Methods for predicting the quality of nylon 612 filament for use as a bristle material

Abstract

SYNOPSISSplaying and curling of bristles is a very important performance characteristic of nylon toothbrushes. For this reason, analytical methods are needed that correlate fundamental physical-chemical properties with the eventural development of bristle splaying. Differential scanning calorimetry, thermogravimetric analysis, and wide-angle X-ray diffraction were each found to identify subtle differences in nylon 612 filament that had been subjected to varying processing conditions during manufacture. These differences were found to be related to water absorption and crystalline perfection and could be correlated with the characteristics of toothbrush wear. From the results, it was concluded that these three methods can be used for quality control and research purposes to predict and to study enduse performance factors such as bristle splaying. 0 1992 John Wiley & Sons, Inc. INTRODUCTlONMost toothbrushes are made from nylon 612 filament. With use, the nylon bristles take on a permanent curl along the outer one-third of their length. This "splaying" process eventually leads to reduced cleaning effciency and to the perception that the brush is "worn out." Filament recovery from bending and machine "scrub" tests are currently used to predict this performance. Such tests are time-consuming, are highly subject to experimental variability, and give only minimal insight into fundamental properties. Thus, analytical methods are needed that rapidly provide information about fundamental physical-chemical properties that are predictive of end-use performance.Wearing out through the development of bristle splaying is one of the most important performance properties of brushes. As part of an effort to ensure consistent filament quality, nylon 612 filament was investigated using thermal analysis and X-ray diffraction techniques. The filament samples were

An in vitro and in vivo Study of Toothbrush Bristle Splaying

“…2 and 4, has not previously been reported. The process variables and filament characteristics that determine nylon filament quality have been reported elsewhere (Rawls et al, 1992). The correspondence between machine-induced and human-induced splaying, as predicted by equation [3], is shown in Table 5.…”

“…du Pont). The 97% filament was taken from a lot prepared for commercial use, while the others were prepared under experimental conditions, as described by Rawls et al (1992). The characteristics of representative filaments are shown in Table 1.…”