POLYPROPYLENE POWDER

Description A slurry of polypropylene powder in hexane/propylene liquid... 

Polyolefins (Polyethylene, Polypropylene) Powder, pellets Tough and chemical resistant. Weak in creep and thermal resistance. Polyethylene maximum use temperature 210 F, polypropylene 260 F. May be injection and extrusion molded, vacuum formed. Low cost. Antistatic sheet and tiles, heat-shrinkable tubing, deicer boots. 

Figure 14 Chemiluminescence oxidation runs at 120°C in oxygen for polypropylene powder samples of different molar mass. The numbers against each curve express the average molar mass in g/mol. 

Figure 15 Chemiluminescence oxidation runs for polypropylene powder at different temperatures the average molar mass of the polymer is 180 kg/mol. 

MILK POWDER POLYPROPYLENE POWDER SOAP POWDER... 

Polypropylene powder was being conveyed by suction through a duct system as an air dispersion, fines being retained in a filter trap upstream of the centrifugal fans. However, the relatively coarse filter allowed very fine powder to pass and it was eventually retained over a long period of time in a silencer on the fan outlet. The thickening deposit eventually self-heated and ignited, and the fire spread very... 

Gitlesen, T., Bauer, M. and Adlercreutz, P. (1997) Adsorption of lipase on polypropylene powder. Biochemica et Biophysica Acta-Lipids and Lipid Metabolisme, 1345, 188-196. 

Plant cleaning incidents, 330 Platinum compounds, 330 Platinum group metals, 331 Poly(aminium) perchlorates, 331 Polyazacaged metal perchlorates, 332 Polycondensation reaction incidents, 332 Poly(dimercuryimmonium) compounds, 332 Poly(dimethylsilyl)chromate, 333 Polymeric peroxyacids, 333 Polymerisation incidents, 333 Polynitroalkyl compounds, 336 Polynitroaryl compounds, 337 Polynitroazopyridines, 340 Polyperoxides, 341 Polypropylene powder, 342 Precious metal derivatives, 342 Preparative hazards, 342... 

Ozonization of the polypropylene powder creates the peroxidic species in the polymer, as well. The activation energy [41] of the thermal decomposition of these peroxides is 100 kJ/mol. In the decomposition of peroxides more than one type of radicals was trapped. Moreover, the three exotherms (peak at 40,90, and 130 °C) were observed on DSC thermograms of ozonized sample which also indicates the presence of several types of peroxides. Besides the peroxidic bonds in polymer, selective thermal decomposition may occur also with such bonds in the polymer as, e.g., with end groups containing the initiator moieties [42], This, however, takes place at higher temperatures than it corresponds to usual temperatures at which the thermo-oxidation starts. 

Active and Inert Substrates. Since acrylonitrile, methylvinylpyri-dine, and mixtures of the two compounds all can be polymerized by (C2H5) oAlCl TiCl3 and benzoyl peroxide, it is desirable to study the free radical reaction in the presence of inert polypropylene powder and to compare its final product with the AFR polymerization under otherwise similar conditions. Deactivated, dry polypropylene powder in hexane suspension was treated with (C2H5)oAlCl-TiCl3, methylvinylpyri-dine, acrylonitrile, and benzoyl peroxide in a prescribed manner. The results are summarized in Table VII. When deactivated dry polypropylene powder was treated with monomers and peroxide, the amount of insoluble polar copolymer decreased as free radical temperature decreased, while for AFR polymer (active polypropylene) this amount of insoluble polar copolymer increased as temperature decreased. The polymerized comonomers in the active polymer were much less extractable than in the inert powder. 

In addition to the AFR block polymer, there is also some copolymer of methylvinylpyridine and acrylonitrile. The amount of this copolymer varies with both the free radical temperature and the amount of benzoyl peroxide used. At room temperature, the AFR polymerization appears to be the main reaction. Both comonomers in the polymer made with inert polypropylene powder at room temperature are found at much lower levels than in the AFR polymer. Furthermore, the polar polymer made with active polypropylene at room temperature is essentially non-extractable. At 50°C. under the condition used the product isolated seemed to be a 50-50% mixture of block polymer and free copolymer. 

Scans by differential thermal analysis show a broadening of the polypropylene melting peak for the AFR polymer as the temperature of free radical polymerization decreases. Samples from inert polypropylene powder do not exhibit this same phenomenon. This suggests that for the AFR polymerization, more methylvinylpyridine and acrylonitrile are incorporated on the polypropylene chain as the free radical polymerization temperature is decreased. The AFR polymerization is favored by low temperatures. 

In summary, the data obtained from the comparative studies of the AFR polymer with active and inert polypropylene powder further support our view that an active polypropylene chain is necessary and that the copolymer block in AFR polymerization does not exist as a mixture with polypropylene but is tied to the polypropylene. The studies also rule out the possibility of a graft polymerization for which active polymer would not be necessary. 

Block Polymer Made with Active and Inactive Polypropylene. Inactive polypropylene powder in hexane suspension was treated with (CH3CH2)2A1C1, TiCl3, water, N,N-dimethylaminoethyl methacrylate, and benzoyl peroxide under the same conditions used to prepare AFR polymer. Just as for the polypropylene-methylvinylpyridine-acrylonitrile system, the inactive polypropylene did not show evidence of incorporation of the free radical polymer (Table XIV). When inactive polypropylene was used, the —COOR absorbance of the polymer was only about 10-30% as great as the —COOR absorbance with active polypropylene. With active polymer conversion to block formation increased as the... 

Inactive polypropylene powder, when treated with N,N-dimethyl-aminoethyl methacrylate and benzoyl peroxide in hexane at 30°C. did not possess detectable amounts of —COOR absorbance. The absence of —COOR absorbance in the resultant polymer gives further evidence that N,N-dimethylaminoethyl methacrylate either did not polymerize under the conditions used or formed only a very low molecular weight polymer which was washed out by the finishing procedure used. It also established that an active polymer chain is necessary and that poly (N,N-di-methylaminoethyl methacrylate) does not exist as a mixture with polypropylene but is tied into the polypropylene chain. 

Ali oev et al. (6) first observed drastic changes in the retention behavior of polyethylene and polypropylene powders in the vicinity of their melting points. 

Verhoeven, J. Schutte, S.C. Perchier, L.J.C. Danhof, M. Junginger, H.E. The design of a dry-coated controlled-release tablet for oxprenolol with microspherous polypropylene powder. J. Control. Release 1989, 10, 205-217. 

Copol3nners prepared by radiation grafting styrene in methanol to polypropylene powder. Sulfonation time, 45 min. 

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