Home
Tags
No Tags
Effect of silicone interlayer on carbon fiber reinforced PMR-15 composite: Processing and characterization
| Title: | Effect of silicone interlayer on carbon fiber reinforced PMR-15 composite: Processing and characterization |
| Author: | Labronici, Marcos |
| Description: | The objective of this work is to study the effect of silicone as an interlayer material in carbon fiber reinforced PMR-15 polyimide composites. Viscous and elastomeric silicones are applied as interlayers to these composites in order to develop a tougher and microcrack resistant composite, while preserving the excellent thermo-oxidative resistance of the PMR-15 polyimide matrix. Carbon fiber is continuously coated with high molecular weight polydimethylsiloxane and polymethylvinylsiloxane (780,000) in hexane. Uncured polydimethylsiloxane (PDMS gum) is the viscous interlayer studied and polydimethylsiloxane (PDMS elastomer) and polymethylvinylsiloxane (PVMS elastomer) cured with peroxides are the two forms of silicone elastomers studied. The effect of the amount and the type of these forms of silicones on the mechanical and dynamic mechanical properties of unidirectional composites are studied. It is shown that the silicone interlayer enhances impact strength, toughness, and microcrack resistance. The enhancement depends on the interlayer thickness, coating process, and laminate fabrication process chosen as well as the type of the silicone. Flexural and interlaminar shear strength is found to drop with the presence of the interlayer. It is demonstrated that the mechanical proper ties of the composites with silicone interlayers is not affected by thermal aging at 300°C for 100 h. The dynamic mechanical properties of the composites are determined and compared with uncoated carbon fiber reinforced PMR-15 polyimide composites. The presence of the interlayers are observed by the appearance of a new relaxation peak in dynamic mechanical spectra. The temperature of this peak is found to be a good indication of the degree of the cure of the silicone elastomer. Apparent activation energy of the α transition of the matrix in the modified composites varies with the amount and type of silicone interlayer in concert with the impact strength. The variation of the activation energy is explained in terms of structural changes within the matrix that arise from interfacial effects due to the presence of the soft interlayer. The main structural change within the matrix is believed to be a decrease in the free volume caused by the relieving of internal stress |
| Permanent Link: |
http://rave.ohiolink.edu/etdc/view?acc_num=case1061308467
http://hdl.handle.net/2374.OX/16097 |
| Date: | 1994 |
Files in this item
| Files | Size | Format | View |
|---|---|---|---|
|
There are no files associated with this item. |
|||