Ci -l,4-Polybutadiene

Crespi, G., and U. Flisi Contribution of the internal energy to the retractive force of vulcanized cis-l,4-polybutadiene. Makromol. Chem. 60, 191 (1963). 

Figure 3. Differential thermal analysis (10°C/minute in nitrogen) of film (pressed at 200°C in air) from suspension PVC (1) and cis-l,4-polybutadiene-PVC (suspension) graft copolymer from monomeric butadiene (Type M) (2) and cis-1,4-polybutadiene (Type P) (3)...

In the papers quoted above, the authors followed the crystallization kinetics from calorimetric data. From the point of view of rheokinetic methods discussed here, no less interesting is one more example of describing crystallization kinetics given in Fig. 26, where there is a comparison of experimental (obtained in Ref. [126]) and calculated by Eq. (18) time dependences of the relative elastic modulus of crystallization of cis-l,4-polybutadiene. A good agreement between experimental and calculated data implies the possibility of describing the crystallization kinetics, with the help of formulas of the type of Eq. (18). 

SBR etc., yet it has been covulcanized with those rubbers to provide useful materials (4). In this work, we have found that poly(isobutylene-co-P >inene) with 10 mole% unsaturation can also be cocured with a high cis- l,4-p<%lHit ene rubber. Covulcanization has been demonstrated by an experiment in which poly(isobutylene-co- -pinene) phis cis-l,4.polybutadiene were mixed cm a laboratory mill for 40 minutes, cured (30 minutes at 160°) and the vulcanizate extracted with n-hexane (24 hours at 65°). The fact that the amount of extractables was 2% indicates a measure of co-vulcanization. The covulcanizate exhibited a tensile strength of 175 kg/cm and elongation at break of 300%. 

Figure 6. Competitive sulfonation of polyisoprene model compound vs. cis-l,4-polybutadiene model compound using acetyl sulfate. PIP c-PBD acetyl sulfate = 1 10 2 (mole). Temperature = 2rC. Solvent = decalin.

Problem 3.27 For a fractionated sample of cis-l,4-polybutadiene of molecular weight 1.23x10° intrinsic viscosities were measured (Moraglio, 1965) in three different solvents at respective theta temperatures. From the results given below detennine the variation of the unperturbed dimensions of the polymer molecule with temperature. 

J/(K mol), very close to that of cis-l,4-polybutadiene [ASj = 32.3 J/(K mol)] This second geometrical isomer of 1,4-poly butadiene does not show any condis phase For both isomers one can easily identify three flexible bonds, i.e. according to the fusion rules of Sect. 1.1, one expects 3 x 9.5 J/(K mol) for the overall entropy of fusion of either isomer, as is observed. The low-temperature transition of the... 

FIGURE 3.2 Magnified NMR spectrum of cis-l,4-polybutadiene after curing. The arrows designate new peaks appearing due to the vulcanization. The first seven represent methine carbons and the other 18 are due to methylene carbons (Clough and Koenig, 1989). 

At Al/Ti > 2.0 the catalytic behavior was quite different. The amorphous precipitate was catalytically active without mother liquor owing to the presence of trapped alkylaluminum compounds. Although the polymers prepared with the washed precipitates were about 60% iraws-1,4-polybutadiene, they nevertheless exhibited, at room temperature, crystallinity characteristic of sterically pure trans-1,4 poylmer. After ether extraction a very pure (> 90%) tmns-l,4-polybutadiene was left. The ether extract afforded very pure (94-95%) cis-l,4-polybutadiene. 

One of the most unusual features of the dialkylaluminum chloride and cobalt salt catalyst is the extremely high effectiveness of the cobalt compound. Although equimolar amounts of the aluminum and cobalt compounds are an effective catalyst, polymer is still formed at ratios as high as Al/Co = 500, using the normal amount of aluminum compound but only traces of the cobalt salt (Gippin, 1962 Longiave et al., 1961). For example, with as little as 0.002 mmole of cobalt salt 43 gm of cis-l,4-polybutadiene were obtained from 45 gm of monomer (Longiave et al., 1961). 

If the above observations are correct, it follows that, in successful polymerizations reported before then, some protic substance was adventitiously present. This must also be true in recent work by Guyot et al. (1962) since they observed that the formation of polymer from butadiene and diethylaluminum chloride occurred with or without added cobalt salt, although only in the former case was cis-l,4-polybutadiene produced. 

Another effective catalyst exists for synthesizing cis-l,4-polybutadiene. This too is based on aluminum and cobalt compounds, but, strictly speaking, it should not be included in this section, the reason being that it does not require an added organometallic component. The purpose in discussing the system here is that it bears a similarity to the catalysts described above. 

Fig. 19.30. Plots of cxjmmon logarithm of the maximum crystal growt.h rate (Gmax) against common logarithm of molecular weight (M) for various pol5uners for chain folding crystallization PTMPS [27], i-PS [28], PLLA [21,25], PESU [29], PET [37], i-PP [36], PEAD [38], cis-PIP [38], cis-PBD [39]. Maximum growth rates for PESU, PET, i-PP and PEAD are observed by our laboratory and those for PTMPS, i-PS, PLLA, cis-PIP and cis-l,4-polybutadiene (cis-PBD) are reported in hteratures. PE maximum growth rates are estimated based on reference data [23]...

In practice, the existence of both UCST and LCST has been established for polymer-solvent systems. About 10 years ago, Schmitt discussed UCST, LCST and combined UCST and LCST behavior in blends of poly(methyl methacrylate) with poly(styrene-co-acrylonitrile) (PMMA-PSAN), Ueda and Karasz reported the existence of UCST in chlorinated polyethylene (CPE) blends using DSC, Inoue found that elastomer blends of cis-l,4-polybutadiene and poly(styrene-co-butadiene) exhibit both UCST and LCST behavior and Cong et al. (72) observed that blends of polystyrene and carboxylated poly(2,6-dimethyl-l,4-phenylene oxide) copolymers with a degree of carboxylation between molar fraction 8% and 10% exhibit both UCST and LCST behavior. They used DSC to establish the phase diagram. 

Adducts of cis-l,4-polybutadiene with benzene- and toluene-4-sulphenyl chlorides can be oxidized quantitatively by 3-chloroperbenzoic acid in a second-stage modification to yield novel sulphone thermoplastics. The fully saturated polymers of structure (3) yielded sulphone products (Scheme 4) with improved thermal stability and higher glass transition temperatures (T, but the oxidation products of partially saturated polymers were very unstable thermally and discoloured on exposure to light. The radical-induced addition of mercaptans... 

The cationic cyclization of polyisoprene with acid catalysts is well documented. The same reaction in polybutadienes requires much more severe conditions, higher temperatures and more acidic catalysts, and until recently has received much less attention. A cyclized polymer with a reduction of 35—40% of the initial unsaturation, can be prepared by treating cis-l,4-polybutadiene with an alkyl aluminium chloride-organic halide catalyst in xylene solution at >100 C."- Such polymers, containing polycyclic sequences apparently at random within the chains, have better skid resistance and tensile properties than the parent polymer. Cyclization has been reported to accompany other reactions in polydienes, for example the radiation-induced addition of carbon tetrachloride to 1,2-polybutadiene, and the direct addition of a o j unsaturated carboxylic acids (acrylic and cinnamic) to polydienes and polypentenamers. It is reported that the thermal isomerization of cis-transoidal poly(phenylacetylene) is accompanied by cyclization, and additionally chain scission and aromatization at temperatures >120°C. ... 

First we show how we can experimentally detect the fast process. Figure 11 shows dynamic scattering laws S(Q,co) of cis-l,4-polybutadiene (PB) below and above Tg (=170 K) [32]. They are obtained with an inverted geometry type of a neutron spectrometer, which is the cause for asymmetric spectra about the origin (ft>=0). The elastic scattering intensity integrated within... 

Irradiation of a dilute solution of cis-l,4-polybutadiene in carbon tetrachloride (CCI4) with UV radiation in air causes the formation of a white insoluble gel. The observed crosslinking reaction is caused by reactive radicals formed from photolysis of CCI4 [1115] ... 

Nylon 66 (planar chain conformation) Syndiotactic 1,2-polybutadiene cis-l, 4-polybutadiene Polymethylene... 

Abdel-Bary, E.M., Sarhan, A.A., Abdel-Razik, E.A. Studies of the photo-oxidation of polydienes Part 1— Photo-stabilising effect of some derivatives of diacetyl-monooxime benzoyUiydrazone nickel (II) chelates on cis-l,4-polybutadiene. Polym. Degrad. Stab. 18, 145-155 (1987)... 

In the temperature range between 50° K and the glass transition temperature, crystallinity and also chain conformation is not of great influence on the heat capacity. In this range the difference between heat capacities of cis-l,4-polyisoprene and cis-l,4-polybutadiene is caused by the presence of the extra methyl group and can be compared to the difference between heat capacities of polypropylene and polyethylene. 

A serious limitation of polystyrene in many applieations is its brittleness and a number of attempts have been made to improve the polymer in this respect. The most successful approach to this problem has been the addition of rubbery materials (usually 5-15%) to the polymer and rubber-modified polystyrene (commonly referred to as impact polystyrene) is an important commercial material. In fact, production of impact polystyrene currently exceeds that of crystal polystyrene. Several rubbers have been tried for the preparation of impact polystyrene but cis-l,4-polybutadiene is the most commonly used. The method of mixing the polystyrene and rubber has a profound effect on the properties of the product. Simple blending of the two polymers in, for example, an internal mixer or two-roll mill gives a product... 

In the same way polyisoprene undergoes cationic rearrangements in the presence of acid catalysts. The same reactions with 1,4-polybutadiene requires much more severe conditions the extent of cyclization reaches 35 to 40% in the case of the system cis-l,4-polybutadiene/alkylaluminum chloride-organic halide in xylene above 100 for cyclization extents between 15 and 60% the average length of cyclized sequences was found to be between three and four cyclohexane rings. 

The same kind of anchimeric assistance holds for the addition of alkenylsulfenyl chlorides to ciS"l,4-polybutadiene and for that of p-toluenesulfonyl chlorides to cis-l,4-polybutadiene. ... 

Acrylate styrene acrylonitrile Acrylate modified st ene acrylonitrile Acrylic acid ester rubber Acrylonitrile butadiene rubber or nitrUe butadiene rubber Acrylonitrile butadiene styrene Acrylonitrile styrene/chlorinated polyethylene Acrylonitrile methyl methacrylate Acrylonitrile styrene/EPR rubber or, acrylonitrile ethylene propylene styrene Alpha methyl st ene Atactic polypropylene Butadiene rubber or, cis-l,4-polybutadiene rubber or, polybutadiene rubber Butadiene styrene block copolymer Butyl rubber Bulk molding compound Casein formaldehyde Cellulose acetate Cellulose acetate butyrate Cellulose acetate propionate Cellulose nitrate Chlorinated polyethylene Chlorinated polyvinyl chloride Chloro-polyethylene or, chlorinated polyethylene. 

Other oxygen species are also reactive with double bonds. Detailed sp ctroscopical studies show hat all oxygen species, i.e. singlet ( O2) and molecular oxygen ( atomic oxygen (0) and ozone (0 ) react with cis-l,4-polybutadiene forming different... 

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