The Preparation Of Polyvinyl Alcohol Film Used For Infrared Thermal Wave Testing

Infrared nondestructive testing is a very commonly used detection methods,it requires the detected absorption rate and infrared waveband surfaces with high visible light and infrared emissivity of metal detection with low emissivity of the surface(such as most of the metal surface)to be detected in the metal surface spraying water soluble black paint but spraying paint process cumbersome,but damage to the specimen.Therefore,the purpose of this paper is to develop a black film with high absorbance,low reflectivity and low infrared emissivity to replace black paint.In this paper,using polyvinyl alcohol(PVA)as the main film-forming material,carbon black as a blackening agent,polyethylene glycol 600(PEG)as grafting agent,glycerol as plasticizer,starch as reinforcing agent and preparation for infrared nondestructive detection of black film.The main research contents and results are as follows:(1)Modified carbon black was prepared by polyethylene glycol modified carbon black.The carbon black in the single factor experiment of the preparation of the absorbance analysis of dispersion in the preparation process,the results show that absorbance had effects of ultrasonic time,grafting agent of polyethylene glycol,the amount of hydrogen peroxide on the dispersion of carbon black,ultrasonic 3h,hydrogen peroxide 2ml and polyethylene glycol as 2ml,dispersion of maximum absorbance;the stability of carbon black,the results showed that modified group dispersion stability is very high,the unmodified carbon black group will appear stratification.(2)Carbon black/polyvinyl alcohol films were prepared by step by step addition method.Using response surface method in film forming process,PVA,glycerol,polyethylene glycol,carbon black,the amount of starch as factors to tensile strength and elongation as response value,the optimum technological conditions for preparation of thin films for glycerol 1.42ml and carbon black as 2.14g,PVA 14.24g,2.31 ml,polyethylene glycol as starch 0.45g,tensile strength up to 23.786MPa under this condition.(3)Finally,the optical properties and micro properties of the films are tested and characterized.The results show that the reflectivity of black film is lower than that of black paint,and the absorbance is greater than that of black paint.The analysis of the optical properties confirms that the black film can be used instead of black paint.The infrared nondestructive testing of black film is compared with that of black paint.It is found that the black film has the same detection effect as black paint.Both of them have a clear description of the defect profile.The black films were characterized by scanning electron microscopy(SEM),thermal gravimetric analysis(TGA)and Fu Liye infrared spectroscopy(FT-IR).SEM results show that the surface of the film is smooth,the carbon black is dispersed evenly,and the agglomerate particles are less.Fourier infrared spectroscopy showed that the carbonyl group appeared in the wavelength 1714cm-1,and the wavelength was widened at 3259cm-1,indicating that hydrogen bonds appeared,which indicated that the chemical stability of the modified films was enhanced.The thermal stability of the films was analyzed by thermogravimetry,and the thermal stability and crystallinity of the films were increased.