Polylactide/Biopolyethylene bioblends
In this work, Polylactide/Biopolyethylene blends were developed. Although some studies have been carried out on polylactide/polyethylene blends, none of them has used polyethylene synthesized with raw material obtained from natural sources. Due to the incompatibility between polylactide and polyethylene, E-GMA and EMA-GMA compatibilizers were used. These compatibilizers present glycidyl methacrylate groups in their structure, which may react with the functional end-groups of polylactide. To evaluate the properties, the blends were characterized by mechanical tests, scanning electron microscopy (SEM) and melt flow index (MFI). The results indicated that the compatibilizers played an important role in the blends, interacting with the blends components, modifying the morphology and improving the mechanical properties.
Injection Molding of Thermoplastic Cellulose Esters and Their Compatibility with Poly(Lactic Acid) and Polyethylene
Interest in biobased polymers from renewable resources has grown in recent years due to environmental concerns, but they still have a minimal fraction of the total global market. In this study, the injection molding of thermoplastic cellulose octanate (cellulose C8) and cellulose palmitate (cellulose C16) were studied. The mechanical properties of injection-molded test specimens were analyzed by using tensile testing, and the internal structure of injection-molded objects was studied by using a field emission scanning electron microscopy (FE-SEM). We showed that thermoplastic cellulose C8 and cellulose C16 were completely processable without the addition of a plasticizer, which is very unusual in the case of cellulose esters. The compatibility of cellulose esters with poly(lactic acid) (PLA) and biopolyethylene (bio-PE) was also tested. By compounding the cellulose esters with PLA, the elongation of PLA-based blends could be improved and the density could be reduced. The tested thermoplastic cellulose materials were fully biobased, and have good future potential to be used in injection molding applications.
Thermoanalytical Studies of the Thermal Stability of High Polymers. II. The Differential Thermal Analysis and Thermogravimetric Analysis of Some Polyethylenes
The thermal stability of polyethylenes has been studied by differential thermal analysis and by thermogravimetric analysis in air and in a nitrogen atmosphere. The crystallinities of some polyethylenes have been evaluated from the data of differential thermal analysis. These values are smaller than the reported value. This discrepancy may be due to differences in the methods. In the differential thermal analysis curve for low-pressure polyethylene Hizex 5000 in air, two small exothermic peaks due to oxidation were observed at about 200 and at about 390°C. The endothermic peaks at 135 and at 457°C correspond to the melting and to the thermal decomposition points of polyethylene. In thermogravimetric analysis in a nitrogen atmosphere, the thermal decomposition of lowpressure polyethylene takes place over the range from 380 to about 450°C, and that of high-pressure polyethylene, from 360 to about 450°C. In the presence of air, the oxidative degradation of low-pressure and high-pressure polyethylenes occurs i...