Neat epoxy resin

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... 

Drzal et al. 90) have investigated the effect of interphase modification on interfacial moisture absorption. The fibers used were a surface treated and a surface treated and finished type A carbon fiber in the same epoxy matrix studied previously. Three equilibrium exposure conditions were investigated. 20 °C, 70 °C and 120 °C were selected for moisture equilibration of single fiber samples and for the neat epoxy resin. The interfacial shear strength was measured both in the saturated and the dehydrated cases and compared to the initial dry values. 

The neat epoxy resin was prepared by casting. The as-received B-stage material was subjected to degasification at 85 °C inside a vacuum oven. The softened resin was then transferred into a preheated silicon-rubber mold. The curing schedule was 121 °C for 2.0 hours, 177 °C for 2.5 hours, followed by a slow cooling at 0.5 °C per minute to room temperature (23.0 °C). 

Figure 14.2. The mechanical properties of 0.5 wt% SWNT/Epoxy composites (a) tensile test of neat epoxy resin (b) tensile test of pristine-SWNT/epoxy ...

Figure 14.11. Tensile strength of CNT/Epoxy composites with the 0.5 wt% SWNT loading (a) neat epoxy resin, (b) pristine SWNT/epoxy, (c) cut-SWNT/Epoxy (11).

Fig. 13 is a TTT cure diagram of three systems a neat epoxy resin and the same epoxy modified with two reactive rubbers at the same concentration level. The times to the cloud point, gelation and vitrification are shown for each system. The cloud point is the point of incipient phase separation, as detected by light transmission. The modified system with the longer times to the cloud point and gelation, and the greater depression of Tg, contains the more compatible of the two rubbers. The difference in compatibility could then be used to account for differences in the volume fractions of the phase separated rubber-rich domains and in the mechanical properties of the neat and the two rubber-modified systems. 

Multifunctional POSS, containing four epoxide groups on the periphery, copolymerized with aliphatic diepoxides and an amine-curing agent increased and broadened the Tg, increased the tensile modulus, but lowered the flexural modulus over that of the neat epoxy resin [2] (Fig. 3). 

In one further work on epoxy-POSS, comparative studies were conducted on epoxy/ladderlike polyphenylsilsesquioxane (PPSQ) blends and the associated nanocomposites [2]. The work revealed that, although a decrease in the flexural strength and modulus of epoxy/POSS nanocomposites in comparison to the neat epoxy resin was observed, only flexural strength deteriorated in the epoxy/PPSQ blends compared to the neat epoxy resin. Flexural modulus of epoxy/PPSQ blends was reported to be much higher than that of the epoxy resin and also increased with an increase in POSS content. It was... 

Ea, above and below Tg. Three case studies illustrate the range of applicability of the bending beam setup and factors contributing to the stress state. The first is a comparison of two polymers for interlayer dielectrics PMDA-ODA (pyromellitic acid dianhydride - oxydiamine) and a bis-benzocyclobutene. The second is of a neat epoxy resin commonly used for microelectronics encapsulation (epoxidized ortho-cresol novolac cured with a phenolic novolac). The third is a screen-printable polyimide coating used for protection of the integrated-circuit chip. An outline of our stress model is sketched, and example results are presented. 

Three case studies are examined which illustrate the use of the bending beam stress experiment. The first is a comparison of two polymers for interlayer dielectrics. The second is of a neat epoxy resin commonly used for microelectronics encapsulation. The third is a polyimide coating used for protection of an integrated-circuit chip. 

MMT and EPON-828, the DSC curve (Fig. 17) indicates that the spontaneous clay exfoliation epoxide polymerization occurred at an onset temperature of 229 °C. On the basis of the integrated peak area, the heat of reaction for the composite was 572 J/g. DSC curves for the neat epoxy resin and the pristine [H3N(CH2)n-COOH]+-MMT are shown for comparison in Figs. 18 and 19 respectively. In the absence of a catalyst, self polymerization of the neat resin occurred at a much higher onset temperature of 384 °C but the heat of reaction (611 J/g) was comparable to that observed for the corresponding nanocomposite (572 J/g), when corrected for the presence of clay (572/0.95) or 602 J/g. 

Matrix-dominated physical and mechanical properties of a carbon-fIber-relnforced epoxy composite and a neat epoxy resin have been found to be affected by sub-Tg annealing In an Inert dark atmosphere. Fostcured specimens of Thornel 300 carbon-fiber/Flberlte 934 epoxy as well as Flberlte 934 epoxy resin were quenched from... 

Differential scanning calorimetry was used to measure both the extent of cure as well as the progress of enthalpy recovery in the neat epoxy resin. A Perkin Elmer DSC-2 differential scanning calorimeter equipped with a scannlng-auto-zero unit for baseline optimization was utilized to measure the heat capacity of the... 

Tensile tests were performed on neat epoxy resins In the following conditions as-cast, as-postcured, as-quenched, and aged at decade Increments from 10 to 10 minutes at 140°C In nitrogen while stored In darkness. A summary of the observed resin stress-strain behavior Is shown In Figure 2. As can be seen, the epoxy polymer was found to be extremely sensitive to thermal history. 

Thermal Stability and Conductivity. Thermal degradation temperature of PMMA, PS, and PVA (poly(vinyl alcohol)) nanocomposites shifts up by 10-100°C. During combustion [179], nanoparticles form a network of char layers that retards the transport of decomposition products. The thermal conductivity of epoxy composites is four times higher than that of the neat epoxy resin with 5 wt% loads. 

Rubber is a viscoelastic solid formed by crosslinking a polymer, which is initially a viscoelastic liquid. In spite of this difference there still are some common issues in understanding the physics of the glass temperature and the viscoelastic mechanisms in the softening dispersion (i.e., called the glass-rubber transition zone in Ferry (1980). A case in point can be taken by comparing the viscoelastic behavior of the neat epoxy resin Epon lOOlF (Plazek and... 

When the neat epoxy resin is modified by the incorporation of submicron rubber particles or glass spheres, the fracture energy can be increased by factors of 4-5 at all levels of temperature, as is shown in Fig. 13.41. Moreover, the increase of toughness with temperature is less abrupt. As we demonstrate, these observations represent an almost classical behavior of transformation toughening by crack-tip shielding of a brittle solid (Evans et al. 1986). 

In the case of Ni-La-Fe-O/epoxy nanocomposites, the thermal degradation showed a more complicated behavior than the neat epoxy resin, with two peaks in the 300-475 °C temperature range. Moreover, the thermal stability of the resin decreased in the presence of Ni-La-Fe-0 nanoparticles, due to the fact that these nanoparticles may act as catalysts to degrade the epoxy matrix [76]. 

Nanocomposites containing functionalized CNTs exhibited increased thermal stability, compared to the neat epoxy resin. In this case the functionalized CNTs had a better affinity for the pol3meric matrix than the un-functionalized CNTs [91]. Kuan et al. reported that the incorporation of the MWCNTs functionalized with vinyltriethoxysylane into an epoxy resin increased its thermal stability [92]. The same effects were obtained in the case of MWCNTs grafted with triethylenetetra-mine [91] and MWCNTs functionalized with silane [88]. 

J. T. Dickinson, L. C. Jensen, and S. Bhattacharya, Fracto-emission from neat epoxy resin (review article), in Die MakromoleChemi MacromoleSymp. 7, 129 (1987). 

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