Polyvinyl chloride (PVC) profiles analyzed factors discoloration

Polyvinyl chloride (PVC) profiles influencing factors analysis discoloration discoloration PVC profile extrusion profiles should include the processing, storage and use of the process of aging discoloration ( yellow, dimmed , etc. ) as well as the gloss disappears after aging profiles and chalking phenomenon ( white profiles ) . Which refers to the white profiles are bright and shiny with a product , gloss white powder disappeared and is still a discoloration profile profiles . The color depends on the PVC profile joint action of external and internal conditions. Which external conditions , including UV irradiation , certain temperature, humidity and  PVC stabilizer oxygen conditions , air pollution ( dust , sulfur , acid rain , etc. ) ; and internal conditions are PVC degradation HCl molecule itself off . This paper analyzes the impact of external climatic conditions on PVC degradation of color in the start, from the recipe sections discuss heat stabilizers, pigments such as titanium dioxide , and other effects on PVC profile discoloration and the controlling factors. So as to analyze the problem and prevent discoloration of PVC profiles , and provide a theoretical basis for the development of high-end PVC profiles . An external factor profiles discolored 1.1 ultraviolet irradiation
Extraterrestrial solar radiation to a continuous air layer is light spectrum , the wavelength range of 0.7-3000nm, wherein the radiation portion of the 300-400nm UV degradation is mainly caused by the polymer . Energy in the range of 290 ~ 400nm ultraviolet photons is 419 ~ 297kJ / E, the polymer was significantly higher than the bond energy of typical bond . Of course, regional ultraviolet irradiation intensity at different latitudes on Earth is not the same , which determines the different parts of the durability of PVC profiles require different formulations . 1.2 Temperature and humidity
In addition to UV radiation , should  aluminium stearate also consider the effects of temperature , humidity and regional climate. As the temperature rises, thermal degradation and photodegradation may overlap, even dominant. This is mainly due to the profile of the infrared absorption of solar light into heat , so that the surface temperature can be high students , can accelerate aging discoloration .
Moisture in the air (humidity ) is one cause of degradation of the PVC . Water can be extracted , and photochemical reactions involved in the hydrolysis of certain pigments or titanium dioxide which affects the PVC degradation. In addition, since the outdoor temperature , condensing moisture in the air condenses on the surface of the profile , wherein the composition contains the oxygen , thereby becoming oxidized water can accelerate the degradation of the polymer . 1.3 Air Pollution
Aging caused by radiation plastic , i.e., the radiation reaches the earth's surface by the direct light of the sun ( " solar radiation" ) and light scattering ( " sky radiation" ) composed of two parts , is inversely proportional to the fourth power of the wavelength of the light scattering power ( Swiss 's law ) . Airborne particles ( dust ) can cause the scattering of sunlight , which means that short-wave scattering wavelength easier to reach the ground. Thus , the particles suspended in the air that reaches the surface of the ultraviolet light may be  PVC stabilizer enhanced to accelerate the degradation of PVC . Sulfur pollution response lead stabilizers for PVC profile system, a relatively high sulfur content in the air conditions , lead stabilizers may occur to generate colored PbS ( black ) . When the profiles are acid rain , in the strong sunlight, acid rain, the remnants of the surface profile generation "HS-" ions , which ions can be dissolved in water and the presence of Pb2 + profile role , can also form precipitates leaving the surface profile generate colored " cure " pollution phenomenon .