Glasses, stressed polymer

Fig. 7.24. Predicted fracture toughness of carbon and glass fiber-polymer matrix composites (CFRP and GFRP) with varying matrix shrinkage stress, n. After Piggott (1981).

Both the Carreau and the Cross models can be modified to include a term due to yield stress. For example, the Carreau model with a yield term given in Equation (2.16) was employed in the study of the rheological behavior of glass-filled polymers (Poslinski et al., 1988) ... 

It is also useful to be able to study stress distributions experimentally. Some materials, especially glasses and polymers, are photoelastic, i.e., they undergo a change in refractive index under the application of mechanical stress. When viewed under polarized light, meehanical models made from these materials give rise to an optieal pattern that can be related quantitatively to the principal stress distribution in the loaded body. Figure 4.26 shows a phototelastic fringe pattern... 

Adhesive bonding uses photoresist, spin-on glasses, or polymers to deposit a planarizing material between two wafers. Such materials can be annealed or UV cured at low temperature to provide a low-stress wafer stack. 

E Devaux, B Chabert. Nature and origin of the transcrystalline interphase of polypropylene/glass fibre composites after a shear stress. Polymer Communications 32 464-468, 1991. 

Stress induced thermal events have been produced in all of the amorphous polymeric glasses examined to date. Surprisingly, these processes are always observable in a narrow temperature range above the ambient temperature, independent of the chemical structure of the polymer. Therefore, these effects are not, as might be expected, associated with the materials sub Tg secondary relaxations. The evidence for this assertion is presented in Figure 7 which shows the response of a variety of similarly stressed polymers approximately one hundred days after compaction. From top to bottom, in order of their respective glass transition temperatures are polystyrene (MW=37,000) ... 

E. Oleynik, S. N. Rudnev, O. B. Salamatina, and V. A. Topolkaraev, Stressed Polymer Glasses-Formation, Microstructure and Properties of Local Plastic Transformations Makromol. Chem. Macromol. Symp. 53, 77—80 (1992). 

Glass and polymer fibers are used to decrease strain under the influence of unwinding stress in unsupported double sided tapes (transfer tapes). 

Glass and polymer microspheres improve the stress distribution in the adhesive layer and the adhesion of thick double-sided tapes [245]. Organic microspheres containing low-boiling liquids can be used to foam an adhesive layer [246]. 

Boyce, M.C., Socrate, M. and Liana, P.G. (2000) Constitutive model for the finite deformation stress-strain behavior of poly(ethylene terephthalate) above the glass transition. Polymer, 41, 2183. 

Chua. P.S. and Piggott, M.R., The glass fibre-polymer interface. II. Work of fracture and shear stresses. Compos. Sci. Technol., 22, 107-119 (1985). 

Venkatai aman K S and Narayanan K S (1998) Energetics of collision between grinding media in ball mills and mechanochemical effects. Powder Technol 96 190-201. Nicolais L and Narkis M (1971) Stress-strain behavior of styrene-acryloiiitrile/glass bead composites in the glass region, Polym Eng Sci 11 194-199. 

Corrosion attack on the polymer is influenced by permeation rate, as weU as internal stresses or fatigue, that distorts or fractures the resin glass fiber... 

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