Molybdenum disulphide—A traditional external lubricant that shows interesting interphase properties in pulp‐based composites

Abstract

Compression molded composites were prepared through a water-assisted mixing of an aqueous suspension of poly(ethylene-co-acrylic acid), additive, and pulp fibers [thermomechanical pulp (TMP) or dissolving pulp (DP)]. The lubricating additives used were magnesium stearate (MgSt) and molybdenum disulphide (MoS 2 ). The composite materials had dry pulp contents ranging from 30 to 70 wt% and 5 wt% additive relative to the weight of the pulp. The adsorption of the additives onto the fibers was confirmed by scanning electron microscopy and energy dispersive X-ray analysis. DMA showed that MgSt and MoS 2 gave similar interphase properties for the TMP samples at all loading contents, but the combination of MgSt and MoS 2 improved the overall properties of the DP-based composites. The tensile modulus, at 70 wt% fiber content (TMP or DP), increased compared to the matrix by a factor of 6.3 and 8.1, without lubricants, and by a factor of 8 and 10.7, with lubricants, respectively. The increase in melt viscosity observed for the lubricated samples was greater for the TMP-based samples containing MoS 2 . At a lubricant content of 5 wt%, in 30 wt% TMP, the MoS 2 behaved as both a lubricant and compatibilizer.

Alkyl ketene dimer modification of thermomechanical pulp promotes processability with polypropylene

“…Adding TMP to PP at 50 wt% gives composite materials of similar strength at break but reduced elongation (Figure 7). It is established that elongation at break will be reduced when TMP fibers are added 39,57–60 . Modification of TMP with AKD Lau generates materials with similar stress and elongation at break as unmodified PP‐TMP composites.…”

“…The TMP used was made from Picea abies (Norway spruce), kindly provided by Stora Enso Hyltebruk, Sweden. Fiber analysis of the TMP, performed using a Kajaani FS300, gave a respective mean fiber length, width and fines distribution of 3.2 mm, 35 μm, and 3% 39 . According to the literature, TMP has 50 wt% of polysaccharides and ca.…”

“…Fiber analysis of the TMP, performed using a Kajaani FS300, gave a respective mean fiber length, width and fines distribution of 3.2 mm, 35 μm, and 3%. 39 According to the literature, TMP has 50 wt% of polysaccharides and ca. 30%-35 wt% lignin.…”

“…It is established that elongation at break will be reduced when TMP fibers are added. 39,[57][58][59][60] Modification of TMP with AKD Lau generates materials with similar stress and elongation at break as unmodified PP-TMP composites. However, modifying the TMP with AKD St generates a reduction in stress (Figure 7A).…”