|Mohmeyer, N.; Schmidt, H.-W.; Kristiansen, P.M.; Altstädt, V.: Influence of Chemical Structure and Solubility of Bisamide Additives on the Nucleation of Isotactic Polypropylene and the Improvement of Its Charge Storage Properties, Macromolecules, 39(17), 5760-5767 (2006) -- DOI: 10.1021/ma060340q|
A comparative study on the influence of chem. structure and soly. of a series of low-mol.-wt. 1,4-phenylene-bisamides in isotactic polypropylene (i-PP) was conducted to explore their performance as nucleating agents and electret additives. The series consists of three isomers of dicyclohexyl-substituted 1,4-phenylene-bisamide and three asym. substituted cyclohexyl/n-alkyl-1,4-phenylene-bisamides with different chain lengths. The symmetry of the mols., the type of substitution and the length of the alkyl chain influence the soly. in the i-PP melt, the nucleation efficiency, the ratio of the a- to b-crystal modification and the charge storage properties. The best b-nucleating efficiency was obsd. for the sym. substituted compds., whereas the nucleation efficiency was substantially reduced in the presence of n-alkyl-substituents. The charge storage behavior of i-PP was improved only for the three dicyclohexyl-substituted 1,4-phenylene bisamides at concns. of 100 ppm and even below. For example, a film comprising 10 ppm additive displayed charge retention of 90% after an accelerated aging (annealing for 24 h at 90 °C).