Michaela Iorga

Properties of Polymer Composites with Cellulose Microfibrils

Polypropylene-based composites containing 10–30% by weight cellulose microfibrils were studied. Composites with polypropylene and cellulose microfibrils were characterised by MS-coupled simultaneous TGA-DSC and the reinforcing effect of cellulose microfibrils was emphasised by mechanical characterization. Experimental results are discussed in connection with the composite preparation method by mixing and extrusion. The effect of cellulose on the thermal stability and degradation behaviour of the polypropylene matrix is pointed out.

Influence of Rutile and Anatase TiO2 Nanoparticles on Polyethylene Properties

Nanocomposites from polyethylene and TiO2 with different shape and size were prepared by direct mixing and masterbatch dilution, respectively. The mechanical properties of nanocomposites were determined and discussed in relation to the nanofiller dispersion. Moreover, the morphological aspects of polyethylene with and without nanofiller were revealed by means of SEM and WAXD. A better dispersion of the nanoparticles and increased mechanical properties were observed in the case of the masterbatch method. No important differences in mechanical and morphological characteristics of anatase and rutile containing polyethylene composites were observed, except a higher increase of the elastic modulus in case of anatase-containing composites.

Effect of SEBS on morphology, thermal, and mechanical properties of PP/organoclay nanocomposites

A simultaneously increase in stiffness and toughness is needed for improving polypropylene (PP) competitiveness in automotive industry. The aim of this paper is to investigate the effects of styrene-(ethylene-co-butylene)-styrene triblock copolymer (SEBS) on mechanical and thermal properties of PP, in the presence and the absence of nanoclay. The amount of SEBS in PP was ranged to obtain the matrix with the most favorable stiffness–toughness balance. For this purpose, SEBS domain size and distribution in PP/SEBS blends was determined by means of atomic force microscopy and correlated with mechanical properties. The influence of SEBS on the crystalline structure of PP in PP/organoclay nanocomposites was investigated by X-ray diffraction and differential scanning calorimetry, a synergistic effect of SEBS and nanoclay being pointed out. Moreover large improvement in the impact strength (almost 22 times) was obtained in the case of SEBS-containing nanocomposite in comparison with the composite without SEBS.

Polypropylene/organoclay/SEBS nanocomposites with toughness–stiffness properties

Polypropylene nanocomposites with a different amount of styrene-ethylene-butylene-styrene block copolymer (SEBS)/clay were prepared via a melt mixing technique. To improve the dispersion of commercial organoclay (denoted as OMMT), various amounts of SEBS were incorporated. At a fixed content of OMMT, the mechanical properties were improved with increasing SEBS content. The obtained nanocomposites were characterized through X-ray diffraction (XRD), differential scanning calorimetry (DSC-TG) and mechanical tests. The thermal–morphological–mechanical properties were investigated. The nanomaterials presented an improved decomposition temperature, a small decrease in tensile strength, a higher Youngs modulus and a spectacular increase of 300% in impact strength.

Morphological and Tribological Properties of PMMA/Halloysite Nanocomposites

From an environmental and cost-effective perspective, a number of research challenges can be found for electronics, household, but especially in the automotive polymer parts industry. Reducing synthesis steps, parts coating and painting, or other solvent-assisted processes, have been identified as major constrains for the existing technologies. Therefore, simple polymer processing routes (mixing, extrusion, injection moulding) were used for obtaining PMMA/HNT nanocomposites. By these techniques, an automotive-grade polymethylmethacrylate (PMMA) was modified with halloysite nanotubes (HNT) and an eco-friendly additive N,N′-ethylenebis(stearamide) (EBS) to improve nanomechanical properties involved in scratch resistance, mechanical properties (balance between tensile strength and impact resistance) without diminishing other properties. The relationship between morphological/structural (XRD, TEM, FTIR) and tribological (friction) properties of PMMA nanocomposites were investigated. A synergistic effect was found between HNT and EBS in the PMMA matrix. The synergy was attained by the phase distribution resulted from the selective interaction between partners and favourable processing conditions. Modification of HNT with EBS improved the dispersion of nanoparticles in the polymer matrix by increasing their interfacial compatibility through hydrogen bonding established by amide groups with aluminol groups. The increased interfacial adhesion further improved the nanocomposite scratch resistance. The PMMA/HNT-EBS nanocomposite had a lower coefficient of friction and lower scratch penetration depth than PMMA/HNT nanocomposite.