Abstract
In our previous studies, we have found the synergistic combinations of stabilizers which follow different mechanisms of stabilization and are approved for food contact applications. The present attempt is to test the potentials of those systems in stabilizing γ-sterilized low-density polyethylene (LDPE). The results were discussed by comparing the stabilizing efficiency of mixtures with and without phenol systems as well as with their counterparts of isotactic polypropylene (iPP) and ethylene-propylene copolymers (EP) matrices. LDPE has been melt-mixed with tertiary hindered amine stabilizer (tert-HAS), oligomeric HAS stabilizer, phenolic and organo-phosphite antioxidants and subjected to γ-sterilization. Stabilization in terms of changes in oxidation products, tensile properties, yellowing and surface morphology was evaluated by FT-IR spectroscopy, Instron, colorimetry, and scanning electron microscopy (SEM), respectively. The results of the present study confirm the validity of those systems for protecting various polyolefins against γ-sterilization. The results showed that the synergism, antagonism and the trend in stabilization efficiency of the binary, ternary and quaternary stabilizer systems were almost similar in LDPE, iPP and EP matrices. The binary system of oligomeric HAS and tert-HAS has shown the antagonistic effect of stabilization, whereas their combination with organo-phosphite has exhibited synergistic effect even at higher doses of γ-sterilization. The combination of oligomeric HAS, tert-HAS, organo-phosphite and hindered phenol exhibited improved stabilization efficiency than single or binary additive systems. The phenol systems have shown long term of stability than that of phenol-free systems. It was found that the consumption of oligomeric stabilizer significantly depends on the components of stabilization mixture. It was concluded that the stability of polyolefins (LDPE, iPP and EP) against γ-sterilization can be achieved by blends of different stabilizers which are approved for food contact applications.
Highlights
lowdensity polyethylene (LDPE) is one of the most popular polymers in the manufacturing of food packaging and medical disposables, because it exhibits high transparency, good mechanical properties, low cost, good sealability and chemical resistance, and can be employed over a wide temperature range
It was concluded that the stability of polyolefins (LDPE, isotactic polypropylene (iPP) and ethylene-propylene copolymers (EP)) against c-sterilization can be achieved by blends of different stabilizers which are approved for food contact applications
Considering the above said aspects, we have found the combinations of synergistic mixtures of oligomeric stabilizers in our previous works [20,21,22] where we have used mixtures of oligomeric Hindered amine stabilizers (HAS) and tert-HAS, primary and secondary antioxidants, which are approved for food contact applications [30], and their selection has been based on different molecular weights and protecting mechanisms in iPP and EP matrices
Summary
LDPE is one of the most popular polymers in the manufacturing of food packaging and medical disposables, because it exhibits high transparency, good mechanical properties, low cost, good sealability and chemical resistance, and can be employed over a wide temperature range. The efficiency of stabilizers is very much dependent upon the type and the grade of polymer in which they are compounded; the judicious selection of stabilizers is very important in the formulation of plastic [11] These additives are not chemically bound to the polymer matrix and migrate or leach out under the influence of physicochemical factors such as temperature, sterilization and type of solvents and pH of the packaged product [12]. The toxicology of food packaging and medical plastics depends on many factors such as the effect of stabilizer loss, toxicity of migrated or leached stabilizers, degradation process and the degradation products and the effect of sterilization methods on the plastics or its constituents [7]. Stabilization should be done with stabilizers which are approved for food contact and biomedical applications
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
