Polypropylenes hydroxylated

This compound, designated Cyagard RF1204, has been recommended for use in polypropylene. Despite its high hydroxyl content, it is proposed not as a polyol but as a stable, high melting additive for polypropylene (108). 

Carbon Cha.in Backbone Polymers. These polymers may be represented by (4) and considered derivatives of polyethylene, where n is the degree of polymeriza tion and R is (an alkyl group or) a functional group hydrogen (polyethylene), methyl (polypropylene), carboxyl (poly(acryhc acid)), chlorine (poly(vinyl chloride)), phenyl (polystyrene) hydroxyl (poly(vinyl alcohol)), ester (poly(vinyl acetate)), nitrile (polyacrylonitrile), vinyl (polybutadiene), etc. The functional groups and the molecular weight of the polymers, control thek properties which vary in hydrophobicity, solubiUty characteristics, glass-transition temperature, and crystallinity. 

Thus in this system, in addition to the usual requirements, the separator has the task of delaying penetration for as long as possible. A membrane would be regarded as perfect which lets hydroxyl ions pass, but not the larger zincate ions. This requirements is best met by regenerated cellulose ( cellophane ) [10,11], which in swollen condition shows such ion-selective properties but at the same time is also chemically very sensitive and allows only a limited number of cycles the protective effects of additional fleeces of polyamide or polypropylene have already been taken into account. 

As it was shown in73, 74), methods that can be used to synthesize these copolymers of PAN are those of radical AN block copolymerization in the presence of an oxidation-reduction system in which the hydroxyl end groups of polyethylene oxide) (PEO)73) and polypropylene oxide) (PPO)74- oligomers serve as the reducing agents and tetravalent cerium salts as the oxidizing agents. 

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. 

The interaction of the polymer with the filler is promoted by the presence of reactive functionality in the polymer, capable of chemical reaction or hydrogen bonding with the functionality, generally hydroxyl, on the surface of the filler. Thus, carboxyl-containing polymers, e.g. ethylene-acrylic acid copolymers and maleic anhydride- and acrylic acid-grafted polyethylene and polypropylene interact readily with fillers. 

Oxidation by flame treatment for polyolefins exposure to a flame of methane, propane or butane and oxygen in excess for a very short time (less than 0.2 seconds) to create oxidation and reactive sites such as hydroxyl, carbonyl, carboxyl... Particularly used for polyethylene and polypropylene. 

Oxidation by ultra-hot-air treatment for polyolefins exposition to a blast of hot air (roughly 500°C) for a short time to oxidize the surface and create reactive sites such as hydroxyl, carbonyl, carboxyl, amides... Rather similar to flame treatment, it is particularly used for polyethylene and polypropylene. 

Moeder M, Martin C, Koeller G (2004) Degradation of hydroxylated compounds using laccase and horseradish peroxidase immobilized on microporous polypropylene hollow fiber membranes. J Memb Sci 245(1) 183-190... 

A polyurethane is fonned by reacting a hydroxyl-terminated polyether or polyester with an isocyanate. An example in commercial practice is the reaction of toluene diisocyanate and polypropylene glycol (PPG) to produce one of the most common forms of polyurethane (see Figure 2.6). 

Evidence for this is rather sparse, but recent XPS work on the interaction of zirconium compounds with polymer particles [5] and corona discharge-treated polypropylene [6] supports the view that zirconium will react with the surface carboxyl functionality. Interestingly, titanium complexes are believed [6] to prefer to bond to surface hydroxyl groups. 

The concept of PO macroinitiators centers on the introduction of an initiation moiety into an olefinic polymer chain for polymerization. The most effective route for preparing PO macroinitiators is by employing functional polyolefins containing hydroxyl groups or other reactive groups. These functional POs are prepared by copolymerization of olefins with functional monomers and post-polymerization reaction, as mentioned above. In the case where an initiation moiety was at the chain-end of the polyolefins, a block type copolymer is produced. It has been reported that thiol-terminated PP was used as polymeric chain transfer agent in styrene and styrene/acrylonitrile polymerization to form polypropylene-b/odc-polystyrene (PP-b-PS) and polypropylene-btock-poly(styrene-co-acrylonitrile) (PP-b-SAN) block copolymer [19]. On the other hand, polymer hybrids with block and graft structures can be produced if initiation moieties are in the polymer chain. 

Although having excellent color in most systems, the antioxidant activity of these compounds in certain systems such as polypropylene and ethylene-propylene rubber has been only fair. Possibly intramolecular hydrogen bonding between the phenolic hydroxyl and the benzylic sulfur... 

The activity of the 4-alkylpyrocatechols (la), 3-alkylpyro-catechols (lb), 3,5-dialkylpyrocatechols (Ic), 3,6-dialkylpyro-catechols (II), 4,5-dialkylpyrocatechols (III), 3,4,6-trialkyl-pyrocatechol (TV), and 4,5- and 4,6-dialkyl-2-alkoxyphenols (V and VI) was studied in isotactic polypropylene at 180 =t 0.1° C. The relative activities Ar were correlated with substituent constants and redox potentials. In the la series the activity of 4-n-alkyl derivatives exceeded that of 4-tert-alkyl derivatives. The length of the main alkyl chain in la and lb and the steric effects in the latter exerted a specific favorable influence. In agreement with these effects, 3-tert-alkyl-5-methyl derivatives are the most active compounds in Series Ic compounds with other combinations of alkyls are weaker antioxidants as are the isomeric substances II and III or compound IV. Etherification of one hydroxyl group exerts an unfavorable effect influences of substitution in 2-alkoxyphenols (V and VI) are generally the same as in the pyrocatechols Z-ZZZ. 

T o stabilize polypropylene against oxidation by atmospheric oxygen, phenolic mononuclear and polynuclear antioxidants containing one hydroxyl group on the aromatic nucleus are used successfully. Thus far the behavior of antioxidants having the structure of polyhydric phenols has not been studied extensively for stabilizing polyolefins. We have systematically observed the properties of dihydric mononuclear phenols with the structure of pyrocatechol and hydroquinone in isotactic poly-... 

The activity of the 2-alkylhydroquinones (la), 2,5-dialkyl-hydroquinones (lb), 2,6-dialkylhydroquinones (Ila), and of 2,5- and 2,6-dialkyl-4-alkoxyphenols (Ic and lib) was studied in isotactic polypropylene at 180 0.1° C. The values obtained were correlated with hydroquinone (Ari) and pyro-catechol (AT2). All compounds studied (la) except the tert-octyl derivative were inferior in activity to hydroquinone. Two alkyls of Types lb and Ha exerted further but nonadditive unfavorable effects, particularly the lb type. Despite over-all low values of Ari, a weak favorable steric effect of the tert-alkyls is apparent in Type la compounds. Etherification even as acetylation of one hydroxyl group (Ic, lib), has a strong favorable effect. These compounds were the most active antioxidants of the entire hydroquinone series studied nevertheless their activity did not reach that of pyrocatechol (At2 < 1). 

Dialkylhydroquinones. The second group of disubstituted derivatives—2,6-dialkylhydroquinones (Ila)—contains two hydroxyl groups which are influenced quite differently by substitution. The total activity of these antioxidants (Table III) was always slightly higher than the sum of the contributions of both substituents this accounts for the fact that Type Ila substances were stronger antioxidants in polypropylene than the 2,5-dialkyl derivatives (a reverse relationship in activities was shown... 

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