Study On Modification Of Waste PVB Film With Small Molecule Cross-linker And Rubber

Polyvinyl butyral (PVB) resin is a product of acetal reaction between polyvinyl alcohol and butyraldehyde under the influence of acid catalysis. PVB film is prepared by the high viscosity plasticized PVB resin, which is widely used in the fields of such as safety glass in automobile, high-rise building and solar photovoltaic cells. Therefore, a mass of PVB film wastes are generated with the rapid development of those fields, causing a lot of seriously environmental and resource waste problems by incineration and landfill. The study of PVB film wastes recycling and re-use is of social and economic significance and becomes a new direction in the research fields of waste plastic recycling.High-performance materials are often prepared by cross-linking reaction between the macromolecules in industry. PVB molecular chain usually contains hydroxyl groups as a result of a not fully complete acetalization reaction. PVB film could be prepared into a cross-linked material under the reaction with crosslinker agent with comprehensive controlling of the types, amount of crosslinker agent and processing conditions. And this cross-linking PVB film is not only with high mechanical property but also with low adhesion. In addition. PVB film is with room-temperature viscoelastic because of hydrogen interaction between molecular chains. At same time, the processing temperature of this material agrees with that of rubber, blending with rubber may expand the application areas of the waste PVB film.In this paper, the chemical composition, processing flow, thermal stability and mechanical properties of several PVB waste films were investigated, and one type of these waste PVB films was selected for the further investigation. With the help of torque rheometer, the blending process between PVB film with borax and boric acid was investigated. Moreover, the extrudate of PVB with maleic anhydride and the toluene diisocyanate was prepared and the melt flow rate, mechanical properties, thermal stability and solubility were characterized. The blends of PVB film waste with ethylene propylene diene monomer, nitrile rubber, styrene-butadiene rubber and reclaimed rubber were produced, respectively. The effects of rubber types on mechanical property, thermal stability and melt flow rate of blends and EPDM content on PVB/EPDM blends properties were studied. Results and conclusions are as follows: (1) The plasticizer of the PVB film can be extracted in the help of n-hexane. The plasticizer is triethylene glycol ethylhexanoate,(2) All of the four PVB film wastes has somehow processing flow ability and keep a good mechanical strength. The un-used GPVB has the best processing flow ability and mechanical properties. The plasticizer content of GPVB is28.5%and the hydroxyl content is0.38mol/100PVB resin.(3) In melting processing, a little amount of borax, boric acid, MAH and TDI can make the MFR of GPVB decline obviously, and has a partial crosslinking reaction with GPVB.(4) Addition of borax, boric acid, MAH, or TDI crosslinking agent has an obvious influence to mechanical property of GPVB. The GPVB/MAH blend has the best comprehensive mechanical property. When the MAH content is0.3wt%, the tear strength of the blend is the1.56times than that of pure GPVB. The mixing time of GPVB/borax blend is600s, the tensile strength constant and breaking elongation decrease with borax content increasing, and the tear strength increasesand and then decreased. When the blending time is900s, tensile strength changes not obviously, while both the breaking elongation and tear strength are decreased. The addition of TDI can make the tensile strength and breaking elongation decrease, but tear strength increase, and boric acid addition make all the mechanical propertied decrease.(5) Addition of borax, MAH and TDI can improve thermal stability of the blends,.However, boric acid addition has disadvantageous influence on the thermal stability of the blends.(6) Compared to SBR, NBR and RR, the addition of EPDM to GPVB can significantly improve mechanical properties, process ability and thermal stability of GPVB. The material blending with2wt%of EPDM could get the best properties, with its tensile strength and tear strength of pure GPVB1.04times and1.38times, respectively. The initial decomposition temperature was35℃higher than pure GPVB.