THE vibroscope is an apparatus for determining the denier of short single filaments quickly and simply. When the denier of the filament has been determined vibroscopically, it can be fixed in an entirely undamaged condition in the Heim tensile tester, where its breaking strength is measured.The Heim tester, used alone, determines the absolute strength of the thread; but used in combination with the vibroscope it can give the relative strength of the thread in grams per 100 denier directly. This instrument can record the strength-elongation curve of the thread photographically, and hence without loss of power. For practical purposes, however, it is usually sufficient to record only the breaking strength and elongation of the fiber being examined, and for this purpose an optical system instead of a camera is attached to the Heim apparatus. By means of this optical system, breaking strength and elongation can be read from the apparatus directly. The whole determination takes only a few minutes, and for many years the method has been applied in the A.K.U. factories and laboratories for production control.Besides furnishing data on strength and elongation, the vibroscopic measuring method makes it possible to collect data on the regularity of the denier. For a continuous-filament rayon these data are important, particularly when the spinneret employed has a great many holes and it is desired to determine the distribution of the denier over the filaments coming from the various holes.In parts I and II of this article the characteristics and the operation of the vibroscope are discussed briefly, and in part III some experimental results are given..

In this article the viscose filtration process is subjected to a further investigation both theoretically and experimentally. Particularly the method applied in practice at present for the determination of the “clogging constant” of dissolver viscose is criticized.

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IntroductionThe longitudinal abrasion of a rayon filament can be achieved in a very simple way. The filament is laid around a rotating roller under a certain tension.The time which passes until the filament breaks can then be determined. This time is a measure of the resistance to longitudinal abrasion.Starting from certain simple theoretical assumptions we have derived a formula indicating the relationship between the time of abrasion until break, t, and the load on the thread. It was found, however, that this formula did not correspond with the experimental results. This meant that during this experiment the wearing-off process did not take place in the simple way which had been assumed originally.The abrasion process was then examined more exactly. Finally, a formula was obtained indicating the relationship between time of abrasion until break and load on the thread in a way which was in far better agreement with the experiment, although this formula must not be considered to be completely accurate.In Part I we derive the simple formula for determining the time of wearing until break, t, as an introduction to the derivation of the improved formula for determining t which is discussed in Part II. In any case, the latter formula gives a clear picture of the initial phenomena during this