PDF Publication Title:
Text from PDF Page: 007
(less than one atmospheric pressure as created by the 25” Hg vacuum). Because of the vacuum differential between the two bags, the Inner Bag is collapsed, instead of “ballooned”, and presses against the composite with a small compaction pressure (created by the vacuum differential of 5” Hg between the two bags), while still producing a 30” Hg full vacuum to assist volatile removal. Under this circumstance, the volatile depletion rate may not be hindered by the slightly compacted fibrous architecture, while the potential for Inner Bag leakage is greatly reduced. The concepts of DVB assembly and processing described above can be easily implemented in any vacuum heating chamber such as a vacuum oven, vacuum press or autoclave as shown schematically in Figure 4. In these cases, one only needs to assemble the Inner Bag for the composite. The chamber wall serves as the Outer Bag, and the stiff perforated tool between the Bags is no longer needed. Separate vacuum ports are built for the Inner Bag and the heating chamber, respectively. For molding composites with poor matrix resin fluidity (i.e., high viscosity) at elevated temperatures, extra pressure can also be applied safely to facilitate composite consolidation after B-stage through platens (in a vacuum press) or pressurized gases (in an autoclave). In fact, with proper tooling designs, the DVB concept for volatile management can be adapted to any composite manufacturing process, including resin transfer molding (RTM), vacuum assisted resin transfer molding (VARTM), solvent assisted resin transfer molding (SARTM) and resin film infusion (RFI) processes, in which the proper removal of volatiles is an issue. These concepts are presently being pursued at the NASA Langley Research Center. 3. Materials Two fiber reinforced polymeric resin composite systems were investigated. The first, LARC‘ PETI-8 (Langley Research Center Phenylethynyl Terminated Imide- 8) aromatic polyimide, is based on 3,3’, 4,4’-biphenyltetracarboxylic dianhydride, a 50:50 molar ratio of 3,4’-oxydianiline and 1,3-bis(3- aminophenoxy)benzene, with 4-phenylethynylphthalic anhydride as the endcapping agent at a theoretical number average molecular weight of ~ 2,500 g/mole. Unidirectional prepregs with ~ 14% volatiles were made by coating an NMP solution of the LARC‘ PETI-8 amide acid oligomers onto unsized IM7 carbon fibers. When cured at elevated temperatures, imidization reactions occur which release water as reaction by-product. The second system, commercial 7781 E-glass/Cycom 6070 prepreg (8 harness satin fabric), was received from Cytec Engineering Materials (Anaheim, CA). This prepreg contains 3-5% volatiles. Cycom‚ 6070 is a 138°C to 160°C (280°F to 320°F) curing phenolic resin. It has a service temperature up to 260°C (500°F) when stepwise post-cured up to 232°C (450°F). Cycom‚ 6070 is a novolac andPDF Image | Evaluation of Double-Vacuum-Bag Process For Composite Fabrication
PDF Search Title:
Evaluation of Double-Vacuum-Bag Process For Composite FabricationOriginal File Name Searched:
Double-Vacuum-Bag-Process-Composite-Fabrication.pdfDIY PDF Search: Google It | Yahoo | Bing
5,000 BF Shipping Container Lumber Dry Kiln For Quality Lumber The 5,000 BF container kiln consists of one 40 foot high-cube aluminum shipping container... More Info
Shipping Container Lumber Dry Kilns by Global Energy Global Energy designed and developed the container kiln back in 1991. The purpose is to give access to portable sawmill owners, furniture makers, and small business the value added profit of dry kiln lumber and quality hardwoods... More Info
Vacuum Kiln Conversion Kit for Lumber and Wood Dry Kilns Convert your existing conventional dry kiln into a fast drying vacuum kiln. Similar to vacuum bagging in the boat building and aircraft industry, we have come up with a proprietary process which allows you to build a very simple vacuum kiln at a fraction of the price, and without the intensive conventional metal chamber structure... More Info
Vacuum Pump Cart System for Bagging Clamping Wood Drying and more Vacuum Cart with 2HP Pump and Dual Pistons with multiple multiplex vacuum ports and liquid reservoir... More Info
Vacuum Bagging Basics Vacuum bagging is a method of clamping, which has traditionally been used in the composites industry, but can also be used for vacuum drying materials, including wood products... More Info
CONTACT TEL: 608-238-6001 Email: greg@globalmicroturbine.com (Standard Web Page)