Mechanisms of ultrasonic joining of textile materials

Abstract

Investigates the potential for building smart seams by incorporating optic fibers ultrasonically. The heating and bonding mechanisms of ultrasonic welding process in fabrics were studied. Battle dress uniform (BDU) (50/50 nylon/cotton), 100 percent cotton, 100 percent polyester and Nomex fabrics were used and were bonded ultrasonically with and without polyurethane adhesives. The effects of three important welding parameters, namely weld pressure, weld time and amplitude of vibration, on the joint strength and the temperature profile at the interface were examined. The temperature profiles for different fabrics were measured during ultrasonic welding process. The attenuation degree of signal transition properties of optic fibers incorporated was tested to determine if ultrasonic process provided a possible way of embedding optic fibers into seams and achieving sufficient joint strength while the signal transmission properties of optic fibers incorporated were not changed significantly.

Ultrasonic sealing of polyester and spectra fabrics using thermo plastic properties

“…The investigators used the Fourier Transform Infrared‐Ahenuated Total Reflectance (FTIR‐ATR) analysis technique to study the possibility of the chemical conversion of polymer at the weld zone, as affected by ultrasonic vibration. Shi and Little3 did not find any chemical bond formation within the normal range of operation, although at extreme conditions polymer degradation may occur. Mozgovoi et al4 also found no new chemical groups or bonds while studying the microstructure of ultrasonically welded polyethylene; hence, it seems that the ultrasonic bonding mechanism is essentially a physical process and not a chemical process.…”

“…Several studies have been conducted with different polymeric fabrics to understand the bond formation mechanism in ultrasonic seaming. Shi and Little3 investigated seam formation using ultrasonic energy with 50/50 nylon/cotton fabric and polyurethane films. The investigators used the Fourier Transform Infrared‐Ahenuated Total Reflectance (FTIR‐ATR) analysis technique to study the possibility of the chemical conversion of polymer at the weld zone, as affected by ultrasonic vibration.…”

The sewing of textiles

“…in addition, more methodological research has been conducted on welded seams and sewn seams separately. Shi and Little (2000) presented work which, as a result of investigating the possibility of using welded seams to incorporate optical fibres into garments as a data channel, gave experimental credence to the three important weld parameters of amplitude, pressure and weld time. Through a 2 3 factorial experimental design, the research indicated a positive increase in weld strength (of up to 15%) with an increase in pressure and, separately, weld time, until a point is reached when the strength begins to decrease due to polymer orientation or energy dissipation, respectively.…”

A low temperature ultrasonic bonding method for PMMA microfluidic chips

“…And they discovered that for the given material and dimensions of energy director, there existed a critical amplitude. The energy director did not melt when ultrasonic amplitude was lower than the critical amplitude no matter how long the bonding time was (Tolunay et al 1983;Shi and Little 2000). In this paper, the energy director should not melt in the bonding process.…”

“…1b and c. It may cause the whole device unusable. Heating mechanisms of ultrasonic welding were intensively studied in the past decades (Shi and Little 2000;Tolunay et al 1983). During the whole welding process, polymer experiences different states of glassy state, rubbery state and viscous flow state.…”