# Polystyrene-Sepiolite Clay Nanocomposites with Enhanced Mechanical and Thermal Properties  
[PERSON]  
1 School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), Islamabad 44000, Pakistan 1  
[PERSON]  
2 School of Natural Sciences (SNS), National University of Science and Technology (NUST), Islamabad 44000, Pakistan 23 Department of Chemistry, University of Wah, Quid Avenue, Wah Cantt, Rawalpantid 47040, Pakistan 3  
[PERSON]  
1 School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), Islamabad 44000, Pakistan 1  
[PERSON]  
1 School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), Islamabad 44000, Pakistan 1  
[PERSON]  
4 Research and Development (R & D) Section, National University of Technology NUTECH, Islamabad 44000, Pakistan 4  
[PERSON]  
5 Department of Chemical Engineering & Materials Science, Michigan State University (MSU), East Lansing, MI 48824, USA 5  
[PERSON]  
6 School of Packaging, Michigan State University, 448 Wilson Rd, East Lansing, MI 48824, USA 6  
[PERSON]  
5 Correspondence: [EMAIL_ADDRESS]; Tel. : +92-51-9085-5212  
clay was used in nylon-based composites by [PERSON] et al. in 1993, capturing the attention of many researchers and motivating them to explore many other formulations [14]. Recently, the trend has been shifted toward needle-like, low-cost sepiolite clay [15]. A considerable amount of published data is available regarding polymer/clay nanocomposites, which address the lamellar layered silicates targeting the montmorillonite and examining the intercalation and exfoliation of the clay; however, polymer/sepiolite nanocomposites is a relatively new area of interest to the researchers. Polystyrene is broadly used worldwide as a commercial polymer. At present, nanocomposites of polystyrene are prepared by various methods, such as in situ polymerization, solution casting and melt intercalation [16; 17; 18; 19]. These three methods are used discretely or in combination. However, polystyrene is not generally preferred as an engineering plastic because of its higher brittleness [20]. To counter this bottleneck, high-impact polystyrene (HIPS) is used for a wider range of applications in several industries. HIPS contains only 5-8% of butadiene, which helps in increasing the impact resistance and provides greater dimensional stability and excellent machinability [21; 22]. These properties facilitate outstanding processing and molding of the materials. However, higher flammability and lower chemical stability in organic solvents are concerning issues, which need to be addressed using specific fillers. Nano clays are extensively probed for the manufacturing of polymeric nanocomposites. These materials are preferred because of the abundant availability, low cost, and eco-friendly nature [23; 24; 25]. The clays commonly used with polystyrene are montmorillonite, bentonite, hectorite and kaolinite. The cation exchange capacity of montmorillonite clay usually ranges around 110 meq/100 g; hectorite clay has 120 meq/100 g, and kaolinite clay has 86.6 meq/100 g [26; 27]. These clays can be dissolved only in hydrophilic polymers, such as poly (ethylene oxide) and poly (vinyl alcohol). It is essential to convert these clays into organophilic nature to make them compatible with hydrophobic polymers [28; 29; 30]. For the preparation of nanocomposites, clay should be selected based on its ordinary surface charge. Sepiolite is composed of magnesium silicate Mg\({}_{4}\)Si\({}_{6}\)O\({}_{15}\)(OH)\({}_{2}\).6H\({}_{2}\)O. It is available in fibers, particles, and fine powder form [31]. It is highly porous in nature with low specific gravity that varies from 0.988 to 1.279 and surface area (95 to 400 m\({}^{2}\)/g) [32]. Octahedral magnesium is sandwiched between two tetrahedral sheets of silica.