Thermo-Mechanical and Thermal Properties of Binary Particle Nanocomposite Exposed to Sea Water Conditioning

Research Article

Ann Materials Sci Eng. 2018; 3(1): 1029.

Thermo-Mechanical and Thermal Properties of Binary Particle Nanocomposite Exposed to Sea Water Conditioning

Tcherbi-Narteh A*, Mohammad Z, Hosur M and Jeelani S

Department of Materials Science Engineering, Tuskegee University, USA

*Corresponding author: Tcherbi-Narteh A, Department of Materials Science Engineering, 127 Chappie James Center, Tuskegee University, Tuskegee, Alabama 36088, USA

Received: May 04, 2018; Accepted: June 05, 2018; Published: June 12, 2018


Objective of this study was to explore binary nanoparticles consisting of Montmorillonite nanoclay Nanomer® I.30E (MMT) and amine functionalized Graphene Nanoplatelets (GNP) as reinforcements in epoxy SC780 composite to minimize seawater absorption and its impact on material properties. Composite samples fabricated were 2 and 3 wt % MMT; 0.1 and 0.2 wt % GNP and binary nanocomposites consisting of 3 wt % MMT/0.1 wt % GNP and conditioned by complete immersion into seawater at room temperature for 240 days. Viscoelastic and thermal properties were characterized prior to and post conditioning using Dynamic Mechanical Analysis (DMA), Thermo-Mechanical Analysis (TMA) and Thermogravimetric Analysis (TGA) respectively. Binary nanocomposites absorbed the least amount of seawater, while 3 wt % MMT and 0.2 wt % GNP absorbed the most. Storage modulus of unconditioned binary nanocomposite increased by nearly 29% compared to neat; however, it showed the highest reduction after conditioning among all samples including neat. Binary samples also showed better dimensional stability at elevated temperatures prior to and post conditioning when compared to all samples. Nanocomposites showed relatively lower glass transition temperatures compared to neat samples.

Keywords: Thermo-mechanical; Binary nanoparticles; Seawater absorption; Nanocomposites


Application of nanoparticles to enhance properties of polymeric composite materials have been widely studied leading to the development of advanced polymer materials with enhanced properties [1-3]. Enhanced barrier and viscoelastic properties of polymer composites are particularly of great importance to marine applications, where most structures are exposed to prolong seawater conditioning. Other targeted properties of polymer include enhanced durability through minimization or delayed detrimental effects of service and environmental factors over time [4,5]. Increasing demand for advanced composite materials across different industries has given rise to the development of next generation state of the art advanced materials systems with multi-functionality. Development of polymer composite systems with multi-functional capabilities requires a thorough understanding of material systems including the use of multiple nanofillers. In recent years binary or hybrid nanoparticles systems have been gaining research attention, where two characteristically different nanoparticles are dispersed together in polymer systems to enhance various material properties [6-8]. Thus, desirable properties of each nanoparticle are targeted and harnessed through their interactions with each other and host polymer resulting in composites with multi-functionality.

Research in this area is however new and requires careful selections of materials with complete understanding of interphase and interfacial chemistry of nanoparticles and appropriate polymer [9,10]. Additionally, the role of individual and combined nanoparticles on chemico-physical and chemico-rheological properties of the polymer is of significant importance. This leads to the development of customized parameters necessary for processing such combination and ultimate curing of the final composite [11,12]. Generally, enhanced properties of polymers by nanoparticles have been attributed to structural morphologies, degree of dispersion throughout the polymer, and interfacial interaction between nanoparticles and host polymers and degree of cure [12,13]. Degree of cure in polymers has been influenced by the type and concentration of nanoparticles present in the polymeric systems [14].

Targeted properties of most materials used in marine and outdoor applications include ability to resist corrosion, minimize moisture absorption and withstand impact of other environmental factors. Polymer composites display such characteristics and hence widely used in marine industries including painting and coating. However, there is a major drawback associated with polymers, thus they are sensitive to temperature, certain basic and acidic solution conditions, and are prone to moisture absorption due to their viscoelastic nature [15].

Numerous studies have been conducted on durability of polymeric composites exposed to different environments using different nanoparticles. These include exposure to UV radiation, extreme temperatures, moisture, alkaline solution, and other fluids [4,5,16]. Moisture aging induces physico-chemical changes in polymer composites, which tend to degrade the material properties over time [16]. These changes include swelling of the matrix by hydrolysis affecting dimensional stability and plasticization, which deteriorates interfacial bonding between fibers and the matrix in Fiber Reinforced Polymer Composite (FRPC), affecting both the mechanical and thermo-mechanical properties [15,16]. Abanilla et al. [17] Studied the effects of alkali solution, freeze-thaw and accelerated aqueous exposure on graphite/epoxy composite and concluded that the strength of the matrix and overall composite degraded mostly due to moisture absorption. They also reported no significant change in the modulus of the composite. Zainuddin et al., [5] reported reduced degradation activities in strength and modulus of the composite samples reinforced with nanoclay and subjected to hot and cold environments. Tcherbi-Narteh et al., studied the effects of UV radiation and associated temperatures on properties of polymer nanocomposites materials [4,12]. The use of nanoparticles as reinforcement in polymer composites has shown significant progress in mitigating some of the impacts from environmental elements.

Graphene nanoplatelets and montmorillonite nanoclays are both two-dimensional nanoplatelets with dimensions commonly used as nano-reinforcements in polymeric composites. In recent years, both have attracted significant attention due to relatively low cost and remarkable enhancements in polymeric composites [1- 3]. Morphologies of MMT and GNP infused polymer composite material exhibit similar states and their targeted properties depend on processing, concentration, chemical compatibility and distribution within the host matrix. Modulus and intrinsic strength of GNP are 1 TPa and 130 GPa respectively, 50 times stronger than steel, with surface area twice as Carbon Nanotubes (CNT) [13]. MMT also displays similar aspect ratios to that of graphene-based filler materials; however, MMT has higher density compared to GNP. In recent years, properties of polymer matrix used in FRPC materials have been modified continually to offset some of these environmental challenges using variety of systems. Significant amount of information has been acquired through studies regarding rates and absorption mechanisms based on the type of reinforcements, polymers and exposed medium [18]. In the current study, two high aspect ratio nanoparticles GNP and MMT with distinct characteristic were used as reinforcements individually and as binary reinforcements to enhance properties of SC-780 epoxy composites. Epoxy samples were fabricated using individual nanoparticles and binary consisting of 3 wt % MMT/0.1 wt % GNP (MMT/GNP) respectively. Fabricated samples were conditioned in seawater for 240 days and various properties characterized. Mechanical and thermal properties were characterized using three-point bending flexure tests, Dynamic Mechanical Analyses (DMA) and Thermo-Mechanical Analysis (TMA). Properties of binary systems were compared to those of unmodified and modified epoxy composites loaded with individual nanoparticles.



A two-part diglycidyl ether of bisphenol A based epoxy, SC-780 consisting of Part A (resin) and part B (curing agent or hardener) from Applied Poleramics Inc. and used in the study. Mixing ratio of the epoxy resin part A and part B is 100:22 by mass. Two different nanoparticle reinforcements used in the study. Graphene Nanoplatelets (GNP) was obtained from ACS Materials LLC, (USA) with particle thickness between 2-10 nm, and Montmorillonite Nanoclay (MMT) was purchased from Sigma Aldrich. Surface of MMT has been modified with 20 - 35 wt % octadeclyamine with average particle size of 10 - 12 nm and sold under the trade name Nanomer® I.30E.

Fabrication of epoxy nanocomposite

Fabrication of unmodified and modified epoxy composites using different loadings of various nanoparticles was done by first dispersing these nanoparticles into part A of epoxy resin. Samples fabricated were 0.1 and 0.2 wt % GNP, 2 and 3 wt % MMT and MMT/ GNP epoxy nanocomposite samples. Measured amount of MMT was dried in a vacuum oven at temperature 50°C for two hours, due to hydrophilic nature of organoclay. MMT/SC780 was magnetically stirred at 400 rpm for 24 hours at room temperature. Calculated amount of GNP was mixed in the epoxy resin, stirred manually followed by ultrasonication for 1 hour. Sonication parameters used were pulse rate of 20sec on and 30secs off using 45 % amplitude, while maintaining the mixture in a cooling bath set at 40° C for both GNP and hBN samples respectively. Sonicated mixture of GNP/SC-780 was magnetically stirred to further disperse for about six hours at 400 rpm. GNP/SC780 mixture was further processed using three-roll shear mixer with gap between the rollers set at 15, 10 and 5μm with speed of rollers at 120 rpm for three passes. For binary nanocomposite fabrications, measured amount of resin was divided into two unequal parts in beakers. Calculated amount of dried nanoclay was mixed and magnetically stirred in the larger portion for 15 hours, while determined amount of GNP nanoparticles were dispersed in the other part of resin part A and sonicated at the same conditions discussed earlier. Sonicated GNP/resin mixture was added to nanoclay mixed resin solution and combined mixture was subsequently processed through three-roll shear mixer using parameters discussed earlier followed by magnetic stirring for six hours. SC-780-part B was added to each nanoparticle dispersed part A, mechanically stirred and degasified using “Thinky” vacuum mixer for 15 minutes, at 30 kPa pressure and 1500 rpm. Figure 1 shows summary of the fabrication of unmodified and modified epoxy nanocomposites.