In the realm of material science, the mechanical properties of nanocomposites play a pivotal role in determining their viability for various applications. Figures 6.32 to 6.35 present a comprehensive analysis of the tensile properties, including tensile strength, Young’s modulus, and elongation at break, in nanocomposites crafted from a modified starch and EVOH (Ethylene Vinyl Alcohol Copolymer). Cloisite 15A, Cloisite 30B, and MMT (Montmorillonite) are the key players in this investigation.
Understanding Tensile Properties in Modified Starch and EVOH Blends
Before delving into the specifics of nanocomposites, it’s crucial to acknowledge the tensile properties showcased in the blends of modified starch and EVOH, as detailed in Figures 5.19 to 5.22 in “Blends of modified starch and EVOH”.
Anionic vs. Cationic Modified Starch: Unraveling the Differences
For nanocomposites derived from anionically modified starch (AS-B or AS-LF) and EVOH, the introduction of organoclays, specifically Cloisite 15A or Cloisite 30B, led to noteworthy enhancements in tensile strength and Young’s modulus. However, this benefit comes at the cost of a reduction in elongation at break. In contrast, nanocomposites containing MMT exhibited minimal changes in tensile properties compared to the blends.
The Role of Organoclay in Mechanical Reinforcement
The distinct improvements observed in nanocomposites containing organoclays can be attributed to the attractive interaction and expansive surface areas between the silicate sheets and the polymer matrix. The ionic interaction between the modified starch’s carboxylate groups and the surfactant on the organoclay’s surface facilitated the exfoliation of layered silicates, resulting in nanometer-sized platelets. These platelets, with their increased surface area, acted as effective cross-linking points within the nanocomposites. This interaction enhanced stress transfer efficiency during tensile tests, ultimately leading to higher tensile strength and modulus.
Delving into Nanocomposite Variations
Figures 6.32 to 6.33 reveal that among the nanocomposites containing organoclays, those with Cloisite 30B displayed superior tensile strength and Young’s modulus compared to those with Cloisite 15A. In contrast, the nanocomposite with MMT, lacking functional groups for attractive interactions, did not exhibit improved tensile properties compared to the blend.
Cationically Modified Starch: Limited Impact of Nanoclays
Intriguingly, when exploring nanocomposites based on cationically modified starch (CS-B or CS-LF) and EVOH, the addition of nanoclays (Cloisite 15A, Cloisite 30B, or MMT) did not yield significant improvements in tensile properties. This observation aligns with our previous findings on the poor dispersion characteristics of nanoclay aggregates in cationically modified starch and EVOH nanocomposites.
In conclusion, this meticulous examination of tensile properties in starch-based nanocomposites sheds light on the nuanced interplay between modified starch, EVOH, and various nanoclays. Understanding these mechanical intricacies paves the way for optimizing nanocomposite formulations for diverse applications in the ever-evolving landscape of material science.