Reaction with polypropylene

This investigation has shown that most antioxidants based on the 2,6-di-terf-butyl-4-alkylphenol moiety behave similarly as inhibitors in the solution oxidation of polypropylene. Although the kinetics of oxidations are complex, the length of the inhibition period is proportional to the phenolic group concentration. With 2-ferf-butyl-4-alkylphenols, the apparent stoichiometry for reaction with polypropylene peroxy radicals is increased from one to two. 

Balabanovich, A. L, Homung, A., Luda, M. P, Koch, W., Tumiatti, V. Pyrolysis study of halogen-containing aromatics reflecting reactions with polypropylene in a post treatment decontamination process. Environ Sci Technol 2005, 39, 5469-5474. 

Some of the most difficult heterophase systems to characterize are those based on hydrocarbon polymers such as mbber-toughened polypropylene or other blends of mbbers and polyolefins. Eecause of its selectivity, RuO staining has been found to be usehil in these cases (221,222,230). Also, OsO staining of the amorphous blend components has been reported after sorption of double-bond-containing molecules such as 1,7-octadiene (231) or styrene (232). In these cases, the solvent is preferentially sorbed into the amorphous phase, and the reaction with OsO renders contrast between the phases. 

Grafting reactions onto a polymer backbone with a polymeric initiator have recently been reported by Hazer [56-60]. Active polystyrene [56], active polymethyl methacrylate [57], or macroazoinitiator [58,59] was mixed with a biopolyester polyhydroxynonanaate [60] (PHN) or polybutadiene to be carried out by thermal grafting reactions. The grafting reactions of PHN with polymer radicals may proceed by H-abstraction from the tertier carbon atom in the same manner as free radical modification reactions of polypropylene or polyhy-droxybutyratevalerate [61,62]. 

The rhodium-catalyzed borylation of alkanes is applied to regiospecific functionalization of polyolefines.165,165a The reaction of polypropylenes (atactic, isotactic, and syndiotactic) with B2pin2 in the presence of Cp Rh( 74-C6Me6) catalyst at 200 °G affords the borylated polymers, which are treated with basic hydrogen peroxide in a mixture of THF and H20 to oxidize the boronate esters to the corresponding alcohols (Scheme 20). The hydroxylated polymers contain 0.2-1.5% hydroxymethyl side-chains. 

Analyses. Samples of reaction mixtures were frozen and sublimed into the vacuum line (10-6 mm Hg). The vapor was passed through a wide-bore U-trap at —45°C which collected acetic acid and volatile oxidation products and allowed any unreacted hexenes to pass. After further fractional condensation the hexene was transferred to a graduated tube to measure the volume and was finally analyzed by GLC using a 12 meter X 6 mm column packed with polypropylene glycol LB-550-X on Chromosorb W. The sublimation residue was analyzed by IR spectroscopy while the acetic acid condensate was subjected to a wet separation (5, 15) to recover the oxidation products for GLC analysis. 

Temperature effects on the polymerization activity and MWD of polypropylene have been examined in the range of —78 °C to 3 °C 82 The MWD of polypropylene obtained at temperatures below —65 °C was close to a Poisson distribution, while the MWD at higher temperatures above—48 °C became broader (Slw/IWIii = 1.5-2.3). At higher temperatures the polymerization rate gradually decreased during the polymerization, indicating the existence of a termination reaction with deactivation of active centers. It has been concluded that a living polymerization of propylene takes place only at temperatures below —65 °C. 

Reduction of bismuth compounds could take place by reaction with polymer radicals propagating the depolymerization of polypropylene, either by electron transfer or ligand transfer which are typical redox reactions between alkyl radicals and metal compounds 59... 

The effects of metal-containing POSS on the combustion behavior of polypropylene have been investigated.46 Metal-POSS was prepared from incompletely condensed structures by reaction with organometallic compounds. The dimeric and oligomeric of Al and Zn-isobutyl silsesquiox-ane (POSS) have been evaluated as potential flame retardants for polypropylene, and the results were compared with PP/octaisobutyl POSS. The cone calorimeter data (Table 8.2) revealed that... 

General Method. All solvents used were of analytical reagent grade. Toluene and THF were refluxed under N2, and over sodium and benzophenone. Pyridine was distilled and stored over KOH pellets. Water was doubly distilled before use. All the silanes were vacuum-distilled and all reactions were performed under N2 atmosphere. Reactions on polypropylene films were normally carried out with pieces of 5 x 5 cm or for industrial applications with foils of 35 x 24 cm. 

Adsorption of y-Aminopropyltrimethoxysilane onto the Polypropylene Film. The reaction with y-aminopropyltri-methoxysilane was performed using 2% v/v toluene solution under N2 atmosphere for 16 hours. The film was successively washed with toluene, chloroform, and acetone. Then the film was washed with water for half an hour. Finally, methanol washing was performed and the film was dried. 

Nonetheless, it was a fairly short step from octopus compounds to dendrimers, and the step was taken by Vogtle in the late 1970s when he attempted to use a cascade reaction to prepare a molecule of the dendrimer type that would now be considered a dendron rather than a fully developed dendrimer. It began with the addition of acrylonitrile to an amine, followed by reduction of the nitrile to amine. This was followed by a further reaction with acrylonitrile, and the process was repeated several times to yield highly branched macromolecules. There were initially problems with the reduction step but these were overcome, and the preparation of these polypropylene imine) dendrimers was later commercialized. 

A reactor was charged with polypropylene containing an ene terminus (250 g), and the temperature was increased and maintained at 185°C. This material was then treated with maleic anhydride (20 g) dissolved in 24 ml of acetone followed by the dropwise addition of di-t-butyl peroxide (6 g). The reaction was maintained at this temperamre for 3 hours and then gradually cooled over 60 minutes. The product was isolated having an 11.3% maleic anhydride content. 

The above-mentioned techniques have been employed in determining the total number of active centers Cp and, in the case of polypropylene, the number of iso-specific Cp, and non-specific Cp centers after polymer fractionation. However, none of these methods appears universal or completely reliable. It is known that the method based on quenching with ROT is complicated by secondary reactions with the aluminum alkyl and by isotopic effects. Even quenching with CO seems to give an underestimated value of the number of active centers 137,138) and, thus, an overestimation of the propagation rate constant as determined according to the correlation ... 

Sorona, DuPont s trade name for polypropylene terephthalate, is a large-volume polymer that can now be made at least in part from glucose derived from a renewable plant source such as corn. A biocatalyst converts D-glucose to 1,3-propanediol, which forms polypropylene terephthalate on reaction with terephthalic acid, as shown in Figure 30.9. 

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