DMA data

Figure 8.1 shows dynamic mechanical analysis (DMA) data for an unfilled and 30 % glass-filled PBT. Note the sharply higher modulus ( ) in the glass-filled blend at all temperatures. 

Figure 8.1 Comparison of DMA data obtained for 30 % glass-filled and unfilled PBT samples...

Figure 8.2 Comparison of DMA data obtained for a PBT-PC blend and a PBT resin...

Table 8 Analysis of XRD and DMA data obtained from different rubber vulcanizates containing expanded organoclay...

Figure 3. Master Curves of PMMA Multiplex DMA Data Represented on Reduced Frequency Nomograph. Master Curves Calculated Using "Universal" WLF Equation.

The utility of empirically determined WLF equations was investigated using DMA data obtained on the PVC acoustical damping material. Using a separate software package (available from DuPont Intruments), E, E" and tan 8 were empirically fit using the time-temperature superposition procedure. A reference temperature is first determined by the computer software. The data are then shifted manually and the WLF equation is fit to the resulting temperature shift factors. Values for and calcu-... 

Figure 8. Master Curves of PYC Acoustical Material Multiplex DMA Data RepresentecJ on Reciuced Frequency Nomograph. Enlargement of Area A in Figure 7. "Universal" WLF Equation.

A Fortran based program has been developed for the IBM XT (or compatible) that uses the principles of time-temperature superposition and the WLF equation to generate master curves of DMA data. 

The polymer is a commercial sample of poly-methylmethacrylate, PMMA. The Rheovibron data from 3.5, 11, 35, and 110 Hz are superposed on the nomograph along with the resonant frequency DMA data using a To value of 175°C for this sample of PMMA. 

Figure 4. Reduced temperature nomograph showing that rheovibron and DMA data for PMMA superpose into single master curves when T — 175°C DMA points are center on each plot. Key A, modulus curve and loss tangent.

The dielectrically measured relaxation maxima are plotted in an Arrhenius plot together with the DMA data (9.3.2) and the result of the Tg(midpoint) determination by DSC (9.3.3),... 

The conclusions [112] are that the char residue amounts of all the NCC were significantly larger than that of the MCC. The DMA data showed a marked increase in storage modulus from 1.7 GPa for pure PVA to 4.2 GPa for PVA/NCC-8 at 30°C, because of the high modulus of NCC. 

In this paper, we analyze the effect of fluorine substitution in the polymers listed above by dielectric analysis (DEA), dynamic mechanical analysis (DMA) and stress relaxation measurements. The effect of fluorination on the a relaxation was characterized by fitting dielectric data and stress data to the Williams, Landel and Ferry (WLF) equation. Secondary relaxations were characterized by Arrhenius analysis of DEA and DMA data. The "quasi-equilibrium" approach to dielectric strength analysis was used to interpret the effect of fluorination on "complete" dipole... 

A comparison with the DMA data is shown in Figure 5.4. A good correspondence was found in the temperature range up to 250 °G. This agreement also demonstrated that the applicability of the simple rule of mixture is valid for the estimation of effective E-modulus. 

Figure 5.4 Comparison of E-modulus between model and DMA data [12]. (With permission from Elsevier.)...

The previously reported method of kinetics data analysis for DSC data is not readily adaptable to raw data obtained in the integral form of fractional conversion or cure obtained from DMA, TGA or spectroscopic methods such as FT-IR. The basic assumption of the kinetics analysis for DMA is that the change in relative modulus at a given time and temperature during the dynamic temperature scan, divided by the change in relative modulus exhibited by the fully cured system at the same temperature, is proportional to the extent of cure at that point of the reaction. This is then used as the fractional degree of cure in the calculations. This normalization of raw DMA data to fractional degree of cure F(t,T) is defined as... 

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