Material defects related problems

Composite materials as well as adhesively bonded joints are not exempt from some problems even though they have great advantages and applicability. Defects related to composite bonded joints can be classified into two main streams- manufacturing defects and in service defects. 

Conjugated polymers like poly(l,4-phenylene-vinylene), PPV, or more generally Poly(arylene-vinylenes), PAVs have evoked considerable interest as electrically conductive and nonlinear optical materials. More recently, electroluminescence properties of PPV have attracted substantial attention, since it was first reported in 1990. Direct synthesis of PPV has been limited by its insolubility. Hence, the most commonly used routes are based on soluble polymer precursors or soluble conjugated precursors. The latter process is also commonly referred to as the sulfonium-based polyelectrolyte precursor route. PPV thin films from these solution-based routes, however, have problems related to contamination by solvents and oxidative defects in the polymer. C VP is an alternate method for the deposition of high quality thin films of PPV. Reported first by Iwatsuki et al., it was investigated for electroluminescence applications by Staring et al. ... 

Connective Tissue Proteins. Collagen comprises the major material of skin and myocommata. Love and his co-workers studied the problem of gaping in which slits or holes appear in the muscle and sometimes the fillet falls apart. This defect is related to the behavior of myocommata proteins (83-87). Gaping is more severe in fishes frozen in-rigor than in those frozen pre-rigor, and the seriousness of this defect varies with the biological condition of the fish (influenced by season, size, age, and whether the fish is healthy or starved), and the fish species. 

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