.82	0.9	2.17	12.24	18.08	0.98	0.69	4.40	5.10	7.57	92.00	0.98
15	7.74	0.9	0.98	4.23	6.09	0.99	0.77	7.82	8.60	6.16	34.29	0.98
17	12.04	0.9	0.49	1.82	0.59	0.98	1.40	124.10	125.50	0.41	0.51	0.98
19	8.13	0.9	0.81	6.05	13.23	0.99	0.86	7.02	7.88	11.36	63.61	0.99
21	8.91	0.9	0.83	5.66	10.01	0.99	0.86	8.35	9.21	11.10	53.31	0.99

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