TGDDM

Fig. 3. Liquid water uptakes for a TGDDM-DDS neat resin at increasing applied hydrostatic relative pressures. (22)...

The curves of Fig. 6, relative to the TGDDM-DDS systems cured with 50 PHR of hardener, have been drawn using the same procedures, although, according to the discussion of the previous section, a low activity term associated with the adsorption on the hydrophilic sites, has also been considered. 

Fig. 6. First (open circles) and second (full circles) equilibrium moisture sorptions in the TGDDM-DDS neat resin...

Table 1. Comparison between water uptakes, dry, wet and theoretical glass transition temperatures of TGDDM-DDS samples...

The free volume model seems to be more adequate to describe the plasticization behaviour of the systems of lower amine content. According to Eq. (5), the higher is the change of the expansion coefficient the lower is the influence of the diluent volume fraction. The three TGDDM-DDS mixtures cured with 20, 30 and 50 PHR of hardener were characterized l2) by changes of the expansion coefficient at the glass transition, respectively, of 0.63, 1.08 and 2.94x 10 3 °C l. The more dense and stiffer resin crosslinked with 50 PHR of DDS should be, in principle, the less... 

Figure 14.4 Chemical structures of two common epoxy chain extenders for PET (a) a diepoxide, e.g. Shell Epon 828, based on bisphenol A diglycidyl ether (b) a tetraepoxide, e.g. Ciba MY721, based on tetraglycidyl diaminodiphenyl methane (TGDDM)...

Epoxy film specimens of two different weight/weight ratios of TGDDM/DDS were evaluated (73/27 and 80/20). The films were cast between teflon sheets using a spacer. The cure cycle was 1 hr at... 

Figure 1. Dynamic mechanical spectra of 73127 and 80/20 TGDDM/DDS epoxy.

Thus, radiation causes degradation, chain scission and further crosslinking. To distinguish between chain scission, crosslinking and degradation products, sorption/desorption studies were conducted. Selected specimens of 73/27 and 80/20 TGDDM/DDS were allowed to absorb acetonitrile to equilibrium. The acetonitrile was desorbed, and the samples were tested. 

The tetraglycldyl 4, 4 dlamlnodiphenyl methane epoxy (TGDDM) resins used were Hercules 3501-6 (catalyzed resin) and 3502 (uncatalyzed resin). The crosslinking reagent is 4, 4 ... 

Figures 10 and 11 show a manufacturing application in which a resin s flow properties are measured in-sltu at a particular point in a thick laminate during cure in an autoclave. The sensor was inserted on the tool surface and in the center of a thick 192 TGDDM graphite epoxy laminate. Figure 10 shows the noise free raw data taken by the center sensor during cure in the 8x4 foot production size autoclave. Using the procedures described, the ionic mobility was measured at both the tool surface and the center of the thick laminate. In Figure 11, the sensor values of a show a 10 to 20 minute time lag in the point of maximum flow on the surface versus the laminate s center. Measurements of a versus q, as shown in...

Neat Epoxv Resin. Neat epoxy resin (TGDDM/DDS) was found to be a relatively weak emitter of photons, electrons and positive ions. The general shape of all the emission curves consists of a relatively rapid burst, followed by a very low intensity decay which lasts approximately 100 jis. We frequently observed that during... 

Figure 2a. Photon detector current as a function of time and corresponding fracture surface micrographs for smooth fracture surfaces of TGDDM/DDS.

Flmre 3- Simultaneous measurements of (a) photon emission and (b) voltage change across a conductive grid from the fracture of a TGDDM/DDS specimen. 

Figure 4. (a) Total pressure change, (b) Mass 18 (HjO) signal, and (c) Mass 64 (SO2) signal from the fracture of TGDDM/DDS. 

TGDDM = tetraglycidyl-A, A -diaminophenyl methane DDS = diaminodiphenyl sulfone... 

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