Poly- 4-methylpent-1 -ene

Factors affecting laboratory polymerisation of the monomer have been discussed and these indicate that a Ziegler-Natta catalyst system of violet TiCl3 and diethyl aluminium chloride should be used to react the monomer in a hydrocarbon diluent at atmospheric pressure and at 30-60°C. One of the aims is to get a relatively coarse slurry from which may be washed foreign material such as catalyst residues, using for example methyl alcohol. For commercial materials these washed polymers are then dried and compounded with an antioxidant and if required other additives such as pigments. 

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There are a number of occasions where a transparent plastics material which can be used at temperatures of up to 150°C is required and in spite of its relatively high cost, low impact strength and poor aging properties poly-(4-methylpent-1 -ene) is often the answer. Like poly(vinyl chloride) and polypropylene, P4MP1 is useless without stabilisation and as with the other two materials it may be expected that continuous improvement in stabilising antioxidant systems can be expected. 

Materials. Commercial polypropylene and poly(4-methylpent-l-ene) powders containing no commercial additives were supplied by I.C.I. (Plastics Division) Ltd. The powders were vacuum pressed into film of 200-/x thickness at 190° and 280°C respectively, for 1 min. The n-hexane was of spectroscopic quality. 

Polymer Luminescence Spectra. Figure 1 shows typical fluorescence and phosphorescence excitation and emission spectra obtained from commercial polypropylene film (or powder). Poly(4-methylpent-l-ene) exhibits similar spectra to those of polypropylene. The excitation spectrum for the fluorescence has two distinct maxima at 230 and 285 nm while that of the phosphorescence has only one distinct maximum at 270 nm with rather weak and diffuse structure above 300 nm. It is clear from these results that the fluorescent and phosphorescent chromophoric species cannot be the same. This, of course, does not rule out the fact that both may arise from carbonyl emitting species, as will be shown later, since these chromophoric groups when linked to ethylenic unsaturation can have quite distinct absorption (14) and emission spectra (15,16,17). 

A further interesting feature of the phosphorescence emission from the polymers is that it is long-lived (5). For the polypropylene and poly(4-methylpent-l-ene) samples examined in this study the emission lifetimes were 1.2 and 0.7 sec, respectively. Long-lived phosphorescence... 

Draw the structural formula (one repeating unit) for each of the following polymers (a) poly(4-methylpent-l-ene) (b) poly(chlorotri uoroethylene) (c) poly(vinyl ethyl ether) (d) poly(vinylidene chloride) (e) polyethyleneimine (f) poly(methyl-2-cyano-acrylate) (g) polychloroprene (h) poly(buty-leneterephthalate) (i) poly(l,2-propylene oxalate) (j) poly(dihydroxymethylcyclohexyl terephthalate) (k) poly-caprolactam (nylon-6) (1) polyformaldehyde (m) poly-oxymethylene (n) poly(propylene oxide) (o) poly (propylene glycol) (p) poly(p-phenylene sulfone) (q) poly(dimethyl siloxane) (r) poly (vinyl butyral) (s) poly (p-phenylene) (t) poly(p-xylylene) (u) polycaprolactone... 

When the steric hindrance of the substituents further augments, the chain attains the minimum of its potential energy for 7 monomeric units in two helix turns (helix 72) it is also the case for polyhex-l-ene and poly(4-methylpent-l-ene), which are characterized by a fiber period (c) of 1.38 nm. 

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