## 4 Results and Discussion
### Temperature-Dependent Measurements
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sample** & \(E_{0}\) **(GPa)** & \(T_{c}\) **(K)** & \(n^{\prime}\) \\ \hline PMMA-Unannealed & 2.80 (\(\pm\)0.03) & 343.56 (\(\pm\)1.81) & 24.29 (\(\pm\)2.54) \\ PMMA-Annealed & 2.45 (\(\pm\)0.14) & 377.26 (\(\pm\)8.99) & 9.09 (\(\pm\)3.19) \\ DR1/PMMA-Unannealed & 3.03 (\(\pm\)0.03) & 344.23 (\(\pm\)2.93) & 28.79 (\(\pm\)4.17) \\ DR1/PMMA-Annealed & 3.06 (\(\pm\)0.25) & 361.35 (\(\pm\)8.42) & 11.43 (\(\pm\)5.39) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Parameters of Young’s modulus as a function of temperature fitting function for unannealed and annealed PMMA and DR1/PMMA fibers. Figure 4: Young’s modulus as a function of temperature for unannealed and annealed PMMA and DR1/PMMA fibers. \begin{table}
\begin{tabular}{l l l} \hline \hline
**Correlations** & \(t_{E_{0}}\) **(Confidence)** & \(t_{T_{c}}\) **(Confidence)** \\ \hline PMMA Annealed vs. Unannealed & 2.50 (0.9876) & 3.67 (0.9998) \\ DR1/PMMA Annealed vs. Unannealed & 0.119 (0.0947) & 1.92 (0.9451) \\ PMMA vs. DR1/PMMA, Both Unannealed & 5.42 (0.9999994) & 0.194 (0.1538) \\ PMMA vs. DR1/PMMA, Both Annealed & 2.13 (0.9668) & 1.29 (0.8029) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: \(T\)-test results (and confidence levels) for \(E_{0}\) and \(T_{c}\) from Table 2.  
\[T_{c}^{\text{Unannealed PMMA}}=T_{c}^{\text{Unannealed DR1}}\]  
The annealed fibers give  
\[E^{\text{Annealed PMMA}}<E^{\text{Annealed DR1}}\]  
and  
\[T_{c}^{\text{Annealed PMMA}}=T_{c}^{\text{Annealed DR1}}\]  
We observe that adding DR1 to PMMA decreases the glass transition temperature \(T_{g}\), while Young's modulus \(E\) increases. Annealed samples have a measured \(T_{g}\) in DR1/PMMA fiber that is lower than annealed PMMA fiber, while its \(E\) is greater. Moreover, in both fibers, annealing increases \(T_{g}\) and decreases \(E\). Adding DR1 to PMMA is expected to decrease its \(T_{g}\) due to DR1's plasticizing effect on PMMA [30] and to reduce the stiffness of the polymer compared with the plain PMMA fibers. However, these fibers show that while \(T_{g}\) in DR1-doped samples decreases, their \(E\) increases. This phenomenon is known as antiplasticization [2; 25; 26; 27; 28; 29]. Here, it is observed that DR1 molecules can induce an antiplasticization effect that can decreases the mobility of the chains and their free volume and increases the packing efficiency of the sample, which increases the modulus [2; 25; 26; 27; 28; 29]. Moreover, annealing decreases polymer chain alignment, which reduces their stiffness and increases their entropy [2]. This process decreases the free volume, thus, yielding a higher \(T_{g}\) compared with unannealed fibers. Stress as a function of temperature is measured for unannealed and preannealed DR1-doped and undoped PMMA fibers. The results for the samples that are heated from 293.15 K to 323.15 K over 4 min are shown in Figure 6. Stress as a function of temperature data is fit to the function  
\[\sigma=\sigma_{0}+\frac{\sigma_{1}}{(1+(\frac{T}{T_{0}})^{n})}, \tag{15}\]  
where \(T\) is the sample temperature and the fit parameters are \(\sigma_{0}\), \(\sigma_{1}\), \(T_{0}\), and \(n\). Figure 5: First derivative of heat flow from differential scanning calorimeter measurements of unannealed and annealed PMMA and DR1/PMMA fibers used to estimate the glass transition. These parameters have physical meaning. \(\sigma_{1}\) is the temperature-dependent stress contribution in the limit of zero temperature while \(\sigma_{0}\) is a stress offset due to the stress applied by the clamps when the sample is mounted. \(T_{0}\) is the temperature at which the temperature-dependent stress falls to half its value. \(n\) is an exponent that quantifies the rate at which the stress changes as a function of temperature at \(T_{0}\). For samples that have multiple phase transitions, the stress would be a sum over expressions of the form given by Equation (15)--one for each phase transition. The stress for the temperature range in the present studies is described well by a single transition.