Poly Polypropylene, isotactic

Thermal and Structural Characterization of Binary and Ternary Blends Based on Isotactic Polypropylene, Isotactic Poly(l-Butene) and Hydrogenated Oligo (Cyclopentadiene)... 

Polypropylene, isotactic Polypropylene, syndiotactic Poly (tetrafluoroethy lene)... 

Poly(ethylene oxide) decomposes upon heating at lower temperatures than does polyethylene. Among the volatile products are found formaldehyde, ethanol, ethylene oxide, carbon dioxide, and water. Polyipropylene oxide) is also less heat stable than polypropylene. Isotactic poly(propylene oxide) is somewhat more stable than the atactic one. 

Numerous attesnpts have been made to predict the effectiveness of potential nxacleating agents with particular attention having been paid to the crystallisation of isotactic polypropylene, isotactic polystyrene (6), polyethylene (2 9) ard poly(ethylene terephthalate) (10,11). However, little can be concluded about the fundamental mechanism of heterogeneous nucleation, or the propeirties of effective nucleating agents. 

Polyethylene, isotactic polypropylene, isotactic polystyrene, poly(etherether ketone) Permanganic acid Lamellar morphology and superstructure are revealed. Artefacts have been reported in low-magnification images... 

In this review the crystal structure and the super-molecular structure of the most used polyolefins is discussed. In particular the latest papers on the morphology of polyethylene, isotactic and syndiotactic polypropylene, isotactic poly(l-butene), and finally isotactic poly(4-methylpentene-l) are summarized and integrated with the fundamental work on the topic. After a short general introduction, the first part of the chapter is dedicated to the analysis of the order at the molecular level (the crystal structure), and the second part deals with the supermolecular structures. 

Poly(ethylene terephthalate) Poly(hexamethyleneadipamide) Poly(pentamethylenecarbonamide) Isotactic polypropylene Polyacrylonitrile copolymers Polyacrylonitrile copolymers ... 

Poly(2,6-dimethyl-l,4-phenylene oxide), chloromethylated Poly(p-phenyleneterephthalamide) (Kevlar), impregnated transition metal catalyst Polypropylene, isotactic, radiation grafted, transition metal catalyst... 

FIGURE 7 16 Poly mers of propene The mam chain IS shown in a zigzag conformation Every other carbon bears a methyl sub stituent and is a chirality center (a) All the methyl groups are on the same side of the carbon chain in isotactic polypropylene (b) Methyl groups alternate from one side to the other in syndiotactic polypropy lene (c) The spatial orienta tion of the methyl groups IS random in atactic polypropylene... 

Similarly, the random introduction by copolymerization of stericaHy incompatible repeating unit B into chains of crystalline A reduces the crystalline melting point and degree of crystallinity. If is reduced to T, crystals cannot form. Isotactic polypropylene and linear polyethylene homopolymers are each highly crystalline plastics. However, a random 65% ethylene—35% propylene copolymer of the two, poly(ethylene- (9-prop5lene) is a completely amorphous ethylene—propylene mbber (EPR). On the other hand, block copolymers of the two, poly(ethylene- -prop5iene) of the same overall composition, are highly crystalline. X-ray studies of these materials reveal both the polyethylene lattice and the isotactic polypropylene lattice, as the different blocks crystallize in thek own lattices. 

In the early 1950s, Ziegler observed that certain heterogeneous catalysts based on transition metals polymerized ethylene to a linear, high density material at modest pressures and temperatures. Natta showed that these catalysts also could produce highly stereospecific poly-a-olefins, notably isotactic polypropylene, and polydienes. They shared the 1963 Nobel Prize in chemistry for their work. 

The commercial poly-(4-methypent-1-ene) (P4MP1) is an essentially isotactic material which shows 65% crystallinity when annealed but under more normal conditions about 40%. For reasons given later the material is believed to be a copolymer. In the crystalline state P4MP1 molecules take up a helical disposition and in order to accommodate the side chains require seven monomer units per two turns of the helix (c.f. three monomers per turn with polypropylene and polybut-I-ene). Because of the space required for this arrangement the density of the crystalline zone is slightly less than that of the amorphous zone at room temperature. 

Polymers that incorporate steric centers into their backbones can display various types of tacticity. The three principal types of tacticity are isotactic, syndiotactic, and atactic, as illustrated in Fig. 1.8 for polypropylene. Other polymers that display tacticity include polystyrene and poly a-olefins,... 

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