The most important agricultural applications of plastic films are greenhouse, walk-in tunnel and low tunnel covers, and mulching. The raw materials are usually low density polyethylene (LDPE) and ethylene-vinyl acetate (EVA) or ethylene-butyl acrylate (EBA) copolymers for the covers and linear low density polyethylene (LLDPE) for mulching. The market is explosively growing in China, and slowly growing in the rest of the world. The key properties for these applications are durability, optical (ultraviolet, visible, near infrared, and middle infrared) properties, and the antidrip or antifog effect. Recent developments in this area include UV-blocking, NIR-blocking, fluorescent, and ultrathermic films.

In this work, polymer films of low density polyethylene and ethylene-vinyl acetate copolymers containing two types of antifog additives (nonionic surfactants) were exposed to two simulated horticultural greenhouse environments, reproducing hot and cold climate conditions. The evolution of the antifog effect was visually observed and that of the additive concentration measured using Fourier transform infrared spectroscopy (FTIR). All the films studied showed good antifog properties, but in all cases, the duration of the antifog effect was longer in the hot-climate test. From the FTIR, we can conclude that the additives studied showed a low migration rate and, therefore, when the antifog effect is lost, important quantities of the additive remain in the bulk.

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The improvement of the barrier character of polylactide by the addition of poly(hydroxy ether) of bisphenol A (Phenoxy) and poly(lactide-co-E-caprolactone) copolymer that acts as a compatibilizer is studied. First, differential scanning calorimetry, Fourier transformed infrared spectroscopy, and scanning electron microscopy show that the addition of the copolymer allows to obtain a miscible ternary system. The permeability of polylactide to water vapor, oxygen, and carbon dioxide is enhanced with the addition of phenoxy but better improvement in its barrier character is obtained with the addition of the compatibilizer. The effects of different factors such as miscibility, glass transition temperature, and crystallinity on the transport properties are analyzed. Several permeability prediction models for heterogeneous systems have been applied obtaining quite good results for water vapor and oxygen permeability.