if titanium added in gelatin-based bioplastic so why the elongation is less.. Its value decreased just bECAUSE OF TIO2 or plasticizer?
Dear Maham Khan, there are mainy possible explanations. First depending on the interface adhesion, whether good or bad. The introduction of small particulate filler/reinforcing agent will acts as a stress concentrator, so, with good adhesion stress is well transmitted but the chain loose their intrinsic mobility, resulting in low deformability. With bad adhesion, matrix failure wil be fast before complete déformation, because the filler is considered as defects positions. Other parameter to consider is the degree of crystallinity. Some additives act as nucleation agents, rendering the material less deforable, tough or stiff. In all these situations, the rate of deformation also has its role. My Regards
TiO2 it's an inorganic filler for plastics or bioplastics and there is no substantial adhesion between the TiO2 surface and the plastic chains or bioplastic ones. The filler with no adhesion to the polymer chains decrease the intrinsic adhesion between the polymers chains (it's a discontinuity in the polymer network) determining as a macrospopic result the decrease of the elongation at Break. You probably used a 99,9% TiO2 that usually aren't in use on a commercial level. See attached brochure of Chemours that produce commercial TiO2 as pigments. At page 2 you see that in most of the cases of a commercial TiO2 there is on the surface an organic treatment of 0.5-1.5% (the chemical nature is not declared but are usual: Stearic acid, Ca Sterate, cytric acid or Glyceryl mono-stearate) that improve the adhesion between the TiOs surface and the polymer matrix. The organic tretment could be "hydrophilic" (first 2 cases) or "hydrophobic" (usually for polyolefins) : in your case probaly you use a bioplastic symilar to a polyester and an "hydrophilic" organic treatment could be the most appropriate for a good adhesion. Another observation is that if you use a 99.9% TiO2 is usually a pro-degradant for the polymers via radical reactions (Ti-IV / Ti-III redox couple) starting an oxydative degradation of the polymer istead the commercial TiO2 have an inert inorganic treatment on the surface of Alumina or better Alumina plus Silica that change the TiO2 (+Al2O3+SiO2) attitude from a pro-degradant to a thermal and Light stabilizer for the plastic becaming an UV screener for UV-light that improve the plastic resistance to the eposure to sun light (see at page 1 durable applications related to TiO2 structure at page 2). if you order to Chemours a sample of R-101 you might check the effect of the surface "hydrophilic" tretment on the elongation at break : https://www.tipure.com/en/support/sample-request
Hi, nanoparticles are too small, well below the critical length of the stress concentration. Any possible effect they might have in this regard is largely overwhelmed by the so-called nano-reinforcement. Basically, the polymer chains get adsorbed on the particle surface which retards their dynamics (ability to move) due to the nanoconfinement. That said, stress concentration becomes an issue in the case of poor dispersion - aggregated nanoparticles act more like regular microparticles. Check out the following references:
Article Effect of Nanoparticle Organization on Molecular Mobility an...
Article Nature of dynamic gradients, glass formation, and collective...
Article Translation of segment scale stiffening into macroscale rein...
Article Mechanical properties of glassy polymers with controlled NP ...
It is also not generally true that metal oxides have no good adhesion to polymers. It might be true for hydrocarbons (mainly PE, PP) but these particles can interact through donor-acceptor groups with polymers containing polar groups including many (most?) biopolymers. That will influence the polymer adsorption on their surface and, subsequently, the dispersion quality and mechanical properties.
Article Phase diagram of bare particles in polymer nanocomposites: U...
Article Thermodynamic Parameters Controlling Nanoparticle Spatial Pa...
Article Bulk Polymer Nanocomposites with Preparation Protocol Govern...
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