Ex-ante life cycle assessment of polymer nanocomposites using organo-modified layered double hydroxides for potential application in agricultural films

Abstract

Biodegradable agricultural films made of poly(butylene adipate-co-terephthalate) (PBAT) are interesting alternatives to the most commonly used low-density polyethylene (LDPE) films. Photodegradation of both types of polymers can be prevented by the addition of UV stabilizers. To prevent leaching of the additives from the films, the stabilizers can be intercalated in layered double hydroxides (LDH). When LDHs are exfoliated in the polymer a nanocomposite is formed with improved material properties. An ex-ante cradle-to-grave life cycle assessment (LCA) is conducted on the application of nanoclays in agricultural mulching films. The PBAT/LDH nanocomposite is compared with PBAT and LDPE, both of which had been UV-stabilized with the conventionally used compound Irganox 1010. Being key ingredients of the nanocomposites we prepare an ex-ante cradle-to-factory gate LCA for different nanoclay compositions containing surfactants and the non-toxic UV stabilizer p-hydroxycinnamic acid intercalated in LDH sheets. Among the nanoclays, the lowest environmental impact is achieved by LDHs based on magnesium oxide/hydroxide and aluminum oxide/hydroxide, with the surfactant stearate as the intercalated anion. Our comparative analysis of mulching films shows that the lowest non-renewable energy use and greenhouse gas emissions are obtained by LDPE films, which are recycled and incinerated with energy recovery after the second life cycle. However, recycling and energy recovery are not always applied, which makes the biodegradable PBAT an interesting alternative. Further study on the UV stability, tensile strength and bio-based feedstock for PBAT indicates that PBAT containing LDH and p-hydroxycinnamic acid can be an environmentally friendly alternative to LDPE agricultural films containing the UV stabilizer Irganox 1010

Green and Clean: Reviewing the Justification of Claims for Nanomaterials from a Sustainability Point of View

“…For the polymer sector, non-renewable energy use has been included in the impact assessment in the studies of [27,28], abiotic depletion has been included in the study from Hervy et al [26] and an overall impact indicator (through the subjective aggregation of 17 impact categories) in the study of Notter et al [29]. In all these studies the results of these impact categories follow the same trend as carbon emissions.…”

“…Moreover, in the same study the PEM FCs used in µ-CHP power plants result in better overall environmental performance compared to µ-CHPs (micro-combined heat and power plant) using a Stirling engine. On the other hand, in the study of Schrijvers et al [28] the use of nano-based polymers in mulching films for the agriculture sector results in worse performance in terms of carbon emissions. The use of nanoclays in PBAT (poly-butylene adipate-co-terephthalate) results in higher carbon emissions compared to LDPE (low-density polyethylene) alternatives.…”

“…However, in the study of Pietrini et al [27] the application of nano-based polymers to vehicle body panels significantly increases the weight of the vehicle compared to the alternatives and thus, it increases the emissions. In the study of Schrijvers et al [28] for the mulching films application, the nanoclay-based PBAT results in worse performance in terms of carbon emissions compared to the alternative LDPE. The reason is that energy credits are given to LDPE due to the incineration process.…”

“…Carbon emissions of nanoclays: [28] • Best case: LDH (based on MgO + Al(OH) 3 + Stearate)-about 6% better than MMT.…”

Two‐Dimensional Hybrid Materials: Transferring Technology from Biology to Society

“…Filler [Polymer] ϾϾ Polymer, and this can be used to make the biosource polymer as relevant as the thermoplastic obtained from a fossil source. [66] Another big challenge for an eco-friendly development is to limit CO 2 impact. By mineralizing atmospheric CO 2 , 2D materials may partially contribute, but probably regarding the massive production coming from cement and fossil extraction (shale gas), other solutions should be explored.…”