The mechanism of plasticizer is that the plasticizer molecules are inserted between the polymer molecular chains, which weakens the stress between the polymer molecular chains, which increases the mobility of the polymer molecular chains and reduces the crystallinity of the polymer molecular chains. Thus, the plasticity of the polymer is increased, that is, the main factor against the plasticization is the stress between the polymer molecular chains and the crystallinity of the molecular chain of the polymer, and they depend on the chemical structure and physical structure of the polymer.
When a plasticizer is added to the polymer, it is important that the plasticizer molecules interact with each other to impart interaction with the polymer molecules. Unless all these interactions (between plasticizer and plasticizer, between plasticizer and polymer, and between polymer and polymer) are the same size, there may be no plasticization and anti-plasticization. effect.
1. Van der Waals force Van der Waals force is a weak gravitational force between molecules and molecules in the aggregate state of matter. Van der Waals forces include dispersive forces, inducing forces, and orientation forces. Van der Waals's range of action is only a few angstroms.
(1) Dispersive force Dispersive force exists between all polar or non-polar molecules due to the interaction of tiny instantaneous dipoles that cause the dipoles of adjacent dipoles to be in a heteropolar adjacent state. However, only in non-polar systems, such as benzene, polyethylene or polystyrene, dispersive forces account for the more dominant components.
(2) Inductive force When a molecule with a fixed dipole induces an induced dipole in an adjacent non-polar molecule, the attraction between the induced dipole and the intrinsic dipole is called the inducing force. Aromatic compounds are particularly strong because of the high polarization of π electrons, such as between low molecular weight esters and polystyrene or between benzene and polyvinyl acetate.
(3) Orientation force When polar molecules are close to each other, a force acting between molecules due to the orientation of the intrinsic dipole is called an orientation force. For example, the interaction of ester plasticizers with PVC or with nitrocellulose is a representative example.
2. Hydrogen bonds containing molecules of -OH group or -NH- group, such as polyamide, polyvinyl alcohol, cellulose, etc., can form hydrogen bonds between molecules and sometimes inside molecules. Hydrogen bonds are a relatively strong interaction bond that prevents plasticizer molecules from intercalating between polymer molecules. If the hydrogen bonds are distributed more closely along the polymer molecular chain, the corresponding action against plasticizer insertion is stronger. Therefore, plasticizers and polymer molecules are required to produce similar strong effects. On the other hand, as the temperature increases, the attraction between molecules is significantly weakened by the reduction of hydrogen bonds because the thermal motion of the molecules hinders the orientation of the polymer molecules.
3. The molecular chain of the spatially structured polymer can crystallize under appropriate conditions, that is, the chain molecules change from a coiled and disordered state to a tightly folded line in a regular state. Under normal conditions, industrially produced polymers may not be completely crystalline, but are often composed of crystallization regions interspersed in amorphous regions.
Obviously, it is much more difficult to insert the molecules of the plasticizer into the crystalline region than to insert the amorphous region because the free space between the crystalline region and the polymer and the chain is minimal. If the molecules of the plasticizer can only be inserted into the amorphous region of the partially crystalline polymer, the plasticizer is a non-solvent plasticizer, also known as a secondary plasticizer. If the molecules of the plasticizer can only be inserted into the amorphous regions of the polymer while being able to be inserted into the crystalline regions, the plasticizer is a solvent-based plasticizer, the so-called primary plasticizer.
Church Candle is used for church, for praying,for memorial. A candle lighted by a worshiper in a church.
Candle originated in the original era of the torch. Primitive man fat or wax like on bark or wood, tied together, made for the lighting of the torch. At about third Century BC the beeswax candles may be seen today. In the west, there is a period of time, the temple in beekeeping to self-made wax, this is mainly because the Catholic church that Mila is a symbol of a virgin conception, so the beeswax as pure light, dedicated to the altar of the church. From the existing literature, beeswax in our country have roughly same time with the west, Japan is in the Nara period (710 to 784 years) in our country was introduced into the candle of, and compared to modern candle, ancient candles have many shortcomings. The Tang Dynasty poet Li Shangyin, "when he cut a total of west window candle" of the poem
Church Candles,Catholic Candles,Church Pillar Candles,Church Candle
HEBEI GEMMY IMP.& EXP.CO.,LTD , https://www.hbgemmy.com