We have detached the subject also try it, meet the requirements of the additional points
Thank you on the third floor, mainly the last one, the mason's paper, the other I have found some similar
Crazing refers to the surface of the material or some of the defects in the stress caused by the concentration of the role caused by the fine holes, these holes and then developed into a very fine marks, known as the crazing. When the deformation is further developed, the orientation of the molecular chain is broken, the crazing is converted to microcracks.
Under low temperature conditions, the molecular mobility in matrix asphalt decreased, the intermolecular distance was shortened, the intermolecular force increased, and the brittleness increased. The matrix asphalt after modification of the polymer, at low temperatures, the modifier particles can play a role in stress concentration, in the external force of the modifier particles around the trigger a lot of crazing or shear zone, the crazing or shear The development of the belt will end with another grain, and when the crazing and the crazing meet, the cramps will be diverted or branched, and the coordination of these processes will greatly delay the destruction of the material. When the material is further stretched, due to the modulus of the asphalt at low temperature is greater than the modulus of SBS and SBR, in the process of converting the crazing into cracks, due to the presence of modifier particles at the interface, it crossed the cracks and blocked the cracks To further expand the development while absorbing and consuming the energy required to break the mixture, thus increasing the elongation at low temperature of the asphalt and increasing the crack resistance.
There is also a good advantage of the crayon, the stress in the early phase of the very difficult, when the stress exceeds a certain value after the beginning of yielding yielding, deformation with the development of time, after the gradual recovery of the strain, deformation with the extension of time The So SBR, SBS modified asphalt at low temperature is not only ductile and good toughness.
Specialized petroleum asphalt is a petroleum asphalt with special properties that can be adapted to certain special environments and to meet certain special requirements. According to its use and use can be divided into protective asphalt, insulating asphalt, process asphalt, sealed asphalt and paint asphalt 5 categories.
The main use of protective asphalt is waterproof, moisture and corrosion. According to their use can be divided into cable asphalt, fiber optic cable asphalt, pipeline preservative asphalt, steel preservative asphalt and waterproof moisture asphalt. The commonality of the protective bitumen is that it must have a high softening point (80 to 140 ° C) and a good adhesion property.
Insulating asphalt is mainly used for electrical equipment insulation filler, according to its use of different environments can be divided into high-pressure insulation asphalt and motor insulation asphalt. High-pressure insulating asphalt can be divided into six grades, mainly used for cable terminal box, grounding and other pouring, such asphalt must have a high voltage and low temperature resistance performance, to ensure that will not be punctured and in low temperature There will be cracks; also must have a certain flexibility and high temperature fluidity, easy to pour construction. Motor insulation asphalt for motor impregnation filled insulation, the withstand voltage value is lower than the high pressure insulating asphalt, but the softening point is very high. Insulating asphalt can only be produced from naphthenic crude or naphthenic-intermediate-based crude oil, and other types of crude oil are difficult to produce qualified products.
The addition of hot or synthetic organic or inorganic materials to the asphalt or asphalt mixture may be melted or dispersed in the asphalt to improve or enhance the road performance of the asphalt. Commonly used modifiers such as rubber modifiers, plastic modifiers, thermoplastic elastomer modifiers, and the like.
Rubber Modifiers: Rubber is a polymer material with high elasticity and stretchability over a wide temperature range, including natural rubber and synthetic rubber. Representative varieties are SBR, CR, EPDM, waste rubber powder. It as a bitumen modifier generally gives good stability to modified asphalt.
Thermoplastic resin modifier: can be repeatedly heated to soften (or melt) and cooling solidified resin, usually linear polymer. Representative varieties are EVA, PE, PP and so on. Thermoplastic resins, as bituminous modifiers, generally impart good high temperature performance to modified asphalt.
Thermoplastic elastomer Modifier: Thermoplastic elastomer, also known as thermoplastic rubber, both rubber and thermoplastic properties, at room temperature shows the rubber elasticity, when heated plastic material is high. According to the nature of cross-linked chemical cross-linked and physical cross-linked type, can also be divided into structural characteristics of block copolymers and graft copolymers. Representative varieties are SBS, SB, SIS and so on. Thermoplastic elastomers generally impart good high and low temperature performance to modified asphalt.
