Thermal and morphological properties of epoxy matrix with chemical and physical hybrid of CNTs and nanoclay

Elnaz Esmizadeh 1, Ali Akbar Yousefi*1, Ghasem Naderi 1, Candida Milone 2

a Faculty of Polymer Processing, Iran Polymer and Petrochemical Institute (IPPI), P.O. Box 14965/115, Tehran, Iran

b Dipartimento di Chimica Industriale e Ingegneria dei Materiali, Facoltà di Ingegneria, Università di Messina, 98166 Messina, Italy

* Corresponding author. Tel: 98 21 44580000, E-mail: A.yousefi@ippi.ac.ir

Abstract: Synergistic effects of nanoclay and CNTs as physical and chemical hybrid on properties of epoxy matrix were studied. High-

temperature decomposition of methane was utilized for synthesis of carbon nanotube (CNT) on nanoclay supports to form chemical hybrid of CNT-

clay (CNC). The organo-modification of montmorillonite (MMT) before catalyst insertion is proposed as a priori to increase CNT yield on nanoclay

supports up to 100% obtained by thermogravimetric analysis (TGA). Formation of CNTs on nanoclay surface is confirmed by transmition electron

microscopy (TEM), scanning electron microscopy (SEM). The process followed by the incorporation of as-prepared CNCs into epoxy matrix to make

Epoxy-CNC composites. Physical mixture of commercial CNTs and nanoclay as physical hybrid of CNT-clay (PNC) was introduced into epoxy matrix

in order to fabricate Epoxy-PNC composites. The performance of the epoxy composites filled with CNT-clay hybrids interlinked with the type of filler

is investigated.

Keywords: Carbon nanotubes; Nanoclay; Catalytic Vapour Deposition; Epoxy; Thermal behavior

Introduction Among various methods of synthesizing carbon

nanotubes chemical vapour deposition (CVD) is

the most versatile one to scale up [1]. CVD is

suitable for the CNT synthesis on substrates called

supports [2]. Clay minerals have drawn extensive

attention as catalyst support of CVD [3]. The

objective of this work is to synthesis the chemical

hybrid of CNT-clay (CNC) by CVD method and

compare the influence of CNC with physical

hybrid of CNT-clay (PNC) in epoxy matrix.

Materials and method Organo-modified clay as the CVD support

Cloisite® 15A purchased from Southern Clay

Products (USA). Metal nitrates (Merck), reaction

gases (Roham-Iran) were used as received. The

polymer matrix (Araldite LY 5052/Aradur HY

5052, Huntsman, Switzerland) was used as epoxy

along with a hardener based on modified

cycloaliphatic amines [4]. Fe-loaded supports are

prepared according to Ref [5]. Growth of CNTs

was carried out using the methane CVD process

950°C. Once the temperature reached to CH4 (30

mL/min) is introduced into the reactor. The CNC

product was characterized by SEM, TEM, TGA.

Then, CNC and PNC were mixed with epoxy at

0.2 wt% by mechanical stirring for 15 min at 900

rpm and sonicated for 30 min.

Results and discussions SEM and TEM images (Figure 1) present an

overview of the synthesized carbon nanostructures

grown on metal catalysts. It is obvious that Fe is

capable to grow carbon nanostructures. TEM

image shows the CNTs with the encapsulated Fe

nanoparticles or nanorods inside them. TGA

results indicate that the yield of CNT on clay is

100%.

Figure 1. SEM and TEM images Fe-loaded nanoclay after

methane CVD

Figure 2 illustrates the effect of CNC and PNC

on the storage modulus (E') and tan δ of Epoxy

nanocomposites. In all nanocomposite samples,

the peak of tan δ is higher than the unfilled

sample. This is an indication that high interactions

between polymeric chains and filler made the

movement of polymer chains more restricted.

Figure 2. DMTA storage modulus and tan δ of epoxy

nanocomposites

Figure 3. HDT of epoxy nanocomposites

Heat distortion temperature (HDT) curve (Figure

3) shows that at a loading of only 0.2 wt.% CNC,

the heat distortion temperature (HDT) increased

by 10 °C compared to the pristine polymer which

causes the highest increase comparing the other

nanofiller (PNC).

TGA results (Figure 4) show that introduction of

CNC and PNC increased the thermal stability of

Epoxy matrix. This is more pronounced in the

case of chemical hybrid of CNT and clay.

Figure 4. TGA and DTA of Epoxy nanocomposites

Figure 5. SEM micrograph of Epoxy-CNC

The high roughness of the fracture surface in

Epoxy-CNC (Figure 5) confirmed good

interaction between polymer matrix and

nanofiller.

Conclusion Fe-loaded clays produced CNTs with 100% yield

after CVD of methane at 950 °C.

Chemical hybrid (CNC) is more effective than

in increasing HDT, Tg and Degradation

temperature.

SEM confirms good interaction between CNC

and Epoxy matrix.

References 1. M. Lu et al. Journal of Materials Science 40 (2005) 3545-3548.

2. P. Zarabadi-Poor et al. Catalysis Today 150 (2010) 100-106.

3. M.-Q. Zhao et al. Applied Clay Science 53 (2011) 1-7.

4. H-S Kim et al. Journal of Nanoscience and Nanotechnology 10

(5):3576-3580.

5. W.-D. Zhang et al. Advanced Materials 18 (2006) 73-77.

85

90

95

100

105

Epoxy Epoxy-CNC Epoxy-PNC

HD

T (°C

)