Polyolefins monomers, chemical structures

Phosphorus FR compounds cover a wide range of chemical structures not only as additives incorporated in the molten state in thermoplastics but also as reactive components introduced as monomers in thermoset polymers phosphates, phosphonates, phosphinates, phosphine oxides, phosphites, red phosphorus, etc. They can be also used as layered silicate modifiers. Organic phosphates and red phosphorus are among the most frequent additive FRs used in various non-polyolefinic polymers. 

Figure 7.1 Chemical structures of monomers used to make polyolefins.

Due to their chemical structure, polyolefins do not absorb any UV light and are therefore technically light-resistant. Their sensitivity to UV radiation is caused by the presence of UV-absorbent structural flaws. They form the initiation points for a series of chemical and physical processes that result in irreversible changes in polyolefins. Because different monomers and different catalyst systems are used for individual polyolefin types, the UV-absorbent flaws differ chemically, and each type exhibits sensitivity specific to one particular wavelength range. 

The polymer we are concerned with is PB-1. In the past this polymer has been referred to as polybutylene, PB, PB-1, and polybutene, as well as its chemically correct name, PB-1. PB-1 is obtained by polymerization of butene-1 with a stereo-specific Z-N catalyst to create a linear, high molecular, isotactic, semicrystalline polymer. PB-1 combines the typical properties of conventional polyolefins with some characteristics of technical polymers. In chemical structure PB-ldiffers from polyethylene and polypropylene only by the number of carbon atoms in Ae monomer molecule, as in Fig. 2.22. 

MAH is one of the monomers most often used for polyolefins functionalization. It is characterized by an extremely low capacity to homopolymerization, and this fact is explained by the steric features of its structure. The reactivity of MAH to macroradicals, however, is comparatively low. From the chemistry viewpoint, a steric hindrance and a lack of electron density in the double bond explain the low reactivity of MAH, which in MAH is symmetrical owing to the presence of two carbonyl groups. Attempts have repeatedly been made to work out procedures for increasing the chemical activity of MAH. Three methods have been proposed to activate the double bonds in MAH (i) to perform a grafting reaction for MAH in presence of an electron-donating monomer, for example, styrene, which is capable of forming a charge transfer complex (CTC) with MAH (ii) substitution... 

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