Material Thoughts: Non-toxic masterbatches repel cable-gnawing critters

Tough as they are, plastic products still are highly susceptible and vulnerable to nature's army of silent assassins: rodents, termites and subterranean insects. Plastic-jacketed wire and cable, pipelines, tubes, automotive parts and many other mission-critical applications can be destroyed by concentrated gnawing.

The plastics industry's solutions to the challenge have not always worked well. Solutions range from the use of traditional neem oil-based pesticides, to armoring, to the use of toxic pesticides. Each of these solutions comes with its own disadvantages. Traditional homegrown remedies are suited for small-scale applications but cannot economically be scaled for broader use. The use of armoring or PA12 leads to expenses that often are unacceptable. Moreover armoring can lead to corrosion and flexibility. The incorporation of masterbatches based on toxic compounds is the most preferred method.

Traditional agricultural pesticides, developed for spraying onto crops in the form of aerosol sprays, are not designed to be used in a plastics masterbatch. They are not suited for processing at elevated temperatures; during plasticizing they often vaporize leading to toxic fumes that can pose a hazard to the personnel working on the shop floor and also lose in part their effectiveness as anti-rodent or anti-termite additives. Also, they can leach out and lead to soil and groundwater pollution.

C-Tech Corp., a chemicals company headquartered in Mumbai, India, believes its Rodrepel and Termirepel-brand materials may be the answer to plastics' rodent troubles. Both are said to be non-toxic and non-hazardous anti-rodent and anti-insect/termite additives supplied for a wide range of applications including wire and cable, automotives, gas pipelines, construction, protection of buildings and houses and more. PolyOne Corp. distributes these products in Europe and the U.S. for the wire and cable sector and also has tested these products.

Rodrepel and Termirepel are RoHS compliant and FIFRA (the U.S. Federal Insecticide, Fungicide, and Rodenticide Act) exempted. They are thermally stable at temperatures up to 400^°C. These products are designed to repel and not kill animals. Both of them work on a multipronged strategy of repellence, discomfort, growth inhibition and unpleasant taste.

According to the supplier, the products do not leach as they are inert within the polymeric matrix. They have a working life span ranging from 15-40 years depending upon the application, and are compatible with many sorts of thermoset plastics and thermoplastics.

Anti-rodent testing undertaken by PolyOne with the Indian Institute of Chemical Technology (IICT) in Hyderabad, India in 2010 demonstrated the efficacy of  Rodrepel in a wire/cable application buried at various depths within a rat-filled enclosure for 30 days. The entire test was captured live by means of an IR camera. Te rats made mincemeat of the control samples, as demonstrated by their average weight loss, compared to the average weight loss for the test samples.

Anti-termite testing at the IICT also proved the chemical's potency. In this test, cable samples were placed in earthen pots that were placed inside termite mounds. The cables were analyzed after 30 days and the results showed significant surface pitting present on the non-treated cables. The cables containing the Termirepel masterbatch were not pitted at all. PolyOne is testing Termirepel at Germany's BAM (the Federal Institute of Materials Research and Testing), and initial results are said to look promising.