By: Jessica Holbrook
April 18, 2013
NEW ORLEANS — Axiall Corp. has developed PVC compounds that swap phthalates and heavy metals for organic alternatives, and give builders controversy-free PVC products that could help them meet environmental and health and safety requirements.
The flexible and rigid PVC compounds were created through collaborations between Atlanta-based Axiall and several partners.
The compounds are designed to be cost neutral and perform equally or better than their traditional counterparts, said Bridget Confait Smith, development chemist at Axiall, in a presentation at the Global Plastics Environmental Conference.
Two years ago, Axiall (then Georgia Gulf Corp.) researchers began work on the firm's overarching sustainability program. At the same time, customers started requesting flexible PVC that didn't contain phthalates — the controversial plasticizers are petroleum-based and non-renewable, and are slowly becoming regulated or banned due to health concerns, Confait Smith said.
The materials major also sought alternatives to the heavy metal stabilizers used in rigid PVC, especially zinc. The element, along with being a questionable metal, can also cause "zinc burning" problems in PVC, she said.
In addition to swapping out controversial components, Axiall set out to make PVC that would meet government regulations.
The solution: flexible PVC that uses plasticizers made from renewable feedstock like plant life, bio-matter and natural oils. And rigid PVC that uses a proprietary organic stabilizer made from proteins.
All of the products in Axiall's bio-based PVC line contain more than 25 percent renewable content, qualifying them for the U.S. Department of Agriculture's BioPreferred Program, Confait Smith said, adding that flexible PVC products contain 39.5 percent to 53 percent renewable content, depending on loading.
The PVC also meets Volatile Organic Compound regulations — vital for builders trying to earn Leadership in Energy and Environmental Design credits, including the strict VOC limits set by the GreenGuard Children & Schools certification program.
GreenGuard tests for indoor air quality. Axiall met the program's requirements at the most stringent level, she said.
Compared to traditional PVC, the new compounds have the same physical properties, but do show improved stability in regards to color hold. The flexible PVC also has a lower brittle point temperature — a significant upgrade "with no additional costs to customers," Confait Smith noted, — and heat temperature is lower for the rigid PVC.
In preliminary "cradle to gate" life cycle analysis, the products show an improved environmental impact with less carbon dioxide emissions, she said.
The bio-based PVC line is commercially available, including a line of PVC for medical operations.
Axiall is currently working on flexible PVC that could be used for wire and cable operations. The material has passed standard volatility tests at 136° C, a requirement for those applications.
GPEC 2013 was held March 20-22 in New Orleans.