Study On Modification Of AC/NaHCO₃Compound Foaming Agent And Its Application In PVB Foaming Material

PVB film has good properties of light resistance, cold endurance, impact resistance and good cohesiveness. PVB film is widely used in the fields of such as safety glass in automobile, high-rise building and solar photovoltaic cells. A lot of PVB film wastes are emerged along with the more widely using of it. Using PVB film wastes to produce foaming material with the plastic working method, it would almost get excellent property foaming material similar to elastomer. The re-use of PVB film wastes can gain both economic and society benefit. The foaming agent is the most important part of foaming material and has important influence of the foaming material properties. The AC/NaHC03foaming agent (AC-SA) is one of the most widely used foaming agent with low cost. However, the decomposition temperatures of AC-SA don’t match, and the decomposition temperature range of AC-SA is wide. It is not beneficial to the foaming material production.In this paper, the composition, construction and property of AC-SA and PVB film waste were systematically investigated. ZnSt、ZnO and nanoZnO were separately used to modify AC-SA. The modified mechanism was studied and then the optimum proportion was obtained. On the basis above, the raw material was abundantly alloying with the help of torque rheometer though orthogonal test. Then foaming experiment was carrying out though moulding foaming method and free foaming method. The influence of the raw material percent on the foaming material property was investigated, and the foaming method on the density of foaming material. Results and conclusions are as follows:(1)The plasticizer of PVB film waste is triethylene glycol ethylhexanoate, and the content is28.5%. The content of hydroxyl group of PVB molecular chain is0.38%. The mechanical property of PVB film waste is preferably, and it is free-flowing. The thermal weight loss of PVB film waste begins at about190℃.(2)The thermal decomposition of composite foaming agent has three stages. The first stage is almost the decomposition of NaHCO3, the second one and third one are the decomposition of AC. ZnSt has prominent activation effect to AC-SA. When the mass ratio of AC-SA and ZnSt is1:4, the primary decomposition reaction of AC and NaHCO3combines. The initial decomposition temperature of NaHCO3is increased from140℃to178℃, and the initial decomposition temperature of AC is dropped from195℃to178℃, the gas evolution is increased to about3times of the pure AC-SA at180℃, and the apparent decomposition rate is reduced to1/4of the pure AC-SA.(3)ZnO and nanoZnO don’t change the thermal decomposition rule of AC-SA. However, the decomposition temperature of NaHC03is increased, and the decomposition temperature range of NaHCO3is shortened, and the primary decomposition reaction of AC is moved toward low temperature. The gas evolution is also increased. The activation effect of nanoZnO is superior to ZnO.(4)The density of foaming material with free foaming method is less than the foaming material with molding foaming method to a great extent, the density of foaming material with free foaming method is reduced to1/2of that with molding method, the lowest is reduced to1/3of that. The lowest density of foaming material is0.257g/cm3with free foaming method.(5)The orthogonal test indicates that clearly, the proper order of the influence condition of the raw material percentage to foaming material property is:foaming agent、nitrile rubber、nanoSiO2、plasticizer、cross-linking agent and talcum powder. The mass ratio of the optimum proportion is that:the foaming agent percent is3%, the DCP percent is0.3%, the DOP percent is5%, the SiO2percent is0.5%, the NBR percent is4%, the talcum powder percent is2%. The density of foaming material which is produced by optimum proportion with moulding foaming method is0.65g/cm3, the tensile strength is5.5MPa, the breaking elongation is208.2%, the tear strength is27.3kN/m. The density of it with free foaming method is0.35g/cm3.