In this study, a new Fourier transform infrared (FTIR) spectroscopy method for measuring lactide ... more In this study, a new Fourier transform infrared (FTIR) spectroscopy method for measuring lactide concentration in a polylactide (PLA) matrix is presented. The lactide ring breathing mode peak at 935 cm-1 is rationed against the asymmetric bending mode of methyl groups at 1454 cm-1 ; because the methyl group is present both in lactide monomer and the polymer, this ratio provides a direct measure of lactide concentration. Using well-defined mixtures of lactide and PLA, a calibration curve is established. For lactide concentrations corresponding to conversions above 75%, a linear relationship between conversion and the peak area ratio exists. Below 75% conversion, the development of a double peak at 1454 cm-1 leads to deviations from linearity; data can then be accurately represented by a second-order polynomial relating conversion to the peak area ratio. Kinetic data for the bulk polymerization of lactide at different temperatures are also obtained and independently verified using rigorous NMR techniques. Finally, conversion as a function of time calculated using the FTIR method is found to be in good agreement with the polymerization kinetics model of Witzke, Narayan, and Kolstad.
This study examined the interfacial adhesion, mechanical, and thermal properties of compatibilizi... more This study examined the interfacial adhesion, mechanical, and thermal properties of compatibilizing agent-treated and non-treated biocomposites as a function of the type of compatibilizing agent. The tensile strength, interfacial adhesion, and heat deflection temperature (HDT) of maleic anhydride-grafted poly(butylene succinate) (PBS-MA) and maleic anhydride-grafted poly(lactic acid) (PLA-MA)-treated biocomposites are greater than those of untreated maleic anhydride-grafted poly(styrene-b-ethylene-co-butylene-b-styrene) triblock copolymer (SEBS-MA)
ABSTRACT The phase behavior of two nematic liquid crystals in a polymer host is studied using the... more ABSTRACT The phase behavior of two nematic liquid crystals in a polymer host is studied using the technique of Thermal Optical Analysis. Results are compared to the predictions of a recent molecular model due to Ballauff and found to give very good agreement for monodisperse polymers of sufficiently high molecular weight. Experimental findings include a widening of the two phase regime with increasing polymer chain length, exclusion of the polymer coils from the nematic phase and a sharp sensitivity of the phase behavior to the polydispersity of the polymer sample. All of these findings are in accord with the model and lend support to the general validity of the Flory-Ronca treatment of the anisotropic energetics responsible for thermotropic behavior.
... 9 That is, video recordings were used to measure the true elongational rate according to the ... more ... 9 That is, video recordings were used to measure the true elongational rate according to the protocol developed under the round robin. ... Cheung, MF; Carduner, KR; Golovoy, A.; Van Oene, H. J. Appl. Polym. Sci.1990, 40, 977−987. ...
... extent that developed world economies are dependent on it for heat, food (through ... Large q... more ... extent that developed world economies are dependent on it for heat, food (through ... Large quantities of petroleum are used to produce present-generation plastics, but oil ... 2.1.3 PLASTICS FROM RENEWABLE RESOURCES Through application of bioengineering in conjunction ...
In this study, a new Fourier transform infrared (FTIR) spectroscopy method for measuring lactide ... more In this study, a new Fourier transform infrared (FTIR) spectroscopy method for measuring lactide concentration in a polylactide (PLA) matrix is presented. The lactide ring breathing mode peak at 935 cm-1 is rationed against the asymmetric bending mode of methyl groups at 1454 cm-1 ; because the methyl group is present both in lactide monomer and the polymer, this ratio provides a direct measure of lactide concentration. Using well-defined mixtures of lactide and PLA, a calibration curve is established. For lactide concentrations corresponding to conversions above 75%, a linear relationship between conversion and the peak area ratio exists. Below 75% conversion, the development of a double peak at 1454 cm-1 leads to deviations from linearity; data can then be accurately represented by a second-order polynomial relating conversion to the peak area ratio. Kinetic data for the bulk polymerization of lactide at different temperatures are also obtained and independently verified using rigorous NMR techniques. Finally, conversion as a function of time calculated using the FTIR method is found to be in good agreement with the polymerization kinetics model of Witzke, Narayan, and Kolstad.
This study examined the interfacial adhesion, mechanical, and thermal properties of compatibilizi... more This study examined the interfacial adhesion, mechanical, and thermal properties of compatibilizing agent-treated and non-treated biocomposites as a function of the type of compatibilizing agent. The tensile strength, interfacial adhesion, and heat deflection temperature (HDT) of maleic anhydride-grafted poly(butylene succinate) (PBS-MA) and maleic anhydride-grafted poly(lactic acid) (PLA-MA)-treated biocomposites are greater than those of untreated maleic anhydride-grafted poly(styrene-b-ethylene-co-butylene-b-styrene) triblock copolymer (SEBS-MA)
ABSTRACT The phase behavior of two nematic liquid crystals in a polymer host is studied using the... more ABSTRACT The phase behavior of two nematic liquid crystals in a polymer host is studied using the technique of Thermal Optical Analysis. Results are compared to the predictions of a recent molecular model due to Ballauff and found to give very good agreement for monodisperse polymers of sufficiently high molecular weight. Experimental findings include a widening of the two phase regime with increasing polymer chain length, exclusion of the polymer coils from the nematic phase and a sharp sensitivity of the phase behavior to the polydispersity of the polymer sample. All of these findings are in accord with the model and lend support to the general validity of the Flory-Ronca treatment of the anisotropic energetics responsible for thermotropic behavior.
... 9 That is, video recordings were used to measure the true elongational rate according to the ... more ... 9 That is, video recordings were used to measure the true elongational rate according to the protocol developed under the round robin. ... Cheung, MF; Carduner, KR; Golovoy, A.; Van Oene, H. J. Appl. Polym. Sci.1990, 40, 977−987. ...
... extent that developed world economies are dependent on it for heat, food (through ... Large q... more ... extent that developed world economies are dependent on it for heat, food (through ... Large quantities of petroleum are used to produce present-generation plastics, but oil ... 2.1.3 PLASTICS FROM RENEWABLE RESOURCES Through application of bioengineering in conjunction ...
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