Pest control by using plastics

Mosquitoes, flies and phlebotoma, as well as other insects, are vectors of several diseases, such as malaria, dengue fever, chikungunya, leishmaniose, etc. These plagues, together with the diseases to what they are related, used to be associated to peoples of the Third World mainly located in tropical areas. But, as a consequence of the climate change that the Earth is suffering, these plagues have successfully proliferated in regions of temperate zones and they are now a problem in many European cities and other regions economically developed. Moreover, there are other kinds of insects that attack cattle and crops, such as cochineals, thrips, blow-flies, among others, which constitute a risk for health (both of humans and animals), and cause huge economic losses.

In order to tackle these problems, several alternatives have been developed: the aerial dispersion of insecticides, the treatment of aquifers and areas where water accumulates and larvae are housed the surface treatment of mosquito nets and canvas with repellent and insecticide substances, and finally, the use of insecticides directly on plastics. In the case of plastics with insecticides, the main advantage is the durability of the effect, because it is more resistant to washing cycles. The main disadvantage is that its performance is not immediate, in contrast with other kind of pest control treatments, which act since they are firstly used.

The insecticides incorporated to plastics diffuse slowly through the polymer to its surface, where they act against insects that rest there. Depending on the type of insecticide used and its compatibility with the plastic matrix, the speed of diffusion will be higher or lower. Likewise, the usage temperature and some polymer characteristics such as crystallinity and the glass transition temperature (Tg), will also affect this migration rate. In order to control the insecticides’ diffusion, these can be encapsulated, making more difficult their pass through the polymer chains and increasing the lasting of the insecticide effect.

The encapsulation method developed also allows the additive handling as powder instead of liquid, avoiding the use of pumps and the dosing difficulties associated.

Plastics with insecticide effect: the project Inmaplesp

For several years, AIMPLAS has carried out several researches on the incorporation of different kinds of insecticides and repellents in plastics. Currently, the project Inmaplesp is being carried out, together with the company Inesfly Corporation and the University of Zaragoza. In this project, the incorporation of different insecticides in foamed polymers it is being made, for applications in shoe soles, mats, packagings, floors, etc. The insecticides used are previously encapsulated by Inesfly Corporation by a patented process and lately incorporated to plastic in a co-rotating extruder. Such encapsulation controls the diffusion speed of insecticides within the plastic and protects them during the processing.