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In this work, uncompatibilized and compatibilized blends of low density polyethylene (LDPE) and poly(lactic acid) (PLA) were subjected to several investigations: Fourier transform infrared (FTIR) spectroscopy, morphological analysis and mechanical testing (tensile, impact, microhardness). The copolymer (ethylene-coglycidyl methacrylate) (EGMA) was used as compatibilizer. The percentages of PLA in LDPE/PLA samples ranged from 0 to 100 wt% while the EGMA was added to the blend 60/40 (LDPE/PLA) at concentrations of 2, 5, 7, 10, 15 and 20 parts per hundred (phr). FTIR analysis showed the absence of any interaction between LDPE and PLA, but after addition of compatibilizer, reactions between epoxy groups of EGMA and carboxylic or hydroxyl groups of PLA were confirmed. Tensile and impact tests revealed a loss of ductility of LDPE with the incorporation of PLA, except for the composition 80/20 (LDPE/PLA). However, the addition of 15 phr of EGMA led to the maximum increase in the elongation-at-break (about three times the value of uncompatibilized blend) and in the impact strength, but a marginal improvement was observed for tensile strength. SEM micrographs confirmed that the enhancement of mechanical properties is due to the improvement of the interfacial adhesion between different phases owing to the presence of EGMA. The microhardness values of the different blends (uncompatibilized or compatibilized) were in good agreement with the macroscopic mechanical properties (tensile and impact strengths).

The crystallinity of unstabilized low-density polyethylene (LDPE) films and those stabilized with hindered-amine light stabilizers (HALS) was studied under natural weathering conditions, up to 170 and 650 days, respectively. The HALS tested was Tinuvin 783, added to the polymer in the concentration of 0.6% (wt/wt). The crystallinity changes were evaluated by means of Fourier-Transform Infrared (FT-IR) spectroscopy, wide-angle X-ray scattering (WAXS), and Differential scanning calorimetry (DSC). The comparison of the results obtained by FTIR and WAXS c o n k e d the accuracy of using the rocking bands 730 and 722cm-'. The trends of the crystallinity measured by DSC were different from those determined by FT-IR and WAXS.