Solution of polypropylene

Fig. 10. 220 MHz proton NMR spectra of solutions of polypropylene, (a) Isotactic polypropylene broad bands between 8.62 and 8.8 r, others hidden by CH3 resonances in the region of 9.0 and 9.25 r (85). (b) Syndiotactic polypropylene a single set of peaks between 8.8 and 9.0 r (85). (c) Soluble polypropylene obtained by polymerization with Zr(benzyl)4 (38).

Polymer precipitahon by cooling to produce microporous membranes was hrst developed and commercialized by Akzo [33,37], which continues to market microhltration polypropylene and poly(vinylidene fluoride) membranes produced by this technique under the trade name Accurel . Flat sheet and hollow fiber membranes are made. Polypropylene membranes are prepared from a solution of polypropylene in N, A-bis(2-liydroxyethyl)tal lowamine. The amine... 

Kershaw, R. W. Malcolm, G. N., "Thermodynamics of Solutions of Polypropylene Oxide in Chloroform and in Carbon Tetrachloride," Trans. Faraday Soc., 64, 323 (1968). 

CUN Cunninghame, R.G. and Malcolm, G.N., The heats of mixing of aqueous solutions of polypropylene glycol and polyethylene glycol, J. Phys. Chem., 65, 1454, 1961. 

KER Kershaw, R.W. and Malcolm, G.N., Thermodynamics of solutions of polypropylene oxide in chloroform and in carbon tetrachloride, Trans. Faraday Soc., 64, 323,1968. 

Sadeghi R, Ziamajidi F (2007) Thermodynamic properties of tripotassium citrate in water and in aqueous solutions of polypropylene oxide 400 over a range of temperatures. J Chem Eng Data 52 1753-1759... 

Cellulose fibers have been immersed in a solution of polypropylene-maleic anhydride copolymer in hot toluene (100 °C) for 5 min, (5% copolymer/fibers proportion) and then Sohxlet-extracted for 48 h in toluene. Contact angle measurements on treated cellulose fibers showed that the fibers had become totally hydrophobic. The reaction between cellulose and the copolymer has been reported as divided in a first step where the copolymer is converted into the more reactive anhydride form, and a second step where esterification of the cellulose fibers takes place, as shown in Figure 3. 

Under yet another set of opiating conditions, electrospinning from a solution of polypropylene and decalin at elevated temperature (below the solvent s boiling point), we observed scattered instances of hollow droplets that appear to have partially transformed into nanofib s as a result of explosive rupture (Fig. 1.10). As discussed by Kornev et we attribute this to a charge-induced cavitation process that can be predicted from theory. 

Aqueous solutions of 50% acrylamide should be kept between 15.5 and 38°C with a maximum of 49°C. Below 14.5°C acrylamide crystallizes from solution and separates from the inhibitor. Above 50°C the rate of polymer buildup becomes significant. Suitable materials of constmction for containers include stainless steel (304 and 316) and steel lined with plastic resin (polypropylene, phenoHc, or epoxy). Avoid contact with copper, aluminum, their alloys, or ordinary iron and steel. 

Molecular Weight. The molecular weight of polypropylene is typically determined by viscosity measurements. The intrinsic viscosity [Tj] of the polymer in solution is related to the molecular weight, Af, by the Matk-Houwink equation ... 

The principal additive shrink-resist treatment uses the polymer Synthappret BAP (Bayer AG) which is a polypropylene oxide polyurethane containing reactive carbamoyl sulfonates (or isocyanate bisulfite adduct groups, —NHCOSO —Na" ). An aqueous solution of this polymer is padded onto woven fabrics, which are immediately dried. Other polymers may be appHed at the same time to modify the handle. 

Corrosion. Aqueous solutions of citric acid are mildly corrosive toward carbon steels. At elevated temperatures, 304 stainless steel is corroded by citric acid, but 316 stainless steel is resistant to corrosion. Many aluminum, copper, and nickel alloys are mildly corroded by citric acid. In general, glass and plastics such as fiber glass reinforced polyester, polyethylene, polypropylene, poly(vinyl chloride), and cross-linked poly(vinyl chloride) are not corroded by citric acid. 

Microemulsions, temporary emulsions, that is, two-layer haH dressHigs, and clear solutions of nonvolatile lubricants are on the market. HaH tonics, usually hydro-alcohoHc, achieve similar effects by including Hpid substances or synthetic em ollients, such as the mono butyl ethers of polypropylene oxides [9003-13-8] (10—50 mol). The primary benefits of these Hpid-based products are lubrication and improvements Hi haH gloss and hair-hoi ding (dressHig)... 

Figure 4. Kinetics of surface grafting of polyethylene (PE) and polypropylene (PP) films with acrylamide (AM) by the vapor phase method measured as light absorption at 600 nm after dipping in an aqueous solution of crystal violet (CV).

Figure 16. Surface grafting of polypropylene film strips after 10 sec. irradiation measured as light absorption after dipping in aqueous crystal violet solution. The presoaking solutions contain 0.2 M benzophenone (all) and 1.3 M acrylamide (1), 0.8 M (2),...

In solution polymerization, monomers mix and react while dissolved in a suitable solvent or a liquid monomer under high pressure (as in the case of the manufacture of polypropylene). The solvent dilutes the monomers which helps control the polymerization rate through concentration effects. The solvent also acts as a heat sink and heat transfer agent which helps cool the locale in which polymerization occurs. A drawback to solution processes is that the solvent can sometimes be incorporated into the growing chain if it participates in a chain transfer reaction. Polymer engineers optimize the solvent to avoid this effect. An example of a polymer made via solution polymerization is poly(tetrafluoroethylene), which is better knoivn by its trade name Teflon . This commonly used commercial polymer utilizes water as the solvent during the polymerization process,... 

The reaction was carried out by adding a THF solution of 9-BBN [equimolar to the polypropylene oxide) (PPO) chain ends] drop by drop to PPO or PPO diallylether and stirring the resulting mixture for 5-7 hours (scheme 3). The structure of polymers obtained was confirmed by 1H- and nB-NMR spectra. From the differential scanning colorimetric (DSC) measurement, no peak due to the melting point was observed to show that the polymer was fully amorphous. 

For the preparation of the triazine membranes, the entire solid support (cellulose or polypropylene membrane) was treated with a 5 m solution of the corresponding amine in l-methyl-2-pyrrolidinone (NMP) and a 1 m solution of cesium phenolate in dimethyl sulfoxide (2 p L of each at one spot) and subsequently heated in a domestic microwave oven for 3 min. After washing the support successively with... 

An 8000-member library of trisamino- and aminooxy-l,3,5-triazines has been prepared by use of highly effective, microwave-assisted nucleophilic substitution of polypropylene (PP) or cellulose membrane-bound monochlorotriazines. The key step relied on the microwave-promoted substitution of the chlorine atom in monochlorotriazines (Scheme 12.7) [35]. Whereas the conventional procedure required relatively harsh conditions such as 80 °C for 5 h or very long reaction times (4 days), all substitution reactions were found to proceed within 6 min, with both amines and solutions of cesium salts of phenols, and use of microwave irradiation in a domestic oven under atmospheric reaction conditions. The reactions were conducted by applying a SPOT-synthesis technique [36] on 18 x 26 cm cellulose membranes leading to a spatially addressed parallel assembly of the desired triazines after cleavage with TFA vapor. This concept was later also extended to other halogenated heterocycles, such as 2,4,6-trichloropyrimidine, 4,6-dichloro-5-nitropyrimidine, and 2,6,8-trichloro-7-methylpurine, and applied to the synthesis of macrocyclic peptidomimetics [37]. 

---