Interlaminar shear strength , polymer

As already mentioned, the first pyrolysis cycle leads to an open porosity of about 20-30 %. This high porosity limits the interlaminar shear strength (ILS). A reduction in the porosity is possible by reimpregnation with polymers and subsequent pyrolysis or CVI (Chemical Vapour Infiltration). 

Including 4-bromophenol in the phenol-formaldehyde resol system impacts the cross-link density of the cured product. In a systematic study of this copolymer, a comparison was made among the polymers obtained using phenol only, a 9 1 mole ratio of phenol to 4-bromophenol and a 1 1 mole ratio of phenol to 4-bromophenol. Comparisons included measurement of interlaminar shear strength and cone calorimetry tests of composites prepared using these phenolic resins and S2-glass fiber plain weave. 

Figure 6.17. Ratio of Raman peak intensities at 1355 and 1575 cm vs. interlaminar shear strength of composites containing carbon fibers of different origin. [Data from Tang L-G, Kardos J L, Polym. Composites, 18,No.l, 1997, 100-13.]...

In addition, for carbon fiber-reinforced con sites, the 90° flex modulus of 1M7/I.30E (6% wt. in epoxy)/Epon 862/W shows a 19% increase conqiared with IM7/Epon 862/W (control), while there is a 12% increase of the modulus for 6% I.30E/Epon 862/W nanoconqiosite con ared with neat Epon 862/W polymer. The interlaminar shear strength measured using 0°, 4-point flex mechanical tests... 

Polymer composites. The composite research at the Institute is led by Prof. Wu Renjie, Deputy director of the Institute. Chen, et al. (14), studied the effect of oxidation of carbon fiber on the wettability by the binder resin. With the aid of ESCA, they showed that the Q/C ratio on the fiber surface increased with the oxidation time. The interlaminar shear strength also increased correspondingly. Cai Weizhen and her colleagues showed me their exceptional setup for a carbon-fiber composite study. They built their own torsion pendulum for the study of dynamic mechanical properties of the composite and a contact angle goniometer for the study of the composite interface. It was apparent that surface treatment of carbon fiber was their major concern. 

In FIG. 14 the interlaminar shear strength (ILSS) of the two types of composites is illustrated in dependence of the deposition time of the plasma polymer. Applying the mixture of S seem acetylene/IS seem air it is found that the ILSS is increase by about 25 % relative to that of the virgin fibre. This result is explained by the improvement of adhesion between fibre and matrix resulting from chemical bonds between qx)xy resin and the functional groups of the plasmapolymerized acetylene. 

It is assumed that the use of such a nanocomposite as a matrix in continuous fiber-reinforced composites will definitely improve the matrix-related properties, such as interlaminar fracture toughness, transverse tensile strength and modulus, as well as interlaminar shear strength. The same should be true for polymer-based tribomaterials, in which such a nanoparticle-modifled resin is used in combination with friction and wear improving fillers, such as short carbon fibers, PTFE particles, and graphite flakes. 

The methods that have been studied in the past for increasing the interlaminar shear ductility are based on coating fibers with rubbery polymers or very ductile thermoplastics from solutions. In these cases, the enhancement in ductihty occurs at the expense of the interlaminar shear rigidity and strength [25, 27]. 

Standard Test Method for Mode I Interlaminar Fracture Toughness of Unidirectional Fiber-reinforced Polymer Matrix Composites Standard Test Method for Apparent Shear Strength of Parallel Fiber Composites by Short-Beam Method... 

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