Natural rubber latex/MXene foam with robust and multifunctional properties
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
e-Polymers 2021; 21: 179–185
Research Article
Ya-Dong Yang, Gui-Xiang Liu, Yan-Chan Wei, Shuangquan Liao*, and Ming-Chao Luo*
Natural rubber latex/MXene foam with robust
and multifunctional properties
https://doi.org/10.1515/epoly-2021-0017 attracted wide attention because of superior perfor-
received December 16, 2020; accepted January 12, 2021 mance, such as excellent elasticity, lightweight, and so
Abstract: Low strength has always been one of the main on (9–15). However, the mechanical strength of NRF is
factors limiting the application of foams. We acquire a low and function of NRF is relatively single, which ser-
natural rubber latex/MXene foam composite with high iously limits its scope of use. Researchers enhance the
strength and versatility by adding MXene to the natural mechanical properties of NRF by filling rice husk (16),
rubber latex. It is shown that natural rubber latex foam kenaf core (17), eggshell (18), and imparting antimicro-
(NRF) with 2 and 3 phr of MXene shows obviously enhanced bial properties to NRF via zinc oxide nanoparticles (19),
tensile strength by 171% and 157% separately as compared silver nanoparticles (20–22), and chitin (23). For instance,
to that of neat NRF. Furthermore, the composite also has Ramasamy et al. incorporated rice husk powder (RHP)
better electrical conductivity and electromagnetic shielding into NR latex compound, and the hardness of RHP-incor-
than NRF, which can be used in the automotive industry, porated NRF increases with increasing RHP filler loading
aviation industry, and many other aspects. (24). In addition, Bashir et al. have demonstrated that the
tensile strength of NRF filled with eggshell power initially
Keywords: natural rubber latex foam, MXene, tensile drops at low eggshell power filler loading and then
strength, electrical conductivity, electromagnetic shielding increases with the increment of filler loading from 5 to
10 phr (18). Moreover, Zhang and Cao have used the nat-
ural antibacterial agent chitin as a loading filler, environ-
mentally friendly and antibacterial NRF was prepared
1 Introduction herein (23). However, in recent progress, to the best of
our knowledge, few studies realize both versatility and
Due to the advantages of low relative density, high spe- mechanical strength for the foam. Thus, it is a challenge to
cific strength, and large specific surface area, foam has expand its application scope and improve its mechanical
been extensively studied by researchers in recent years properties at the same time.
(1–8). For example, natural rubber latex foam (NRF) has MXenes, a new family of 2D materials, were discovered
by scientists of Drexel University in 2011 (25). The general
chemical formula of MXenes is expressed as Mn+1XnTx,
where M is a transition metal (Ti, Mo, Cr, Ta, etc.), X is C
* Corresponding author: Shuangquan Liao, Key Laboratory of
Advanced Materials of Tropical Island Resources of Ministry of
or N, and Tx is a surface termination function (–OH, –O,
Education, Natural Rubber Cooperative Innovation Center of Hainan or –F), n = 1, 2, or 3 (26,27). High-concentration etchant
Province and Ministry of Education of PRC, School of Materials containing hydrofluoric acid and sodium L-ascorbate is
Science and Engineering, Hainan University, Haikou, 570228, China, used to prevent oxidation (28). In particular, its wide sur-
e-mail: lsqhnu@hainanu.edu.cn face area and metallic properties make MXenes possess
* Corresponding author: Ming-Chao Luo, Key Laboratory of
excellent properties in functionalized materials, such as
Advanced Materials of Tropical Island Resources of Ministry of
Education, Natural Rubber Cooperative Innovation Center of Hainan energy conversion and storage (29,30), thermoacoustic
Province and Ministry of Education of PRC, School of Materials devices (31,32), electromagnetic shield (33–35), and so on.
Science and Engineering, Hainan University, Haikou, 570228, China, In this study, natural rubber latex/MXene foams
e-mail: mchluo@hainanu.edu.cn (NRMFs) are prepared by Dunlop processes. MXene is
Ya-Dong Yang, Gui-Xiang Liu, Yan-Chan Wei: Key Laboratory of
uniformly dispersed in NRF and NRMF shows excellent
Advanced Materials of Tropical Island Resources of Ministry of
Education, Natural Rubber Cooperative Innovation Center of Hainan
properties. For example, NRF with 2 phr of MXenes shows
Province and Ministry of Education of PRC, School of Materials higher tensile strength of 0.60 MPa more than cure NRF
Science and Engineering, Hainan University, Haikou, 570228, China of 0.35 MPa. Moreover, nanocomposites also possess
Open Access. © 2021 Ya-Dong Yang et al., published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0
International License.
180 Ya-Dong Yang et al.
electrical conductivity and electromagnetic interference reduced to 0.20–0.25% by stirring, then 2.5 g sulfur, 1.5 g
(EMI) shielding performances and NRMF composites 2-mercaptobenzothiazole, and 1.5 g zinc diethyl dithio-
could be widely applied to automotive industry, aviation carbamate were added to natural rubber latex with 100 g
industry, and many other aspects for future applications. dry rubber content. The composite latex was stirred for
This work provides a good guide toward the design 1 h and then stored for 24 h to make it fully prevulcanized.
of NRF with excellent mechanical and multifunctional A total of 10 g of 10 wt% potassium oleate solution and
properties. MXene (0, 1, 2, 3, 4, 5 wt%) were added to the composite
latex to reach four times its original volume. The gelled
foam is cured by 2.5 g of zinc oxide and 1.5 g of sodium
silicofluoride, then vulcanized in an oven at 120°C for
2 Materials and methods 25 min. Finally, it was washed with deionized water to
remove residual reagents and dried at 50°C for 2 h. We
denote NRF with MXene as NRMF-x, where x is the weight
2.1 Materials
fraction of MXene.
Titanium aluminum carbide (Ti3AlC2) was supplied by
11 Technology Co. Ltd., Changchun, China. Lithium
fluoride (LiF, AR, 99%) and hydrochloric acid (HCl,
36.0–38.0 wt% in H2O) were purchased from Aladdin 2.2 Characterization
Reagent Co. Ltd., China. High ammonia (HA) natural rubber
latex (60%) was supplied by China Hainan Rubber Industry MXenes were characterized with a Rigaku Smart Lab
Group Co., Ltd. Potassium oleate and sodium silicofluoride X-ray diffractometer (XRD). The scanning range of XRD
were purchased from Aladdin. Zinc oxide, sulfur, 1,4-diben- is 10–90°, and the scanning speed is 5° per minute. The
zyloxybenzene, and 2-mercaptobenzothiazole were of morphology and microstructure of Ti3C2Tx sheets and
industrial grade. nanocomposite were observed with scanning electron
Figure 1a shows composite foam preparation. A total microscope (SEM, Verios G4 UC) at a low acceleration
of 1.0 g of Ti3AlC2 powder was gradually added to the voltage of 3 keV at room temperature. Prior to examina-
etchant that was prepared by adding 1.8 g of LiF to tion, samples were gold sputter coated to render them
20 mL of 9 M HCl and left under continuous stirring for electrically conductive. Transmission electron microscope
5 min, and the reaction was allowed to run for 35 h at (TEM) images for samples were obtained on FEI Talos
45°C. The acidic mixture was washed with deionized F200C TEM at an accelerating voltage of 200 kV. Ultrathin
H2O via centrifugation (6 min per cycle at 3,500 rpm) for sections for TEM were prepared by a Leica EM FC7 ultra-
multiple cycles until pH 5 was achieved. The centrifugal microtome with a diamond knife at −60°C.
product was sonicated for 0.5 h and then filtered by Zeta potentials of composite latex were determined
vacuum to obtain the film. Finally, dry it in vacuum at by a Zeta sizer Nano S90 (UK). Mechanical properties of
100°C for 24 h. Ammonia concentration in HA latex was samples were measured using GOTECH AI-3000 testing
Figure 1: (a) Schematic illustrating the fabrication process of NRMF; (b) XRD patterns of MAX (Ti3AlC2) and exfoliated MXene (Ti3C2Tx).
NRMF with robust and multifunctional properties 181
Figure 2: (a) SEM image of MAX (Ti3AlC2); (b–d) SEM images of Mxene (Ti3C2Tx).
machine. Uniaxial tensile measurements were performed 3 Results
at room temperature with a strain rate of 100 mm/min. The
specimen was a dumbbell-shaped thin strip with central
3.1 Structure characterizations
dimensions of 25 × 5 × 3 mm. Dynamic mechanical proper-
ties were measured in tensile mode on a TA Instruments
The structure evolution of Ti3C2Tx sheets is observed
Q800 with a gas cooling accessory under a nitrogen atmo-
through morphological observation and XRD scanning.
sphere for the determination of glass transition tempera-
The removal of the Al layer causes the (002) peak to
ture (Tg) and storage modulus (E′). The dimensions of the
move from 9.68° of Ti3AlC2 (JCPDS No. 52-0875) to 5.56°
specimens tested were 12 × 5 × 3 mm. The Tg and E′ were
of Ti3C2Tx (Figure 1b). The interlayer spacing increase and
determined at a heating rate of 1°C/min and a frequency of
1 Hz. Tg values were measured by taking the maximum in the tightly packed Ti3AlC2 (Figure 2a) are transformed
the loss tangent (tan δ) as the Tg values. In all cases, a into a loose-layered structure (Figure 2b–d).
preload force of 0.01 N was applied. The temperature The preparation of NRMF is achieved by forming a
range was from −100°C to 0°C. uniform dispersion of Ti3C2Tx and NR. As shown by the
Differential scanning calorimeter (DSC) curves of sam- Zeta potential (Figure 3a), a uniform NR/Ti3C2Tx disper-
ples were obtained on TA Instruments Q100 under a sion is formed. Figure 3b and c show cross-section photo-
nitrogen atmosphere. The temperature range was from graphs of cure NRF and NRMF-1. Although foam composed
−70°C to 0°C, and the heating rate was 10°C/min. The of non-uniform cell size with irregular shape, generally,
EMI shielding performance was analyzed by a AGILENT the holes are evenly distributed. Through SEM and TEM,
E5071C within the frequency range of 8.2–12.4 GHz and the the overall distribution of MXene sheets in NR was verified
dimensions of the specimens tested were 23 × 10 × 2 mm. (Figure 3d–h). Taking NRMF-3 as an example, the minimum
Electrical conductivities of nanocomposites were mea- layer spacing is 1.59 nm of MXene, which is shown in the
sured with a 4-probe Tech ST-2253 resistivity meter at inset in Figure 3h. In addition, the bright outline in the
room temperature and the dimensions of the specimens energy-dispersive spectroscopy (EDS) element mapping is
tested were 12 × 5 × 3 mm. consistent with the distribution of the Ti and F elements in
182 Ya-Dong Yang et al.
Figure 3: (a) Zeta potentials of different MXene copies to natural rubber latex; (b and c) SEM images of cure NRF and NRMF-1; (d–f) SEM
images of NRMF-3; (g and h) TEM images of NRMF-3; the inset of (h) is high-resolution TEM of MXene sheets; and (i) EDS elemental mapping.
MXene, and the light-colored area is the natural rubber thickness after compression is tested to characterize its
mainly containing C and O elements (Figure 3i). rebound rate. After adding MXene, excellent elasticity of
NRMF is still maintained, as shown in Table 1. Figure 4a
depicts the typical stress–strain curves of NRMF. Happily,
3.2 Mechanical properties of NRMF MXene shows a significant enhancement effect on NRF.
Specifically, compared with pure NRF (0.35 MPa), the
Due to their porous structure, polymer foam materials tensile strengths of NRMF-2 (0.60 MPa) and NRMF-3
often possess excellent elasticity and poor mechanical (0.55 MPa) are significantly increased by 171% and
properties. When the expansion ratio is four times, the 157%. At the same time, the percentage of breaking elon-
thickness is compressed to 50% for 22 h, and the recovery gation of the samples increased from NRF (645%) to
Table 1: Resilience rate of NRMF
NRMF sample NRF NRMF-1 NRMF-2 NRMF-3 NRMF-4 NRMF-5
Initial thickness (mm) 15.8 14.2 14.7 15.6 14.8 15.0
Compressed thickness (mm) 15.1 13.6 13.9 14.9 14.0 14.2
Resilience rate (%) 95.7 95.8 94.6 95.5 94.6 94.7
NRMF with robust and multifunctional properties 183
Figure 4: (a) Representative stress–strain curves. (b) DSC heat flow curves of samples.
NRMF-3 (689%), and the elasticity of the sample was and NRMF-3 (−55.7°C) is consistent with DSC results
further improved. However, although NRMF-4 and (Figure 5b).
NRMF-5 have improved compared with pure NRF, the
comparison between NRMF-2 and NRMF-3 has declined.
Due to the nanosheet structure of MXene, we believe
that as the number of additions increases, its agglomera- 3.3 Electrical and EMI shielding properties
tion in NRF affects the further improvement of perfor- of NRMF
mance. Tg of NRMF-2 reaches the highest temperature,
at which MXene limits the movement of rubber networks With the increasing use of electronic devices and rapid
(Figure 4b). expansion of telecommunication networks, for polymer
To further resolve the changes in molecular structure nanocomposites with excellent flexibility, it is very
network, dynamic mechanical analyzer is used to obtain necessary to have EMI shielding applications to expand
the temperature dependence of storage modulus (E′) their scope of use. The layered network of MXene is con-
and loss factor (tan δ) curves. NRMF-2 (4,008 MPa) and ducive to multiple scattering and interface polarization of
NRMF-3 (2,606 MPa) storage modulus are greatly incident electromagnetic waves. The incident waves can
improved compared to NRF (923 MPa), as shown in be mostly dissipated and attenuated, which significantly
Figure 5a. Another important phenomenon is that tan δ increases the absorption contribution. NRMF-2 and
peak of samples shifts toward higher temperature, such a NRMF-3 conductivities are two orders of magnitude
Tg changing trend of NRF (−56.1°C) to NRMF-2 (−55.3°C) higher than that of NRF, and EMI shielding is also
Figure 5: (a) Temperature-dependent curves of storage modulus (E′) and (b) temperature dependent curves of tan δ.
184 Ya-Dong Yang et al.
Figure 6: (a) Electrical conductivities, (b) total EMI shielding effectiveness (SET), (c) microwave reflection (SER), and (d) microwave
absorption (SEA) of NRMF nanocomposites at different MXene loadings.
significantly improved in Figure 6. With the increase in Sciences (No. XDC06010100) and the Startup Funding and
the number of MXenes added to the natural rubber latex, the Scientific Research Foundation of Hainan University (No.
the NRMF performance decreases due to agglomeration. KYQD(ZR)1988).
Author contributions: Ya-Dong Yang: investigation and
writing – original draft; Gui-Xiang Liu: investigation;
4 Conclusions Yan-Chan Wei: formal analysis; Shuangquan Liao:
resources and writing – review and editing; Ming-Chao
In this article, robust and multifunctional composites of Luo: conceptualization, writing – original draft, and writing –
NRMF are prepared by Dunlop processes. Consequently, review and editing.
compared with pure NRF, the tensile strengths of NRMF-2
and NRMF-3 are significantly increased by 171% and Conflict of interest: The authors declare no competing
157%, Tg increases by about 0.8–1°C. Moreover, nano- financial interests or personal relationships that could
composite foaming shows the electrical conductivity of have appeared to influence the work reported in this
6.18 × 10−4 Sm−1 and an EMI shielding performance of article.
6.0 dB with NRMF-2. This work provides a simple way
to manufacture high-strength elastic foams with elec-
trical conductivity and EMI shielding capabilities, which
expands the potential applications of natural latex foam References
materials.
(1) Parsa M, Trybala A, Malik DJ, Starov V. Foam in pharmaceutical
Research funding: This work was supported by the Strategic and medical applications. Curr Opin Colloid.
Priority Research Program of the Chinese Academy of 2019;44:153–67.NRMF with robust and multifunctional properties 185
(2) Beneš H, Vlčková V, Paruzel A, Trhlíková O, Chalupa J, (19) Rathnayake WGIU, Ismail H, Baharin A, Bandara IMCCD,
Kanizsová L, et al. Multifunctional and fully aliphatic bio- Rajapakse S. Enhancement of the antibacterial activity of
degradable polyurethane foam as porous biomass carrier for natural rubber latex foam by the incorporation of zinc oxide
biofiltration. Polym Degrad Stab. 2020;176:109156–66. nanoparticles. J Appl Polym Sci. 2014;131:39601–8.
(3) Maréchal M, Estrada EC, Moulin G, Almeida G, Lv P, Cuvelier G, (20) Rathnayake I, Ismail H, Azahari B, Bandara C, Rajapakse S.
et al. New insulating and refractory mineral foam: structure Novel method of incorporating silver nanoparticles into nat-
and mechanical properties. Mat Sci Eng A. ural rubber latex foam. Polym-Plast Technol. 2013;52:885–91.
2020;780:193153–67. (21) Rathnayake I, Ismail H, Azahari B, Darsanasiri ND,
(4) Stochero NP, de Moraes EG, Moreira AC, Fernandes CP, Rajapakse S. Synthesis and characterization of nano-silver
Innocentini MDM, Novaes de Oliveira AP. Ceramic shell incorporated natural rubber latex foam. Polym-Plast Technol.
foams produced by direct foaming and gelcasting of 2012;51:605–11.
proteins: permeability and microstructural characterization (22) Rathnayake I, Ismail H, Azahari B, De Silva C, Darsanasiri N.
by X-ray microtomography. J Eur Ceram Soc. Imparting antimicrobial properties to natural rubber latex
2020;40:4224–31. foam via green synthesized silver nanoparticles. J Appl Polym
(5) Lee L, Zeng C, Cao X, Han X, Shen J, XU G. Polymer nano- Sci. 2014;131:40155–64.
composite foams. Compos Sci Technol. 2005;65:2344–63. (23) Zhang N, Cao H. Enhancement of the antibacterial activity of
(6) Zhang H, Liu T, Li B, Li H, Cao Z, Jin G, et al. Anti-shrinking natural rubber latex foam by blending it with chitin. Materials.
foaming of polyethylene with CO2 as blowing agent. J Supercrit 2020;13:1039–54.
Fluids. 2020;163:104883–92. (24) Ramasamy S, Ismail H, Munusamy Y. Soil burial, tensile
(7) Jiang S, Agarwal S, Greiner A. Low-density open cellular properties, morphology, and biodegradability of (rice husk
sponges as functional materials. Angew Chem Int Ed. powder)-filled natural rubber latex foam. J Vinyl Addit Techn.
2017;56:15520–38. 2015;21:128–33.
(8) Garcia NG, Dos Reis EAP, Budemberg ER, Agostini DLSS, (25) Naguib M, Kurtoglu M, Presser V, Lu J, Niu J, Heon M, et al.
Salmazo LO, Cabrera FC, et al. Natural rubber/leather waste Two-dimensional nanocrystals produced by exfoliation of
composite foam: a new eco-friendly material and recycling Ti3AlC2. Adv Mater. 2011;23:48–53.
approach. J Appl Polym Sci. 2015;132:41636–45. (26) Alhabeb M, Maleski K, Anasori B, Lelyukh P, Clark L, Sin S,
(9) Wei YC, Liu GX, Zhang L, Xu WZ, Liao S, Luo MC. Mimicking et al. Guidelines for synthesis and processing of two-dimen-
mechanical robustness of natural rubber based on sacrificial sional titanium carbide (Ti3C2Tx MXene). Chem Mater.
network constructed by phospholipids. ACS Appl Mater 2017;29:7633–44.
Interfaces. 2020;12:14468–75. (27) Naguib M, Gogotsi Y. Synthesis of two-dimensional materials
(10) Wang S, Huang D, Guo C, Yuan Q, Chen Y, Lin P, et al. Bottom by selective extraction. Acc Chem Res. 2015;48:28–35.
fire behaviour of thermally thick natural rubber latex foam. (28) Zhao X, Vashisth A, Prehn E, Sun W, Shah SA, Habib T, et al.
e-Polymers. 2019;19:9–14. Antioxidants unlock shelf-stable Ti3C2Tx (MXene) nanosheet
(11) Bayat H, Fasihi M. Effect of coupling agent on the morpho- dispersions. Matter. 2019;1:513–26.
logical characteristics of natural rubber/silica composites (29) Fang R, Lu C, Chen A, Wang K, Huang H, Gan Y, et al. 2D MXene-
foams. e-Polymers. 2019;19:430–6. based energy storage materials: interfacial structure design
(12) Yu WW, Xu WZ, Xia JH, Wei YC, Liao S, Luo MC. Toughening and functionalization. ChemSusChem. 2020;13:1409–19.
natural rubber by the innate sacrificial network. Polymer. (30) Yu H, Wang Y, Jing Y, Ma J, Du CF, Yan Q. Surface modified
2020;194:122419–25. MXene-based nanocomposites for electrochemical energy
(13) Perera SJ, Egodage SM, Walpalage S. Enhancement of conversion and storage. Small. 2019;15:1901503–22.
mechanical properties of natural rubber–clay nanocomposites (31) Gou GY, Jin ML, Lee BJ, Tian H, Wu F, Li YT, et al. Flexible two-
through incorporation of silanated organoclay into natural dimensional Ti3C2Tx MXene films as thermoacoustic devices.
rubber latex. e-Polymers. 2020;20:144–53. ACS Nano. 2019;13:12613–20.
(14) Tessanan W, Phinyocheep P, Daniel P, Gibaud A. Microcellular (32) Guo Q, Zhang X, Zhao F, Song Q, Su G, Tan Y, et al. Protein-
natural rubber using supercritical CO2 technology. J Supercrit inspired self-healable Ti3C2Tx MXenes/rubber-based supra-
Fluids. 2019;149:70–8. molecular elastomer for intelligent sensing. ACS Nano.
(15) Ariff ZM, Zakaria Z, Tay LH, Lee SY. Effect of foaming tem- 2020;14:2788–97.
perature and rubber grades on properties of natural rubber (33) Hong Ng VM, Huang H, Zhou K, Lee PS, Que W, Xu JZ, et al.
foams. J Appl Polym Sci. 2008;107:2531–8. Recent progress in layered transition metal carbides and/or
(16) Ramasamy S, Ismail H, Munusamy Y. Tensile and morpho- nitrides (MXenes) and their composites: synthesis and appli-
logical properties of rice husk powder filled natural rubber cations. J Mater Chem. 2017;5:3039–68.
latex foam. Polym-Plast Technol. 2012;51:1524–9. (34) Yang W, Liu J-J, Wang L-L, Wang W, Yuen ACY, Peng S, et al.
(17) Kudori SNI, Ismail H, Khimi SR. Tensile and morphological Multifunctional MXene/natural rubber composite films with
properties on kenaf core or bast filled natural rubber latex exceptional flexibility and durability. Compos Part B-Eng.
foam (NRLF). Mater Today Proc. 2019;17:609–15. 2020;188:107875–85.
(18) Bashir ASM, Manusamy Y, Chew TL, Ismail H, Ramasamy S. (35) Luo J-Q, Zhao S, Zhang H-B, Deng Z, Li L, Yu Z-Z. Flexible,
Mechanical, thermal, and morphological properties of (egg- stretchable and electrically conductive MXene/natural rubber
shell powder)-filled natural rubber latex foam. J Vinyl Addit nanocomposite films for efficient electromagnetic interference
Techn. 2017;23:3–12. shielding. Compos Sci Technol. 2019;182:107754–63.You can also read
