The Aqueous Suspension Grafting Polymerization Of Porous Polyethylene And Its Properties

In this thesis, the special functional groups were introduced in the porouspolyethylene by suspension grafting polymerization. The using monomersrelated to water-soluble monomers: acrylic acid(AA) and vinyl acetate(VAc);oil-soluble monomers: styrene(St), methyl methacrylate(MMA),2,2,2-Tri-fluoroethyl Methacrylate (TFEMA), Perfluorooctylmethacrylate (G06B) andthe mixture between the two. The polymerization condition: benzoyl peroxideas initiator, water as suspension medium, the systematic study of reactioncondition on grafting rate(Gr) and grafting efficiency(Ge). Proved by themeasured porosity and SEM images of the polyethylene, porous polyethylenewas the best grafting polymer substrate for its' high porosity, large inside andoutside surface area. Results by experiments showed that the best conditionsfor all of the monomers, we have the best Gr for them: AA' Gr is12%, VAc' Gr is4%, St' Gr is56%, MMA58%,TFEMA27%and G06B52%. The ruleis same about initiator on Gr and Ge. When the initiator was higher the certainvalue, Gr and Ge decreased; monomer concentration increased, Gr and Geincreased firstly and then decline; the reaction temperature was higher than90℃, Gr and Ge decreased; the reaction time was longer than2hours, Gr andGe maintained; water was smallyimpacted on oil-soluble monomers, butwater-solublemonomers was very low Gr, this because mainly monomers wasdissolved in water, then polymerized into homopolymers. The graftingpolymerization of AA, we added some salt in water, reducing solubility ofmonomer in water, the same conditions, Gr increased of2.5%.By FTIR, XPS, CA, DSC, MI, Tensile test and SEM, we couldcharacterize the grafting copolymers and its properties. The monomers weregrafted onto PE by FTIR spectra. XPS characterize the elements of graftingcopolymer membranes, PE-TFEMA membrane surface contained fluorineand oxygen atom by the XPS spectra. CA determined hydrophobicity ofsurface, PE-TFEMA film increased25-30than PE measured by CA. Thetensile and impact test characterized materials' mechanical propertiesPE-TFEMA tensile tests confirmed that the tensile strength increasedelongation at break decreased. SEM images of impact fracture surface can beseen that the sample of higher Gr had large non-melting particles. DSCdiagram illustrated that Gr increased, degree of crystallinity decreased, thecrystallization temperature shifted to lower temperature.