In this study, we describe the synthesis of amides and evaluate their use as slip additive agents in polypropylene films. The additives N-isopropyl-stearamide and N,N-diisopropyl-stearamide were synthesized and characterized and then used to prepare masterbatches. Erucamide, a commercial masterbatch, was used as the reference standard. A 32 factorial experimental design was used to create the different compositions of slip additives in polymer films. The films were processed via flat-die extrusion and stored in an oven at a constant temperature of 40 °C for seven days. The following are the properties evaluated in the study: thermal decomposition temperature, fusion temperature, fusion enthalpy, coefficient of friction, surface energy, contact angle, and seal initiation temperature. The results were evaluated by analysis of variance (ANOVA) at a 90 % confidence interval. The analysis of the results showed that N-isopropyl stearamide and N,N-diisopropyl stearamide do not provide an adequate surface slip for polypropylene films at the conditions used in the study. In turn, at the same conditions, erucamide, the commercial amide, also does not provide the required surface energy for printing and lamination processes required for polypropylene films.
Summary Polymeric membranes were prepared using the mass copolymerization of styrene/acrylic acid (St/AA) at 90/10, 92/8 and 94/6 ratios. Divinyl benzene (DVB) was also added at concentrations of 0.1 and 0.001% weight for each St/AA ratio. The obtained copolymers were sulfonated by treating the materials with concentrated sulfuric acid for 0, 30 and 85 minutes to enhance their ion exchange capacities. The materials were characterized by Fourier transform infrared spectroscopy (FTIR), thermal analysis by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), cross‐linking level by gel percentage and acidity through sodium hydroxide titration. The FTIR spectra of the membranes before sulfonation showed the existence of traditional bands that corresponded to the polymer components; some homopolymer main bands were lost, whereas two new bands appeared during the copolymerization reaction. The TGA analyses showed a higher decomposition temperature for the DVB cross‐linked membranes, while DSC did not provide much information due to the hygroscopic nature of the membranes. The gel percentage was effectively related to the DVB level. The membranes acidity increased with increasing acrylic acid content, sulfonation time and DVB percentage; however, the acidic values are highly dependent on the solubility of the materials.
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