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Leslie H. Sperling - One of the best experts on this subject based on the ideXlab platform.
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A new instrument to study the role of chain rupture in the fracture of glassy polymers
Polymer Testing, 2003Co-Authors: N. Mohammadi, R. Bagheri, G. A. Miller, Andrew Klein, Leslie H. SperlingAbstract:Abstract An instrument has been developed to determine the number of chain scissions and energy consumed per unit fracture area. This instrument utilizes a fine Dental Burr connected to a rheometer. Its motions are such that it grinds off about 4000 A in height from the polymer films per pass. The first application is to partly annealed polystyrene latex films where it is shown that four regimes of fracture exist as annealing progresses.
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Molecular basis of fracture of latex blends of polystyrene and poly(methyl methacrylate)
Journal of Materials Science, 2001Co-Authors: P. Suwanmala, A. Klein, Leslie H. SperlingAbstract:The molecular basis of fracture of polystyrene and poly(methyl methacrylate) homopolymers and their latex blends was investigated with a custom-built Dental Burr grinding instrument (DBGI). About a third of the chains were cut several times, the remainder not at all. The number of chain scissions in polystyrene and poly(methyl methacrylate) was quantitatively interpreted by the microscopic parameters of craze fibrils and the energy balance between chain scission and chain disentanglement (chain pullout). The probability that a polymer strand in the craze fibrils is scissioned or disentangled was calculated from the fracture energy balance. In addition, the fracture energy of the latex blends of polystyrene and poly(methyl methacrylate) was studied. The large interface between the polystyrene and the poly(methyl methacrylate) did not lead to a small fracture energy, as initially expected. Rather, the latex blend of the two immiscible polymers primarily absorbs the fracture stress by strong co-continuous bulk phases.
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The molecular basis of fracture in crosslinked glassy polymers
Journal of Applied Polymer Science, 1997Co-Authors: M. Sambasivam, Andrew Klein, Leslie H. SperlingAbstract:Crosslinked polystyrene (XPS) and poly(methyl methacrylate) (XPMMA) were prepared by photopolymerization of the respective monomers in the presence of reversible crosslinkers, acrylic acid anhydride (AAA), and methacrylic acid anhydride (MAA). Fracture studies on the crosslinked samples were carried out using a Dental Burr Grinding Instrument (DBGI). The fracture energy in all cases showed a maximum around 1.5-5.0 mol % crosslinker. The samples were decrosslinked by hydrolysis using dilute aqueous ammonium hydroxide solutions to determine the number of chain scissions as a result of grinding. The number of chain scissions increased asymptotically with crosslink density in the range of a 0.0-10.0 mol % crosslinker. The number of bonds activated per scission, obtained from the calculated total chain scission energy (after subtracting the chain pullout energy) and the experimental number of chain scissions, remained fairly constant for AAA-PS and AAA-PMMA at 312 ± 150 bonds and 202 ± 50 bonds, respectively, in the region below the fracture energy maximum. In an attempt to explain the fracture energy increases, increasing physical entanglements with crosslinking is considered.
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Molecular basis of fracture in plastics
1995Co-Authors: M. Sambasivam, Andrew Klein, Leslie H. SperlingAbstract:Fracture behavior of polystyrene (PS) and poly(methyl methacrylate) (PMMA) latex films were studied using a custom built Dental Burr Grinding Instrument which grinds at a depth of 5000 {Angstrom} per pass. Latexes were made by direct mini-emulsification from polystyrene of low M (32,000 g/mol; PDI=1.04); and medium M (151,000 g/mol; PDI=1.02) and high M (600,000 g/mol; PDI=1.02)molecular weights. Films were molded at 110{degrees}C for 20 minutes under a pressure of 10 MPa. Annealing of the films was carried out at 144{degrees}C for different times before fracture. PMMA films with M{sub n}=485,000 g/mol (PDI=1.47)were molded at 150{degrees}C for 25 minutes under a pressure of 10 MPa. Molecular weight measurements were made before and after grinding by using GPC to obtain the number of scissions per unit volume. Fracture energy was obtained from the grinding instrument. From the number of chain scissions/m{sup 3}, the chain scission energy and the chain uncoiling energy were calculated. Using an energy balance approach, the chain pull-out energy was obtained. Total fracture energies under fully annealed conditions for low M, medium M, and blend polystyrene latex (containing high and low M) films were about 174x10{sup 6} J/m{sup 3}, 470x10{sup 6} J/m{sup 3}, and 320x10{sup 6} J/m{sup 3},more » respectively. The contributions from chain scission to the total energy was about 0% for low M and about 40% for medium M, and about 25 % for the blend system. For the PMMA latex films, the energy was about 860x10{sup 6} J/m{sup 3} and the contribution from scission was about 75%.« less
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The molecular basis of fracture in polystyrene films: Role of molecular weight
Journal of Applied Polymer Science, 1995Co-Authors: M. Sambasivam, Andrew Klein, Leslie H. SperlingAbstract:The molecular basis for fracture was examined using a custom-built Dental Burr Grinding Instrument, which cuts at a depth of 500 nm per pass. A direct miniemulsification method was used to form uniform-sized latex particles from narrow molecular weight distribution, anionically synthesized polystyrenes. Several polystyrenes were examined as a function of molecular weight, and blends were made of high and low molecular weight polystyrenes. In addition, a broad molecular weight polystyrene was included for comparison. These latexes were dried and cleaned, and molded under mild conditions, followed by annealing for various lengths of time at 144°C. The Dental Burr Grinding Instrument measures the total energy required to fracture the sample. The total number of chains undergoing scission per unit volume was determined via GPC before and after the fracture process. Using an energy balance approach, the total number of chains undergoing pullout (from either side of the fracture surfaces) was estimated. In order to obtain a broader picture of the process, data collected by Mohammadi et al., and by Sambasivam et al., were integrated into the analysis. Basically, at very low molecular weights, ca. 32,000 g/mol, substantially 100% pullout occurs. At the midmolecular weight range, about 150,000 to 180,000 g/mol, chain scission and chain pullout contributions to the total energy are approximately equal. For very high molecular weights, the chain scission contribution is about 90%. A scaling relationship is proposed between the molecular weight of the polymer and the fraction of chains undergoing scission. © 1995 John Wiley & Sons, Inc.
M. Sambasivam - One of the best experts on this subject based on the ideXlab platform.
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The molecular basis of fracture in crosslinked glassy polymers
Journal of Applied Polymer Science, 1997Co-Authors: M. Sambasivam, Andrew Klein, Leslie H. SperlingAbstract:Crosslinked polystyrene (XPS) and poly(methyl methacrylate) (XPMMA) were prepared by photopolymerization of the respective monomers in the presence of reversible crosslinkers, acrylic acid anhydride (AAA), and methacrylic acid anhydride (MAA). Fracture studies on the crosslinked samples were carried out using a Dental Burr Grinding Instrument (DBGI). The fracture energy in all cases showed a maximum around 1.5-5.0 mol % crosslinker. The samples were decrosslinked by hydrolysis using dilute aqueous ammonium hydroxide solutions to determine the number of chain scissions as a result of grinding. The number of chain scissions increased asymptotically with crosslink density in the range of a 0.0-10.0 mol % crosslinker. The number of bonds activated per scission, obtained from the calculated total chain scission energy (after subtracting the chain pullout energy) and the experimental number of chain scissions, remained fairly constant for AAA-PS and AAA-PMMA at 312 ± 150 bonds and 202 ± 50 bonds, respectively, in the region below the fracture energy maximum. In an attempt to explain the fracture energy increases, increasing physical entanglements with crosslinking is considered.
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Molecular basis of fracture in plastics
1995Co-Authors: M. Sambasivam, Andrew Klein, Leslie H. SperlingAbstract:Fracture behavior of polystyrene (PS) and poly(methyl methacrylate) (PMMA) latex films were studied using a custom built Dental Burr Grinding Instrument which grinds at a depth of 5000 {Angstrom} per pass. Latexes were made by direct mini-emulsification from polystyrene of low M (32,000 g/mol; PDI=1.04); and medium M (151,000 g/mol; PDI=1.02) and high M (600,000 g/mol; PDI=1.02)molecular weights. Films were molded at 110{degrees}C for 20 minutes under a pressure of 10 MPa. Annealing of the films was carried out at 144{degrees}C for different times before fracture. PMMA films with M{sub n}=485,000 g/mol (PDI=1.47)were molded at 150{degrees}C for 25 minutes under a pressure of 10 MPa. Molecular weight measurements were made before and after grinding by using GPC to obtain the number of scissions per unit volume. Fracture energy was obtained from the grinding instrument. From the number of chain scissions/m{sup 3}, the chain scission energy and the chain uncoiling energy were calculated. Using an energy balance approach, the chain pull-out energy was obtained. Total fracture energies under fully annealed conditions for low M, medium M, and blend polystyrene latex (containing high and low M) films were about 174x10{sup 6} J/m{sup 3}, 470x10{sup 6} J/m{sup 3}, and 320x10{sup 6} J/m{sup 3},more » respectively. The contributions from chain scission to the total energy was about 0% for low M and about 40% for medium M, and about 25 % for the blend system. For the PMMA latex films, the energy was about 860x10{sup 6} J/m{sup 3} and the contribution from scission was about 75%.« less
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The molecular basis of fracture in polystyrene films: Role of molecular weight
Journal of Applied Polymer Science, 1995Co-Authors: M. Sambasivam, Andrew Klein, Leslie H. SperlingAbstract:The molecular basis for fracture was examined using a custom-built Dental Burr Grinding Instrument, which cuts at a depth of 500 nm per pass. A direct miniemulsification method was used to form uniform-sized latex particles from narrow molecular weight distribution, anionically synthesized polystyrenes. Several polystyrenes were examined as a function of molecular weight, and blends were made of high and low molecular weight polystyrenes. In addition, a broad molecular weight polystyrene was included for comparison. These latexes were dried and cleaned, and molded under mild conditions, followed by annealing for various lengths of time at 144°C. The Dental Burr Grinding Instrument measures the total energy required to fracture the sample. The total number of chains undergoing scission per unit volume was determined via GPC before and after the fracture process. Using an energy balance approach, the total number of chains undergoing pullout (from either side of the fracture surfaces) was estimated. In order to obtain a broader picture of the process, data collected by Mohammadi et al., and by Sambasivam et al., were integrated into the analysis. Basically, at very low molecular weights, ca. 32,000 g/mol, substantially 100% pullout occurs. At the midmolecular weight range, about 150,000 to 180,000 g/mol, chain scission and chain pullout contributions to the total energy are approximately equal. For very high molecular weights, the chain scission contribution is about 90%. A scaling relationship is proposed between the molecular weight of the polymer and the fraction of chains undergoing scission. © 1995 John Wiley & Sons, Inc.
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Energy-Consuming Micromechanisms in the Fracture of Glassy Polymers. 2. Effect of Molecular Weight on the Fracture of Polystyrene
Macromolecules, 1995Co-Authors: M. Sambasivam, Andrew Klein, Leslie H. SperlingAbstract:Narrow molecular weight distribution polystyrene latex films of low molecular weight (M n = 32000; PDI= 1.04) and medium molecular weight (M n = 151 000; PDI= 1.02) were made by using a direct miniemulsification technique. Compression molding of the cleaned and dried latex powder was carried out at 110°C and 10 MPa for 20 min, followed by annealing at 144°C for various times. Fracture of the latex films was carried out using a custom-built Dental Burr grinding instrument from which the total fracture energy was determined. Molecular weights before and after fracture were determined using GPC. From the number of chain scissions, the chain scission energy and the uncoiling energy (due to rubber elasticity) were calculated. Then, by using an energy balance approach, the viscoelastic energy for pullout was calculated. Total fracture energies of 174×10 6 J/m 3 (or 17 J/m 2 ) and 460×10 6 J/m 3 (or 230 J/m 3 ) were obtained for fully annealed, low and medium molecular weight latex films, respectively. About 1×10 24 scissions/m 3 (or 7×10 17 /m 2 )were obtained for the fully annealed, medium molecular weight sample via GPC, while the low molecular weight latex films did not show any apparent change in the molecular weight on grinding. Under fully annealed conditions, the contribution to the total energy from chain scission was about 40% for the medium molecular weight and about 0% for the low molecular weight film. Present data are compared with high molecular weight polystyrene (M n = 420000; PDI= 1.19), where about 90% chain scission and 10% pullout were reported at long annealing times. In all cases, the contribution from the uncoiling energy was negligible. Molecular frictional coefficient values obtained using Prentice's model indicate that the temperature for the chain pullout process is about 150-250°C
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Molecular basis of healing and fracture at polymer interfaces
Polymers for Advanced Technologies, 1994Co-Authors: Leslie H. Sperling, Andrew Klein, M. SambasivamAbstract:The interdiffusion of polymer chains across a polymer–polymer interface, and subsequent fracture to re-create the interface is reviewed. In particular, films formed via latex coalescence provide a very large surface area. Of course, latex film formation is a very important practical problem. Healing of the interface by interdiffusion is treated using the de Gennes reptation theory and the Wool minor chain reptation model. The self-diffusion coefficients of polystyrene and the polymethacrylates obtained by small-angle neutron scattering, SANS, direct non-radiative energy transfer, DET, and other techniques are compared. Reduced to 150,000 g/mol and 135°C, both polystyrene and poly(methyl methacrylate) have diffusion coefficients of the order of 10−16−10−17 cm2/sec. Variations in the diffusion coefficient values are attributed to the experimental approaches, theoretical treatments and molecular weight distribution differences. An activation energy of 55 kcal/mol was calculated from an Arrhenius plot of all polystyrene data reduced to a number-average molecular weight of 150,000 g/mol, using an inverse square molecular weight conversion method. Interestingly, this is in between the activation energies for the α and β relaxation processes in polystyrene, 84 and 35 kcal/mol, respectively. Fracture of polystyrene was considered in terms of chain scission and chain pull-out. A Dental Burr apparatus was used to fracture the films. For low molecular weights, chain pull-out dominates, but for high molecular weights, chain scission dominates. At 150,000 g/mol, the energy to fracture is divided approximately equally between the two mechanisms. Above a certain number average molecular weight (about 400,000 g/mol), the number of chain scissions remains constant at about 1024 scissions/m3. Energy balance calculations for film formation and film fracture processes indicate that the two processes are partly reversible, but have important components of irreversibility. From the interdiffusion SANS data, the diffusion rate is calculated to be about 1 A/min, which is nine orders of magnitude slower than the Dental Burr pull-out velocity of about 0.8 cm/sec.
Andrew Klein - One of the best experts on this subject based on the ideXlab platform.
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A new instrument to study the role of chain rupture in the fracture of glassy polymers
Polymer Testing, 2003Co-Authors: N. Mohammadi, R. Bagheri, G. A. Miller, Andrew Klein, Leslie H. SperlingAbstract:Abstract An instrument has been developed to determine the number of chain scissions and energy consumed per unit fracture area. This instrument utilizes a fine Dental Burr connected to a rheometer. Its motions are such that it grinds off about 4000 A in height from the polymer films per pass. The first application is to partly annealed polystyrene latex films where it is shown that four regimes of fracture exist as annealing progresses.
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The molecular basis of fracture in crosslinked glassy polymers
Journal of Applied Polymer Science, 1997Co-Authors: M. Sambasivam, Andrew Klein, Leslie H. SperlingAbstract:Crosslinked polystyrene (XPS) and poly(methyl methacrylate) (XPMMA) were prepared by photopolymerization of the respective monomers in the presence of reversible crosslinkers, acrylic acid anhydride (AAA), and methacrylic acid anhydride (MAA). Fracture studies on the crosslinked samples were carried out using a Dental Burr Grinding Instrument (DBGI). The fracture energy in all cases showed a maximum around 1.5-5.0 mol % crosslinker. The samples were decrosslinked by hydrolysis using dilute aqueous ammonium hydroxide solutions to determine the number of chain scissions as a result of grinding. The number of chain scissions increased asymptotically with crosslink density in the range of a 0.0-10.0 mol % crosslinker. The number of bonds activated per scission, obtained from the calculated total chain scission energy (after subtracting the chain pullout energy) and the experimental number of chain scissions, remained fairly constant for AAA-PS and AAA-PMMA at 312 ± 150 bonds and 202 ± 50 bonds, respectively, in the region below the fracture energy maximum. In an attempt to explain the fracture energy increases, increasing physical entanglements with crosslinking is considered.
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Molecular basis of fracture in plastics
1995Co-Authors: M. Sambasivam, Andrew Klein, Leslie H. SperlingAbstract:Fracture behavior of polystyrene (PS) and poly(methyl methacrylate) (PMMA) latex films were studied using a custom built Dental Burr Grinding Instrument which grinds at a depth of 5000 {Angstrom} per pass. Latexes were made by direct mini-emulsification from polystyrene of low M (32,000 g/mol; PDI=1.04); and medium M (151,000 g/mol; PDI=1.02) and high M (600,000 g/mol; PDI=1.02)molecular weights. Films were molded at 110{degrees}C for 20 minutes under a pressure of 10 MPa. Annealing of the films was carried out at 144{degrees}C for different times before fracture. PMMA films with M{sub n}=485,000 g/mol (PDI=1.47)were molded at 150{degrees}C for 25 minutes under a pressure of 10 MPa. Molecular weight measurements were made before and after grinding by using GPC to obtain the number of scissions per unit volume. Fracture energy was obtained from the grinding instrument. From the number of chain scissions/m{sup 3}, the chain scission energy and the chain uncoiling energy were calculated. Using an energy balance approach, the chain pull-out energy was obtained. Total fracture energies under fully annealed conditions for low M, medium M, and blend polystyrene latex (containing high and low M) films were about 174x10{sup 6} J/m{sup 3}, 470x10{sup 6} J/m{sup 3}, and 320x10{sup 6} J/m{sup 3},more » respectively. The contributions from chain scission to the total energy was about 0% for low M and about 40% for medium M, and about 25 % for the blend system. For the PMMA latex films, the energy was about 860x10{sup 6} J/m{sup 3} and the contribution from scission was about 75%.« less
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The molecular basis of fracture in polystyrene films: Role of molecular weight
Journal of Applied Polymer Science, 1995Co-Authors: M. Sambasivam, Andrew Klein, Leslie H. SperlingAbstract:The molecular basis for fracture was examined using a custom-built Dental Burr Grinding Instrument, which cuts at a depth of 500 nm per pass. A direct miniemulsification method was used to form uniform-sized latex particles from narrow molecular weight distribution, anionically synthesized polystyrenes. Several polystyrenes were examined as a function of molecular weight, and blends were made of high and low molecular weight polystyrenes. In addition, a broad molecular weight polystyrene was included for comparison. These latexes were dried and cleaned, and molded under mild conditions, followed by annealing for various lengths of time at 144°C. The Dental Burr Grinding Instrument measures the total energy required to fracture the sample. The total number of chains undergoing scission per unit volume was determined via GPC before and after the fracture process. Using an energy balance approach, the total number of chains undergoing pullout (from either side of the fracture surfaces) was estimated. In order to obtain a broader picture of the process, data collected by Mohammadi et al., and by Sambasivam et al., were integrated into the analysis. Basically, at very low molecular weights, ca. 32,000 g/mol, substantially 100% pullout occurs. At the midmolecular weight range, about 150,000 to 180,000 g/mol, chain scission and chain pullout contributions to the total energy are approximately equal. For very high molecular weights, the chain scission contribution is about 90%. A scaling relationship is proposed between the molecular weight of the polymer and the fraction of chains undergoing scission. © 1995 John Wiley & Sons, Inc.
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Energy-Consuming Micromechanisms in the Fracture of Glassy Polymers. 2. Effect of Molecular Weight on the Fracture of Polystyrene
Macromolecules, 1995Co-Authors: M. Sambasivam, Andrew Klein, Leslie H. SperlingAbstract:Narrow molecular weight distribution polystyrene latex films of low molecular weight (M n = 32000; PDI= 1.04) and medium molecular weight (M n = 151 000; PDI= 1.02) were made by using a direct miniemulsification technique. Compression molding of the cleaned and dried latex powder was carried out at 110°C and 10 MPa for 20 min, followed by annealing at 144°C for various times. Fracture of the latex films was carried out using a custom-built Dental Burr grinding instrument from which the total fracture energy was determined. Molecular weights before and after fracture were determined using GPC. From the number of chain scissions, the chain scission energy and the uncoiling energy (due to rubber elasticity) were calculated. Then, by using an energy balance approach, the viscoelastic energy for pullout was calculated. Total fracture energies of 174×10 6 J/m 3 (or 17 J/m 2 ) and 460×10 6 J/m 3 (or 230 J/m 3 ) were obtained for fully annealed, low and medium molecular weight latex films, respectively. About 1×10 24 scissions/m 3 (or 7×10 17 /m 2 )were obtained for the fully annealed, medium molecular weight sample via GPC, while the low molecular weight latex films did not show any apparent change in the molecular weight on grinding. Under fully annealed conditions, the contribution to the total energy from chain scission was about 40% for the medium molecular weight and about 0% for the low molecular weight film. Present data are compared with high molecular weight polystyrene (M n = 420000; PDI= 1.19), where about 90% chain scission and 10% pullout were reported at long annealing times. In all cases, the contribution from the uncoiling energy was negligible. Molecular frictional coefficient values obtained using Prentice's model indicate that the temperature for the chain pullout process is about 150-250°C
N. Mohammadi - One of the best experts on this subject based on the ideXlab platform.
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A new instrument to study the role of chain rupture in the fracture of glassy polymers
Polymer Testing, 2003Co-Authors: N. Mohammadi, R. Bagheri, G. A. Miller, Andrew Klein, Leslie H. SperlingAbstract:Abstract An instrument has been developed to determine the number of chain scissions and energy consumed per unit fracture area. This instrument utilizes a fine Dental Burr connected to a rheometer. Its motions are such that it grinds off about 4000 A in height from the polymer films per pass. The first application is to partly annealed polystyrene latex films where it is shown that four regimes of fracture exist as annealing progresses.
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Molecular basis of fracture in polystyrene films
1993Co-Authors: M. Sambasivam, N. Mohammadi, Andrew Klein, T.n. Thomas, Leslie H. SperlingAbstract:To understand the molecular mechanisms involved in the fracture of polystyrene films, a custom built Dental Burr grinding instrument was used. Films were made from latexes, compression molded polystyrene, and by photopolymerization. Latexes were prepared by direct miniemulsification of polystyrene using sodium lauryl sulfate as surfactant and cetyl and stearyl alcohols as co-surfactants. Grinding of various films was carried out at room temperature. GPC was used to determine the molecular weight before and after grinding. From the molecular weight reduction, the number of chain scissions per unit volume was determined. The energy required for the grinding process was also measured. The results are consistent with a model of exciting 300{+-}150 bonds (per chain fracture) to the breaking point. The most probable deformation mode, consuming maximum energy is envisaged as the scissor-like opening of the 109{degrees} -C-C-C bond angle.
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Polymer chain rupture and the fracture behavior of glassy polystyrene
Macromolecules, 1993Co-Authors: N. Mohammadi, Andrew Klein, Leslie H. SperlingAbstract:Uniform latexes of anionically polymerized polystyrene (M n = 180 000, 250000, and 420000) were prepared by direct miniemulsification. The 1200-A-diameter particles were sintered, and the resulting films were annealed for various periods of time at 144°C. The films were fractured with fine Dental Burr instrumentation at a depth of 4000 A/pass. The number of chain ruptures and consumed energy per unit area were measured, as well as tensile strength. Three regimes, mixed, peak and recovery, were found in the number of chain scissions per unit area and the tensile strength-annealing time correlation. Data in the mixed regime confirm portions of the de Gennes and Tirrell theory which predicts a 0.5 power dependence on annealing time and portions of the Wool theory
B Flautre - One of the best experts on this subject based on the ideXlab platform.
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biomechanical characterization of a biodegradable calcium phosphate hydraulic cement a comparison with porous biphasic calcium phosphate ceramics
Journal of Biomedical Materials Research, 1998Co-Authors: Minoru Ikenaga, P Hardouin, Jacques Lemaitre, Hortense Andrianjatovo, B FlautreAbstract:Biomechanical properties of a biodegradable calcium phosphate hydraulic cement (CPHC) were tested with rabbits. The cement was composed of β-tricalcium phosphate (β-TCP), monocalcium phosphate monohydrate (MCPM), and calcium sulfate hemihydrate (CSH), β-TCP-MCPM-CSH cement. Cylinders of 4.7 mm in diameter and 10 mm in length were put into bone cavities created in the distal epiphysis of femurs in rabbits. Cylinders of the same size of porous biphasic calcium phosphate ceramics (BCPC, 75% hydroxyapatite and 25% β-TCP) were implanted as references. Two, 4, 12, and 16 weeks after the operation, the rabbits were sacrificed. Histomorphometry showed that the cement was resorbed, leaving only 7.67 ± 1.81% of bone cavity after 12 weeks. Newly formed bone occupied 34.59 ± 4.00% of the cavity. Cylindrical bone–material composites were cut out with a small Dental Burr. Compressive force was applied to the specimens and compressive strength, elastic modulus, and toughness were calculated. The same tests were performed on cylinders of normal bone from the same site, which served as controls. The compressive strength and the toughness of the cement–bone composite were higher than those of normal bone and porous ceramics 12 weeks after the operation (p < 0.05). At 16 weeks the compressive strength and the toughness returned to the normal bone values. The elastic modulus of the porous ceramic–bone composite was higher than the normal bone at 4, 12, and 16 weeks after surgery (p < 0.05). We found that the β-TCP-MCPM-CSH cement is replaced by new bone and that the cement–new bone composite has similar or better mechanical properties than normal bone within 16 weeks. This study suggests the usefulness of a particular cement for filling bone defects or for temporary fixation of orthopedic implants. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 40, 139–144, 1998.