Characterization, mechanical, and thermal properties of gamma irradiated starch films reinforced with mineral clay

Abstract

Composite fabricated from starch and different concentrations of clay was prepared by solution casting method. The casted film was irradiated to different gamma irradiation doses 10, 20, 30, and 40 kGy. The dispersion of clay into starch was investigated by using X-ray diffraction (XRD). The structural morphology of the composite was measured by scanning electron microscope and infrared spectroscopy. Film properties, such as water vapor transmission, mechanical, and thermal properties were also measured. The gel content and swelling behavior of the starch/clay composite were investigated. It was found that the gel content increases with increasing clay content and irradiation dose. The results obtained indicate that the starch/clay composite showed an increase in the tensile strength, thermal stability. Moreover, there is a decrease in water vapor transmission (WVRT) which improves its barrier properties. Both XRD and infrared spectroscopy showed that starch can be intercalated into the clay galleries. Also antibiotic drug Chlortetracycline HCl was loaded into the starch/clay composite by direct adsorption method. Chlortetracycline HCl adsorption capacity of composite was found to increase from 1.13 to 4.20 mg Chlortetracycline HCl per gram dry film with increasing amount of drug concentration. In vitro drug release studies in different buffer solutions showed that the basic parameters affecting the drug release behavior of the film are pH of the solution, drug concentration, and time.

Advanced Nano-biocomposites Based on Starch

“…(Chiou et al 2006(Chiou et al , 2007Chivrac et al 2010a;Cyras et al 2008;Dai et al 2009a;de Carvalho et al 2001;Gao et al 2012;Huang et al 2004Huang et al , 2005aIbrahim 2011;Lilichenko et al 2008;Maksimov et al 2009;M€ uller et al 2011;Pandey and Singh 2005;Park et al 2002Park et al , 2003Tang et al 2008b, c;Wang et al 2009bWang et al , 2010b, oxygen barrier property (Zeppa et al 2009), and biodegradation rate (Magalhães and Andrade 2009), generally meaning improved performance, even though the elongation at break was observed to be reduced in most studies (Chivrac et al 2008b(Chivrac et al , 2010cCyras et al 2008;Dai et al 2009a;de Carvalho et al 2001;Hassan Nejad et al 2011;Huang et al 2004Huang et al , 2005aIbrahim 2011;Ma et al 2007b;Maksimov et al 2009;Pandey and Singh 2005;Park et al 2002Park et al , 2003Qiao et al 2005;Ren et al 2009;Tang et al 2008b, c;Wang et al 2009b;Wilhelm et al 2003b). While these changes could usually be ascribed to the structur...…”

“…Starch-based systems reinforced by phyllosilicates normally exhibit increases in tensile strength (Chivrac et al 2008b(Chivrac et al , 2010dCyras et al 2008;Dai et al 2009a;de Carvalho et al 2001;Gao et al 2012;Hassan Nejad et al 2011;He et al 2012;Huang et al 2004Huang et al , 2005aHuang et al , b, 2006Ibrahim 2011;Kvien et al 2007;Lilichenko et al 2008;Ma et al 2007b;Maksimov et al 2009;Mondragón et al 2008;M€ uller et al 2011;Park et al 2002Park et al , 2003Qiao et al 2005;Ren et al 2009;Tang et al 2008bTang et al , 2008cWang et al 2009b, 2010b; Xie et al 2011), Young's modulus (Chaudhary 2008;Chivrac et al 2009bChivrac et al , 2010cCyras et al 2008;de Carvalho et al 2001;Hassan Nejad et al 2011;He et al 2012;Huang et al 2004Huang et al , 2005aLilichenko et al 2008;Ma et al 2007b;Maksimov et al 2009;Mondragón et al 2008;M€ uller et al 2011;Nejad et al 2010;…”

“…-Moisture resistance: the homogeneous dispersion of high-aspect-ratio silicate layers (a) introduces tortuous and thus longer pathways through the starch polymer matrix for the diffusion of water molecules (Cyras et al 2008;Dai et al 2009a;Ibrahim 2011;Lilichenko et al 2008;Maksimov et al 2009;Mondragón et al 2008;Park et al 2003;Tang et al 2008c;Wang et al 2009bWang et al , 2010b and also (b) causes the shielding of the exposed water-sensitive hydroxyl groups of the starch (M€ uller et al 2011;Wang et al 2009bWang et al , 2010b, both of which contribute to a reduction in the moisture sensitivity. -Oxygen barrier property: a higher oxygen barrier can be ascribed to the silicate layers inducing a higher tortuosity and longer diffusion pathways for oxygen molecules (Lilichenko et al 2008;Maksimov et al 2009;Zeppa et al 2009).…”

“…Glycerol has been a widely used plasticizer in the preparation of starch-phyllosilicate nanobiocomposites (Bagdi et al 2006;Chiou et al 2007;Chivrac et al 2008aChivrac et al , b, 2009bChivrac et al , 2010aCyras et al 2008;de Carvalho et al 2001;Huang et al 2004;Ibrahim 2011;Kampeerapappun et al 2007;Lilichenko et al 2008;Liu et al 2011c;Andrade 2009, 2010;Maksimov et al 2009;Mondragón et al 2008;M€ uller et al 2011;Pandey and Singh 2005;Park et al 2002Park et al , 2003Tang et al 2008b, c;Wang et al 2009b, d;Wilhelm et al 2003b;Zeppa et al 2009;Zhang et al 2007). It has been demonstrated in the previous studies (Cyras et al 2008;Park et al 2002) that, because of the strong polar interactions between the hydroxyl groups from the starch polymer chains, from the glycerol, and from the silicate layers, glycerol and/or starch chains can enter into silicate interlayers to form intercalated starch-MMT nano-biocomposites.…”

“…-Oxygen barrier property: a higher oxygen barrier can be ascribed to the silicate layers inducing a higher tortuosity and longer diffusion pathways for oxygen molecules (Lilichenko et al 2008;Maksimov et al 2009;Zeppa et al 2009). -Thermal stability: improvement in the thermal stability can be due to several concomitant phenomena such as (a) the higher thermal stability of the inorganic phase (phyllosilicate) compared to the organic one (starch), (b) the phyllosilicate acting as a heat barrier which enhances the overall stability (Cyras et al 2008;Ibrahim 2011), (c) the increase in the tortuosity of the diffusion pathways for oxygen and the combustion (pyrolysis) gas (Alexandre and Dubois 2000;Chiou et al 2007;Chivrac et al 2010d;Cyras et al 2008;Namazi et al 2009;Xu et al 2005), and (d) the reorganization of the starch structure with less exposed hydroxyl groups and thus less susceptibility to degradation (Pandey and Singh 2005;Wang et al 2010b;Wilhelm et al 2003b). …”