Study of some physical properties of biodegradable films based on blends of gelatin and poly(vinyl alcohol) using a response-surface methodology

Phase transitions in biodegradable films based on blends of gelatin and poly (vinyl alcohol)

“…on the whole, the behaviors observed for the phase properties (equations 2-4) were not necessarily similar to those observed on previous works with biodegradable films for some physical properties of the same type (CArvAlho et al, 2009). For example, neither the hydrolysis degree, nor the concentration of the PvA directly affected the puncture force, affecting only by means of the interaction terms, and the hydrolysis degree did not affect the puncture deformation of the films based on blends of gelatin and PvA.…”

“…For example, neither the hydrolysis degree, nor the concentration of the PvA directly affected the puncture force, affecting only by means of the interaction terms, and the hydrolysis degree did not affect the puncture deformation of the films based on blends of gelatin and PvA. Moreover, the complete linear model was statistically significant to represent the behavior of the elongation at break data, but was not statistically significant for the tensile strength (CArvAlho et al, 2009). Nevertheless, Silva et al (2008), working with similar biodegradable films, observed a direct relationship between Tg, determined in the first scan, and the mechanical resistence of the respective films.…”

“…besides, PvA was first homogenized in distilled water and then dissolved at 90 °C (ChIellINI et al, 2001a) over magnetic stirring brasil). More details on this preparation can be observed in previously published works (MeNDIeTA-TAboADA et al, 2008;MArIA et al, 2008;CArvAlho et al, 2009). …”

“…Among these alternatives, the mixing of these biopolymers with the poly (vinyl alcohol) (PvA) has gained interest in the last years. The PvA is a synthetic, hydrophilic and biodegradable polymer (MATSuMurA et al, 1999) which has been used in studies on the development and characterization of films, such as PvA/wheat (DIChArry et al, 2006), PvA/collagen hydrolysate (SArTI; SCANDolA, 1995;AleXy et al, 2003), and PvA/gelatin (ChIellINI et al, 2001a,b,c;berGo et al, 2006;MArIA et al, 2008;MeNDIeTA-TAboADA et al, 2008;SIlvA et al, 2008;MorAeS et al, 2008;CArvAlho et al, 2009), among others.…”

“…Thus, the knowledge of the glass transition temperature (Tg) of films is also important, as a property defining the limit between the rubbery and glassy states (rooS; KArel, 1991;SlADe;levINe, 1991). very recently, Carvalho et al (2009) used a response-surface methodology to study the effect of the hydrolysis degree (hD) and the concentrations of two types of PvA (Celvol-418, hD = 91.8%; Celvol-350, hD = 98.6%) and of the effect of the type and the concentration of plasticizers (sorbitol or glycerol) on mechanical properties, color, opacity, moisture content and solubility in water of films based on blends of gelatin and PvA. In that study, the effect of both independent variables on the physical properties of films was explained in a statistical way.…”