Study On Supprression Plasticizer Of Dop Migration From Flexible Pvc Sheets

Polyvinyl chloride (PVC) is one of the most important plastic matrixes for fruit preservation films. Dioctyl phthalate (DOP) is a kind of conventional plasticizers in our country. DOP can escape easily from PVC matrix when it contacts with air, liquid, and an absorbent solid material. DOP migration can reduce the functional performance of PVC, which is potentially harmful to the human body and environment.Inorganic nano-particles, polymeric plasticizer Poly(1,2-propylene glycol adipate)(PPA), creating "fence" structure by using montmorillonite (MMT) and solvent short-time soaking was employed to suppress DOP migration from flexible PVC sheets. It was studied that DOP extraction rate, DOP volatilization rate, tensile properties, shore hardness, morphology and TGA analysis of PVC samples. The approaches of suppressing DOP migration were researched and the results are as follows.1. DOP migration can be resisted by addition of nano-particles in PVC matrix. The addition of5phr nano-CaCO3reduced the DOP extraction rate by20.2%compared to the reference, and the addition of5phr nano-SiO2reduced by26.8%. The tensile strength and elongation at break of PVC reduced as the increasing content of nano-particles. The hardness of PVC was strengthened as the nano-particles.2. The effect of resistance of DOP migration was better as the increasing content of PPA. The DOP extraction rate of PPA-20/DOP-30/PVC was7.65%, which was reduced by76.1%compared to the reference. And the mechanical properties of the PVC sample were kept well.3. The combination of PPA and nano-CaCO3decreased the DOP migraion rate of PVC. DOP extraction rate of CaCO3-1/PPA-20/DOP-30/PVC was5.3%, reduced by76.8%compared to the reference. And its tensile properties were well kept. The dispersion of nano-CaCO3was not good, which decrease the tensile properties. The thermal stability of PVC was strengthened by PPA and nano-CaCO3through TGA analysis.4. Montmorillonite (MMT) plate-like structure creates a maze which plasticizer molecules travel though in the polymer matrix, so plasticizer molecules must travel longer and tortuous paths to penetrate through the PVC sheet. After treated by solvent short-time soaking, the membranes are formed on the PVC surface and DOP migration can be limited because of the "barrier". Then the "fence" structure was created. The extraction rate of MMT-2/DOP-50/PVC treated by hexane short-time soaking was10.6%, decreased by58.8%compared to the reference.