Study On Migration Of Additives From Polylactic Acid Packaging Materials And Its Safety Assessment

The classification and the application of biodegradable materials,the advantages and disadvantages of polylatic acid（PLA）materials,the modification of PLA materials and the safety of PLA materials were reviewed.The research contents and main results are as follows:（1）A method using gas chromatography-mass spectrometer（GC-MS）to detect two slip agents,i.e.stearamide and erucamide,in polylactic acid（PLA）foaming containers,was established.The migration of two slip agents in three simulants（isooctane,95%ethanol and ethanol）was studied.The safety assessment of two slip agents was performed to determine the safety of the foaming containers by threshold of toxicological concern（TTC）.The results showed that the migration of two slip agents into ethanol and 95%ethanol was almost the same,both of which were higher than the migration into isooctane.Compared with erucamide,stearamide migrated to food simulants faster.The estimated daily intake（EDI）of stearamide and erucamide migrated to food simulants were both lower than the safety threshold,which indicated that two kinds of slip agents in the PLA foaming containers were safe.（2）The metal elements in PLA dinner plate were determined by inductively coupled plasma optical emission spectrometer（ICP-OES）.The migration of these metal elements from PLA dinner plate into 3%acetic acid was investigated.Three subsequent migration experiments to simulate migration under multiple-use conditions were conducted.The results revealed that the migration of metal elements increased with the temperature and time.High temperature and acid environment led to the hydrolysis of PLA materials.The cleavage of the ester linkages increased the migration.The migration mainly occurred from the surface of PLA dinner plate when the exposure time was shorter,while the migration not only occurred from the surface but also from the interior of PLA dinner plate when the exposure time was long due to the corrosion of acid to the material.None of the metal elements in the plates exceeded their specific migration limits（SML）or tolerable upper intake level（UL）.（3）Five kinds of PLA/PBAT/CaCO₃ films containing different contents of calcium carbonate（CaCO₃）were detected by ICP-OES.The migration of calcium to3%acetic acid was studied.The migration of calcium to food simulant due to ultraviolet aging was also studied.The effect of ultraviolet aging on the migration of calcium was investigated.Conducted the overall migration tests and explored the relationship between the concentration of calcium and overall migration.The films were characterized by Fourier infrared spectrometer（FTIR）and scanning electron microscope（SEM）.The results showed that ultraviolet aging may lead to cross-linking and chain fracture of the material,which has different effects on the migration of calcium.There is an approximate linear relationship between the concentrations of calcium and overall migration in 3%acetic acid.The overall migration of the five kinds of films to 3%acetic acid exceeded the overall migration limit（OML）,and when the contents of CaCO₃ are 25%,the overall migration to 95%ethanol also exceeded the OML.