Poly(lactic acid) based nanocomposites: mechanical, thermal and rheological properties and morphology

Açık, Eda
The aim of this study was to increase the potential applications of poly(lactic acid) (PLA) by incorporating reactive functionalities with different nano-scale fillers. To investigate the effects of nanoclay types, five different organically modified nanoclays (Cloisites®15A, 25A and 30B and Nanofils®5 and 8) were used. Two elastomeric compatibilizers, ethylene-glycidyl methacrylate (E-GMA) and ethylene-butyl acrylate-maleic anhydride (E-BA-MAH), were added to the nanocomposites produced via melt compounding. The degree of clay dispersion was determined by the chemical compatibility between the polymer matrix and the modifier. Compatibility between C25A, C30B and E-GMA resulted in better dispersion and thus, enhanced tensile modulus and toughness. The network structure formed owing to the high reactivity of the epoxide group of GMA towards the PLA end groups resulted in high impact toughness and solid-like behavior in the melt state. Effects of filler loadings with different production methods (melt compounding and solution mixing) were investigated with expanded graphite (EG) as the filler. Filler loading was kept below 2 wt. % to minimize the dispersion problem and solvent usage. No significant changes were observed in filler dispersion in both methods. However, when E-GMA was added, melt compounded blends had phase separated matrix morphology and solution mixed blends had continuous matrix morphology. Significant decreases in ultimate tensile strength and elastic modulus, but increased strain at failure were observed for samples prepared by solution mixing. Enhancements in elastic behavior and complex viscosity of composites in the melt state are other remarkable outcomes of addition of E-GMA by the solution mixing method.


Dielectric and piezoelectric properties of PZT ceramics doped with strontium and lanthanum
Kalem, Volkan; Çam, İbrahim; Timucin, Muharrem (Elsevier BV, 2011-05-01)
PZT based piezoelectric ceramics obtained by doping with various levels of Sr2+ and La3+, designated as PSLZT, were prepared by conventional processing techniques. The effects of Sr2+ and La3+ additions, and that of the Zr/Ti ratio on microstructure, on phase constitution, and on the dielectric and piezoelectric properties were investigated. XRD data revealed that all PSLZT compositions had perovskite structure in which increasing Sr and/or decreasing Zr/Ti ratio increased the tetragonality. In PSLZT cerami...
Poly(lactic acid) blends, composites and fibers and direct pyrolysis mass spectrometry for nanoclay composites
Özdemir, Esra; Hacaloğlu, Jale; Kayran İşçi, Ceyhan; Department of Polymer Science and Technology (2017)
In the first part of this study, poly(lactic acid)-poly(ethylene glycol), PLA-PEG, blends, composites and electrospun fibers of PLA and PLA composites, PLA-PEG blends and PLA-PEG, blends composites were prepared and characterized. X-ray Diffractometer (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Gel Permeation Chromatography (GPC), Simultaneous Thermal Analyzer (STA) and Direct Pyrolysis Mass Spectrometer (DP-MS) techniques were used for characterization studies. Both T...
Poly(lactic acid)-layered silicate nanocomposites: The effects of modifier and compatibilizer on the morphology and mechanical properties
Cumkur, Eda Acik; Baouz, Touffik; Yılmazer, Ülkü (2015-10-10)
Poly(lactic acid) (PLA) based nanocomposites were prepared to investigate the effects of types of nanoclays. Five different organically modified nanoclays (Cloisites((R))15A, 25A, and 30B, and Nanofils((R))5 and 8) were used. Two rubbery compatibilizers, ethylene-glycidyl methacrylate (E-GMA) and ethylene-butyl acrylate-maleic anhydride, were used in the nanocomposites as compatibilizer-impact modifier. The degree of clay dispersion, the chemical compatibility between the polymer matrix and the compatibiliz...
Microtensile Bond Strength of Self-Adhesive Resin-Based Dental Cement to Bleached Enamel
Tamam, Evsen; Keskin, Selda; Ucatasli, Mine Betuel (Informa UK Limited, 2010-01-01)
This study investigated the effectiveness of bleaching agents on the micro tensile bond strength (mu TBS) of self-adhesive luting cement and enamel. A total of 126 samples were prepared from the labial surfaces of permanent human maxillary central incisors and assigned into three groups with 42 samples each as: control, enamel bleached with 10% hydrogen peroxide (HP), and enamel bleached with 10% carbamide peroxide (CP). Rely X Unicem (R) (3 M, ESPE) was used as self-adhesive resin cement. The total testing...
Enhancing electrochemical and electrochromic performances of carbazole comprising monomer via copolymerization with 3,4-ethylenedioxythiophene (EDOT)
Kalay, Isil; Yigit, Deniz; GÜLLÜ, Mustafa; DEPCİ, TOLGA; Toppare, Levent Kamil; Hacioglu, Serife O. (Elsevier BV, 2020-09-01)
In this study, two novel electrochromic copolymers (CoP1.3 and CoP1.5) were synthesized via electrochemical methods and characterized. The comonomers used in the synthesis were 3,4-ethylenedioxythiophene (EDOT) and a carbazole comprising monomer; 9-(2-(4-(Phenyldiazenyl) phenoxy) ethyl)-3,6-di(thiophen-2-yl)-9H-carbazole (M1). Carbazole containing monomer (M1) and EDOT were combined with two different comonomer feed ratios, 1: 3 and 1: 5 respectively in order to investigate the effect of increasing EDOT amo...
Citation Formats
E. Açık, “Poly(lactic acid) based nanocomposites: mechanical, thermal and rheological properties and morphology,” Ph.D. - Doctoral Program, Middle East Technical University, 2014.