DOI: 10.18419/darus-2021
title: Humidity and thermal triggered Shape Memory Effect - Rheology-based numerical modelling - Dynamic Mechanical Thermal Humidity Analysis

description: This data contains iso-thermal and iso-humid shear frequency-sweep measurements of Shape Memory Polymers (SMP). 
The SMP is a polyurethane-based Polymer, which is produced from SMP Technologies Inc.
The SMP filament were processed with a 3D printer (Ultimaker 3, Ultimaker, Geldermarsen, Netherlands).
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Frequency-sweeps were performed in a temperature range (5 °C - 85 °C) and at relative humidity 0 %, 30 %, 50 %, 70 % and 100 %. 
A preheating step was performed before each frequency measurement to relieve residual stresses stored by the manufacturing process. Subsequently, at a temperature T = 60 °C above the glass transition temperature (T_G), the relative humidity is set and held for 5 days to fully saturate the sample.
After that, the sample is slowly cooled down to 10 °C in order not to store residual stresses in the sample. 
The sample geometry is measured again and then the actual frequency measurement is performed.
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The frequency measurements are performed in the frequency range from 0.01 Hz to 10 Hz at isothermal and isohumid conditions. The shear strain amplitude is set below T_G with gamma = 0.1 % and above T_G with gamma = 0.2 %. The sample is drawn below T_G with a normal force of F_N = - 0.4 N and above T_G with a normal force of F_N = - 0.2 N. So that the specimen is always drawn and does not bend, which affects the shear measurements.
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With the results of the isothermal and isohumid frequency measurements, on the one hand, temperature shifts at different humidities can be presented. The temperature shifts are used to determine the humidity-dependent T_Gs. On the other hand, master curves can be determined at different humidities. With the humidity-dependent master curves, the viscoelastic material behavior is determined in a larger frequency range (&lt;a href="https://en.wikipedia.org/wiki/Time%E2%80%93temperature_superposition"&gt;Time-Temperature Superpositon&lt;/a&gt;).
In addition, the shift parameters (alpha_T) determined for the master curves are included.
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The data is organized in the following folder structure, e.g.
dynamic thermal humid analysis at dry condition = dmtha_dry.
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&lt;ul&gt;
&lt;li&gt;&lt;b&gt;dmtha_dry&lt;/b&gt;
&lt;ul&gt;
&lt;li&gt;frequency_sweep_SMP_dry
&lt;li&gt;mastercurve_SMP_dry
&lt;li&gt;alpha_T_dry
&lt;/ul&gt;
&lt;li&gt;&lt;b&gt;dmtha_redry&lt;/b&gt;
&lt;ul&gt;
&lt;li&gt;frequency_sweep_SMP_redry
&lt;li&gt;mastercurve_SMP_redry
&lt;li&gt;alpha_T_redry
&lt;/ul&gt;
&lt;li&gt;&lt;b&gt;dmtha_30&lt;/b&gt;
&lt;ul&gt;
&lt;li&gt;frequency_sweep_SMP_30
&lt;li&gt;mastercurve_SMP_30
&lt;li&gt;alpha_T_30
&lt;/ul&gt;
&lt;li&gt;&lt;b&gt;dmtha_50&lt;/b&gt;
&lt;ul&gt;
&lt;li&gt;frequency_sweep_SMP_50,
&lt;li&gt;mastercurve_SMP_50,
&lt;li&gt;alpha_T_50
&lt;/ul&gt;
&lt;li&gt;&lt;b&gt;dmtha_70&lt;/b&gt;
&lt;ul&gt;
&lt;li&gt;frequency_sweep_SMP_70
&lt;li&gt;mastercurve_SMP_70
&lt;li&gt;alpha_T_70
&lt;/ul&gt;
&lt;li&gt;&lt;b&gt;dmtha_wet&lt;/b&gt;
&lt;ul&gt;
&lt;li&gt;frequency_sweep_SMP_wet
&lt;li&gt;mastercurve_SMP_wet
&lt;li&gt;alpha_T_wet
&lt;/ul&gt;