Surface-active, perfluoroalkyl-terminated block copolymers were synthesized and characterized. These heterophase block copolymers were made by terminating a variety of living anionic polymerizations with a chlorosilane derivative containing a perfluoroalkyl group. This synthetic methodology was successfully applied to the anionic polymerization of styrene and 1,3-dienes. Perfluoroalkyl-terminated poly(olefin)s were obtained via hydrogenation of the unsaturated poly(diene) materials. Excellent control of the molar mass, molar mass distribution, and functionality was verified using conventional characterization techniques such as gel permeation chromatography, NMR, and elemental analysis. In addition, time-of-flight secondary ion mass spectrometry (TOF-SIMS) was employed to characterize the absolute molar masses and molar mass distributions and also the extent of functionalization.

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KEYWORDS: Floor System, Nondestructive Evaluation, . Currently, the use of stress wave techniques is limited to NDE . individual wood members. Evaluating each member of a . structural system is labor intensive and time consuming. For he Forest Products Laboratory, USDA Forest Ser-. in situ inspection of timber structures, a more efficient stratvice, has been developing nondestructive evaluation . egy would be to screen whole structural systems or subsys-(NDE) techniques to identify degradation of wood . tems in terms of their overall performance and serviceability. in structures and the performance characteristics . Examining the dynamic response of the structural system trasonic transmission NDE techniques for both laboratory any organisin reduces the strength and stiffness of the mathat remain in the structure. This work has focused on using . might provide an alternative way to gain insight into the dynamic testing techniques, particularly stress wave and ul-. ongoing performance of the system. Deterioration caused by and field investigations.. . terials and thus could affect the dynamic behavior of the . system. If, for example, one structural system or sections of Our initial efforts were aimed at using stress wave tech-. the system were found to respond to dynamic loads in a manniques to identify wood degradation. In a previous publica-. ner significantly different from that of other similar systems tion, 1 we reported on an inexpensive experimental technique . or the surrounding sections of the system, a more extensive that was developed to observe longitudinal stress wave be-. inspection of that system or section would be warranted. havior in small wood specimens. The technique utilized a .mechanical impactor to induce a wave in the specimen. Wave . Based on this conceptual strategy, we began to investigate propagation was observed by placing a piezo film sensor on . the possibility of using transverse vibration techniques to inspect full-size wood floor T the surface of the wood. Output of the sensor was recorded and displayed on a digital storage oscilloscope. This technique enabled us to examine fundamental wave propagation characteristics and the biological degradation of wood. Recently, we investigated the use of speed of sound transmission to locate degraded regions in wood materials. 2 The test setup we developed consisted of two 84-kHz rolling transducers coupled to an ultrasonic systems by evaluating component systems. This paper describes the experimental setup developed for our research and typical results obtained from its use. TRANSVERSE VIBRATIONTransverse vibration techniques have received considerable attention for NDT applications in the wood industry.3 To illustrate these methods, an analogy can be drawn between the behavior of a vibrating beam and the vibration of a mass that is attached to a weightless spring transmitting and receiving Fig. I : Mass-spring dashpot vibration model (left) and unit. A stress wave was introduced into a specimen in the transverse direction by transversely...