No abstract

Poly(lactic acid), PLA, composites containing 0, 1, 3, and 5 wt % zeolite type 4A were prepared using extrusion/injection compounding techniques. Morphological characterizations were carried out by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Physical properties were evaluated by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) and mechanical properties by standard tensile testing. The morphological studies showed a homogenous dispersion of zeolite particles within the PLA matrix. As the fracture stress propagated, zeolite particles remained embedded into the matrix, indicating the existence of good interfacial adhesion between zeolite particles and the PLA matrix. The improvement in the interfacial adhesion was also confirmed by applying Nicolais-Narkis and Pukanszky models. The percent crystallinity of the PLA and the temperature-dependant elastic and viscous modulus of the composite increased with the proportion of zeolites.

Biodegradable composites based on poly(L-lactic acid) (PLLA) and metal organic frameworks (MOFs) were developed. PLLA without and with the addition of 1, 3 and 5 wt% MOFs was melt compounded in a microextruder. The optical, physical, thermal, mechanical and thermomechanical properties of the composites were evaluated. The Fourier transform infrared, ultraviolet and colorimetric studies showed selected absorption at particular wavelengths due to the presence of copper and benzene belonging to the MOFs. The dynamic mechanical analysis results revealed that the heat deflection temperature, storage modulus and loss modulus of the PLLA-MOF composites did not significantly change compared with the neat PLLA samples. However, a significant decrease in the brittleness of the PLLA-MOF composite was found as evidenced by an increase of 15% in Izod impact strength and 170% in elongation at break. Overall, the brittleness of the PLLA-MOF composite sample decreased as the amount of MOF in the PLLA increased.

Biodegradable multifunctional polymeric membranes based on poly(l-lactic acid), PLLA, and metal–organic framework compounds (MOFs) were developed. PLLA with and without the addition of 5 wt % MOF was melt compounded in a microextruder, and the solubility parameters, water sorption isotherm, and permeability coefficients to oxygen, carbon dioxide, water, ethyl acetate, hexane, and cyclohexane were determined. The sorption capacity of the PLLA–MOF composite films increased up to 2-fold at each relative humidity to which it was exposed when compared with the PLLA films. The sorption and desorption curves of the PLLA–MOF films show hysteresis. The presence of MOF in the composite films did not significantly modify the permeability coefficients of the PLLA–MOF films.

Aluminum‐oxide‐coated PLA pellets, particles derived from aluminum oxide sol‐gel, and calcinated α‐Al2O3 powders were used to fabricate PLA/AlOx composites. The formation of aluminum oxide was confirmed by FTIR and EDS. SEM images suggested the melt compounding system provided a fairly homogeneous dispersion of AlOx particles in the PLA matrix. XRD analysis showed PLA and PLA/AlOx composites were both amorphous. The incorporation of AlOx particles did not alter the melting temperature of PLA. However, the shape and intensity of the melting endotherms was significantly changed, suggesting bimodal melting behavior. UV‐Vis transmission spectra suggested that PLA/AlOx composites may act as a better UV barrier than neat PLA.magnified image