Ethylene Bis-stearamide Research Articles

De-Lubrication Behavior Of Novel EBS Based Admixed Lubricant In Aluminum P/M Alloy

Abstract The objective of the present research is to develop a novel lubricant for Al-Cu-Mg P/M alloy and to address the effects of the lubricant and compaction pressure on sintered properties. A lubricant mixture consisting of Ethylene Bis Stearamide, Zn-Stearate, and fatty acid was newly developed in this study, and the de-lubrication behavior was compared with that of other commercial lubricants, such as Ethylene Bis Stearamide, Zn-Stearate, and Al-Stearate. Density and transverse rupture strength of sintered materials with each lubricant were examined, respectively. The microstructural analysis was conducted using optical microscope.

Enhanced crystallization of poly (lactic acid) through reactive aliphatic bisamide

The poor crystallization rate of poly (lactic acid) (PLA) is a major drawback in terms of controlling the properties of final products. To overcome this, a nucleating agent is normally applied. In this work, the aliphatic bisamide, N, N'-(1,3-propylene) bis(10-undecenamide) (PBU), having reactive functional groups is used as a crystallization promoter for PLA by adding PBU in various concentration (0.1-0.7 wt%) into PLA together with peroxide via reactive melt blending. The conventional ethylene bis-stearamide(EBS) is used for a comparison. The extruded samples are characterized for gel content and FT-IR spectroscopy. The crystallization behaviour and rate, and spherulites morphology are investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM), respectively. It is found that the addition of PBU into PLA results in the dramatic increase in crystallinity and crystallization rate of PLA compared with neat PLA and PLA added EBS. The crystallinity increases to 24.9-28.3% higher than neat PLA under even cooling rate of 7°C/min. The addition of 0.7 wt% PBU shows the fastest crystallization rate with t1/2 value isothermally crystallized at 130°C of only 6 min. POM images indicate the increase in the nucleation density and very fine spherulitesof PLA added PBU, promoting the fast crystallization.

Compressibility of a Ti-based alloy with varying amounts of surfactant prepared by high-energy ball milling

The combined effects of varying amounts of surfactant (ethylene bis-stearamide; EBS) and milling time on the compressibility of ball-milled Ti–10Nb–3Mo (wt.%) alloy were investigated. Ball milling process was performed on the elemental powders with different amounts of EBS (0–3wt.%) for 5 and 10h, and the ball-milled powders were consolidated by a uniaxial cold pressing in the range of 500–1100MPa. Results indicated that the addition of surfactant in ball milling process lead to significant changes in particle packing density. The relative density was higher for powders ball milled with larger amounts of EBS and for the shorter milling time. The compressibility of powders was examined by the compaction equation developed by Panelli and Ambrosio Filho. The densification parameter (A) increased with the increasing amount of EBS, and decreased with increasing milling time.

Recent advances in production of poly(lactic acid) (PLA) nanocomposites: a versatile method to tune crystallization properties of PLA

A new approach leading to poly(lactic acid) (PLA) nanocomposites designed with improved nucleating/crystallization ability has been developed. As proof of concept, nanofillers of different morphology (organo-modified layered silicates, halloysite nanotubes and silica) were surface-treated with ethylene bis-stearamide (EBS), a selected fatty amide able to promote chain mobility during PLA crystallization from the melt and nucleation. The fine dispersion of the nucleating additive via nanoparticles (NPs) as ‘nano-template’ is leading to nanocomposites showing unexpected improvements in PLA crystallization rate. This was evidenced by differential scanning calorimetry (DSC) from the high values of the degree of crystallinity (20–40%) with respect to neat PLA (4.3%) and the sharp decrease in crystallization half-time under isothermal conditions (at 110°C), even below one minute. Furthermore, after injection molding the outstanding crystallization properties of PLA were again confirmed. Accordingly, the PLA-nanofiller/EBS nanocomposites revealed remarkable degree of crystallinity (in the range of 30–40%). Surprisingly, the presence of EBS can significantly increase the impact resistance of PLA and PLA based nanocomposites. By considering the remarkable increasing in crystallinity, a key parameter to allow PLA utilization in durable applications, the development of the new approach is expected to lead to significant improvements in the processing and performances of PLA products.

The addition of a surfactant at regular time intervals in the mechanical alloying process

The impact of regular additions of a surfactant (ethylene bis-stearamide; EBS) at different time intervals was investigated on the powder characteristics of a biomedical Ti–10Nb–3Mo alloy (wt.%). Ball milling was performed for 10h on the elemental powders in four series of experiments at two rotation speeds (200 and 300rpm). The addition of 2wt.% total EBS at different time intervals during ball milling resulted in noticeable changes in particle size and morphology of the powders. The surfactant addition at shorter time intervals led to the formation of finer particles, a more homogenous powder distribution, a higher powder yield, and a lower contamination content in the final materials. Thermal analysis of the powders after ball milling suggested that differing decomposition rates of the surfactant were responsible for the measured powder particle changes and contamination contents. The results also indicated that the addition of surfactant during ball milling at 200rpm caused a delay in the alloy formation, whereas ball milling at 300rpm favored the formation of the titanium alloy.

Effects of lubricant on green strength, compressibility and ejection of parts in die compaction process

Abstract Lubricants improve the flow of metal powders, reduce friction and extend tool life during the die compaction process. Fe-2%Cu-0.5%C powders mixed with various amounts (0–0.8 wt.%) of ethylene-bis-stearamide (EBS) were used to determine the effects of lubricant amount on several green properties of the die-compacted parts in the present study. The green density and green strength for the powder mixed with various amounts of EBS increased with increase in compaction pressure. The effect of lubricant on the green density was found to be marginal at high compaction pressures. The green strength however decreased with the addition of EBS. Regression analysis was carried out to evaluate the applicability of existing models to predict the green strength as well as the compression behavior of the powder mixtures. The green strength models developed by Kawakita, Halldin et al., and German showed reasonable applicability for predicting the strength of compacted powders with varying amounts of EBS. The compression models developed by Kawakita, Heckel and Panelli–Ambrosio Filho were suitable for correlating the variation of compressibility of the powders with increasing amounts of EBS. The compressibility of the powders increased with an increase in the amount of EBS. In situ compression curves were experimentally obtained to determine the compressibility of powders as a function of increasing compaction pressure. The compressibility curves for powder with varying amounts of EBS were fitted to a power law equation. The ejection forces were found to be sensitive to the dimensions of the part as well as the amount of EBS. A new model was developed to estimate the ejection force based on the part dimensions and amount of EBS. The models showed a reasonable agreement with the experimental data. It is anticipated that the models evaluated in the present study will be useful in identifying appropriate amounts of lubricants required to optimize various green properties in die compaction components.

Low-molecular weight aliphatic amides as nucleating agents for poly (L-lactic acid): Conformation variation induced crystallization enhancement

Two kinds of low molecular weight aliphatic amides, N, N′-ethylenebis (12-hydroxystearamide) (EBH) and N, N′-ethylenebisstearamide (EBSA), have been selected in present study to mediate the crystallization behavior of poly (L-lactic acid) (PLLA). The results showed that the crystallization rate of PLLA was significantly improved with the addition of EBH and EBSA, and EBH presented a stronger nucleating efficiency. The correlation between the variation of chain conformation during the early stages of isothermal crystallization and the enhancement of crystallization rate for pure PLLA and its mixtures was investigated by time-resolved FTIR. The formation of interchain conformational-ordered structure and intrachain 103 helix structure for amide-doped PLLA preceded that for pure PLLA, suggesting a stimulatory nucleating effect of EBH and EBSA. In the case of PLLA/EBH, the interchain interactions of –(COC + CH3) and –CH3 groups were faster than the –(CH3+CC) intrachain interactions, while the interchain interactions and the intrachain 103 helix formation were nearly synchronous for PLLA/EBSA. The hydrogen bond interaction between hydroxyl groups in EBH and the carbonyl groups in PLLA was proposed to be an important factor influencing the conformation variation during isothermal crystallization of PLLA.

An investigation on the application of process control agents in the preparation and consolidation behavior of nanocrystalline silver by mechanochemical method

In this paper, the effect of various amounts and types of process control agent (PCA), i.e., stearic acid (SA) and ethylene bis-stearamide (EBS), in the production and consolidation behavior of nanocrystalline silver prepared by mechanochemical reduction of Ag2O by graphite was studied. The structural evolution and morphology of powders were investigated using XRD, HRSEM and particle size analyzer techniques. The results showed the nanocrystalline Ag formed after 25h of milling and the addition of PCA prolonged the synthesis process time. Also, the effect of EBS on prevention of the excessive cold welding of ultra-fine Ag particles in the final stages of milling was more serious than SA. In fact, the presence of PCA effectively inhibited the creation of coarse Ag particles and finally decreased the crystallite size to 14nm. Moreover, with the addition of PCAs, the Brinell hardness of sintered Ag samples was considerably increased.

Flowability and Mechanical and Thermal Properties of Nylon 6/Ethylene bis-Stearamide/Carboxylic Silica Composites

Nylon 6 (PA 6)/ethylene bis-stearamide (EBS)/SiO2- carboxylic acid-functionalized silica nanoparticles (COOH) composites were prepared by in-situ polymerization of caprolactam. SiO2-COOH was used to enhance the compatibility between SiO2 and PA 6 matrix. For comparison, pure PA 6 and PA 6/EBS composites were also prepared via the same method. The PA 6/EBS/SiO2-COOH composites with low content of EBS and SiO2-COOH had greater melt-flow index (MFI) (the value of MFI increased by 50%–80%) than the pure PA 6. The results of mechanical properties showed almost no decrease in the tensile strength of PA 6/EBS/SiO2-COOH composites, with the bending strength decreasing by 17%–21%. However, the Izod impact strength of the PA 6/EBS/SiO2-COOH composites was greatly improved compared with pure PA 6, which indicated that the toughness of PA 6/EBS/SiO2-COOH had been greatly improved. The morphology of Izod impacted fractured surfaces of PA 6/EBS/SiO2-COOH was observed by scanning electron microscopy. The results revealed that the PA 6/EBS/SiO2-COOH composites presented a typical ductile fracture behavior with large amounts of long and large strip-like cracks. When the content of SiO2-COOH was 0.2 wt%, the SiO2-COOH particles were uniformly dispersed over the entire body of the PA 6 matrix. The results from differential scanning calorimetry indicated that the melting point (Tm), degree of crystallinity (Xc), and crystallization temperatures (Tc) of PA 6/EBS/SiO2-COOH composites were lower than the pure PA 6.

Study on the Role of Stearic Acid and Ethylene-bis-stearamide on the Mechanical Alloying of a Biomedical Titanium Based Alloy

The present study examines the influence of different contents and types of process control agent (PCA), i.e., stearic acid (SA) and ethylene-bis-stearamide (EBS), on the microstructural evolution and characteristics of Ti-16Sn-4Nb (wt pct) alloy powders and bulk samples. The characterization of the powders and bulk samples was carried out by using chemical analysis, optical microscopy, scanning electron microscopy (SEM) combined with energy-dispersive spectrometry (EDS), and X-ray diffractometry. Results indicated that the powder recovered from the ball milling containers increased with increasing amounts of SA and EBS. Furthermore, adding more SA or EBS to the powder mixture resulted in a considerably smaller particle size, with a flaky-shaped morphology for the given ball milling time. Also, a slightly higher effectiveness was found for EBS when compared to SA. Meanwhile, the addition of both SA and EBS led to a delay in the alloy formation during mechanical alloying (MA) and caused contamination of the material with mainly carbon (C) and oxygen (O). An optimum amount of 1 wt pct PCA led to a good balance between cold welding and fracturing, and thus favored the formation of the titanium alloy. The microstructural observation of the bulk alloy showed a homogeneous distribution of fine Nb-rich β-phase colonies within the α-Ti matrix with the addition of PCA less than 1 wt pct.

Effect of process control agent on the porous structure and mechanical properties of a biomedical Ti–Sn–Nb alloy produced by powder metallurgy

The influence of different amounts and types of process control agent (PCA), i.e., stearic acid and ethylene bis-stearamide, on the porous structure and mechanical properties of a biomedical Ti–16Sn–4Nb (wt.%) alloy was investigated. Alloy synthesis was performed on elemental metal powders using high-energy ball milling for 5 h. Results indicated that varying the PCA content during ball milling led to a drastic change in morphology and particle-size distribution of the ball-milled powders. Porous titanium alloy samples sintered from the powders ball milled with the addition of various amounts of PCA also revealed different pore morphology and porosity. The Vickers hardness of the sintered titanium alloy samples exhibited a considerable increase with increasing PCA content. Moreover, the addition of larger amounts of PCA in the powder mixture resulted in a significant increase in the elastic modulus and peak stress for the sintered porous titanium alloy samples under compression. It should also be mentioned that the addition of PCA introduced contamination (mainly carbon and oxygen) into the sintered porous product.

Improving mechanical performance of injection molded PLA by controlling crystallinity

AbstractCurrently, use of poly(lactic acid) (PLA) for injection molded articles is limited for commercial applications because PLA has a slow crystallization rate when compared with many other thermoplastics as well as standard injection molding cycle times. The overall crystallization rate and final crystallinity of PLA were controlled by the addition of physical nucleating agents as well as optimization of injection molding processing conditions. Talc and ethylene bis‐stearamide (EBS) nucleating agents both showed dramatic increases in crystallization rate and final crystalline content as indicated by isothermal and nonisothermal crystallization measurements. Isothermal crystallization half‐times were found to decrease nearly 65‐fold by the addition of only 2% talc. Process changes also had a significant effect on the final crystallinity of molded neat PLA, which was shown to increase from 5 to 42%. The combination of nucleating agents and process optimization not only resulted in an increase in final injection molded crystallinity level, but also allowed for a decreased processing time. An increase of over 30°C in the heat distortion temperature and improved strength and modulus by upwards of 25% were achieved through these material and process changes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Determination of N, N′-ethylenebisstearamide additive in polymer by normal phase liquid chromatography with evaporative light scattering detection

A new method for N, N′-ethylenebisstearamide (EBS) analysis was developed and validated in normal phase-HP liquid chromatography (NP-HPLC) with diol column at 50 °C with 100% CHCl 3 at 1 mL min −1 and evaporative light scattering detection with elution time at 3.0 min. EBS solubility was the best at 0.80 g L −1 in CHCl 3/methanol 90:10. The molecular structure of commercial samples of EBS was determined by GC–MS which ascertained that the main structure is C18/C18 at approximately 45%. The remaining part was constituted by molecules with different alkyl chain length. The HPLC quantification method was proved linear ( r = 0.9983), accurate (99.6%) and precise (1.95%). Limit of quantification (LOQ) and limit of detection (LOD) were equal to 2.0 and 0.8 μg mL −1, respectively. The suitability of this method was assessed with a dissolution/precipitation extraction procedure of EBS from ethylene vinyl acetate (EVA) polymer which showed that other additives and polymer do not interfere with EBS analysis. The intra-day and day-to-day precisions of extraction method were equal to 9.1% and 9.9%, respectively.

Catalytic effect of Fe/C powder on the formation of gas-phase products of vacuum pyrolysis of N,N′-ethylenebisstearamide

Abstract In the present work N,N′-ethylenebisstearamide (EBS) in its free form and mixed with iron/carbon powder was thermolyzed in a closed system under vacuum to produce gas-phase products (GPP). A catalytic effect of the iron/carbon surface on the gasification of thermolyzed EBS is observed over the 573–973 K temperature range. The overall yield of GPP measured after one hour of heating at a constant temperature increased with temperature (T The total yield, and the yields of the main identified GPP (CO, CH4, CO2 and C2H4), measured for free EBS are significantly lower (∼30 times) than those observed for mixture of EBS with iron/carbon powder. The catalytic formation of H2/N2, H2O and small amounts of other volatile 1 organic products is assumed at temperatures below 973 K. The formation of GPP from low volatility products of EBS decomposition is assumed to proceed via at least two competing mechanisms (EBS → Primary products → 2CO (1) or CO2 (2)). This mechanistical model can be used as a basis for understanding the delubrication mechanism of ferrous compacts and for the catalytic gasification of heavy amides (EBS) or polyamides (Nylon) widely used in industry.

Lubrication effectiveness of composite lubricants during P/M electrostatic die wall lubrication and warm compaction

The lubrication effectiveness of the composite lubricants, 50wt% ethylene bis-stearamide (EBS) wax + 50wt% graphite and 50wt% EBS wax + 50wt% BN, during the powder metallurgy (P/M) electrostatic die wall lubrication and warm compaction was studied. The results show that the combination of 50wt% EBS wax and 50wt% graphite has excellent lubrication performance, resulting in fairly high green densities, but the mixture of 50wt% EBS wax and 50wt% BN has less beneficial effect. In addition, corresponding die temperatures should be applied when different die wall lubricants are used to achieve the highest green densities.

Improvements in P/M Green Strength using Micronized Cellulose Particles (MCP)

New P/M lubricant formulations implement micron-sized (“micronized”) cellulose particles (MCP) to create MCP-enhanced lubricants. Surprising increases in green strength, up to 70% for iron and even higher for stainless steel are obtained with standard transverse rupture bars shapes made with 0.75 wt-% additive concentrations in iron (MPIF F-0000) and 316L stainless steel powders in comparison with the same parts made under the same conditions with industry standard lubricantbinders of zinc stearate, ethylene-bis-stearamide (EBS), and oxidized polyolefin (OP) wax. Two specific forms of new MCP materials are used in these tests: micronized cotton fibers (MCF), and micronized starch particles (MSP). The findings support expectations of significantly increased process yields for green parts and related production cost savings.

Microscopic characterisation of topography and lubricant distribution on surface of powder compacts

An experimental investigation has been performed in order to explain the microscopic interaction between the powder compact, lubricant and tool wall during powder pressing. Interference microscopy was used to characterise the compact topography, X-ray photoelectron spectroscopy and scanning electron microscopy were used to analyse the lubricant distribution on the compact surface. Water atomised iron powder, compacted at 600 MPa, with ethylene bisstearamide content <1 wt-%, was determined to be covered by a monomolecular film of lubricant. The volume of surface porosity was identified as a key parameter that will determine the minimal lubricant content to achieve lubrication. On debinded components, this volume has been determined experimentally to 0·4 μm3 per μm2 for compaction pressures between 400 and 800 MPa. On green compacts, with lubricant contents between 0·6 and 1 wt-%, 1% of this volume will be unfilled by lubricant, at 0·5 wt-% this value will increase to 20%.

In situ formation and compounding of polyamide 12 by reactive extrusion

AbstractThe anionic polymerization of lauryllactam was initiated at 270°C using sodium hydride as an initiator and N,N′‐ethylene‐bisstearamide (EBS) as an activator (NaH:EBS molar ratio of 2). Polymerization occurred in less than 2 min and was successfully performed in an internal mixer and a twin‐screw extruder with corotating intermeshing screws (Werner &amp; Pfleiderer ZSK 25). The content of residual monomer, as determined by thermogravimetric analysis, was lower than 0.5 wt %. Molecular weight, as measured by size exclusion chromatography, was governed by the lauryllactam:NaH molar ratio calculated on a Mn of 25 kg/mol at a constant NaH:EBS molar ratio of 2. Blends were prepared in situ by polymerization of lauryllactam solutions of various polymers. When poly(ethylene‐co‐butylacrylate) (Lotryl®; Atofina) was dissolved in lauryllactam, rubber‐toughened polyamide 12 blends were obtained. Mechanical properties of the injection‐molded polymers were examined by stress–strain as well as notched Charpy impact tests at different temperatures. Blend morphologies were imaged by scanning electron microscopy (SEM). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 344–351, 2003

Effects of lubricants and compacting pressure on the processability and properties of aluminum P/M parts

Lubricants are generally admixed to metal powders to ease compaction and minimize the interaction between the tooling and the compact during ejection. The type and concentration of the lubricant have a significant impact on the processability and the characteristics of the material. While extensive work has been performed with iron-based mixes, relatively few studies have been published on the effects of lubricants and shaping conditions on the processing behavior and characteristics of aluminum (Al) components fabricated by powder metallurgy (P/M). This paper presents the effects of the lubricant type (ethylene bisstearamide vs. polyethylene wax), the lubricant concentration (0.7–1.5 wt.%), as well as the compacting pressure (138–413 MPa) on the powder characteristics and the properties of press and sintered 2xxx series aluminum alloy specimens (AMB-2712). Compaction and ejection characteristics, surface finish, green density and strength, dimensional change during sintering, sintered density and mechanical properties are presented and discussed.

Effect of lubricant addition on the powder properties and compacting performance of spray-dried molybdenum powders

Polymeric binders, such as polyvinyl alcohol, are usually added into molybdenum powders so that, after spray drying, large spherical agglomerates with good flow properties can be produced. Since these binders may help to reduce the friction among powders and between powders and the die wall, the necessity of mixing an additional lubricant, such as ethylene bis-stearamide (EBS), to facilitate compaction has come under question. This study investigated the effect of EBS on the apparent density, flow rate, variation on compact weight, green density, green strength, and compactability. The results show that, when flow properties, dimensional control, and low ejection force are desirable, the optimum content of EBS addition should be between 0.1% and 0.2%. When high green density, green strength, and compactability are required, no lubricant should be added.