Influence of α‐tocopherol/MCM‐41 assembly on physical and antioxidant release properties of low‐density polyethylene antioxidant active films

Abstract

α‐Tocopherol, usually used as an antioxidant in the packaging industry, was loaded into inner pore channels of Mobil composition of matter NO.41(MCM‐41) mesoporous silica material to control its release from packaging materials into fatty food simulant. Different amount of α‐tocopherol/MCM‐41 assembly were coextruded with low‐density polyethylene (LDPE) granulates to prepare antioxidant active films by flat extrusion. The influence of the assembly addition amounts on the properties of LDPE films including physical properties and antioxidant release profiles were thoroughly investigated. The results showed that the addition amounts obviously influenced the physical properties of LDPE films as well as migration profiles of the antioxidant. As compared to pure LDPE, tensile strength of LDPE films loaded with 4% (w/w) of the assembly decreased by ∼20% on machine direction. As to release profiles of the antioxidant, LDPE films loaded with 0.2% of the assembly showed the fastest release rate, and the highest amount of the assembly gave rise to the longest release period, which was ∼23% longer than that of 0.2% additives. These results may offer theoretical instructions for further industrial applications of LDPE antioxidant active films loaded with α‐tocopherol/MCM‐41 assembly. POLYM. ENG. SCI., 58:1710–1716, 2018. © 2017 Society of Plastics Engineers

Characterization of α‐tocopherol‐loaded MCM‐41 mesoporous silica with different pore sizes and antioxidant active packaging films

“…It can be seen from these results that the values of the melting temperatures of LDPE/α‐tocopherol/MCM‐41 films stay constant at around 108°C with different mesopore sizes and morphologies of mesoporous materials incorporated, which means that these two factors have negligible influence on thermal properties of controlled release films. According to a previous study, 14 the melting temperatures of controlled release films are nearly the same as those of pure LDPE. Similar results have been found in other researches: Olmos et al found that silica nanoparticles with various addition amounts did not obviously influence melting temperature of LDPE 34 .…”

“…Tensile strength and elongation of controlled release films are shown in Table 3. It can be found that, as compared with tensile properties of LDPE films, 14 these properties are improved by incorporating with controlled release assemblies. It can also be seen that tensile strength and Young modulus increase slightly from L1 to L4, which may, on the one hand, be attributed to the increase of crystallinity of these samples; on the other hand, this may be due to the increase of pore size from M1 to M4 as reported by Wang et al 40 Specifically, LDPE chain may be introduced in the mesopores of silica materials during film making process, and the chain in the larger pores can extend more easily along the channels to the openings enhancing interactions between polymeric matrix and the assemblies, thus leading to increasing tensile strength of samples from L1 to L4 films.…”

“…Tensile strength and elongation of controlled release films are shown in Table 3. It can be found that, as compared with tensile properties of LDPE films, 14 these properties are improved by incorporating with controlled release assemblies. It can also be seen that tensile strength and Young modulus increase slightly from L1 to L4, which may, on the one hand, be attributed to the increase of crystallinity of these samples; on the other hand, this may be due to the increase of pore size from M1 to M4 as reported by Wang et al 40 interactions between larger pore assemblies and polymeric matrix, another factor for the increasing elongation from L1 to L4 may be larger α-tocopherol loading amount of assembly in film matrix, because α-tocopherol has been found to have a plasticizing effect in film matrix, which can help improve the elongation of the polymer films.…”

“…13 Besides, as a kind of nanofiller, the effects of addition amount of the assembly on physical and controlled release properties of LDPE controlled release packaging films have also been investigated. 14 Moreover, researchers also investigated the effect of organically modified MCM-41 being incorporated on physical properties of poly(lactic acid) films, and they claimed the possibility of the films being used for sustainable food packaging. 15 By now, it has been proven by researchers that mesoporous silica materials with different porous structures and interactions with various active compounds have the effect of controlling the release of active compounds being encapsulated in packaging films.…”

“…It was found in our previous study that low‐density polyethylene (LDPE) films loaded with α‐tocopherol/MCM‐41 assembly showed controlled release effect as compared with LDPE films loaded with pure α‐tocopherol 13 . Besides, as a kind of nanofiller, the effects of addition amount of the assembly on physical and controlled release properties of LDPE controlled release packaging films have also been investigated 14 . Moreover, researchers also investigated the effect of organically modified MCM‐41 being incorporated on physical properties of poly(lactic acid) films, and they claimed the possibility of the films being used for sustainable food packaging 15 .…”