Testing methods polymer acoustics

This article covers the use of acoustics as a molecular probe of polymer structure and describes various acoustic applications of polymers. Enough theory and experimental details are given to make the presentation understandable, but the emphasis is on the experimental results for polymers. Most of the presentation is for small-amplitude waves in solid polymers. References to some speciaUzed topics are given (see also Mechanical properties Test Methods). 

In l02) the authors describe the design of an experimental plant for studies of acoustic cavitation in flowable high polymers with the help of optic methods the plant employs a flat-slit transprent-wall capillary acoustic treatment of a polymer was carried out at a frequency of 17.8 kHz, and amplitude of vibration between 0 and 15 mcm. The study was conducted on 1,2 polybutadienes of narrow molecular-mass distribution tests were arranged at room temperature. It has been demonstrated that static mechanical stresses occur in a stationary (non-flowing) polymer under the action of acoustic treatment isochrome lines in the viscosimetric tank form a cellular structure with cell size of about 1-3 mm, and in the capillary the isochromes are observed in form of longitudinal strips (Fig. 19). The authors have also found that acoustic... 

Very recently, in our group, enhanced self-reinforced PP composites based on commercial PP fabrics were obtained by the film stacking method followed by compression molding introducing different contents of micron-sized quartz particles in the matrix films (unpublished results). Simultaneous improvements of composite tensile strength, ductility and fracture toughness were observed from the addition of quartz to the polymer matrix (Table 14.1). Enhanced degree of consohdation was obtained for the composites with quartz as evidenced from the improved mechanical properties and by SEM observations. This was also confirmed by acoustic emission analysis in situ in tensile tests. 

The literature on NDT of polymers and PMC comprises the classes shown in Table 1. References illustrate the available range of literature or a specific topic. Omission or inclusion of a reference does not imply a rating by the authors. The amount of information available in electronic format only is steadily increasing, eg, References 2-8, and many journals feature electronic on-line editions. Electronic database searches are sensitive to spelling, eg, non-destructive yields 27, and nondestructive 384, active standards of the American Society for Testing and Materials International. Most NDT methods apply to various material classes. Those documents that explicitly mention polymers or PMC deal with effects specific to certain materials, eg, the Felicity effect in PMC (9), or with polymer products used in large quantities (10-14). Standards tend to lag behind technical developments, as discussed for acoustic emission (15), but similar arguments hold for other NDT methods. 

In the second half of the 1990s, mainly Park et al. from Korea published several papers on BF-reinforced composites. They tested polycarbonate (PC)" and epoxy resin (EP) based polymer composites with the methods of single fiber fragmentation and acoustic emission. It was found that in the case of PC matrix composite (when aminosilane was used as a treating agent), the number of acoustic events correlated well with the value of the interfacial shear strength determined from the fragmentation tests. 

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