Prepregs, epoxy resins

Table 3. Typical Epoxy Resin Prepreg Formulation...

Epoxy resin prepregs were characterized by RPC on C 18 columns with a water/ tetrahydrofuran gradient, either linear from 40 to 100% B within 30 min or concave from 40 to 80% B in 50 min 89). Reversed-phase chromatography revealed more details than the SEC of the sample. Samples that looked similar in SEC showed marked differences in RP-HPLC (Fig. 25). 

Fig. 25 a and b. Analysis of epoxy resin prepregs. a = SEC with UV detection at 280 nm, comparison of sample SP 250 with formulation standard, b = Gradient elution of these samples on a RP 18 column with water/THF gradient program 40 to 80% B in 50 min, non-linear. (From Ref. e9) with permission)... 

Figure 3.20. Successive FT-IR emission spectra from a thin film of resin from a carbon-epoxy-resin prepreg during cure. Bands that change during cure are marked (George et al., 2006).

Figure 3.21. Detail from Figure 3.20 marked with showing the decrease and growth of emission bands during cure of thin film of epoxy-resin prepreg.

Isothermal Cure Kinetics of an Epoxy Resin Prepreg... 

The isothermal cure kinetics of a glass fiber-epoxy resin prepreg is investigated using high performance liquid chromatography (HPLC) and differential scanning calorimetry (DSC). The... 

The most widely used process for the fabrication of glass fabric prepreg involves solvent/solution techniques. The resins have to be soluble in appropriate solvents preferrably methylethylketone, acetone or other low boiling solvents. Therefore BMI building blocks with improved solubility are desired. Sometimes bismaleimides are used in epoxy resins to improve the glass transition temperature (T,), then solubility in epoxy resin is required. It has been found that tetraalkyl- 4,4 -MDA -BMIs(27), which melt at around 150°C and... 

The catalyst composition in Fiberite 934 and Hercules 3501 prepregs was investigated by 19F NMR. The epoxy resin in these commercial C-fiber/TGDDM-DDS prepregs was dissolved in DMSO. 

Resin Components Epoxy resins used in this study were fabricated from the same components employed to prepare most of the commercially available graphite-epoxy prepreg resins used in military aircraft, namely Narmco 5208,... 

In Table 15.3 are shown the chemical structures and Tg and of some representative thermoplastic polymers for use at high temperature (3,9). These matrices have high continuous service temperatures (120-200° C) even under wet environmental conditions. Advantages of thermoplastic over thermoset matrices are their shorter fabrication cycle (generally controlled environment storage is not required) and the possibility to be reprocessed and reconsolidated after manufacture. Poly(ether ether ketone) is a strong contender with epoxy resins for use as a matrix in composite prepregs with carbon fibers to be utilized in structural aircraft components. 

The fabrication of components from advanced composite materials also requires suitable tooling to shape and conform the prepreg during lay-up and epoxy have a role to play in this operation as well. Whilst less durable than conventional tooling constructed from steel or aluminum, tooling prepared from carbon fiber reinforced epoxy resins offers lightweight and, most importantly, a good match with the... 

As can be seen in Figures I and II, the processing involves impregnating the fiberglass with the uncured epoxy resin solution, and finally fully curing layers of the prepreg with copper foil into a finished laminate. From this point the laminate is fabricated into a finished printed circuit board. 

The problem of reliably analysing the epoxy-resin component of a carbon-fibre epoxy prepreg has also been addressed by using FT-IR emission spectroscopy (FTIES)... 

In the mid-60 s carboxyl-terminated polybutadiene/acrylo-nitrile (CTBN) liquid polymers were introduced for the purpose of epoxy resin modification. These telechellc polymers are essentially macromolecular diacids. They offer processing ease (and therefore advantage) over the solid carboxylic nitrile elastomers. It is no surprise that the epoxy prepreg industry (adhesive and non-adhesive varieties) found the liquid and solid carboxylic nitrile elastomer species useful together in processing liquid and lower molecular weight solid epoxy resins where elastomer modification was needed. 

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