Achieving an in-depth understanding of the mechanical properties of polymeric materials can be complex due to their diverse chemical compositions and physical structures. A polymer with a specific molecular weight and at a specific temperature can behave as either a liquid or solid, depending on the time scale of the test. Obtaining a comprehensive understanding of this viscoelastic behavior on the molecular level is important for developing polymers with enhanced properties.
The mechanical and tribological properties of polymers depend on several factors beyond just the monomer unit comprising it, such as the stereochemistry of the linkage, crystallinity, and the degree of crosslinking. Polymer blends may also be used to enhance properties beyond what can be obtained through a single polymeric species. Properties of polymer blends highly depend on the degree of dispersion, size of dispersion phases, and interfacial phase interaction between the components of the blend. The ability to quantitatively characterize individual constituents of the morphology and interfacial behavior is required to engineer new polymeric materials with unique properties.
Nanoscale dynamic mechanical analysis provides the ability to measure viscoelastic properties at the molecular level, on individual polymer phases, and on polymeric interfaces. nanoDMA is a hybrid nanoindentation testing technique that allows the quantitative measurement of storage modulus, loss modulus, and tan-delta over a broad frequency range. Quantitative dynamic nanoindentation measurements can be performed at a localized test site or in a mapping mode to determine spatially resolved viscoelastic properties of polymers over multiple phases. Combined with temperature control capabilities, time-temperature-superposition studies can be performed on nanoscale volumes of material.
Creep and stress relaxation properties are important material parameters to characterize when polymers are subjected to deformation for prolonged periods of time. Nanoindenters operating under tight feedback control algorithms can reliably perform creep and stress relaxation measurements on features within the microstructure of the polymer. Bruker’s proprietary control algorithms assure drift-free, quantitative nanoscale creep and stress relaxation measurements over long time durations.
Polymers generally have low friction coefficients and high corrosion resistance, making them widely used for many tribological applications. The molecular weight, stereochemistry, degree of crosslinking, polymer blend composition, and chemical affinity all play a role in tribological performance. Bruker's Hysitron test equipment provides the ability to quantitatively characterize friction and wear properties on specific microstructures as well as map tribological properties across phases/interfaces.