Crystalline Dibutyl phthalate

Comparison of Table 5.4 and 5.7 allows the prediction that aromatic oils will be plasticisers for natural rubber, that dibutyl phthalate will plasticise poly(methyl methacrylate), that tritolyl phosphate will plasticise nitrile rubbers, that dibenzyl ether will plasticise poly(vinylidene chloride) and that dimethyl phthalate will plasticise cellulose diacetate. These predictions are found to be correct. What is not predictable is that camphor should be an effective plasticiser for cellulose nitrate. It would seem that this crystalline material, which has to be dispersed into the polymer with the aid of liquids such as ethyl alcohol, is only compatible with the polymer because of some specific interaction between the carbonyl group present in the camphor with some group in the cellulose nitrate. 

Polychloroethene (polyvinyl chloride), as usually prepared, is atactic and not very crystalline. It is relatively brittle and glassy. The properties of polyvinyl chloride can be improved by copolymerization, as with ethenyl ethanoate (vinyl acetate), which produces a softer polymer ( Vinylite ) with better molding properties. Polyvinyl chloride also can be plasticized by blending it with substances of low volatility such as tris-(2-methylphenyl) phosphate (tricresyl phosphate) and dibutyl benzene-1,2-dicarboxylate (dibutyl phthalate) which, when dissolved in the polymer, tend to break down its glasslike structure. Plasticized polyvinyl chloride is reasonably flexible and is widely used as electrical insulation, plastic sheeting, and so on. 

The dependence of Tg on the concentration of EBBA shows the expected decrease of Tg values at lower EBBA concentrations where the liquid crystalline additive exists as a homogeneous solution in PC. EBBA shows a plasticizing effect which is less pronounced than that observed for typical plasticizers like dibutyl phthalate and chlorinated phenyls. The blends of these compounds were prepared... 

The exact location of the plasticizer is frequently evaluated to better understand the structure of plasticized polymers. In poly[(vinylidene fluoride)-co-hexafluoropropene], VDF/HFP plasticized with dibutyl phthalate, SAXS measurements indicate that DBP resides in the amorphous zone outside the lamellar stacks. If ciystallization is slow the inclusion of DBP inside the lamellar stacks is also possible. In another contribution for the same copolymer, plasticizer was also found in amorphous phase close to the interface with crystalline stmctures which was evidenced by almost constant spacing in the range of tricresyl phosphate studied.In the plasticized PVC, the plasticizer molecules were found in the amorphous area but were also present in the interlamellar, intefibrillar, inter-spheralitic regions and in the amorphous fold surfaces. ... 

Figure 10.59. Crystallinity of plasticized poly[(vinylidene fluoride)-co-hexafluoropropene] vs. concentration of dibutyl phthalate plasticizer. [Data from Marigo A Marega C Bassi M Fumagalli M San-guineti A,Polym. Inti, 50, No.4, April 2001, p.449-55.]...

Crystallinity of polyethylene oxide plasticized with DOP in the concentration range from 0 to 25% was fairly constant. " Dibutyl phthalate did not affect the amoimt of VDF/HFP which crystalhzed in the presence of up to 50% of the plasticizer. Reduced crystallinity in polybutadiene urethane was found when DOS concentration was increased from 17 to 34% but this was compensated by the annealing process at 100°C. " Concentration of the plasticizer up to 50% in plasticized PVC did not affect its crystalhne order.Very little difference in crystallinity was observed between implasticized PVC and PVC containing 33% tricresyl phosphate (78 and 73%, respectively). Figure 10.58 is characteristic of results discussed so far. Crystallinity of plasticized PVC remains constant with the plasticizer concentration changing from... 

Poly(ethylene terephthalate) is most usually encountered in the crystalline form and, as such, it is soluble at normal temperatures only in proton donors which are capable of interaction with the ester group. Effective solvents of this kind are chlorinated and fluorinated acetic acids, phenols and anhydrous hydrofluoric acid. The polymer is soluble at elevated temperatures in various organic liquids, which include anisole, aromatic ketones, dibutyl phthalate and dimethyl sulphone. Chloroform has the peculiar property of dissolving amorphous poly(ethylene terephthalate) at temperatures below 0°C,but on warming such solutions the polymer separates in crystalline form. Chloroform is without effect on polymer which has already been crystallized. 

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