Poly 4-methyl pentene Density

Poly(methyl pentene), unfilled Low-density Medium-density High-density Ultra high-molecular-weight Glass-fiber- reinforced, high-density Ethylene-vinyl acetate copolymer... 

Poly (methyl pentene). An optically clear thermoplastic in its orginal form it has the lowest density (0.83 g/cm ) of all the plastics. Suitable for manufacturing laboratory vessels and other containers. Trade name TPX (UK). 

Glycidyl methacrylate High density polyethylene Isotactic copolymer of styrene and p-methyl styrene Isotactic poly(ethyl methacrylate) Isotactic poly(methyl methacrylate) Isotactic polystyrene Low density polyethylene Linear low density polyethylene Maleic anhydride Poly(4-methyl pentene) Random copolymer of phenyl ether and phenyl ketone... 

Spherulites make films and foils opaque when their diameters are greater than half in wavelength of the light and when, in addition, inhomogeneities exist in relation to the density or to the refractive index. Spherulitic poly(ethylene), for example, is opaque, but spherulitic poly(4-methyl-pentene-1) is glass clear (at room temperature), even when the latter has the same number of spherulites with the same dimensions as poly(ethylene). 

Another commercially produced polyolefin is isotactic poly(4-methyl pentene-1). The polymer carries a trade name of TPX. This material is known for high transparency, good electrical properties, and heat resistance. PoIy(4-methyI pentene-1) has a density of 0.83 g/cm. This polyolefin exhibits poor load-bearing properties and is susceptible to UV degradation. It is also a poor barrier to moisture and gases and scratches readily. This limits its use in many applications. 

P.H. Geil I don t think that s the case for polypropylene because it crystallizes at the lower, not the upper of our Tg relaxations. It might take care of poly(4-methyl pentene-1) or polybutene though. I ll just point out that polystyrene also has a rather bulky side chain and I m not exactly sure what the density difference is between the crystalline and amorphous forms in that sample, whether there might not be a similar process. 

J.K. Kruger I think that there are certainly striking similarities between several quantities like density, viscosity, etc. for 7// and T . Are there any materials which show both transitions For example, for poly(4-methyl pentene-1) discussed by Prof. Geil, [P.H. Geil, contribution in this volume], does it show a 7/ We have found what we call 7 in this material. Is there a 7//, in addition, or not ... 

Direct fluorination of polymer or polymer membrane surfaces creates a thin layer of partially fluorinated material on the polymer surface. This procedure dramatically changes the permeation rate of gas molecules through polymers. Several publications in collaboration with Professor D. R. Paul62-66 have investigated the gas permeabilities of surface fluorination of low-density polyethylene, polysulfone, poly(4-methyl-1 -pentene), and poly(phenylene oxide) membranes. 

The commercial production of high-density polyethylene started almost at the same time in late 1956 by Phillips using a chromium-based catalyst in a medium-pressure process and by Hoechst using a Ziegler catalyst in a low-pressure process. Polypropylene production began in Montecatini and Hercules plants in 1957. Poly(l-butene) and poly(4-methyl-1-pentene) have been produced in small commercial quantities since about 1965. The commercial production of ethylene/propylene-based rubbers started in 1960 [241]. 

Griffith, J. H., and B. G. RA.nby Dilatometric measurements on poly (4-methyl-l-pentene), glass and melt transition temperatures, crystallization rates and unusual density behavior. J. Polymer. Sci. 44, 369—381 (1960). 

Joining in Bassett, Rastogi et al. (1991) have found that poly(4-methyl-1-pentene), also flexible, forms a nematic liquid crystal either when pressure is changed at a constant temperature, or when temperature is changed at a constant high pressure. The phase transition process is reversible. However, because the density of the crystal phase is unusually lower than the noncrystalline phase, the transition of crystal-to-nematic liquid crystal occurs at a high pressure when temperature is decreased rather than increased. Nevertheless, the nematic phase does exist in this flexible aliphatic polymer. 

Above the the rate of polymer chain relaxation is faster than the diffusion of CO2, and hence Fickian diffusion is to be expected. The diffusion of CO2 is believed to occur within the amorphous domains of the polymer matrix, and for this reason the diffusion in semi-crystalline polymers may be more complex than it in the case for glassy polymers. In the case of semi-crystalline polymers, CO2 is not soluble in the crystalline domains, and therefore the degree of crys-taUinity and hence the amorphous fraction available for CO2 molecules may influence the diffusion characteristics. Furthermore, C02-induced crystallization is likely to lead to an increase in the tortuosity factor, and thus the diffusion path length may increase as a function of time. Syndiotactic polystyrene and poly(4-methyl-l-pentene) [45] are semi-crystalline polymers which have crystalline phases (helical in the case of sPS) with lower densities than that of the amorphous phase and are exceptions, as CO2 access is not restricted to the amorphous domains, in fact CO2 diffuses faster in the helical sPS than in the amorphous polymer [46]. 

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