Determination of Polychloroprene Content in Rubber Blend Containing Ethylene Propylene Diene Monomer by Infrared Techniques

Rigoli, Paulo Santos; Barros, Alexandra Helena de; Magalhães, Rachel Farias; Murakami, Lidia Mattos Silva; Carrara, Alexandre Estevão; Dutra, Jorge Carlos Narciso; Mattos, Elizabeth da Costa; Dutra, Rita de Cássia Lazzarini

doi:10.1590/jatm.v13.1197

Acessibilidade / Reportar erro

Brasil

Journal of Aerospace Technology and Management

Español English

Brasil

Español English

sumário « anterior atual seguinte »

Sumário

ORIGINAL PAPER • J. Aerosp. Technol. Manag. 13 • 2021 • https://doi.org/10.1590/jatm.v13.1197 copy

Determination of Polychloroprene Content in Rubber Blend Containing Ethylene Propylene Diene Monomer by Infrared Techniques

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

Ethylene propylene diene monomer rubber is used as flexible thermal protection for rocket engines, as well as in blends with polychloroprene, which can be applied in the aeronautical sector, and with great potential in the defense sector. However, there is not a considerable number of studies considering both polymers as a blend. In general, elastomer content quantification in blends is done by more complex instrumental methods. When performed by Fourier transform-infrared spectroscopy, the conventional transmission mode is used, usually without including the developed methodology error. Therefore, the Fourier transform infrared spectroscopy (FT-IR) methodology is proposed using the universal attenuated total reflection mode, with sample treatment (pyrolysis) to determine polychloroprene content in the mixture with ethylene propylene diene monomer. In accordance with the infrared spectrometer precision limits and rubber blends studies data found in the literature, the methodology error analysis shows a value close to 2%. In addition, it has the advantage of being a less complex methodology. This actual study uses a simple FT-IR analytical tool, scarce, especially for the rubber research community, to determine the content of rubber minor phase within the major phase. It is valuable in weapons reverse engineering, aiming at the knowledge of new thermal protections.

Keywords
Blend; CR; EPDM; FT-IR; Transmission; UATR

Components		Content (mass %)
EPDM Keltan 6950 (ET: 48% e ENB: 7.5%)		56.3; 43.8; 31.3; 18.8 e 6.3
Polychloroprene (Neoprene W)		6.3; 18.8; 31.3; 43.8 e 56.3
Naphthenic Oil NH-140 (plasticizer)		14.1
Carbon black N550 (charge)		19.7
Stearic acid (activator)		0.6
Zinc oxide (activator)		1.1
6PPD (antioxidant)		0.4
Sulfur (vulcanizing agent)		0.5
TMTD (activator)		1.1

EPDM/CR (%)	A₈₁₄	Parameters
90/10	0.010	$\hat{μ}$ = 0.011
	0.012	R = 0.002
	0.011	$\hat{σ}$ ≈ 0.001
	0.010	${\hat{σ}}_{\hat{μ}}$ ≈ 0.0004
	0.012	RD = 3.5%
70/30	0.018	$\hat{μ}$ = 0.018
	0.017	R = 0.002
	0.018	$\hat{σ}$ ≈ 0.001
	0.018	${\hat{σ}}_{\hat{μ}}$ ≈ 0.0004
	0.016	RD = 2.1%
50/50	0.024	$\hat{μ}$ = 0.022
	0.021	R = 0.003
	0.024	$\hat{σ}$ ≈ 0.001
	0.022	${\hat{σ}}_{\hat{μ}}$ ≈ 0.001
	0.022	RD = 2.6%
30/70	0.029	$\hat{μ}$ = 0.029
	0.029	R = 0.002
	0.029	$\hat{σ}$ ≈ 0.001
	0.029	${\hat{σ}}_{\hat{μ}}$ ≈ 0.0004
	0.027	RD = 1.3%
10/90	0.036	$\hat{μ}$ = 0.036
	0.036	R = 0.004
	0.033	$\hat{σ}$ ≈ 0.002
	0.037	${\hat{σ}}_{\hat{μ}}$ ≈ 0.001
	0.035	RD = 2.1%

A₈₁₄ (5 measures)	Parameters	CR content – x (%)
0.014	$\hat{μ}$ = 0.014	Applying Eq. 4:
0.014	R = 0.001	y = 0.014 → x = 20 %
0.015	$\hat{s}$ ≈ 0.0004	y = 0.014 → x = 20 %
0.014	${\hat{σ}}_{\hat{μ}}$ ≈ 0.0002	Calculated CR content: 20%
0.014	RD = 1.3%	Calculated EPDM content: 80%

A₈₁₄ (5 measures)	Parameters	CR content – x (%)
0.021	$\hat{μ}$ = 0.020	Applying Equation 4:
0.020	R = 0.004	y = 0.020 → x ≈ 40 %
0.018	$\hat{s}$ = 0.002	y = 0.020 → x ≈ 40 %
0.020	${\hat{σ}}_{\hat{μ}}$ ≈ 0.001	Calculated CR content: 40%
0.022	RD = 38 %	Calculated EPDM content: 60%

A₈₁₄ (5 measures)	Parameters	CR content – x (%)
0.024	$\hat{μ}$ = 0.024	Applying Eq. 4:
0.024	R = 0.001	y = 0.024 → x ≈ 54 %
0.024	$\hat{s}$ ≈ 0.0004	y = 0.024 → x ≈ 54 %
0.025	${\hat{σ}}_{\hat{μ}}$ ≈ 0.0002	Calculated CR content: 54%
0.024	RD = 0.8%	Calculated EPDM content: 46%

A₈₁₄ (5 measures)	Parameters	CR content – x (%)
0.031	$\hat{μ}$ = 0.032	Applying Equation 4:
0.032	R = 0.002	y = 0.032 → x ≈ 80 %
0.033	$\hat{s}$ ≈ 0.001	y = 0.032 → x ≈ 80 %
0.033	${\hat{σ}}_{\hat{μ}}$ ≈ 0.0004	Calculated CR content: 80 %
0.031	RD = 1.2%	Calculated EPDM content: 20 %

EPDM/CR (%)	A₈₁₄/A₈₈₅	Parameters
90/10	0.300	$\hat{μ}$ = 0.450
	0.555	R = 0.255
	0.300	$\hat{s}$ = 0.110
	0.473	${\hat{σ}}_{\hat{μ}}$ ≈ 0.049
	0.450	RD = 10.9%
70/30	0.720	$\hat{μ}$ = 0.720
	0.739	R = 0.137
	0.613	$\hat{s}$ = 0.059
	0.655	${\hat{σ}}_{\hat{μ}}$ = 0.026
	0.750	RD = 3.6%
50/50	0.893	$\hat{μ}$ = 0.958
	0.958	R = 0.178
	0.950	$\hat{s}$ = 0.076
	1.040	${\hat{σ}}_{\hat{μ}}$ = 0.034
	1.071	RD = 3.6%
30/70	1.167	$\hat{μ}$ = 1.034
	1.034	R = 0.167
	1.062	$\hat{s}$ = 0.072
	1.000	${\hat{σ}}_{\hat{μ}}$ = 0.032
	1.030	RD = 3.1%
10/90	1.172	$\hat{μ}$ = 1.077
	1.077	R = 0.064
	1.114	$\hat{s}$ = 0.027
	1.050	${\hat{σ}}_{\hat{μ}}$ = 0.012
	1.079	RD = 1.1 %

Departamento de Ciência e Tecnologia Aeroespacial Instituto de Aeronáutica e Espaço. Praça Marechal do Ar Eduardo Gomes, 50. Vila das Acácias, CEP: 12 228-901, tel (55) 12 99162 5609 - São José dos Campos - SP - Brazil
E-mail: submission.jatm@gmail.com

Acompanhe os números deste periódico no seu leitor de RSS

[1] *Corresponding author: alexandre.ecarrara@gmail.com