Preparation of DOPO Derivative Modified Carbon Nanotubes and Their Effect on Flame Retardancy of Polylactic Acid

doi:10.7503/cjcu20210670

Abstract

Abstract:

Using carboxyl carbon nanotubes（CNT-COOH）and 9，10-dihydro-9-oxa-10-phosphaphenanthrene-10- oxide（DOPO） derivative DOPO-NH₂ as raw materials， a new type of inorganic-organic hybrid flame retardant（CNT-DOPO） was prepared through acid chlorination and condensation reactions. The structure was characterized by Fourier transform infrared spectroscopy， transmission electron microscopy， X-ray photoelectron spectroscopy and thermogravimetric analysis， and the grafting rate was quantitatively tested. CNT-COOH， DOPO-NH₂ and CNT-DOPO were added to polylactic acid（PLA） in the same mass fraction of 5% to prepare flame-retardant PLA composites. The results showed that DOPO-NH₂ was successfully grafted onto carbon nanotubes with a grafting rate of about 50%. The cone calorimetric test results showed that the peak heat release rate of PLA/5CNT-COOH， PLA/5DOPO-NH₂ and PLA/5CNT-DOPO was 46%， 3.4%， 39.8% lower than that of pure PLA， respectively. The morphology and structure analysis of the char residues showed that the char layer of PLA/5CNT-DOPO had the highest degree of graphitization， and carbon nanotubes and DOPO-NH₂ had a certain promoting effect on the condensed phase flame retardancy. The rheological results showed that the addition of carbon nanotube had a great effect on the viscoelastic transition of PLA composites. PLA/5CNT-COOH and PLA/5CNT-DOPO basically exhibited elastic behavior. The addition of carbon nanotube or modified carbon nanotube increased the viscosity of PLA composites at low frequency， and promoted the formation of consistent and compact char layer in the later stage of combustion， Accordingly， the heat release rate and the smoke production of PLA composites decreased significantly.

Key words: Poly（lactic acid）, 9, 10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide derivative, Carbon nanotubes, Flame retardancy

CLC Number:

O631

TrendMD:

GAO Jing, HE Wentao, WANG Xinxin, XIANG Yushu, LONG Lijuan, QIN Shuhao. Preparation of DOPO Derivative Modified Carbon Nanotubes and Their Effect on Flame Retardancy of Polylactic Acid[J]. Chem. J. Chinese Universities, 2022, 43(3): 20210670.

Figures/Tables 16

Scheme 1 Synthetic route of functionalized carbon

Fig.1 Observation of CNT?DOPO and CNT?COOH dispersion in DMF and THF after ultrasonication for 5 mina. CNT-DOPO in DMF； b. CNT-DOPO in THF； c. CNT-COOH in DMF； d. CNT-COOH in THF.

Fig.2 TEM images of CNT?COOH(A, B) and CNT?DOPO(C, D) with different magnifications

Fig.3 FTIR spectra(A) and TG curves(B) of DOPO?NH2, CNT?COOH and CNT?DOPO

Table 1 TG data of CNT-COOH, DOPO-NH2 and CNT-DOPO

Sample	T_5%/℃	Mass fraction at 700 ℃（%）
CNT?COOH	394	90.2
DOPO?NH₂	361	22.7
CNT?DOPO	298	54.8

Fig.4 XPS survey spectra(A) and the corresponding high resolution specta of C1s (B), N1s (C) and O1s (D) of CNT?DOPO

Table 2 Atomic fraction and binding energy of various elements in CNT-DOPO

Element	Atomic fraction（%）	E_b /eV
C₁_s	83.72	285.1
N₁_s	4.70	399.4
O₁_s	7.73	532.2
P₂_s	1.71	190.3
P₂_p	2.14	132.7

Fig.5 TG(A) and DTG(B) curves of PLA and PLA composites in N2 atmospher

Table 3 TG and DTG datas of PLA and PLA composites in N2 atmosphere

Sample	T_5%/℃	T_max/℃	Mass fractionat at 600 ℃（%）
PLA	349.8	381.6	0.9
PLA/5CNT?COOH	338.5	371.6	5.3
PLA/5DOPO?NH₂	350.1	394.5	2.5
PLA/5CNT?DOPO	326.9	368.2	3.7

Fig.6 HRR(A), THR(B), COP(C) and CO2P(D) curves of PLA and PLA composites in cone calorimeter testing at 50 kW/m2

Table 4 Main heat combustion parameters of PLA and PLA composites at 50 kW/m2

PLA

PLA/5CNT?COOH

316

462

834

703.5

378.4

168.6

165.3

22.62

23.10

Table 5 Main non-heat combustion parameters of PLA and PLA composites at 50 kW/m2

PLA

PLA/5CNT?COOH

0.015

0.011

1.723

0.726

0.46

0.56

0.250

0.127

99.4

96.9

0.6

3.1

Table 6 Quantitative assessment of the flame-retardant modes for PLA and PLA composites

Sample	E_Physical_barrier（%）	E_{Flame inhibition}（%）	E_{Catalytic charring}（%）
PLA/5CNT?COOH	45.14	-2.12	2.52
PLA/5DOPO?NH₂	-0.52	1.19	0.80
PLA/5CNT?DOPO	39.05	-2.03	1.11

Fig.7 Digital photos(A—D1) and SEM images(B2—D2) of the specimens after cone calorimeter test（A） PLA；（B1， B2） PLA/5CNT-COOH；（C1， C2） PLA/5DOPO-NH2；（D1， D2） PLA/5CNT-DOPO.

Fig.8 Raman spectra of PLA/5CNT?COOH(A), PLA/5DOPO?NH2(B) and PLA/5CNT?DOPO(C)

Fig.9 Storage modulus(A), loss storage(B), complex viscosity(C) verse frequency and Han plot(D) of PLA and PLA composites

References 32

1	Bourbigot S.， Fontaine G.， Polym. Chem.， 2010， 1（9）， 1413—1422
2	Tawiah B.， Yu B.， Fei B.， Polym.， 2018， 10（8）， 876—896
3	Nazir R.， Gaan S.， J. Appl. Polym. Sci.， 2020，137（1）， 47910—47925
4	Jiang P.， Gu X.， Zhang S.， Wu S.， Zhao Q.， Hu Z.， Ind. Eng. Chem. Res.， 2015， 54（11）， 2974—2982
5	Gu L.， Qiu J.， Yao Y.， Sakai E.， Yang L.， Compos. Sci. Technol.， 2018， 161， 39—49
6	Yin W.， Chen L.， Lu F.， Song P.， Dai J.， Meng L.， ACS Omega， 2018， 3（5）， 5615—5626
7	Wang X. X.， He W. T.， Long L. J.， Huang S. W.， Qin S. H.， Xu G.M.， J. Therm. Anal. Calorim.， 2021， 145， 331—343
8	Long L. J.， Yin J. B.， He W. T.， Qin S. H.， Yu J.， Ind. Eng. Chem. Res.， 2016， 55， 10803—10812
9	Long L. J.， Chang Q. F.， He W. T.， Xiang Y. S.， Qin S.H.， Yin J. B.， Yu J.， Polym. Degrad. Stab.， 2017 ， 139， 55—66
10	He W. T.， Song P. A.， Yu B.， Fang Z. P.， Wang H.， Prog. Mater. Sci.， 2020， 114， 100687
11	Tang G.， Deng D.， Chen J.， Zhou K.， Zhang H.， Huang X.， Zhou Z.， J. Therm. Anal. Calorim.， 2017， 130， 763—772
12	Yu T.， Jiang N.， Li Y.， Compos. Sci. Technol.， 2014， 104， 26—33
13	Wu H. X.， Tong R.， Qiu X. Q.， Yang H. F.， Lin Y. H.， Cai R. F.， Carbon. 2007， 45（1）， 152—159
14	Ma H. Y.， Tong L. F.， Xu Z. B.， Fang Z. P.， Adv. Funct. Mater.， 2008， 18（3）， 414—421
15	Xing W.， Yang W.， Yang W.， Hu Q.， Si J.， Lu H.， ACS Appl. Mater. Interfaces， 2016， 8（39）， 26266—26274
16	Díez⁃Pascual A. M.， Naffakh M.， Carbon， 2012， 50（3）， 857—868
17	Wang S.， Xin F.， Chen Y.， Qian L.， Chen Y.， Polym. Degrad. Stab.， 2016， 129， 133—141
18	Okpalugo T.， Papakonstantinou P.， Murphy H.， McLaughlin J.， Brown N.， Carbon， 2005， 43（1）， 153—161
19	Yang S. Y.， Ma C. M.， Teng C. C.， Huang Y. W.， Liao S. H.， Huang Y. L.， Carbon， 2010， 48（3）， 592—603
20	An Q.， Rider A. N.， Thostenson E. T.， Carbon， 2012， 50（11）， 4130—4143
21	Chen W.， Liu Y.， Liu P.， Xu C.， Liu Y.， Wang Q.， Sci. Rep.， 2017， 7（1）， 1—12
22	Hapuarachchi T. D.， Peijs T.， Composites Part A， 2010， 41（8）， 954—963
23	Kashiwagi T.， Grulke E.， Hilding J.， Groth K.， Harris R.， Butler K.， Polym.， 2004， 45（12）， 4227—4239
24	Peeterbroeck S.， Laoutid F.， Swoboda B.， Lopez‐Cuesta J. M.， Moreau N.， Nagy J. B.， Macromol. Rapid Commun.， 2007， 28（3）， 260—264
25	Gallo E.， Schartel B.， Acierno D.， Russo P.， Eur. Polym. J.， 2011， 47（7）， 1390—1401
26	Tang S.， Wachtendorf V.， Klack P.， Qian L.， Dong Y.， RSC Adv.， 2017， 7（2）， 720—728
27	Brehme S.， Köppl T.， Schartel B.， Altstädt V.， Polym.， 2014， 14（3）， 193—208
28	Wang X. X.， He W. T.， Xu G. M.， Long L. J.， Huang W. J.， Yu J.， Acta Polym. Sin.， 2019， 50（4）， 419—428（王欣欣，何文涛，徐国敏，龙丽娟，黄伟江，于杰. 高分子学报， 2019， 50（4）， 419—428）
29	Bartholmai M.， Schartel B.， Polym. Adv. Technol.， 2004， 15（7）， 355—364
30	Ma H.， Tong L.， Xu Z.， Fang Z.， Polym. Degrad. Stab.， 2007， 92（8）， 1439—1445
31	Kashiwagi T.， Mu M.， Winey K.， Cipriano B.， Raghavan S.， Pack S.， Polym.， 2008， 49（20）， 4358—4368
32	Wu D.， Wu L.， Zhang M.， Zhao Y.， Polym. Degrad. Stab.， 2008， 93（8）， 1577—1584

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