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Short glass fiber Type E was coated with electrically conducting polyaniline (PAn) by in situ chemical polymerization. The resulting PAn coated glass fiber, with surface conductivity of 3.3 × 10−1 S/cm, was melt‐compounded with isotactic polypropylene (iPP). Polypropylene grafted with maleic anhydride was investigated as an adhesion promoter for these composites. Differential scanning calorimeter and polarized light microscopy indicates that the PAn coated glass fiber has a strong nucleating activity towards iPP. Scanning electron microscopy showed the improvement in the wetting and dispersion of the fibers when the adhesion promoter was added, although this also led to fiber encapsulation and lowering the electrical conductivity of the composites. The adhesion promoter greatly improved the Young's modulus of the composites, and a reaction between the maleic anhydride groups of the adhesion promoter and the PAn was proposed. Composites with an electrical conductivity greater than 10−9 S/cm were achieved using a 30 wt % of PAn coated glass fiber. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

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The hevea brasiltensis rubber contains, besides the insoluble branched entities, linear and branched molecules in the soluble fraction. The branching characteristics found by analyzing fractions of different molecular weight of rubber coagulated from freshly tapped latex, stabilized with hydroxylamine hydrochloride are: (a) molecules with molecular weights above 6.5×104−1.0×105g/mol (depending on the branch points functionality) are branched and molecules below these limits are linear. (b) The relationship between number of branch points and the logarithm of molecular weight is linear. (c) The branching density is not independent of molecular weight, as has been assumed for several polymers, but it has a maximum. The maximum branching density found in the soluble fraction is between 10.2×10−6 and 31.6×10−6mol/g, which varies little with the molecular weight; it is possible that molecular species with higher values become insoluble. (d) Branching results ˜λ and gel content (36%) of the whole rubber gave a total of 93–98% of branched entities (sol and gel) and 2–7% of linear species.