DMA scan

Hansma H G, Sinsheimer R L, Groppe J, Bruice T C, Elings V, Gurley G, Bezanilla M, Mastrangelo I A, Hough P V C and Hansma P K 1993 Recent advances in atomic force microscopy of DMA Scanning 15 296... 

Fig. 3. Programmed dma scan of a resole phenoHc resin heating rate is 5°C/min.

Thermal and Dynamic Mechanical Analyses. The thermal and mechanical properties of the new photocured films were evaluated by DMA and TGA. The initial DMA scan of the photocured polymer (prepared from a 3 1 blend of 4-allyloxystyrene DVE-3) to ensure crosslinking on UV exposure shows two transitions at 62°C and 232°C, as shown in Figure 4, scan a. The low temperature transi-... 

DSC and DMA scans of, 18 778 Novolac epoxy resins, 10 349 Novolac resins, 15 163. See also Novolacs in coatings, 18 782 in fiber bonding, 18 792 from phenolic resin polymerization,... 

DSC, TGA, and DMA were performed using a DuPont 9000 system. DSC runs were performed at scan rates of 10° C/minute and repeated at least one time. TGA runs were also carried out at 10° C/minute. DMA scans were at 5° C/minute with a 0.2 mm oscillation amplitude. 

Samples, chosen for ready availability and to illustrate a large range of properties, are listed in Table 1. Dimensions were chosen to keep instrument compliance corrections less than 10%. Removal of moisture and residual cure potential of the composites required repetitive DMA scans under nitrogen to achieve +1 C damping peak reproducibility in successive scans. 982 DMA temperature scans (shown in Figure 4) were also made after the stress relaxation experiments, to check property stability. Stress relaxations were all done below the maximum temperature attained in the DMA pre-scans. 

Figure 5.47. A series of dynamic DMA scans for the reaction of an epoxy resin at heating rates of 2°C/min [top (a), (b)], 5°C/min [middle (c), (d)], and 10°C/min [bottom (e), (f)]. On increasing the heating rate from slow to fast the number of loss modulus peaks decreases progressively from three to one (from Dillman, 1988, with permission of S. H. Dillman).

Figure 7.15 Plots of tan 8 versus temperature for DMA scans of extruded soy protein sheets at different moisture contents (reprinted from Polymer, 42(6), J. Zhang, P. Mungara and J. Jane, Mechanical and thermal properties of extruded soy protein sheets, 2569-2578. Copyright (2001), with permission from Elsevier) and amylose films plasticized with different glycerol contents (reprinted from Carbohydrate Polymers, 22(3), G. K. Moates, T. R. Noel, R. Parker and S, G. Ring, Dynamic mechanical and dielectric characterisation of amylose-glycerol films, 247-253. Copyright (2001), with permission from Elsevier.)...

Differential scanning calorimetry (DSC) scans also point out a clearly different behavior the e y transition produces poor enthalpic effects (only a very broad endothermic peak centered at 105 °C) while the 8 mesomorphic Y transition presents a well-defined endothermic peak (at 102 °C, associated with formation of the mesomorphic form) followed by an exothermic peak (at llO C, associated with yphase crystallization) [44], Moreover,several features of the dynamic mechanical analysis (DMA) scans can be rationalized on the basis of the different routes of thermal transitions of e and 8 phases toward the Y phase, being direct and through a mesomorphic phase, respectively [44],... 

On [ 45°]i4 samples, after the first DMA scan, an additional run was carried out on the same specimen. 

The curves representing the temperature dependence of the real part of the complex modulus E curves measured by DMA are summarized in Figure 5 and Figure 6 for composite A and B respectively. In the above mentioned figures the reported curves are relative to both [0°] and [ 45 ]i4 lay up s. The tanS and E curves are not shown in the figures. The [ 45°]i4 specimens were submitted to successive DMA scans in order to check whether the Tg has changed after the heavy thermal treatment experienced by the sample in the first run (the maximum temperature reached was 250°C). 

Figure 3. DMA scans of neatPB3200 and PB3200/15A nanocomposites atdifferent clay laodings.

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