Failure Analysis of LDPE Compressor Bolts

2006 ◽  
Author(s):  
Saeed Y. Al-Shahrani ◽  
Shahreer Ahmed
Keyword(s):  
Electron Microscopy ◽  
Cylinder Head ◽  
Energy Dispersive Spectrometry ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Metallographic Examination ◽  
Start Up ◽  
Discharge Valve ◽  
Two Stages ◽  
Scanning Electron

In Low Density Polyethylene (LDPE) plant, the ethylene gas is compressed up to a pressure of 3000 bar. This is achieved by compressing the ethylene gas using two stages as primary [18 °C (64.4 °F), 1700 bar] and secondary [90 °C (194 °F), 3000 bar] stage compressors. The studs under investigation were used to clamp the flange of the suction and discharge valves to the cylinder head (Studs from the Flanges of 1st Stage - Secondary Hyper Compressor). Six cylinders are present in each stage and 6 studs are used to fix each flange on the suction or discharge valve to the cylinder head. The material used to fabricate these studs was B7 and the threads were produced by rolling. In the 1st stage cylinders frequent failures of studs started within two months of operation. Since the start up about 11 studs from different location have been failed. A metallographic examination using optical and scanning electron microscopy as well as energy dispersive spectrometry (EDS) revealed that the failure was due to fatigue.

scholarly journals Fabrication of LDPE/PS interpolymer resin particles through a swelling suspension polymerization approach

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 361-368
Author(s):  
Nianqing Zhu ◽  
Hailong Chen ◽  
Xinxing Gao ◽  
Rongjie Hou ◽  
Zhongbing Ni ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Suspension Polymerization ◽  
Low Density Polyethylene ◽  
Polymerization Temperature ◽  
Low Density ◽  
Polymerization Time ◽  
Initiator Concentration ◽  
Spectroscopy Analysis ◽  
Swelling Agent ◽  
Scanning Electron

AbstractA facile method to prepare low-density polyethylene (LDPE)/polystyrene (PS) interpolymer resin particles by swelling suspension polymerization without addition of extra swelling agent was developed. The polymerization temperature, polymerization time, and initiator concentration were investigated. Fourier transform infrared spectroscopy analysis confirmed that the LDPE/PS interpolymer resin particles were successfully prepared and a small amount of PS-g-LDPE existed in the resin. Scanning electron microscopy revealed that PS was uniformly distributed in the LDPE matrix, indicating excellent compatibility between PS and LDPE. The mechanical properties of LDPE/PS interpolymer resin were intermediate between PS and LDPE polymers.

scholarly journals Low-density polyethylene films incorporated with silver nanoparticles to promote antimicrobial efficiency in food packaging

2019 ◽  
Vol 26 (4) ◽  
pp. 353-366
Author(s):  
Sabrina da Costa Brito ◽  
Joana D Bresolin ◽  
Kátia Sivieri ◽  
Marcos D Ferreira
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Silver Nanoparticles ◽  
Food Packaging ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Bacterial Cells ◽  
Scanning Calorimetry ◽  
Polyethylene Films ◽  
Scanning Electron

Technological innovations in packaging are intended to prevent microbiological contaminations for ensuring food safety and preservation. In this context, researchers have investigated the antimicrobial effect of low-density polyethylene films incorporated with the following concentrations of silver nanoparticles: 1.50, 3.75, 7.50, 15.00, 30.00, 60.00, and 75.00 µg/ml. The films were characterized using field emission gun scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetry, and differential scanning calorimetry. From the results of these techniques, it could be concluded that the silver nanoparticles incorporated in the low-density polyethylene films did not influence their physical, chemical, and thermal properties. The direct contact assays, shake-flask assays, and bacterial images obtained using scanning electron microscopy were used to analyze the antimicrobial activity of the films. In the microbial analyses, it was verified that the nanostructured films exhibited antimicrobial properties against all the microorganisms studied, although more notably for fungi and Gram-negative bacteria than the Gram-positive bacteria. Moreover, it was discovered that the packages, in which silver nanoparticles were incorporated, inhibited the growth and reproduction of bacterial cells during the early stages. These results suggest that the extruded low-density polyethylene films incorporated with silver nanoparticles may be an essential tool for improving food quality and safety.

Development and Characterization of an Antimicrobial Packaging Film Coating Containing Nisin for Inhibition of Listeria monocytogenes

2004 ◽  
Vol 67 (3) ◽  
pp. 475-479 ◽  
Author(s):  
JENNIFER L. GROWER ◽  
KAY COOKSEY ◽  
KELLY J. K. GETTY
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Rate ◽  
Film Coating ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Water Vapor Transmission Rate ◽  
Packaging Film ◽  
Water Vapor Transmission ◽  
Scanning Electron

The purpose of this study was to develop and characterize a packaging film coating containing nisin. A spot-on-lawn assay was used to determine the effect of acid type (ascorbic, acetic, hydrochloric, lactic) and nisin level (equal increments from 10,000 IU to 9 IU) to be used in the formulation of the film coating. Zones of inhibition were measured after incubation on tryptic soy agar (37°C, 48 h). Low-density polyethylene films coated with differing levels of nisin were characterized by field emission scanning electron microscopy, tensile strength, elongation, and water vapor transmission rate. The MIC of nisin in solution was 157 mg/ml. All acids were equally inhibitory (P > 0.05), but acetic acid produced the largest zone of inhibition (21 mm). Field emission scanning electron microscopy confirmed that the cloudy appearance of the films was due to sodium chloride found in the commercially prepared nisin. Tensile strength increased as nisin concentration increased, which also corresponded to increasing film thickness. The nisin coatings (10,000 and 2,500 IU/ml) did not have a significant effect (P > 0.05) on the water vapor transmission rate of the low-density polyethylene film.

Morphology of Silicone/Organic Blends

1998 ◽  
Vol 4 (S2) ◽  
pp. 832-833
Author(s):  
Hongxi Zhang ◽  
Wei Chen
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Low Density Polyethylene ◽  
Dispersed Phase ◽  
Low Density ◽  
Melt Index ◽  
Phase Dispersion ◽  
Enhanced Properties ◽  
Thermoplastic Resins ◽  
Scanning Electron

Silicone materials may be incorporated into organic thermoplastic resins to provide enhanced properties. Good dispersion of silicone with plastics is believed to be one of the keys to control the applications of these multiphase blends. In this study, we investigated the morphologies of mechanically mixed silicone/organic blends using scanning electron microscopy (SEM). Results provide an important piece of information that the optimum silicone phase dispersion can be achieved by matching the viscosities of the blend components.Most silicone and organic polymers are thermodynamically immiscible, forming multiphase structures for their blends. For example, a blend consisting of 90 wt% polydimethylsiloxane (PDMS) and 10% low density polyethylene (LDPE) was revealed by SEM to have a multiphase structure shown in Figure 1A where the PDMS was a Dow Corning® 3-5016 silanol-terminated siloxane fluid that forms the dispersed phase and the LDPE a Dow Chemical polyethylene having a melt index of 4.

Phase inversion and co-continuity domain in immiscible polyethylene/polystyrene blends

e-Polymers ◽  
2003 ◽  
Vol 3 (1) ◽  
Author(s):  
Frédéric Prochazka ◽  
Romulus Dima ◽  
Jean-Charles Majesté ◽  
Christian Carrot
Keyword(s):  
Electron Microscopy ◽  
Phase Inversion ◽  
Single Point ◽  
Selective Extraction ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Wide Range ◽  
Internal Mixer ◽  
Scanning Electron

Abstract Blends of polystyrene and high-density or linear low-density polyethylene have been prepared in an internal mixer and studied in a wide range of compositions. Phase inversion compositions have been determined using selective extraction and scanning electron microscopy. It appears that phase inversion can occur in a domain of compositions rather than at a single point. The existing models of phase inversion are not complete enough to explain the entire phenomenon, and percolation of each component may be considered to describe the formation of co-continuity.

scholarly journals Fungicides Films of Low-Density Polyethylene (LDPE)/Inclusion Complexes (Carvacrol and Cinnamaldehyde) Against Botrytis Cinerea

Coatings ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 795 ◽  
Author(s):  
Daniel Canales ◽  
Lissette Montoille ◽  
Lina M. Rivas ◽  
J. Andrés Ortiz ◽  
Mauricio Yañez-S ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Essential Oil ◽  
Inclusion Complexes ◽  
Polymer Matrix ◽  
Active Agent ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Active Compounds ◽  
Scanning Electron

Low density polyethylene (LDPE) films were prepared with the incorporation of natural agents (carvacrol and trans-cinnamaldehyde) by the melting process. The co-precipitation method was used successfully to complex the carvacrol or trans-cinnamaldehyde with β-cyclodextrin (β-CD). The active compounds encapsulated in β-CD achieved ca. 90% encapsulation efficiency (E.E.). The inclusion complex studied by scanning electron microscopy (SEM) found particles of different sizes, ca. 4 μm. The active compounds were added directly (1 and 5 wt %) into the polymer matrix, yielding LDPE + carvacrol and LDPE + cinnamaldehyde films. The active compounds encapsulated in β-cyclodextrin (β-CD) were added to LDPE, yielding LDPE + β-CD-carvacrol and LDPE + β-CD-cinnamaldehyde films. The incorporation of carvacrol and trans-cinnamaldehyde, and their corresponding inclusion complexes with β-cyclodextrin, did not affect the thermal properties of LDPE. The microcapsules distributed in all polymer matrices had sizes of 5–20 μm as shown by scanning electron microscopy (SEM). In terms of mechanical properties, the polymers showed a slight decrease of Young’s modulus (12%) and yield stress compared (14%) to neat LDPE. This could be due to the essential oil acting as a plasticizer in the polymer matrix. The LDPE + carvacrol and LDPE + cinnamaldehyde films had the capacity to inhibit fungi by 99% compared to neat LDPE. The effectiveness against fungi of LDPE+β-CD + active agent was slower than by the direct incorporation of the essential oil in the LDPE in the same amount of active agent. The biocidal properties were related to the gradual release of active compound from the polymer. The results confirm the applicability of carvacrol, trans-cinnamaldehyde, and their corresponding inclusion complexes in active packaging, as well as their use in the food delivery industry.

Effect Of PP-G-MAH on the Compatibility of Lignin/LDPE Composites

2011 ◽  
Vol 194-196 ◽  
pp. 1476-1479 ◽  
Author(s):  
Xin Ying Lv ◽  
Yan Hua Zhang ◽  
Ming Wei Di
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Weight Ratio ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Interfacial Bonding Strength ◽  
Ldpe Composites ◽  
Chinese Standard ◽  
Compatibilizing Agent ◽  
Scanning Electron

Lignin have been blended with low density polyethylene (LDPE). Maleic anhydride grafted polypropylene (PP-g-MAH) has been added as compatibilizing agent. The weight ratio of LDPE, ligin and PP-a-MAH were 75:25:5, 75:25:7.5 and 75:25:10, respectively. The mechanical properties of the blends were investigated according to Chinese standard GB/1447-2005 and compared with those of lignin/LDPE composites without compatibilizing agent. Scanning electron microscopy (SEM) was used to investigate the dispersion of the lignin and LDPE and the compatibilizing mechanism was analyzed. The results reveal that addition of compatibilizing agent increased the interfacial bonding strength of the composites, improved the mechanical properties and obtained the better dispersion of the lignin and LDPE.

Scanning Electron Microscopic and Electrophoretic Observations on Barium Sulphate Used to Adsorb Clotting Factors

1975 ◽  
Vol 33 (02) ◽  
pp. 256-270
Author(s):  
R. M Howell ◽  
S. L. M Deacon
Keyword(s):  
Electron Microscopy ◽  
Factor Xa ◽  
Barium Sulphate ◽  
High Density ◽  
Low Density ◽  
Factor X ◽  
Clotting Factors ◽  
Electron Microscopic ◽  
Complementary Techniques ◽  
Scanning Electron

SummaryElectron microscopy and particle electrophoresis were found to be complementary techniques with which to complete the physical data from an earlier study on barium sulphates used to adsorb clotting factors from serum. The differences revealed by scanning electron microscopy (S. E. M.) in the physical shape of low and high density grades of barium sulphate particles appear to be of greater significance than charge as expressed by electrophoretic mobility, in determining whether or not precursor or preformed factor Xa is eluted.This conclusion was based on the finding that at pH values close to 7, where the adsorption from serum occurs, all samples with the exception of natural barytes were uncharged. However as the high-density, or soil-grade, was found by S. E. M. to consist of large solid crystals it was suggested that this shape might induce activation of factor X as a result of partial denaturation and consequent unfolding of the adsorbed protein. In contrast, uptake of protein into the centre of the porous aggregates revealed by S. E. M. pictures of low-density or X-ray grade barium sulphate may afford protection against denaturation and exposure of the enzyme site.The porous nature of particles of low-density barium sulphate compared with the solid crystalline forms of other grades accounts not only for its lower bulk density but also for its greater surface/gram ratio which is reflected by an ability to adsorb more protein from serum.Neither technique produced evidence from any of the samples to indicate the presence of stabilising agents sometimes used to coat particles in barium meals.

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