Journal of Polymer Science: Polymer Physics Edition, 1977
Samples of ultradrawn high density polyethylene were studied by thermomechanical analysis. The pu... more Samples of ultradrawn high density polyethylene were studied by thermomechanical analysis. The purpose was to study the dimensional changes in polyethylene morphologies of extreme orientation. Dimensional changes were measured from -140 to +7OoC with a precision of better than 1%. A negative thermal expansion coefficient was observed along the length (c axis) of the fibers containing the polyethylene morphologies of extreme orientation. A change in negative coefficient is observed between -35 and -45OC. The sign and magnitude of the expansion coefficient confirm, along with other evidence, the existence of extended chain structures in these morphologies. A series-parallel model has been developed for the ultradrawn polyethylenes to describe the dimensional changes with temperature.
Journal of Polymer Science: Polymer Physics Edition, 1975
High-density polyethylene filaments prepared by a solid-state deformation in an Instron capillary... more High-density polyethylene filaments prepared by a solid-state deformation in an Instron capillary rheometer show unusually high crystal orientation, chain extension, axial modulus, and ultimate tensile strength. The Young's modulus and ultimate tensile strength have been determined from stress-strain curves. Gripping of this high modulus polyethylene has been a problem heretofore, but the measurement of ultimate tensile strength has now been made feasible by a special gripping procedure. Tensile moduli show an increase with sample preparation temperature and pressure. Values as high as 6.7 X 1 0 ' ' dyne/cm2 are obtained from samples extruded a t 134°C and 2400 atm and tested a t a strain rate of 3.3 X 10-4 sec-1. The effect of strain rate and frequency on modulus has also been evaluated by a combination of stressstrain data and dynamic tension plus sonic measurements over nine decades of time.
... Eng. Jpn. Powell, R. Hydrogen Peroxide; Noyes: New York, 1968. Sano, Y.; Yamaguchi, N.; Adach... more ... Eng. Jpn. Powell, R. Hydrogen Peroxide; Noyes: New York, 1968. Sano, Y.; Yamaguchi, N.; Adachi, T. J . Chem. Eng. ... Mathematical Model for High-pressure Tubular Reactor for Ethylene Po 1 ymer izat ion Adriana Brandolin, Numa J. Capiati, Jorge N. Farber, and Enrique 114. ...
A study has been made on the effects of molecular weight on the physical and mechanical propertie... more A study has been made on the effects of molecular weight on the physical and mechanical properties of cold-extruded high density polycthylene. Prior data indicate that such ultra-drawn strands contain a significant fraction ofextended-chain crystals. Four samples, spanning the molecular weight range of 59,000 to 147,000, were cold-extruded under the same conditions and were examined with respect to their melting point, degree of crystallinity, linear expansion coefficient, Young's modulus, strain to break, and tensile strength. The degree ofcrystallinity, linear expansion coefficient, and modulus did not change significantly with molecular weight. The melting point, strain to break, and tensile strength do increase with increasing molecular weight. This leads to the conclusion that the amount of extended-chain crystals is invariant with molecular weight. Higher molecular weight polymers are seen as providing a greater number of tie chains, thus giving the fiber a higher tensile strength.
This work deals with a novel glass fiber surface modification and subsequent metallocenic propyle... more This work deals with a novel glass fiber surface modification and subsequent metallocenic propylene polymerization onto it. Experimental results are presented on methylaluminoxane (MAO) fixation at the fiber surface, followed by propylene-␣-olefin graft copolymerization catalyzed by EtInd 2 ZrCl 2 /MAO. First results indicate that part of the produced polymer is chemically bonded to the glass fiber. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray disperse energy microanalysis characterization confirm the permanence of a thin polymer layer as well as aluminum and oxygen (from the MAO) on the glass surface, even after a severe solvent extraction treatment. From these results, the copolymerization of hydroxy-␣-olefin, grafted on MAO pretreated glass fiber, is foreseen as a possible way to improve fiber-matrix adhesion in glass fiber thermoplastic composites.
The polystyrene molecule can suffer chain scission by beta-cleavage mechanism in the presence of ... more The polystyrene molecule can suffer chain scission by beta-cleavage mechanism in the presence of Lewis acids. This is an undesirable secondary reaction, particularly when the Friedel-Crafts alkylation is applied to immiscible polyolefin/polystyrene (PS) blends compatibilization. It competes with the main copolymerization reaction, degrading the PS and impairing the properties of the blend. A simple experimental procedure of styrene (St) addition is proposed to compensate the PS degrada-tion. The effect of St on the chain scission is studied by the PS molecular weight variation and reaction gases evolution. Some hypotheses are worked out to get a basic description of this complex cationic reactive process.
Thermal expansion coefficients have been measured on ultraoriented polyethylene fibers. Samples w... more Thermal expansion coefficients have been measured on ultraoriented polyethylene fibers. Samples were prepared by a solid-state (crystalline) extrusion in an Instron Capillary Rheometer at 136 ~ 2100 atm. and at a draw ratio of 50. The expansion coefficients between --150 and +50 ~ perpendicular to the fiber axis, were positive and of the oraer of 10-~~ -t. Conversely, parallel to that direction, the observed values were both negative and small, of the order --10 -G ~ -1. Length changes were reversible and reproducible between --150 and < +50 ~ Negative coefficients were attributed to the presence of highly-extended and fully-aligned chains along the fiber. Valuable information about chain conformation, dynamics and lattice perfection can be obtained for the ultraoriented morphologies simply by measuring the linear thermal expansion.
Industrial & Engineering Chemistry Process Design and Development, 1970
... Bergles and Morton (1965) have reviewed work on these and other augmen-180 Ind. Eng. Chem. Pr... more ... Bergles and Morton (1965) have reviewed work on these and other augmen-180 Ind. Eng. Chem. Process Des. Develop., Vol. 9, No. 2, 1970 ... Eng. Sei. 21 197-9 (1966). Bergles, AE, Morton, HLR, Dept. of Mechanical Engineering, MI T., AD-619511, Tech. Rept. 5382-34 (1965). ...
This work deals with the development of a new approach to improve the interfacial adhesion and pr... more This work deals with the development of a new approach to improve the interfacial adhesion and properties of polypropylene-glass fiber composites. The chemical anchoring of the matrix polymer on glass fibers was improved by direct metallocenic polymerization of propylene onto the fibers surface. The experimental route involves an initial contact with methylaluminoxane (MAO) and hydroxy-a-olefin to generate the anchorage points on the fiber surface, followed by a propylene polymerization catalyzed by EtInd 2 ZrCl 2 (metallocene)/MAO. During the polymerization reaction, polypropylene chains grow on the glass fiber surface. This reaction was studied for different hydroxy-a-olefin concentrations and its effectiveness was characterized by scanning electron microscopy (SEM) with X-ray disperse energy microanalysis. An evaluation of the fiber-matrix interfacial shear strength (ISS) was performed by single-fiber fragmentation tests on model composites. Depending on the hydroxy-a-olefin concentration, the surface treatment induced an increase of the ISS with respect of the untreated fibers by a factor ranging from 1.7 up to 2.1. The improved interfacial adhesion level was also confirmed by SEM observations of the morphology of the fiber-matrix region of cryogenic-fractured surfaces of composites.
The aim of this work was to obtain films of polypropylene (PP)/polyethylene co-octene (POE) blend... more The aim of this work was to obtain films of polypropylene (PP)/polyethylene co-octene (POE) blends and study the influence of their composition and mixing conditions on final morphology and ultimate properties (thermal, mechanical, oxygen and water vapour transmission rates).
Page 1. Chapter 20 Reactive Compatibilization of Binary and Ternary Blends Based on PE, PP, and P... more Page 1. Chapter 20 Reactive Compatibilization of Binary and Ternary Blends Based on PE, PP, and PS Mónica F. Dıaz,1 Silvia E. Barbosa,1 and Numa J. Capiati1 20.1 INTRODUCTION Multicomponent materials (fiber-reinforced ...
Journal of Polymer Science: Polymer Physics Edition, 1977
Samples of ultradrawn high density polyethylene were studied by thermomechanical analysis. The pu... more Samples of ultradrawn high density polyethylene were studied by thermomechanical analysis. The purpose was to study the dimensional changes in polyethylene morphologies of extreme orientation. Dimensional changes were measured from -140 to +7OoC with a precision of better than 1%. A negative thermal expansion coefficient was observed along the length (c axis) of the fibers containing the polyethylene morphologies of extreme orientation. A change in negative coefficient is observed between -35 and -45OC. The sign and magnitude of the expansion coefficient confirm, along with other evidence, the existence of extended chain structures in these morphologies. A series-parallel model has been developed for the ultradrawn polyethylenes to describe the dimensional changes with temperature.
Journal of Polymer Science: Polymer Physics Edition, 1975
High-density polyethylene filaments prepared by a solid-state deformation in an Instron capillary... more High-density polyethylene filaments prepared by a solid-state deformation in an Instron capillary rheometer show unusually high crystal orientation, chain extension, axial modulus, and ultimate tensile strength. The Young's modulus and ultimate tensile strength have been determined from stress-strain curves. Gripping of this high modulus polyethylene has been a problem heretofore, but the measurement of ultimate tensile strength has now been made feasible by a special gripping procedure. Tensile moduli show an increase with sample preparation temperature and pressure. Values as high as 6.7 X 1 0 ' ' dyne/cm2 are obtained from samples extruded a t 134°C and 2400 atm and tested a t a strain rate of 3.3 X 10-4 sec-1. The effect of strain rate and frequency on modulus has also been evaluated by a combination of stressstrain data and dynamic tension plus sonic measurements over nine decades of time.
... Eng. Jpn. Powell, R. Hydrogen Peroxide; Noyes: New York, 1968. Sano, Y.; Yamaguchi, N.; Adach... more ... Eng. Jpn. Powell, R. Hydrogen Peroxide; Noyes: New York, 1968. Sano, Y.; Yamaguchi, N.; Adachi, T. J . Chem. Eng. ... Mathematical Model for High-pressure Tubular Reactor for Ethylene Po 1 ymer izat ion Adriana Brandolin, Numa J. Capiati, Jorge N. Farber, and Enrique 114. ...
A study has been made on the effects of molecular weight on the physical and mechanical propertie... more A study has been made on the effects of molecular weight on the physical and mechanical properties of cold-extruded high density polycthylene. Prior data indicate that such ultra-drawn strands contain a significant fraction ofextended-chain crystals. Four samples, spanning the molecular weight range of 59,000 to 147,000, were cold-extruded under the same conditions and were examined with respect to their melting point, degree of crystallinity, linear expansion coefficient, Young's modulus, strain to break, and tensile strength. The degree ofcrystallinity, linear expansion coefficient, and modulus did not change significantly with molecular weight. The melting point, strain to break, and tensile strength do increase with increasing molecular weight. This leads to the conclusion that the amount of extended-chain crystals is invariant with molecular weight. Higher molecular weight polymers are seen as providing a greater number of tie chains, thus giving the fiber a higher tensile strength.
This work deals with a novel glass fiber surface modification and subsequent metallocenic propyle... more This work deals with a novel glass fiber surface modification and subsequent metallocenic propylene polymerization onto it. Experimental results are presented on methylaluminoxane (MAO) fixation at the fiber surface, followed by propylene-␣-olefin graft copolymerization catalyzed by EtInd 2 ZrCl 2 /MAO. First results indicate that part of the produced polymer is chemically bonded to the glass fiber. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray disperse energy microanalysis characterization confirm the permanence of a thin polymer layer as well as aluminum and oxygen (from the MAO) on the glass surface, even after a severe solvent extraction treatment. From these results, the copolymerization of hydroxy-␣-olefin, grafted on MAO pretreated glass fiber, is foreseen as a possible way to improve fiber-matrix adhesion in glass fiber thermoplastic composites.
The polystyrene molecule can suffer chain scission by beta-cleavage mechanism in the presence of ... more The polystyrene molecule can suffer chain scission by beta-cleavage mechanism in the presence of Lewis acids. This is an undesirable secondary reaction, particularly when the Friedel-Crafts alkylation is applied to immiscible polyolefin/polystyrene (PS) blends compatibilization. It competes with the main copolymerization reaction, degrading the PS and impairing the properties of the blend. A simple experimental procedure of styrene (St) addition is proposed to compensate the PS degrada-tion. The effect of St on the chain scission is studied by the PS molecular weight variation and reaction gases evolution. Some hypotheses are worked out to get a basic description of this complex cationic reactive process.
Thermal expansion coefficients have been measured on ultraoriented polyethylene fibers. Samples w... more Thermal expansion coefficients have been measured on ultraoriented polyethylene fibers. Samples were prepared by a solid-state (crystalline) extrusion in an Instron Capillary Rheometer at 136 ~ 2100 atm. and at a draw ratio of 50. The expansion coefficients between --150 and +50 ~ perpendicular to the fiber axis, were positive and of the oraer of 10-~~ -t. Conversely, parallel to that direction, the observed values were both negative and small, of the order --10 -G ~ -1. Length changes were reversible and reproducible between --150 and < +50 ~ Negative coefficients were attributed to the presence of highly-extended and fully-aligned chains along the fiber. Valuable information about chain conformation, dynamics and lattice perfection can be obtained for the ultraoriented morphologies simply by measuring the linear thermal expansion.
Industrial & Engineering Chemistry Process Design and Development, 1970
... Bergles and Morton (1965) have reviewed work on these and other augmen-180 Ind. Eng. Chem. Pr... more ... Bergles and Morton (1965) have reviewed work on these and other augmen-180 Ind. Eng. Chem. Process Des. Develop., Vol. 9, No. 2, 1970 ... Eng. Sei. 21 197-9 (1966). Bergles, AE, Morton, HLR, Dept. of Mechanical Engineering, MI T., AD-619511, Tech. Rept. 5382-34 (1965). ...
This work deals with the development of a new approach to improve the interfacial adhesion and pr... more This work deals with the development of a new approach to improve the interfacial adhesion and properties of polypropylene-glass fiber composites. The chemical anchoring of the matrix polymer on glass fibers was improved by direct metallocenic polymerization of propylene onto the fibers surface. The experimental route involves an initial contact with methylaluminoxane (MAO) and hydroxy-a-olefin to generate the anchorage points on the fiber surface, followed by a propylene polymerization catalyzed by EtInd 2 ZrCl 2 (metallocene)/MAO. During the polymerization reaction, polypropylene chains grow on the glass fiber surface. This reaction was studied for different hydroxy-a-olefin concentrations and its effectiveness was characterized by scanning electron microscopy (SEM) with X-ray disperse energy microanalysis. An evaluation of the fiber-matrix interfacial shear strength (ISS) was performed by single-fiber fragmentation tests on model composites. Depending on the hydroxy-a-olefin concentration, the surface treatment induced an increase of the ISS with respect of the untreated fibers by a factor ranging from 1.7 up to 2.1. The improved interfacial adhesion level was also confirmed by SEM observations of the morphology of the fiber-matrix region of cryogenic-fractured surfaces of composites.
The aim of this work was to obtain films of polypropylene (PP)/polyethylene co-octene (POE) blend... more The aim of this work was to obtain films of polypropylene (PP)/polyethylene co-octene (POE) blends and study the influence of their composition and mixing conditions on final morphology and ultimate properties (thermal, mechanical, oxygen and water vapour transmission rates).
Page 1. Chapter 20 Reactive Compatibilization of Binary and Ternary Blends Based on PE, PP, and P... more Page 1. Chapter 20 Reactive Compatibilization of Binary and Ternary Blends Based on PE, PP, and PS Mónica F. Dıaz,1 Silvia E. Barbosa,1 and Numa J. Capiati1 20.1 INTRODUCTION Multicomponent materials (fiber-reinforced ...
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