Long polypropylene

Inversion ofMon cjueous Polymers. Many polymers such as polyurethanes, polyesters, polypropylene, epoxy resins (qv), and siHcones that cannot be made via emulsion polymerization are converted into latices. Such polymers are dissolved in solvent and inverted via emulsification, foUowed by solvent stripping (80). SoHd polymers are milled with long-chain fatty acids and diluted in weak alkaH solutions until dispersion occurs (81). Such latices usually have lower polymer concentrations after the solvent has been removed. For commercial uses the latex soHds are increased by techniques such as creaming. 

Long-chain aUphatic acids such as adipic acid (qv) [124-04-9] are generally used to improve flexibiUty and enhance impact properties, demonstrating subtle improvements over resins modified with the ether glycols (diethylene glycol) and polyether glycols (polypropylene glycol) (see PoLYETHERs). 

Their physieal properties are essentially those of the alkanes. It is the unsaturated linkages that dominate the ehemistry and the main reaetion is one of addition (e.g. hydrogen, halogen, and hydrogen halides) aeross the double bond to produee saturated eompounds. This reaetivity is utilized in the manufaeture of long-ehain polymers, e.g. polyethylene and polypropylene. 

Synthetic large molecules are made by joining together thousands of small molecular units known as monomers. The process of joining the molecules is called polymerisation and the number of these units in the long molecule is known as the degree of polymerisation. The names of many polymers consist of the name of the monomer with the suffix poly-. For example, the polymers polypropylene and polystryene are produced from propylene and styrene respectively. Names, and symbols for common polymers are given in Appendix F. 

Example 2.2 A polypropylene beam is 100 mm long, simply supported at each end and is subjected to a load W at its mid-span. If the maximum permissible strain in the material is to be 1.5%, calculate the largest load which may be applied so that the deflection of the beam does not exceed 5 mm in a service life of 1 year. For the beam / = 28 mm and the creep curves in Fig. 2.5 should be used. 

A piece of thin wall polypropylene pipe with a diameter of 300 mm is rotated about its longitudinal axis at a speed of 3000 rev/min. Calculate how long it would take for the diameter of the pipe to increase by 1.2 mm. The density of the polypropylene is 909 kg/m. ... 

A polypropylene bar with a square section (10 mm x 10 mm) is 225 mm long. It is pinned at both ends and an axial compressive load of 140 N is applied. How long would it be before buckling would occur. The relationship between the buckling load, Fc, and the bar geometry is... 

A polypropylene rod, 150 mm long is to be designed so that it will buckle at a critical strain of 0.5%. C culate a suitable diameter for the rod and the compressive load which it could transmit for at least one year. 

A rod of polypropylene, 10 mm in diameter, is clamped between two rigid fixed supports so that there is no stress in the rod at 20°C. If the assembly is then heated quickly to 60°C estimate the initial force on the supports and the force after 1 year. The tensile creep curves should be used and the effect of temperature may be allowed for by making a 56% shift in the creep curves at short times and a 40% shift at long times. The coefficient of thermal expansion for polypropylene is 1.35 x 10 °C in this temperature range. 

A rectangular section beam of solid polypropylene is 12 mm wide, 8 mm deep and 300 mm long. If a foamed core polypropylene beam, with a 2 mm solid skin on the upper and lower surfaces only, is to be made the same width, length and weight estimate the depth of the composite beam and state the ratio of the stiffness of the two beams, (p = 909 kg/m, p = 500 kg/m ). 

Fig. 5-12. Separation of d,1-leucine in hollow-fiber membrane extraction using a Al- -dodecyl-l-hydrox-yproline solution in octanol as the enantioselective extraction liquid. The modules used were 32 cm long and contained 96 Celgard X-20 polypropylene fibers [57].

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. 

Polypropylene glycol is a family of long-chain polymers attached to a glycerin backbone. 

Polymers such as the acrylic PVM/MA copolymer are added to prevent bacteria from breaking down pyrophosphates. Other long polymers used are polyethylene glycol (PEG) in various weights (PEG-6, PEG-8, PEG-40, etc.), and polypropylene glycol (PPG). 

In the Cape Basin region of the South Atlantic, polyethylene and polypropylene pellets were observed at concentrations of 1333-3600 pellets km (48). Since this area is far from any major shipping lane and is dominated oceanographically by the Antarctic West-Wind Drift with possibly some input from the Brazil Current, the source of the floating plastic was thought to be ships transporting the raw material in the South Atlantic (48). The weathered appearance of the pellets indicated that they had been adrift for an extended period and, therefore, carried long distances by the ocean currents. 

Method A Agitated Glass Ampoule. The bench scale apparatus developed for these runs consisted of a 12 mm O.D. glass ampoule suspended in a fluidized bed heater (Figure 1). Approximately 1 g of polypropylene pellets (Himont) were placed in the ampoule and preheated for 2 min. at 220°C. A 29 cm long screw with a pitch of 1 mm and a diameter of 6 mm driven at approximately 160 rpm was inserted into the ampoule. The appropriate amount of free-radical initiator, 2,5-dimethyl-2,5-bis(t-butyl peroxy) hexane (Lupersol 101, Lucidol), required for a 0.04 wt% initiator concentration was then injected into the sample... 

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