Enhancing compatibility between poly(lactic acid) and thermoplastic starch using admicellar polymerization

An alternative method to improve the compatibility between poly(lactic acid) (PLA) and cassava starch (CS) is proposed and investigated. Admicellar polymerization is used to modify the surface of CS with poly(methyl methacrylate) (PMMA) in order to make it more hydrophobic and hence more compatible with PLA. The increased hydrophobicity of PMMA modified cassava starch (MS) is validated by contact angle measurement. Results from iodine test, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X‐ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) confirm the formation of PMMA film on MS surface. Mechanical properties of PLA‐CS and PLA‐MS blends are investigated to compare their compatibility. Noticeable improvements in blend tensile strength and elongation at break evidently show that MS is more hydrophobic as well as more compatible with PLA than CS. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43755.     

Thermal decomposition processes in aromatic amine-based polybenzoxazines investigated by TGA and GC-MS

Three different aromatic amine-based polybenzoxazines are subjected to thermal decomposition in a thermogravimetric analyzer. The degradation products, which are volatile compounds evaporating out of the furnace as gases, are trapped and analyzed further by a gas chromatograph which is coupled with a mass selective detector (GC-MS). All the degradation products are separated by GC and come out at different retention times, as seen in the total ion chromatogram. All the compound's mass are selectively identified by MS. The chromatograms are divided into two regions; the low column temperature region containing low molecular weight and highly volatile compounds, and the high column temperature region containing higher molecular weight and less volatile compounds. The evolved gas analysis performed by GC-MS allows us to identify the molecular weight and also the structure of the volatiles. This information is then used to illustrate the processes occurring during the thermal decomposition of aromatic amine-based polybenzoxazines.     

Radiation-induced admicellar polymerization of isoprene on silica: Effects of surfactant's chain length

This research compared radiation-induced admicellar polymerization with the traditional thermal process and studied the influence of the hydrocarbon chain length of different surfactants on film formation. Three types of surfactants were used in this study: dodecyl trimethyl ammonium bromide (DTAB), tetradecyl trimethyl ammonium bromide (TTAB) and cetyl trimethyl ammonium bromide (CTAB). Isoprene was used as a monomer for the formation of thin film inside the surfactant bilayers, called admicelle, adsorbed on silica surface. The results showed that an optimum dose can lead to a better film formation on silica, compared with the thermal method. However, when the dose was over the optimum value, the formation of polyisoprene film was diminished. The formation of polyisoprene film was found to depend not only on the hydrocarbon chain length of the surfactant, but also on the density of adsorbed surfactant on silica surface.     

Poly(ethylene glycol) methyl ether methacrylate‐graft‐chitosan nanoparticles as a biobased nanofiller for a poly(lactic acid) blend: Radiation‐induced grafting and performance studies

In this study, we aimed to modify chitosan (CS) as a novel compatible bio‐based nanofiller for improving the compatibility including the thermal and mechanical properties of poly(lactic acid) (PLA). The modification of CS with poly(ethylene glycol) methyl ether methacrylate (PEGMA) was done by radiation‐induced graft copolymerization. The effects of the dose rate, irradiation dose, and PEGMA concentration on the degree of grating (DG) were investigated. The chemical structure, packing structure, thermal stability, particle morphology, and size of the PEGMA‐graft‐chitosan nanoparticles (PEGMA‐graft‐CSNPs) were characterized by fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, and transmission electron microscopy. The compatibility of the PEGMA‐graft‐CSNP/PLA blends was also assessed by field emission scanning electron microscopy. The PEGMA‐graft‐CSNPs exhibited a spherical shape with the DG and particle sizes in the ranges of 3–145% and 35–104 nm, respectively. The PEGMA‐graft‐CSNPs showed compatible with PLA because of the grafted PEGMA segment. A model case study of the PEGMA‐graft‐CSNP/PLA blend demonstrated the improvement not only the compatibility but also thermal stability flexibility, and ductility of PLA. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42522.