Biobased Poly(ethylene terephthalate)/Poly(lactic acid) Blends Tailored with Epoxide Compatibilizers

To increase the biobased content of poly(ethylene terephthalate) (PET), up to 30 wt % poly(lactic acid) (PLA) was blended with PET using twin-screw compounding and injection molding processes. Multifunctional epoxide compatibilizers including a chain extender and an impact toughening agent were used as blend modifiers to improve the poor mechanical properties of PET/PLA blends. The mechanical and thermodynamic performances were investigated along with the morphological features through scanning electron microscopy, atomic force microscopy, and interfacial tension determination. From rheological and differential scanning calorimetry results, it was observed that the molecular weight of both PET and PLA increased with compatibilizers because of epoxide reactions. The toughening agent, poly(ethylene-n-butylene-acrylate-co-glycidyl methacrylate) (EBA-GMA), provided a 292% increase in impact strength over the blend but reduced modulus by 25%. In contrast, 0.7 phr addition of the chain extender, poly(styrene-acrylic-co-glycidyl methacrylate) (SA-GMA), yielded comparable performance to that of neat PET without sacrificing the tensile and flexural properties. When both compatibilizers were present in the blend, the mechanical properties remained relatively unaltered or decreased with increasing EBA-GMA content. The differences in mechanical performance observed were considered in relation to the strengthening mechanism of the two differing compatibilizers and their effects on the miscibility of the blend.

Polylactide/graphene oxide nanosheets/clove essential oil composite films for potential food packaging applications

Antimicrobial nanopackaging films were developed by incorporating clove essential oil (CLO) (15-30% w/w) and graphene oxide (GO) nanosheets (1% w/w) into polylactide (PLA), suitable for use as food packaging, via solution casting. Addition of CLO into PLA matrix improved the flexibility of the composite films by lowering tensile stress, complex viscosity (η*), and glass transition temperature (T_g). GO improved the T_g, η* and lowered the oxygen permeability of the plasticized PLA matrix. Optical and anti-UV properties of the film were influenced by both GO and CLO incorporation. FTIR spectra exhibited a change in the molecular organization of the plasticized PLA film after incorporation with CLO. Microstructural studies revealed that the reinforcement of GO prevented porosity of plasticized PLA/CLO film surface. The developed composite film showed excellent antibacterial activity against Staphylococcus aureus and Escherichia coli and therefore, has a potential to be used as active packaging material for food safety and preservation.

Solid polymer electrolyte based on ionic bond or covalent bond functionalized silica nanoparticles

This article reports a solid polymer electrolyte based on ionic bond or covalent bond functionalized silica nanoparticles for lithium ion batteries.

An Investigation of the Effect of Chitosan on Isothermal Crystallization, Thermal Decomposition, and Melt Index of Biodegradable Poly(L-lactic acid)

Biodegradable chitosan (CS) was introduced into another biodegradable poly(L-lactic acid) (PLLA) to prepare the PLLA/CS composites, and the effect of CS on thermal behavior and melt index of PLLA was investigated using modern testing technologies including optical depolarizer, thermogravimetric analysis instrument, and melt index instrument. The relevant testing results showed that both crystallization temperature and CS concentration affected the isothermal crystallization behavior of PLLA. Compared to neat PLLA, thet1/2of PLLA/5% CS decreased from 2991.54 s to the minimum value 208.76 s at 105°C. However, thet1/2of PLLA/CS composites in high crystallization temperature zone was different from that in low crystallization temperature zone. The increase of CS concentration and heating rate made the thermal decomposition temperature of PLLA/CS composites shift to higher temperature. The melt index results indicated that 3% CS made the fluidity of PLLA become better.

Effect of graphene modified by a long alkyl chain ionic liquid on crystallization kinetics behavior of poly(vinylidene fluoride)

To investigate the effects of graphene (Gra) modified by 1-hexadecyl-3-methylimidazolium bromide (IL) on the crystallization kinetics behaviour of PVDF, a series of PVDF/IL blend, PVDF/Gra and PVDF/IL/Gra nanocomposites were prepared.

Photo-crosslinked hierarchically honeycomb-patterned/macroporous scaffolds of calcium phosphate cement promote MC3T3-E1 cell functions

Novel photo-crosslinked hierarchically honeycomb-patterned/macroporous scaffolds of calcium phosphate cement were fabricated through a facile process using a breath-figure method. MC3T3-E1 cell functions were significantly enhanced on these scaffolds compared to others.