Glass transition and polymer dynamics in silver/poly(methyl methacrylate) nanocomposites

Abstract

It is a common industrial practice to blend virgin polymer with the same polymer recycled from scrap plastic that, in general, has not undergone relevant degradation. In this article, the influence that incorporating recycled material has on injection processes, especially on the rheological behavior of the material was studied. With this aim in mind, a mixture of two materials with the same nature or composition and similar viscosity was used, which is the system that is most commonly seen in industry. The mixture studied is composed of virgin PP (polypropylene) typically found in injection processes, and recycled copolymer PP from scrap plastic. A complete characterization of the materials and applied existing models was carried out in order to predict the mechanical behavior of the mixtures. A model to predict the behavior of the mixtures during processing, based on the rheological characteristics of the materials used was developed. This predictive model has been experimentally validated using filling tests in injection molding machines, as well as by specific simulation software.

Influence of the presence of medium-soft paraffin wax on the morphology and properties of iPP/silver nanocomposites

“…According to Table 1 the melting enthalpies of iPP and iPP in iPP/wax and iPP/Ag are very similar, so the differences in their storage moduli cannot be the result of differences in iPP crystallinity. It has been reported previously that the nanoparticles can have a plasticizing effect on a polymer [20], and therefore the lower storage modulus in the case of iPP/Ag is probably the result of such a plasticizing effect. The storage modulus is the lowest when both wax and Ag are present.…”

“…In this case both the (-and )-peaks appear at lower temperatures than those of pure iPP. This is an indication that Ag particles to some extent have plasticized iPP, giving rise to an increase in iPP chain mobility in the amorphous phase [20]. The decrease in the )-transition temperature must be related to the presence of the Ag particles in the inter-crystalline amorphous areas of iPP.…”

Interfacial surfactant competition and its impact on poly(ethylene oxide)/Au and poly(ethylene oxide)/Ag nanocomposite properties

“…Experiments performed on polymer nanocomposites showed a relationship between polymer mobility and T g 24,25. T g of polystyrene/Au nanocomposites was found to decrease gradually with increasing nanoparticle concentration compared to that of neat polystyrene 24.…”

Dielectric and thermal studies of the segmental dynamics of poly(methyl methacrylate)/silica nanocomposites prepared by the sol–gel method

“…By following the evolution of the b relaxation toward the high-frequencies region, a change of the slope can be detected at about 358 K. This change reflects the beginning of the merging of the b with the a relaxations, which is a typical behavior for PMMA and acrylates in general. 17,[46][47][48]63 The observation of this change verifies the partially co-operative character of the b relaxation, which is strongly affected by the forthcoming segmental dynamics. Another point that should be considered is the second change of the slope, observed at lower temperatures (at about 303 K) mainly for the nanocomposites.…”

“…An interesting point in the Arrhenius plot is the region of the merging of a and b relaxations in a complex ab, as mentioned earlier. 17,[46][47][48] This complex process is faster than the b relaxation (smaller slope) and slower than the a relaxation (bigger slope). Also, the ab relaxation, even if it is attributed to the rubber state of the polymer above T g and it is originated from segmental molecular motions, is better described by an Arrhenius equation [eq.…”