Property improvement of room temperature vulcanized silicone elastomer by surface-modified multi-walled carbon nanotube inclusion

doi:10.1016/j.jallcom.2015.10.129

Journal of Alloys and Compounds

Volume 657, 5 February 2016, Pages 472-477

https://doi.org/10.1016/j.jallcom.2015.10.129 Get rights and content

Highlights

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Surface modification of MWCNTs is crucial for property improvement of RTV silicone rubber composites.
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Well dispersion of MWCNTs treated by polydimethylsiloxane solution in silicone rubber was achieved.
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Properties of silicone rubber were improved by using polydimethylsiloxane solution modified MWCNTs.

Abstract

Room temperature vulcanized (RTV) silicone rubber composites reinforced by multi-walled carbon nanotubes (MWCNTs) were prepared. The effect of surface modification methods and MWCNT contents on the properties of the RTV silicone rubber composites was investigated. The properties of the composites were improved when the treated MWCNTs were used. After treated by polyester-modified polydimethylsiloxane solution (BKY-310), the MWCNTs were uniformly dispersed in the silicone rubber matrix. When 5 phr of MWCNTs was added, the composite achieved good comprehensive performance. Its tensile strength, tear strength, elongation and onset decomposition temperature reach 2.0 MPa, 11.7 kN/m, 238% and 510 °C, respectively. But the above said values for the composite with untreated MWCNTs are only 1.1 MPa, 7.0 kN/m, 83% and 484 °C, respectively.

Introduction

Carbon nanotubes (CNTs) have attracted a great deal of interest because of their excellent properties [1], [2]. As one kind of multifunctional fillers, CNTs have been widely used in rubbers/elastomers [3], [4], [5], [6], [7], [8], [9], [10]. It is well known that a homogeneous dispersion of CNTs in rubber matrix and a strong bonding force between each other are the key factors for property improvement. Various methods have been exploited to improve the dispersion of CNTs in rubber matrix and to strengthen the binding force between them: 1) rubber processing or CNT-dispersion method improvement: melt compounding [8], kneader dispersion [9], ultrasonication coupling “rotation-revolution” mixing [11]; 2) CNT treatment: surface graft or encapsulation [3], [4], [5], [12], [13], [14], surfactant modification [10], [13], chitosan salt or graphene assisted dispersion [15], [16].

Room temperature vulcanized (RTV) silicone rubber is one of the important synthetic elastomers. RTV silicone rubber not only has the general characteristics of silicone rubber (excellent flexible at low temperature, heat stability, abrasion resistance, low flammability and durability) [17], but also is easy to use and mold. Thus, it has wide applications in building industry, automotive industry, healthcare, aerospace [17], [18]. As we know, silicone rubber without any reinforcement has very low strength and no actual application. Many methods have been used to improve the property of RTV silicone rubber, especially for filler adding. Various fillers were applied, such as silica nanoparticles, montmorillonite, carbon fibers, CNTs and graphene [19], [20], [21], [22], [23]. As above said, a well dispersion of CNT in rubber and strong bonding force between CNT and rubber matrix are still the key factors for property improvement of CNT/silicone rubber composite. Usually, different methods were used according to the rubber matrix. But there are only few reports about the CNT/RTV silicone rubber composite. In this paper, we prepared RTV silicone rubber composites containing multi-wall CNTs (MWCNTs), and investigated the effect of surface modification methods and contents of MWCNTs on their dispersion in silicone matrix and the mechanical, thermal, ablation properties of the composites.

Section snippets

Materials

RTV silicone (107#, 99 wt.%), 3-aminopropyltriethoxysilane (KH550, AR), tetraethyl orthosilicate (AR) and dibutyltin dilaurate (AR) were purchased from Shanghai Resin Factory Co., Ltd. Fumed silica (AS-380, ≥99.8 wt.%,) was purchased from Shenyang Chemical Co., Ltd. Four kinds of surface-modifying additives were supplied by BYK Chemical Inc: methoxypropylacetate solution of a structured acrylate copolymer with pigment affinic groups (Disperbyk-2025, non-volatile matter: 70 wt.%),

Results and discussion

TEM images in Fig. 1 show that the raw and acid-treated MWCNTs have straight morphology and smooth walls. The diameters of most raw MWNTs are in the range of 40–90 nm. Fig. 2 is the IR spectra of the MWCNTs before and after acid treatment. For the untreated MWCNTs, main peaks locate at around 1100 cm⁻¹ (C–O stretching), 1620 cm⁻¹ (C double bond C stretching of MWCNT backbone) and 3440 cm⁻¹ (bending vibration of –OH group). New peaks appear in the spectrum of the acid-treated MWCNTs at about 1200, 1300, 1700

Conclusions

In conclusion, MWCNT-contained silicone rubber composites were prepared and the effect of MWCNT treatment methods and contents on the mechanical, thermal, ablation properties of the composites was studied. When the treated MWCNTs were used, the properties of the composites were improved, especially for MWCNTs treated by xylene solution of a polyester modified polydimethylsiloxane (BYK-310). The tensile and tear strengths of this composite are 2.0 MPa and 11.7 kN/m, respectively. The above

Acknowledgment

This work was supported by the Fundamental Research Funds for the Central Universities of China (JD1406).

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Property improvement of room temperature vulcanized silicone elastomer by surface-modified multi-walled carbon nanotube inclusion

Highlights

Abstract

Introduction

Section snippets

Materials

Results and discussion

Conclusions

Acknowledgment

Comp. Sci. Technol.

J. Ind. Eng. Chem.

Compos. Sci. Technol.

J. Phys. Chem. Solids

Appl. Surf. Sci.

J. Colloid Interface Sci.

Compos. Sci. Technol.

Chem. Phys. Lett.

Mater. Sci. Eng. A

Compos. Sci. Technol.

Compos. Sci. Technol.

Mater. Sci. Eng. A

Mater. Res. Bull.