Ethylene Bis-stearamide Research Articles

Green microstructure effects on densification and distortion in liquid phase sintering

Microstructure attributes such as solid volume fraction, dihedral angle, initial porosity, and initial pore size are important to densification and distortion control in liquid phase sintering (LPS). In our experiments, these parameters were varied to measure densification and distortion behavior during LPS using W–Ni–Cu alloys. Green compacts were formed using ethylene- bis-stearamide (EBS) as a pore-forming agent with the amount of polymer controlling the initial porosity. Different initial pore sizes were generated by varying the polymer particle size. Dihedral angle was varied by changing the Ni:Cu ratio in the alloys. Finally, the solid:liquid ratio was adjusted via the tungsten content. Dilatometry was employed to measure shrinkage and shrinkage rate during heating. Real time video imaging and quenching experiments isolated the sequence of densification and distortion events in LPS. Distortion was quantified using profiles determined with a coordinate measuring machine (CMM) to calculate a distortion parameter. Sintering results showed that at full densification, initial porosity and pore size have no observable effect on distortion for 80W–16Ni–4Cu alloy while distortion reduces with increasing solid volume fraction and dihedral angle. Microgravity experiments are proposed for further understanding of microstructure effects on densification and distortion in LPS.

The experimental evaluation of die compaction lubricants using deterministic chaos theory

The use of lubricants in die compaction is becoming an increasingly important issue in the P/M industry, both from an economic and environmental perspective. Until this time, the evaluation of lubricants has been limited to apparent density, tap density, and various elementary flow tests. This paper examines the application of deterministic chaos theory and fractal geometry to characterize the effects of lubricants on powder flowability. The lubricants that were investigated included zinc stearate, polyvinyl fluoride, Teflon™ (polytetrafluoroethylene—PTFE), and Acrawax C (ethylene bis-stearamide), ad-mixed with irregular iron powders. This paper evaluates the applicability of this new technique for characterizing powder flowability. In addition to distinguishing between the efficacy of various lubricants, data are presented on the statistical reproducibility, the effect of testing history on subsequent measurements, and the effect of machine operating parameters on the data. Parameters that can be used to describe the flow data produced by this new technique will be discussed.

The Application of Chaotic Theory and Fractal Geometry to Measure the Effects of Lubricants for Uniaxial Die Compaction

The use of lubricants in die compaction is becoming an increasingly important issue in the P/M industry, both from an economic and environmental perspective. Until this time, the evaluation of lubricants has been limited to apparent density, tap density, and various elementary flow tests. This paper examines the application of chaotic theory and fractal geometry to characterize the effects of lubricants on powder flowability. The lubricants that were investigated included zinc stearate, polyvinyl fluoride, Teflon®, and Acrawax C (ethylene bisstearamide), ad-mixed with Hoeganaes A-1000C iron powder. This paper presents a completely novel technique to assess lubricant effects on powder flowability using the Aeroflow® produced by Amherst Process Instruments.

Lubricant systems for rigid PVC applications

AbstractLubricants are used in extrusion processing of rigid polyvinyl chloride (PVC) compounds to control fusion and reduce shear heating. Without lubricants, conversion to the melt state results in excessive shear heating and degradation of the compound. The present work compares new lubricant systems containing complex esters with conventional systems based on ethylene bisstearamide (EBS) and paraffin. These new systems provide improved compound stability, weatherability, and physical properties. In addition, use of these systems results in lower compound viscosity compared with the conventional lubricant packages. The effects of other characteristics of these systems, such as the degree of esterification on compound properties, are also discussed.

Quantification and characterization of the trifluoroacetic anhydride derivatives of N,N′-ethylenebisstearamide and N,N′-ethylenebisoleamide

An analytical technique for the measurement of low levels (0.1–3.0%) of N,N′-ethylenebisstearamide (EBS) and N,N′-ethylenebisoleamide (EBO) in polymeric matrices has been developed. The method involves reaction of the secondary bis-amides with trifluoroacetic anhydride (TFAA) followed by high-performance liquid chromatographic (gel permeation chromatographic) separation and quantification of the N-trifluoroacyl derivatives. The method is linear in ranges typical of polymer compounding applications and offers a direct measurement of EBS and EBO without the need for prior extraction. The TFAA derivatives were isolated and characterized by infrared and direct-probe mass spectrometry.