Search results
Results from the WOW.Com Content Network
Most clays are crystalline, but some clays or some parts of clay minerals are amorphous. [16] The clays of a soil are a mixture of the various types of clay, but one type predominates. [17] Typically there are four main groups of clay minerals: kaolinite, montmorillonite-smectite, illite, and chlorite. [18]
Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer propylene . Polypropylene belongs to the group of polyolefins and is partially crystalline and non-polar .
The PP and PE components of a blend constitute the "crystalline phase", and the rubber and branched PE chains and PE/PP end groups gives the "amorphous phase". If PP and PE are the dominant component of a TPO blend then the rubber fraction will be dispersed into a continuous matrix of "crystalline" polypropylene.
Polyamorphism is also an important area in pharmaceutical science. The amorphous form of a drug typically has much better aqueous solubility (compared to the analogous crystalline form) but the actual local structure in an amorphous pharmaceutical can be different, depending on the method used to form the amorphous phase.
For example, atactic polypropylene is usually amorphous and transparent while syndiotactic polypropylene, which has crystallinity ~50%, is opaque. [30] Crystallinity also affects dyeing of polymers: crystalline polymers are more difficult to stain than amorphous ones because the dye molecules penetrate through amorphous regions with greater ease.
The amorphous polyalphaolefins are synthesized by a catalyst system based on a Z-N supported catalyst and an alkyl aluminum co-catalyst. The polymerization process produces a mostly amorphous polymer with low crystallinity. Crystallinity depends on the catalyst system and on the use of co-monomers.
An amorphism, in chemistry, crystallography and, by extension, to other areas of the natural sciences is a substance or feature that lacks an ordered form. In the specific case of crystallography, an amorphic material is one that lacks long range (significant) crystalline order at the molecular level.
sand ≥ 50% of coarse fraction passes No.4 (4.75 mm) sieve clean sand SW well-graded sand, fine to coarse sand SP poorly graded sand sand with >12% fines SM silty sand SC clayey sand Fine grained soils 50% or more passing the No.200 (0.075 mm) sieve silt and clay liquid limit < 50 inorganic: ML silt CL lean clay organic: OL organic silt ...