A novel biodegradable nanocomposite based on poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) and silylated kaolinite/silica core–shell nanoparticles

a r t i c l e i n f o Keywords: Biodegradable polymer PHBHHx Kaolin Core–shell nanoparticle Nanocomposite A novel biodegradable nanocomposite was fabricated based on poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and silane-modified kaolinite/silica core–shell nanoparticles (SMKS), via solution-casting method using chloroform as solvent. Unmodified (ORK) and glycidoxypropyltrimethoxysilane (G-silane) surface-modified kaolin (SMK) were also introduced into PHBHHx matrix for comparison. SMKS significantly improved the mechanical properties of the PHBHHx compared to that of ORK and SMK. The composite filled with a low loading of SMKS increased the tensile strength and toughness from 18.2 to 23.5 MPa and 2.6 to 4.2 MPa, respectively. Transmission electron microscopy (TEM) indicated that SMKS was finely distributed in the PHBHHx matrix compared with the other two kinds of fillers. These significant improvements in these mechanical properties were attributed to the fine dispersion of SMKS into the polymer and covalent interaction between polymer chains and the surface of SMKS. Recently, an increasing number of biodegradable polymers have been developed, with the aim to solve the environmental problem caused by the disposal of large volumes of non-biodegradable materials (Okada, 2002; Alata et al., 2007; Williams, 2007). The copolymer PHBHHx is one of the most promising biodegradable semi-crystalline aliphatic polyesters of the polyhydroxyalkanoate family This is primarily due to the fact that it has a unique combination properties, including full anaerobic degradability, moisture resistance, good barrier properties, relatively high shelf stability (under distribution and home-storage conditions), processability on conventional equipment, and easy dyeability (Furukawa et al., 2007). It has potential applications in the manufacture of storage bags, shopping bags, slip covers, coatings in automobiles and furniture (Cheng et al., 2008; Lee et al., 2008). This particular copolymer has the advantage of biodegradability, but is somewhat lacking in strength (Noda et al., 2004; Venkitachalam et al., 2005), which restricts its use in certain applications. One way to overcome this problem is to modify natural polymers by incorporation of inorganic fillers that can further extend their applications in aggressive environments. Such additions of nanoparticles to form nanocomposites has in fact been the focus of recent research to improve the performance properties of such polymers (LeBaron et al., 1999; Zhang et al., 2007; Zini et al., 2007). Examples of desired property improvements include improved thermal, mechanical, and other physical properties in comparison to the corresponding neat polymer (Ray et al. In order to achieve this, surface of nanoparticles is usually modified so …