AIC 53rd Annual Meeting

Introduction

Over the last thirty years, scientists and conservators have become increasingly interested in the physical-chemical processes involved in the degradation of synthetic and semi-synthetic polymers in cultural institutions in order to present conservation proposals for these materials and, more recently, in order to select suitable plastics for packaging, displaying and transporting objects in collections. Among the different topics being researched, the emission of volatile and semi-volatile organic compounds (VOCs/SVOCs) from plastics has received considerable attention due to both the harmful effects of some chemical compounds on human health and the hazardous potential of some VOCs to objects stored in the vicinity of emitting plastics. Due to the enormous environmental discussion involving petrochemical plastics and the commitment of cultural institutions to achieving sustainability goals, interest in bioplastics as artistic materials and conservation materials, especially in the field of industrial packaging, has increased. In this work, the organic compounds emitted from unaged bioplastic samples were identified. The focus was on analyzing VOCs/SVOCs to point out dominating emissions, toxic substances, harmful compounds to objects in the vicinity and possible degradation products.

Experimental Results

Headspace solid phase micro extraction (HD-SPME) was used to collect the emitted VOCs/SVOCs from 8 samples of 4 different bioplastics: polylactic acid (PLA), polycaprolactone (PCL), biopolyethylene (Bio PE) and poly (butylene adipate-co-terephthalate) (PBAT). The adsorbed compounds were thermally desorbed, and gas chromatography coupled with mass spectrometry was successfully used to separate and identify the VOCs/SVOCs emitted of the 8 samples. Among the bioplastics under study, Bio PE presented the lowest emission potential and PBAT showed the highest emission potential. Relevant emissions were alcohols, esters, amides, aromatic and aliphatic hydrocarbons and organic acids. Substances suspected to cause adverse health effects were detected: phenol, N-dimethylformamide, N,N-dimethylacetamide, diisobutyl phthalate, dibutyl phthalate, oxolane, 2-butoxyethanol, benzyl alcohol and 1,2,3-trichloropropane. Acrylic monomers, organic acids and some esters were evaluated as reactive compounds. The hydrolysis of PLA was observed, resulting in the formation of acetic acid, whose hazardous potential in the museum environment is well discussed and documented.

Conclusions

A broad spectrum of substances could be identified by HS-SPME coupled to GC/MS. Some of the identified compound are typical residues from solvents and additives, which are widely used in the industrial process. Bioplastics identified as a source of reactive compounds should be handled with caution or avoided as conservation materials. The use of samples with emission of toxic substances should be completely avoided for health reasons. Since some of the samples under study were provided by artists, they will be advised about the adverse health effect of some of VOCs identified in the bioplastic samples.