Nanocomposite Anchored PlasticizersEPA Contract Number: 68D02060
Title: Nanocomposite Anchored Plasticizers
Investigators: Myers, Andrew
Small Business: TDA Research Inc.
EPA Contact: Richards, April
Project Period: June 1, 2002 through June 1, 2004
Project Amount: $225,000
RFA: Small Business Innovation Research (SBIR) - Phase II (2002) Recipients Lists
Research Category: Nanotechnology , Air Quality and Air Toxics , SBIR - Pollution Prevention , Pollution Prevention/Sustainable Development , SBIR - Air Pollution , Small Business Innovation Research (SBIR)
Plasticizers are small, often volatile molecules added to hard, stiff plastics to make them softer and more flexible. Traditional plasticizers are not directly bound to the polymer chain and can escape from the plasticized material. Loss of plasticizers is undesirable, leading to brittle and unusable materials as well as contamination of the surrounding environment. This is particularly a problem for polyvinyl chloride (PVC), which can be highly plasticized and often is used in toys for infants and medical tubing and solution bags. A system that immobilizes the plasticizing agent within a polymer without compromising other necessary physical properties would find a ready commercial market. One solution is to anchor the plasticizing moiety to the surface of a nanoparticle. Properly designed, the plasticizing nanoparticles would show good dispersion without the loss of physical properties observed with plasticizers based on larger particles.
TDA Research, Inc. (TDA) has developed a nanoparticle technology that is easily dispersed into and processed with PVC. TDA successfully dispersed nanoparticles into both rigid and flexible PVC formulations, making both materials softer. PVC nanocomposite formulations were melt-processed in a Brabender polymer mixer and a Leistritz twin screw extruder. TDA's nanoparticles showed excellent compatibility with both the host resin as well as the processing methods.
Plasticizers are designed to make the host material softer, decrease the tensile strength and modulus, and increase the elongation; TDA was able to affect these changes in rigid and flexible PVC. Most importantly, TDA was able to accomplish this while keeping the nanoparticle anchored plasticizer migration to zero. As an added feature, adding small concentrations (2-5 percent) of nanoparticle anchored plasticizers improved the retention of traditional phthalate plasticizers in flexible PVC. Addition of TDA's nanoparticles improved retention of phthalates against loss to volatilization to air, migration to activated carbon, and extraction to aqueous and organic solvents.
The new plasticizer system will be characterized by high permanence, which will eliminate exposure to plasticizers that escape from polymers and will increase the useful lifetime of the base polymer. Potential commercial applications for anchored plasticizers include markets with a need for longer-lived plasticized materials, products with a low threshold for plasticizer contamination, or areas where consumer concern over leached species is high. These include construction applications (roofing, wire and cable sheathing), intravenous tubing and solution bags, and toys and paraphernalia for infants and toddlers in which dermal and oral contact is high.