Rabeh Elleithy - Academia.edu (original) (raw)
Papers by Rabeh Elleithy
Applied Mechanics and Materials, 2013
A feasible and effective method of thermal hydrolysis to prepare poly (lactic acid) (PLA) oligome... more A feasible and effective method of thermal hydrolysis to prepare poly (lactic acid) (PLA) oligomers with different controlled molecular weight from PLA is presented in this paper. The thermal hydrolytic reaction was carried out by immerging PLA resin pellets in boiling distilled water for a certain period of time. Ester groups in PLA chains are hydrolytically degraded in the presence of water and thermal, so PLA oligomers with different molecular weight were prepared. The structures and properties of PLA oligomers were characterized by FT-IR, GPC, DSC, etc. The results showed that thermal hydrolytic reaction could effectively reduce the molecular weight of PLA, which declines with the increase of the thermal hydrolytic reaction time. Meanwhile, the content of terminal hydroxyl group, glass transition temperature, melting point of PLA oligomers prepared from thermal hydrolytic reactions exhibit gradual changes with the extension of the thermal hydrolytic time.
Journal of Vinyl & Additive Technology, Dec 1, 2000
This study discusses the influence of molecular weight, melt temperature, mold temperature, and a... more This study discusses the influence of molecular weight, melt temperature, mold temperature, and aging on the impact characteristics of molded PVC. Tensile impact (uniaxial), instrumented drop-dart impact miaxial), and Izod impact (triaxial) methods were utilized to assess the impact properties of the material under investigation. It was found that the impact properties were affected by aging more than by the changes in the melt temperature or the mold temperature. Additionally, the molecular weight played a significant role in influencing the impact properties of PVC.
Journal of Applied Polymer Science, Mar 7, 1995
The tensile properties of three urethane-methacrylate resins that varied in the soft segment cont... more The tensile properties of three urethane-methacrylate resins that varied in the soft segment content of the urethane were characterized. The strain birefringence at a circular hole was observed during loading-unloading cycles to progressively higher displacements. The shear strain distribution at the hole was calculated from the isochromatic fringe contours and compared with results from linear elastic analysis. When the onset of nonlinearity, and the subsequent appearance of residual strain at the root of the hole, were correlated with features of the macroscopic stress-displacement curves, three regions of prefracture deformation were defined. A region of linear elastic behavior was observed at the lowest strains. The maximum shear strain at the linear limit was the same in all the resins, and appeared to correlate with the yield condition at the hole. When the shear strain at the hole exceeded about 2.8%, the fringe patterns started to deviate from the elastic prediction. However, strain was fully recoverable in this region as indicated by the absence of residual birefringence at the hole after unloading. This region of nonlinear, recoverable deformation extended to progressively higher strains as the amount of urethane soft segment increased. This feature was attributed to the network structure of the urethane-methacrylate resins. A region characterized by nonrecoverable deformation at the hole followed at higher strains; the urethane soft segment content had a major effect on the amount of permanent deformation sustained before fracture. The fracture surfaces exhibited features typical of brittle fracture without crazing. 0 1995 John Wiley & Sons, Inc * To whom correspondence should be addressed.
Journal of Elastomers and Plastics, Jan 3, 2013
Poly(lactic acid) (PLA) and biodegradable elastomer were melt blended and molded in an injection ... more Poly(lactic acid) (PLA) and biodegradable elastomer were melt blended and molded in an injection molding machine. The crystallinity, viscoelasticity, thermal and mechanical properties of the molded blend and annealed blend samples were studied. Differential scanning calorimetry was used to evaluate the crystallinity and thermal property of all the samples. It was found that the melting temperature decreased as the amount of elastomer increased. Additionally, the presence of elastomer tended to increase the crystallinity of PLA at 10 and 20 wt%. The injection molding led to the diminishing of neat PLA crystallinity to be 20.79%; however, annealing could recover it to be 29.94%. This result was supported by x-ray diffraction and dynamic mechanical analysis tests. The complex viscosity and storage modulus of PLA melt decreased upon addition of elastomer. The elongation at break increased as the content of elastomer increased. However, the Young’s modulus and tensile strength decreased severely due to the addition of elastomer.
Journal of Applied Polymer Science, Feb 15, 2011
Polypropylene (PP) was melt blended with nano organo‐clay masterbatch at different ratios; namely... more Polypropylene (PP) was melt blended with nano organo‐clay masterbatch at different ratios; namely 5, 10, and 15 wt % of nano‐clay. The effect of organo‐clay content on the viscoelastic properties of the nano‐composite was studied. A miniature laboratory mixing extruder, LME, was used to blend the nano organo‐clay masterbatch with PP at 260°C and 250 rpm. The blend was pelletized first, and then a thin ribbon was extruded. Two viscoelastic tests were performed; frequency sweep at constant temperature of 80°C, and temperature sweep at constant frequency of 1.0 rad/s. As the loading of nano‐clay increased, the storage modulus, G', and the thermal resistance increased as well. Different viscoelastic models were tried and 3‐elements Maxwell model was found to describe well the viscoelastic properties of the nano‐composites. The ratio of the complex modulus to the corresponding matrix modulus at different frequencies was found to vary proportional to the nanoclay loading. This dependency was described reasonably well by modified Guth model using particle aspect ratio of 12.1. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Journal of Vinyl & Additive Technology, Dec 1, 1999
... of PVC Compounds F. RYAN SULLIVAN The GEON Company One Geon Center Auon Me, Ohio 4401 2 RABEH... more ... of PVC Compounds F. RYAN SULLIVAN The GEON Company One Geon Center Auon Me, Ohio 4401 2 RABEH H. ELLEITHY* and AMJAD ABU-ALI Polymer Diagnostics Inc. ... 5, No. 4 201 Page 3. F. Ryan Sullivan, Rabeh H. EUeithy, and Amjad Abu-Ali 45-40 - s: 35 - 2, Pm-...
Polymer Composites, Oct 1, 2000
The hierarchical structure and flexure behavior of woven carbon fibers epoxy composite were inves... more The hierarchical structure and flexure behavior of woven carbon fibers epoxy composite were investigated in this work. First, the hierarchical structure of the composite is characterized on three levels: composite, ply, and yarn. Structural imperfections, * such as, ply-ply misalignment, ply-ply offset, and resin pockets, are identified and described. Second, a four-point bending arrangement is used to study the flexure properties of the composite. Additionally, in-situ traveling microscope and acoustic emission (AE) techniques are utilized to gain insight to the failure processes during flexure test. AE showed early stages of matrix cracking before visual observation, which makes it a valuable tool for early failure detection.
Journal of Vinyl & Additive Technology, Sep 1, 1999
The viscoelastic nature of PVC cannot be ignored during the injection molding process. Strains im... more The viscoelastic nature of PVC cannot be ignored during the injection molding process. Strains imposed on the compound during the injection stage display recovery dynamics that are indicative of the temperature at which the strains were imposed. A mathematical model, employing "approximate" time-temperature modulus relationships, provided the basis for interpreting the shrinkage data. A distribution map of the various relative temperatures attained within the part during injection was determined.
Journal of Applied Polymer Science, Jul 12, 2011
In this study, a series of high‐density polyethylene and micro/nanocalcium carbonate polymer comp... more In this study, a series of high‐density polyethylene and micro/nanocalcium carbonate polymer composites (HDPE/CaCO3 nanocomposites) were prepared via melt blend technique using a twin screw extruder. Nanocomposite samples were prepared via injection molding for further testing. The effect of % loading of CaCO3 on mechanical and fracture toughness of these composites has been investigated in details. The effect of precrack length variation on the fracture toughness of the composite samples was evaluated, and the morphology of the fractured samples was also observed using scanning electron microscopy (SEM). It was found that increasing the % of CaCO3 and precrack length decreased the fracture toughness. Fracture surface examination by SEM indicated that the diminished fracture properties in the composites were caused by the aglomerization of CaCO3 particles which acted as stress concentrators. A finite element analysis using ANSYS was also carried out to understand the effect of agglomeration size, interaction between the particles and crack tip length on the fracture properties of these composites. Finally, a schematic presentation of the envisioned fracture processes was proposed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Journal of King Saud University: Engineering Sciences, 2011
In this study, the rheological characteristics of metallocene linear low density polyethylene (mL... more In this study, the rheological characteristics of metallocene linear low density polyethylene (mLLDPE) were analyzed. Cyclohexane was used to prepare the dilute solutions of mLLDPE. The concentrations used in this study ranged from 1000 to 4500 ppm with 1000 ppm increments. The test temperatures ranged between 293 and 323 K at 10 K increments. The shear rate range was from 0.8 and 600 s À1. Rheological measurements were performed on a rotational rheometer model AR-G2 with parallel plate geometry. The solution rheology was affected by shear rate, polymer concentration, and testing temperature. Different models were used to describe the rheological behavior of the mLLDPE dilute solutions. A model that accounted for concentration was successful in describing the rheological behavior as compared to models that were developed for polymer melt, which do not take the polymer concentration into account.
Journal of Applied Polymer Science, Apr 13, 2010
High density polyethylene (HDPE) with micro calcium carbonate (CaCO 3) masterbatch was pelletized... more High density polyethylene (HDPE) with micro calcium carbonate (CaCO 3) masterbatch was pelletized by using a twin screw extruder and different ASTM specimens were molded by an injection molding machine. The morphology of the composites was characterized by scanning electron microscopy (SEM) and Image Analysis software. The dispersion and interfacial interaction between CaCO 3 and the polymer matrix were also investigated by SEM. The thermal properties of HDPE and its composites were investigated by differential scanning calorimetry (DSC). The crystallization process of the composites samples was found to be slightly different than that of the neat HDPE. Otherwise, the presence of CaCO 3 did not have a considerable effect on the melting behavior of the composites. Thermogravimetric analysis (TGA) revealed that the composites had better thermal stability than the neat HDPE resin as indicated by a higher temperature of 50% weight loss (T 50%) for the composites as compared to that of the neat resin. The viscoelastic properties of the composites and HDPE were also investigated via torsional and rotational techniques. The presence of CaCO 3 increased the shear modulus at low frequency of the composites at 80 C over that of the neat resin. However, at higher frequencies, the difference between the neat resin and the composites' shear modulus was less than that at low frequencies. The complex viscosity of the composite increased upon the addition of CaCO 3. However, the shear sensitivities of the neat resin and the microcomposite were similar. V
Materials in engineering, Dec 1, 2009
The present work was undertaken to examine the effect of some environmental media (sodium hydroxi... more The present work was undertaken to examine the effect of some environmental media (sodium hydroxide NaOH solution, water, ice, UV irradiation dose and pre-heat treatment) on the mechanical (quasistatic tensile creep-recovery and relaxation) and physical/thermal (melting and crystallinity) behaviour of the ultra high molecular weight polyethylene (UHMWPE-GUR 410-medical grade), that has several biomedical and engineering applications. The results show changes in the mechanical properties due to these environmental effects. The pre-heat treatment has significantly enhanced the tensile properties compared to virgin specimens' properties. Improvement due to pre-heat treatment at 100°C is more than that at 50°C. Specimens' storing in ice, NaOH and water has not affected significantly the tensile properties. All properties except fracture strain have enhanced due to specimens exposure to UV irradiation. The differential scanning calorimetry results indicate that environmental media have not any noticeable effects on the melting temperature. However, a significant increase in the degree of crystallinity was observed for all specimens versus that for virgin specimens. The creep and permanent strains of the tested virgin material increase with temperature and lineally increase with applied load. The specimens' exposure to environmental media has improved the creep resistance and the permanent creep strain when compared with that for virgin ones. Remarkable increase was observed in the initial relaxation and residual stress of the exposed specimens against that for virgin specimens.
Journal of Applied Polymer Science, Nov 5, 2008
A new look at a traditional method of thermal characterization is offered. Oxidative induction te... more A new look at a traditional method of thermal characterization is offered. Oxidative induction temperature method is modified and revised to give a thermal profile of the polymer instead of a single-point measurement. This article is an effort to not only describe a portion of the thermal behavior of polymers, but also to identify some thermal parameters. These parameters; thermal stability, strength, and stiffness, are proposed to be used like tensile properties to differentiate between the behavior of polymers under controlled conditions. The thermal parameters were successfully used to differentiate between two grades of polypropylene (PP), to study reprocessed PP, and to identify an injection molding problem for a client.
La presente description comprend des receptacles comportant un motif de perforation ameliore qui ... more La presente description comprend des receptacles comportant un motif de perforation ameliore qui peut etre perfore sans deformation importante du receptacle. De tels receptacles sont particulierement concus pour etre utilises dans la preparation de boissons a l'aide de machines automatiques, en particulier celles utilisees pour la preparation de boissons en dosette individuelle. L'invention se rapporte egalement a des materiaux thermoplastiques presentant une aptitude a la perforation amelioree destines a etre utilises dans des receptacles, a des receptacles destines a la preparation d'une boisson et a des procedes de preparation d'une boisson a l'aide de tels receptacles.
L'invention concerne des procedes de fabrication de recipients, comprenant la fourniture d... more L'invention concerne des procedes de fabrication de recipients, comprenant la fourniture d'une feuille de materiau (200) ayant au moins deux couches barrieres (204) et au moins deux couches polymeres (202), la formation de la feuille de materiau en un tube (312), la fermeture du tube au niveau d'une zone de fermeture, et le moulage par soufflage du tube pour former un recipient dans lequel les au moins deux couches barrieres forment une barriere sensiblement continue au niveau de la zone de fermeture.
Thermoplastic Polyurethane or TPU is a member of the thermoplastic elastomers or TPE group. TPUs ... more Thermoplastic Polyurethane or TPU is a member of the thermoplastic elastomers or TPE group. TPUs bring together the flexibility of elastomers with the processability of thermoplastics. Changing TPU chemistry would alter its hardness to cover a wide range from about 70D to 80A. To obtain softer grades down to 60A, plasticizers are added. A new generation of soft TPUs is a plasticizer free TPU. Controlling and manipulating the TPU chemistry achieve this unique plasticizer free TPU. In previous work 1 , the short term properties of Elastollan ® C75A15HPM (which is plasticizer free) was
The ability of Raman spectroscopy to nondestructively evaluate thermal degradation in graphite re... more The ability of Raman spectroscopy to nondestructively evaluate thermal degradation in graphite reinforced epoxy composites was examined. A series of composite samples, exposed to temperatures ranging from 150 to 400 °C for periods of 2 to 20 minutes, were analyzed by Fourier transform Raman and reflectance infrared spectroscopies. The intensity of the Raman and infrared polymeric backbone vibration at 1 600 cm' diminishes with increasing thermal exposures and can be correlated to failure strain and flexural strength measured by four point bending tests, as well as acoustic emission events. These data, along with infrared transmission spectra of species evolved from composite pyrolysis, suggest that thermal degradation occurs in three stages: 1) polymeric fragmentation (possibly microcracking), 2) advanced polymer degradation observed as delamination between the four ply layers, and 3) final composite failure with fiber fracture.
Applied Mechanics and Materials, 2013
A feasible and effective method of thermal hydrolysis to prepare poly (lactic acid) (PLA) oligome... more A feasible and effective method of thermal hydrolysis to prepare poly (lactic acid) (PLA) oligomers with different controlled molecular weight from PLA is presented in this paper. The thermal hydrolytic reaction was carried out by immerging PLA resin pellets in boiling distilled water for a certain period of time. Ester groups in PLA chains are hydrolytically degraded in the presence of water and thermal, so PLA oligomers with different molecular weight were prepared. The structures and properties of PLA oligomers were characterized by FT-IR, GPC, DSC, etc. The results showed that thermal hydrolytic reaction could effectively reduce the molecular weight of PLA, which declines with the increase of the thermal hydrolytic reaction time. Meanwhile, the content of terminal hydroxyl group, glass transition temperature, melting point of PLA oligomers prepared from thermal hydrolytic reactions exhibit gradual changes with the extension of the thermal hydrolytic time.
Journal of Vinyl & Additive Technology, Dec 1, 2000
This study discusses the influence of molecular weight, melt temperature, mold temperature, and a... more This study discusses the influence of molecular weight, melt temperature, mold temperature, and aging on the impact characteristics of molded PVC. Tensile impact (uniaxial), instrumented drop-dart impact miaxial), and Izod impact (triaxial) methods were utilized to assess the impact properties of the material under investigation. It was found that the impact properties were affected by aging more than by the changes in the melt temperature or the mold temperature. Additionally, the molecular weight played a significant role in influencing the impact properties of PVC.
Journal of Applied Polymer Science, Mar 7, 1995
The tensile properties of three urethane-methacrylate resins that varied in the soft segment cont... more The tensile properties of three urethane-methacrylate resins that varied in the soft segment content of the urethane were characterized. The strain birefringence at a circular hole was observed during loading-unloading cycles to progressively higher displacements. The shear strain distribution at the hole was calculated from the isochromatic fringe contours and compared with results from linear elastic analysis. When the onset of nonlinearity, and the subsequent appearance of residual strain at the root of the hole, were correlated with features of the macroscopic stress-displacement curves, three regions of prefracture deformation were defined. A region of linear elastic behavior was observed at the lowest strains. The maximum shear strain at the linear limit was the same in all the resins, and appeared to correlate with the yield condition at the hole. When the shear strain at the hole exceeded about 2.8%, the fringe patterns started to deviate from the elastic prediction. However, strain was fully recoverable in this region as indicated by the absence of residual birefringence at the hole after unloading. This region of nonlinear, recoverable deformation extended to progressively higher strains as the amount of urethane soft segment increased. This feature was attributed to the network structure of the urethane-methacrylate resins. A region characterized by nonrecoverable deformation at the hole followed at higher strains; the urethane soft segment content had a major effect on the amount of permanent deformation sustained before fracture. The fracture surfaces exhibited features typical of brittle fracture without crazing. 0 1995 John Wiley & Sons, Inc * To whom correspondence should be addressed.
Journal of Elastomers and Plastics, Jan 3, 2013
Poly(lactic acid) (PLA) and biodegradable elastomer were melt blended and molded in an injection ... more Poly(lactic acid) (PLA) and biodegradable elastomer were melt blended and molded in an injection molding machine. The crystallinity, viscoelasticity, thermal and mechanical properties of the molded blend and annealed blend samples were studied. Differential scanning calorimetry was used to evaluate the crystallinity and thermal property of all the samples. It was found that the melting temperature decreased as the amount of elastomer increased. Additionally, the presence of elastomer tended to increase the crystallinity of PLA at 10 and 20 wt%. The injection molding led to the diminishing of neat PLA crystallinity to be 20.79%; however, annealing could recover it to be 29.94%. This result was supported by x-ray diffraction and dynamic mechanical analysis tests. The complex viscosity and storage modulus of PLA melt decreased upon addition of elastomer. The elongation at break increased as the content of elastomer increased. However, the Young’s modulus and tensile strength decreased severely due to the addition of elastomer.
Journal of Applied Polymer Science, Feb 15, 2011
Polypropylene (PP) was melt blended with nano organo‐clay masterbatch at different ratios; namely... more Polypropylene (PP) was melt blended with nano organo‐clay masterbatch at different ratios; namely 5, 10, and 15 wt % of nano‐clay. The effect of organo‐clay content on the viscoelastic properties of the nano‐composite was studied. A miniature laboratory mixing extruder, LME, was used to blend the nano organo‐clay masterbatch with PP at 260°C and 250 rpm. The blend was pelletized first, and then a thin ribbon was extruded. Two viscoelastic tests were performed; frequency sweep at constant temperature of 80°C, and temperature sweep at constant frequency of 1.0 rad/s. As the loading of nano‐clay increased, the storage modulus, G', and the thermal resistance increased as well. Different viscoelastic models were tried and 3‐elements Maxwell model was found to describe well the viscoelastic properties of the nano‐composites. The ratio of the complex modulus to the corresponding matrix modulus at different frequencies was found to vary proportional to the nanoclay loading. This dependency was described reasonably well by modified Guth model using particle aspect ratio of 12.1. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Journal of Vinyl & Additive Technology, Dec 1, 1999
... of PVC Compounds F. RYAN SULLIVAN The GEON Company One Geon Center Auon Me, Ohio 4401 2 RABEH... more ... of PVC Compounds F. RYAN SULLIVAN The GEON Company One Geon Center Auon Me, Ohio 4401 2 RABEH H. ELLEITHY* and AMJAD ABU-ALI Polymer Diagnostics Inc. ... 5, No. 4 201 Page 3. F. Ryan Sullivan, Rabeh H. EUeithy, and Amjad Abu-Ali 45-40 - s: 35 - 2, Pm-...
Polymer Composites, Oct 1, 2000
The hierarchical structure and flexure behavior of woven carbon fibers epoxy composite were inves... more The hierarchical structure and flexure behavior of woven carbon fibers epoxy composite were investigated in this work. First, the hierarchical structure of the composite is characterized on three levels: composite, ply, and yarn. Structural imperfections, * such as, ply-ply misalignment, ply-ply offset, and resin pockets, are identified and described. Second, a four-point bending arrangement is used to study the flexure properties of the composite. Additionally, in-situ traveling microscope and acoustic emission (AE) techniques are utilized to gain insight to the failure processes during flexure test. AE showed early stages of matrix cracking before visual observation, which makes it a valuable tool for early failure detection.
Journal of Vinyl & Additive Technology, Sep 1, 1999
The viscoelastic nature of PVC cannot be ignored during the injection molding process. Strains im... more The viscoelastic nature of PVC cannot be ignored during the injection molding process. Strains imposed on the compound during the injection stage display recovery dynamics that are indicative of the temperature at which the strains were imposed. A mathematical model, employing "approximate" time-temperature modulus relationships, provided the basis for interpreting the shrinkage data. A distribution map of the various relative temperatures attained within the part during injection was determined.
Journal of Applied Polymer Science, Jul 12, 2011
In this study, a series of high‐density polyethylene and micro/nanocalcium carbonate polymer comp... more In this study, a series of high‐density polyethylene and micro/nanocalcium carbonate polymer composites (HDPE/CaCO3 nanocomposites) were prepared via melt blend technique using a twin screw extruder. Nanocomposite samples were prepared via injection molding for further testing. The effect of % loading of CaCO3 on mechanical and fracture toughness of these composites has been investigated in details. The effect of precrack length variation on the fracture toughness of the composite samples was evaluated, and the morphology of the fractured samples was also observed using scanning electron microscopy (SEM). It was found that increasing the % of CaCO3 and precrack length decreased the fracture toughness. Fracture surface examination by SEM indicated that the diminished fracture properties in the composites were caused by the aglomerization of CaCO3 particles which acted as stress concentrators. A finite element analysis using ANSYS was also carried out to understand the effect of agglomeration size, interaction between the particles and crack tip length on the fracture properties of these composites. Finally, a schematic presentation of the envisioned fracture processes was proposed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Journal of King Saud University: Engineering Sciences, 2011
In this study, the rheological characteristics of metallocene linear low density polyethylene (mL... more In this study, the rheological characteristics of metallocene linear low density polyethylene (mLLDPE) were analyzed. Cyclohexane was used to prepare the dilute solutions of mLLDPE. The concentrations used in this study ranged from 1000 to 4500 ppm with 1000 ppm increments. The test temperatures ranged between 293 and 323 K at 10 K increments. The shear rate range was from 0.8 and 600 s À1. Rheological measurements were performed on a rotational rheometer model AR-G2 with parallel plate geometry. The solution rheology was affected by shear rate, polymer concentration, and testing temperature. Different models were used to describe the rheological behavior of the mLLDPE dilute solutions. A model that accounted for concentration was successful in describing the rheological behavior as compared to models that were developed for polymer melt, which do not take the polymer concentration into account.
Journal of Applied Polymer Science, Apr 13, 2010
High density polyethylene (HDPE) with micro calcium carbonate (CaCO 3) masterbatch was pelletized... more High density polyethylene (HDPE) with micro calcium carbonate (CaCO 3) masterbatch was pelletized by using a twin screw extruder and different ASTM specimens were molded by an injection molding machine. The morphology of the composites was characterized by scanning electron microscopy (SEM) and Image Analysis software. The dispersion and interfacial interaction between CaCO 3 and the polymer matrix were also investigated by SEM. The thermal properties of HDPE and its composites were investigated by differential scanning calorimetry (DSC). The crystallization process of the composites samples was found to be slightly different than that of the neat HDPE. Otherwise, the presence of CaCO 3 did not have a considerable effect on the melting behavior of the composites. Thermogravimetric analysis (TGA) revealed that the composites had better thermal stability than the neat HDPE resin as indicated by a higher temperature of 50% weight loss (T 50%) for the composites as compared to that of the neat resin. The viscoelastic properties of the composites and HDPE were also investigated via torsional and rotational techniques. The presence of CaCO 3 increased the shear modulus at low frequency of the composites at 80 C over that of the neat resin. However, at higher frequencies, the difference between the neat resin and the composites' shear modulus was less than that at low frequencies. The complex viscosity of the composite increased upon the addition of CaCO 3. However, the shear sensitivities of the neat resin and the microcomposite were similar. V
Materials in engineering, Dec 1, 2009
The present work was undertaken to examine the effect of some environmental media (sodium hydroxi... more The present work was undertaken to examine the effect of some environmental media (sodium hydroxide NaOH solution, water, ice, UV irradiation dose and pre-heat treatment) on the mechanical (quasistatic tensile creep-recovery and relaxation) and physical/thermal (melting and crystallinity) behaviour of the ultra high molecular weight polyethylene (UHMWPE-GUR 410-medical grade), that has several biomedical and engineering applications. The results show changes in the mechanical properties due to these environmental effects. The pre-heat treatment has significantly enhanced the tensile properties compared to virgin specimens' properties. Improvement due to pre-heat treatment at 100°C is more than that at 50°C. Specimens' storing in ice, NaOH and water has not affected significantly the tensile properties. All properties except fracture strain have enhanced due to specimens exposure to UV irradiation. The differential scanning calorimetry results indicate that environmental media have not any noticeable effects on the melting temperature. However, a significant increase in the degree of crystallinity was observed for all specimens versus that for virgin specimens. The creep and permanent strains of the tested virgin material increase with temperature and lineally increase with applied load. The specimens' exposure to environmental media has improved the creep resistance and the permanent creep strain when compared with that for virgin ones. Remarkable increase was observed in the initial relaxation and residual stress of the exposed specimens against that for virgin specimens.
Journal of Applied Polymer Science, Nov 5, 2008
A new look at a traditional method of thermal characterization is offered. Oxidative induction te... more A new look at a traditional method of thermal characterization is offered. Oxidative induction temperature method is modified and revised to give a thermal profile of the polymer instead of a single-point measurement. This article is an effort to not only describe a portion of the thermal behavior of polymers, but also to identify some thermal parameters. These parameters; thermal stability, strength, and stiffness, are proposed to be used like tensile properties to differentiate between the behavior of polymers under controlled conditions. The thermal parameters were successfully used to differentiate between two grades of polypropylene (PP), to study reprocessed PP, and to identify an injection molding problem for a client.
La presente description comprend des receptacles comportant un motif de perforation ameliore qui ... more La presente description comprend des receptacles comportant un motif de perforation ameliore qui peut etre perfore sans deformation importante du receptacle. De tels receptacles sont particulierement concus pour etre utilises dans la preparation de boissons a l'aide de machines automatiques, en particulier celles utilisees pour la preparation de boissons en dosette individuelle. L'invention se rapporte egalement a des materiaux thermoplastiques presentant une aptitude a la perforation amelioree destines a etre utilises dans des receptacles, a des receptacles destines a la preparation d'une boisson et a des procedes de preparation d'une boisson a l'aide de tels receptacles.
L'invention concerne des procedes de fabrication de recipients, comprenant la fourniture d... more L'invention concerne des procedes de fabrication de recipients, comprenant la fourniture d'une feuille de materiau (200) ayant au moins deux couches barrieres (204) et au moins deux couches polymeres (202), la formation de la feuille de materiau en un tube (312), la fermeture du tube au niveau d'une zone de fermeture, et le moulage par soufflage du tube pour former un recipient dans lequel les au moins deux couches barrieres forment une barriere sensiblement continue au niveau de la zone de fermeture.
Thermoplastic Polyurethane or TPU is a member of the thermoplastic elastomers or TPE group. TPUs ... more Thermoplastic Polyurethane or TPU is a member of the thermoplastic elastomers or TPE group. TPUs bring together the flexibility of elastomers with the processability of thermoplastics. Changing TPU chemistry would alter its hardness to cover a wide range from about 70D to 80A. To obtain softer grades down to 60A, plasticizers are added. A new generation of soft TPUs is a plasticizer free TPU. Controlling and manipulating the TPU chemistry achieve this unique plasticizer free TPU. In previous work 1 , the short term properties of Elastollan ® C75A15HPM (which is plasticizer free) was
The ability of Raman spectroscopy to nondestructively evaluate thermal degradation in graphite re... more The ability of Raman spectroscopy to nondestructively evaluate thermal degradation in graphite reinforced epoxy composites was examined. A series of composite samples, exposed to temperatures ranging from 150 to 400 °C for periods of 2 to 20 minutes, were analyzed by Fourier transform Raman and reflectance infrared spectroscopies. The intensity of the Raman and infrared polymeric backbone vibration at 1 600 cm' diminishes with increasing thermal exposures and can be correlated to failure strain and flexural strength measured by four point bending tests, as well as acoustic emission events. These data, along with infrared transmission spectra of species evolved from composite pyrolysis, suggest that thermal degradation occurs in three stages: 1) polymeric fragmentation (possibly microcracking), 2) advanced polymer degradation observed as delamination between the four ply layers, and 3) final composite failure with fiber fracture.