Creep response of a LDPE‐based nanocomposite

Abstract

Polymer nanocomposites and their behavior have been widely investigated by several paths, including mechanical, rheological, and permeability tests, finding that several parameters (such as the polymer matrix, the nanofiller, their amounts, the presence of compatibilizers, processing parameters, etc.) can influence the main properties. However, less information is available regarding the creep response of polymer nanocomposites; in particular, few or no data are reported about the combined effect of different loads and different temperatures. In this article, the creep behavior of a low density polyethylene/organomodified clay nanocomposite has been investigated. The characterization of viscoelastic response has taken into account both the effects of applied load and temperature, which are often considered separately. Dynamic–mechanical and structural analysis was also performed in order to get a deeper understanding of the involved phenomena. The nanocomposite showed lower creep deformations (up to ∼20%) and the relative differences with the neat polymer matrix were found to be increasing upon increasing the applied load (up to ∼24%) and the temperature (up to ∼38%). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44180.

Photooxidation Behavior of a LDPE/Clay Nanocomposite Monitored through Creep Measurements

“…This behavior can be correlated to the higher rigidity of the nanocomposite in comparison to the matrix [22,23,24], with a consequent lower deformability. This result is in agreement with that reported by other researchers on similar systems [7,10] and could be attributed to lower macromolecular mobility induced by the presence of clay particles and the obtained intercalation degree [13]: as shown by the XRD traces in Figure 2, the presence of the nanoclay in the nanocomposite shifts 2θ angle to lower values, and therefore the interplanar distance to higher ones, in particular from 2.62 to 3.44 nm, thus indicating that a moderate intercalation effect of the nanoclay, due to the LDPE chains , was obtained.…”

“…It has been reported in our previous works [13,26] that the photooxidation of polyethylene leads to two competitive mechanisms, namely macromolecule breaking and the formation of branching and cross-linked structures. This means that, under the current testing conditions, the increase of molecular weight and the formation of branching are favored with respect to the breaking of the macromolecules.…”

“…Most of them [7,8,9,10,11] focused on polyolefin-based nanocomposites (containing either clay or fumed silica) finding, on average, a significant increase of the creep resistance (provided that a good exfoliation degree is achieved, if clay was used); similar conclusions were found in a study [12] on elastomer-clay nanocomposites. In a previous work [13] we found that LDPE/clay nanocomposites, subjected to different temperatures and stresses, showed lower creep deformations in comparison to the neat polymer, and the relative differences increased upon increasing the applied stress and the temperature.…”

Creep Behavior of Poly(lactic acid) Based Biocomposites

“…The samples are mounted between the two clamps and the tests start when suitable weights are applied at the end of the extensometer, as described in our previous works [42,45]. More in details, two different temperatures (40 and 60 °C) were applied, under constant tensile stress (i.e., 3 MPa) for one week.…”

“…Creep tests were conducted on both the composites and the woven fabrics, using a new dedicated apparatus (IDEA, Termini Imerese, Italy), consisting in an oven, equipped with four extensometers, directly connected to mobile clamps and to weight holders. The samples are mounted between the two clamps and the tests start when suitable weights are applied at the end of the extensometer, as described in our previous works [ 42 , 45 ]. More in details, two different temperatures (40 and 60 °C) were applied, under constant tensile stress (i.e., 3 MPa) for one week.…”