Synthesis, characterization and performance evaluation of a flame retardant plasticizer for poly(vinyl chloride) derived from biobased vanillic acid

Abstract

The utilization of biobased resources presents a novel approach for the development of high-performance plasticizers with exceptional flexibility. Nevertheless, the combustibility of flexible poly(vinyl chloride) (PVC) products containing high content plasticizers is frequently disregarded. The development of PVC functional plasticizers requires careful consideration of a good balance between flame retardancy, migration resistance and plasticity through molecular structure design. Currently there is a dearth of biobased plasticizers that exhibit exceptional comprehensive properties. Therefore, a novel biobased flame-retardant plasticizer (VA8-P) has been synthesized from vanillic acid and fully characterized using NMR, IR and MS. The VA8-P plasticized PVC exhibits a lower glass transition temperature and higher low temperature resistance, while its elongation at break is 1141.6% higher than unmodified PVC. Transmittance, haze, cross-sectional SEM and 2D/3D AFM all demonstrate its good optical properties and the compatibility of the plasticizer with polymer matrix. PVC plasticized using VA8-P exhibits better hydrophilicity and especially superior migration resistance than does the same polymer plasticized using DOP. The thermal stability and char residue rate for decomposition of VA8-P plasticized PVC are better than the same parameter of material plasticized with DOP. In cone calorimeter tests, VA8-P plasticized PVC showed excellent heat barrier effect. Additionally, PVC-P3 reached the UL-94 VTM-0 level in the vertical burning test. Its flame-retardant mode of action was also verified by TGA–FTIR analysis. A functional biobased plasticizer with excellent comprehensive properties has been synthesized. This material exhibits greater flexibility than many traditional flame-retardant additives and its use can be expected to improve the fire resistance of flexible PVC.