The GelMA was dissolved in D2O for analysis using 400-Hz nuclear magnetic resonance (Bruker AVANCE AV Ⅱ-400 MHz). The degree of methacrylate substitution was determined by the formula: 1 − (lysine integration signal of GelMA/lysine integration signal of unsubstituted Gelatin) × 100% (Brinkman et al., 2003 (link); Nichol et al., 2010 (link); Loessner et al., 2016 (link)). The morphology of the GelMA hydrogel was observed by scanning electron microscope (SEM). Dynamic Mechanical Analyzer (TA Instruments, Q-800, USA) was used to test the storage modulus and loss modulus of the GelMA hydrogel. The rheological properties of the GelMA hydrogel were analyzed by rheometer (MCR302, Anton Paar) (Zhou, 2021 (link)).
Dynamic mechanical analyzer
Manufactured by TA Instruments
Sourced in United States
The Dynamic Mechanical Analyzer (DMA) is a laboratory instrument used to measure the viscoelastic properties of materials. It applies a small, controlled deformation to a sample and measures the material's response, providing information about its stiffness, damping, and transition temperatures.
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Lab products found in correlation
8 protocols using dynamic mechanical analyzer
1
Characterization of GelMA Hydrogels
2
Mechanical Characterization of Swollen Hydrogels
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Example 2
The mechanical strength of a swollen hydrogel can be studied by modulus measurements. Particularly, the uniaxial compression tests were performed and gave reproducible results. The mechanical strength of the swollen hydrogels made from a reaction mixture with 2 wt. % CMG:HPG crosslinked with 8.0 wt. % CA or DVS, respectively, where the weight ratio of CMG to HPG is 3:1, were determined by uniaxial compression of swollen hydrogels (of dimensions 15.0 mm diameter and 10.8 mm height) between two parallel plates of RSA-III (TA instruments, USA) using Dynamic Mechanical Analyzer at 25° C. The crosshead speed was maintained at 1 mm/min. The appearance of the swollen hydrogels and mounting of a sample in DMA are shown in
The modulus for equilibrium swollen CMG:HPG-CA and CMG:HPG-DVS hydrogels made from the same reaction mixture as above were also compared. As shown in
3
Evaluating Cocoa Spread Melting Properties
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The melting properties of cocoa spread samples were measured using a Differential Scanning Calorimeter DSC Q100 (TA Instruments). Approximately 5 mg of samples were weighed into aluminum pans. The hermetically sealed pans were then heated from 10 to 50 °C (5 °C/min) in the DSC using an empty aluminum pan as reference. The onset temperature (Tonset), peak maximum (Tpeak), conclusion temperature (Tend) and enthalpy of melting (Hmelt) were automatically calculated after integrating the melting peaks using data analysis software (TA Instruments, New Castle, DE, USA) [27 (link)].
The cocoa spread samples were heated from 10 °C to 50 °C with a heating rate of 5 °C per minute using a Differential Scanning Calorimeter DSC 910, Thermal Analyzer 990 and Dynamic Mechanical Analyzer (TA Instruments, New Castle, DE, USA). 5 mg of the spread sample was measured into aluminum pans and the pierced covers were sealed in place. An empty, hermetically sealed aluminum pan was used as a reference.
The melting properties of the spread samples were defined using DSC parameters: onset temperature (Tonset), peak temperature (Tpeak) and conclusion temperature (Tend). Tonset is the temperature at which a specific crystal form starts to melt, Tpeak is the temperature at which melting rate is the greatest and Tend is the temperature at which melting ends [28 (link)].
The cocoa spread samples were heated from 10 °C to 50 °C with a heating rate of 5 °C per minute using a Differential Scanning Calorimeter DSC 910, Thermal Analyzer 990 and Dynamic Mechanical Analyzer (TA Instruments, New Castle, DE, USA). 5 mg of the spread sample was measured into aluminum pans and the pierced covers were sealed in place. An empty, hermetically sealed aluminum pan was used as a reference.
The melting properties of the spread samples were defined using DSC parameters: onset temperature (Tonset), peak temperature (Tpeak) and conclusion temperature (Tend). Tonset is the temperature at which a specific crystal form starts to melt, Tpeak is the temperature at which melting rate is the greatest and Tend is the temperature at which melting ends [28 (link)].
4
Optical and Mechanical Properties of Hydrogel Lenses
5
Viscoelastic Behavior of UHMW-PE
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The storage and loss moduli of the UHMW-PE were measured using a Dynamic Mechanical Analyzer (TA Instruments) at an applied frequency of 1 Hz using a temperature sweep from −60 °C to +30 °C. The strain was not constant during the temperature sweep as the instrument was setup in auto strain adjustment mode. However, the strain variation measured was negligible (0.05% to 0.03%) and within the linear viscoelastic range.
6
Esophageal Graft Tensile Strength Assessment
7
Hydrogel Coating Delamination Durability
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Delamination of the hydrogel coating after uniaxial stretching was assessed as a measure of coating durability. Hydrogel composites were prepared from photopolymerized PEGDA 3.4 kDa or large (20 × 20 mm) IPN composites at swollen thicknesses of 0.3 and 0.8 mm (n = 6). Samples were cut to 15 × 5 mm. Hydrogels were dyed with food coloring for better visualization of failure. The composite materials were placed between the grips of a Dynamic Mechanical Analyzer (TA Instruments) and strained to 100% at a rate of 1 mm s−1. Composite stretching was video recorded. The point at which visible damage to the hydrogel coating occurred was noted and strain at failure was determined at this point. Strain was determined by measuring the length of the hydrogel coating region before and at the end of testing to minimize the effect of the electrospun mesh substrate yielding.
8
Rheological Characterization of Hydrogels
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Rheological data was obtained using a hybrid Discovery HR-2 Rheometer/Dynamic Mechanical Analyzer (TA Instruments, New Castle, DE, USA). All hydrogels were characterized within the materials’ pseudolinear viscoelastic range with a 1.00 mm gap, at room temperature. A conditioning step was performed at the start of each test to ensure an axial force between 0.1 and 0.3 N. Oscillatory strain sweeps for thixotropy investigation were conducted with a 20 mm parallel plate geometry within a strain range of 1–100% and an angular frequency of 10 rad/s. The gels went through 3 cycles with a 30 s rest between each cycle. Oscillatory frequency sweeps from 100 Hz to 0.1 Hz with stress of 50 Pa were performed to classify the storage modulus of the gels.
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