Macro-, Micro- and Nanomechanical Characterization of Crosslinked Polymers with Very Broad Range of Mechanical Properties

Abstract

This work is focused on the comparison of macro-, micro- and nanomechanical properties of a series of eleven highly homogeneous and chemically very similar polymer networks, consisting of diglycidyl ether of bisphenol A cured with diamine terminated polypropylene oxide. The main objective was to correlate the mechanical properties at multiple length scales, while using very well-defined polymeric materials. By means of synthesis parameters, the glass transition temperature (Tg) of the polymer networks was deliberately varied in a broad range and, as a result, the samples changed their mechanical behavior from very hard and stiff (elastic moduli 4 GPa), through semi-hard and ductile, to very soft and elastic (elastic moduli 0.006 GPa). The mechanical properties were characterized in macroscale (dynamic mechanical analysis; DMA), microscale (quasi-static microindentation hardness testing; MHI) and nanoscale (quasi-static and dynamic nanoindentation hardness testing; NHI). The stiffness-related properties (i.e., storage moduli, indentation moduli and indentation hardness at all length scales) showed strong and statistically significant mutual correlations (all Pearson′s correlation coefficients r > 0.9 and corresponding p-values < 0.001). Moreover, the relations among the stiffness-related properties were approximately linear, in agreement with the theoretical prediction. The viscosity-related properties (i.e., loss moduli, damping factors, indentation creep and elastic work of indentation at all length scales) reflected the stiff-ductile-elastic transitions. The fact that the macro-, micro- and nanomechanical properties exhibited the same trends and similar values indicated that not only dynamic, but also quasi-static indentation can be employed as an alternative to well-established DMA characterization of polymer networks.

A hybrid methacrylate‐norbornene‐thiol photopolymerization system with tunable physical and mechanical properties

“…The EGDEMA-EBM formulations showed an increase in G' at the plateau with increasing crosslink density, which is consistent with the literature. 42 The crosslinked polymers with a thiol:ene ratio between 0.5 and 0.75 show a similar trend in high G' plateau values, with the highest corresponding to a thiol-ene ratio of 0.7 with G' = 4.7 Â 10 3 Pa. The high G' plateau values are indicative of strong, cohesive behavior, which is crucial for PSAs.…”

“…41 The examined materials' viscoelasticity is characterized by their dynamic characteristics: G 0 is indicative of the materials' stiffness and elasticity, G 00 represents the flow and viscosity, and the loss factor (tanδ) signifies structural transitions like the T g or gel formation. 41,42 T A B L E 5 Experimental results of EGDEMA-EBM polymers with variable thiol:ene ratios in the range of 0.2-1.25. The storage modulus (G 0 ) was measured in a frequency sweep test measured at a shear strain of 1% of the sample thickness and in a frequency range of ω ¼ 0:1 À 100 rad s À1 , the value is reported at an angular frequency of rad s À1 .…”

Biodegradable Thermoplastic Starch/Polycaprolactone Blends with Co-Continuous Morphology Suitable for Local Release of Antibiotics

“…The mechanical properties measured in this work can be divided into two groups: stiffness-related properties ( G ′, E IT , H IT , and H M ) and viscosity-related properties ( G ″, tan(δ), C IT , and η IT ). The same division of mechanical properties was employed and justified in our previous work [ 40 ]. The stiffness-related properties were more important here because the soft TPS matrix was expected to harden thanks to the PCL addition.…”

“…Five micromechanical properties were obtained from F – h curves (where F is the loading force and h is the indenter penetration depth) according to ISO 14577-1 standard: indentation modulus ( E IT ), indentation hardness ( H IT ), Martens hardness ( H M ), indentation creep ( C IT ), and elastic part of indentation work ( η IT ). Figure 1 shows the principle of MHI measurement and evaluation in the case of our TPS/PCL blends; further details can be found in our recent papers [ 40 , 41 ].…”

Effects of technology-integrated formative assessment on students' conceptual and procedural knowledge in chemical equilibrium

“…According to Slout et al [9], in order to develop a higher level of cognitive understanding and processes in chemistry, students must study the macroscopic, sub-microscopic, and symbolic levels of chemical knowledge. Students of chemistry at all educational levels must have a thorough understanding of scientific principles at all three levels as well as the capacity to synthesize their learning [10], [11].…”