Influence of Environmentally Friendly Plasticizers on Cellular Morphology and Mechanical Properties of Flexible PVC Foam

Polymeric foam production continues to grow at a rapid pace owing to its interesting features, such aslight weight, excellent strength/weight ratio, superior insulating abilities, and energy absorbingperformance and comfort. In the market, flexible PVC foam is widely used as a carpet backing and itsprocess involves addition of plasticizer to control flexiblity of the foam. A common plasticizer used inthe PVC foam is phthalic esters, which become increasingly concerned due to its chronic toxicity.Contamination of plasticized PVC has made the recycling of waste plastic material more difficult.Thereby, the current study focuses on using environmetally friendly plasticizers, such as dioctyladipate (DOA), diisononyl adipate (DINA), and epoxidized soybean oil (ESO) to produce the flexiblePVC foam and compares with the common types, dioctyl phthalate (DOP) and diisononyl phthalate(DINP). The amount of plasticizers was varied (50, 60 and 70 phr). The prepared plastisols alsocontained a chemical blowing agent, azodicarbonamide. The effect of chemical structure and contentof plasticizers on the cellular morphology and mechanical properties of the foams was investigated.The results showed that when the content of plasticizer was increased, viscosity of the plastisols wasdropped, and a slight change in blowing ratio was observed. By adding the aliphatic esters (DOA andDINA), the viscosity of the plastisols was reduced, whereas ESO plasticizer increased the plastisolviscosity, compared with DOP and DINP containing plastisols. SEM micrographs suggested that thecellular structure appeared to be smaller size when the amount of plasticizers was increased. Theresultant foams elongated more with increasing plasticizer content, while there was a small decrease inthe stress at break; thus the tensile strength of the foams was slightly decreased.