Accelerated Weathering of Polylactide-Based Composites Filled with Linseed Cake: The Influence of Time and Oil Content within the Filler

Abstract

This paper presents the effects of accelerated weathering on the properties of polylactide (PLA) composites filled with linseed cake. The particle-shaped waste filler with different linseed oil content (0.9–39.8 wt %) was incorporated with constant amount of 10 wt % to a polymeric matrix and subjected to accelerated weathering tests with different exposition times. The structure of the composites, their mechanical, thermal, and thermo-mechanical properties were evaluated by means of scanning electron microscopy, tensile test, dynamic mechanical thermal analysis, and differential scanning calorimetry prior to and after weathering. The results of the measurements were analyzed in reference to the amount of crude oil contained in the filler. The behavior of the multiphase composite during weathering was described. It was found that the oil-rich samples during the first stage of the process showed increased resistance to hydrolytic degradation due to their relatively high crystallinity. The presence of water and elevated temperatures caused swelling of the filler and cracking of the polymeric matrix. Those discontinuities enabled the plasticizing oil to be rinsed out of the composite and thus water penetrated into the samples. As a result, the PLA-based composites containing oil-rich linseed cake were found to be more vulnerable to hydrolytic degradation in a longer time.

Preparation and Characterization of Bio-Based PLA/PBAT and Cinnamon Essential Oil Polymer Fibers and Life-Cycle Assessment from Hydrolytic Degradation

“…The presence of the oil in the F3 formulation would avoid the mentioned effect it gives the fiber a more hydrophobic character. During the first stage of the hydrolytic degradation process, the samples containing oil as plasticizer are resistant to hydrolytic degradation, as degradation progresses, the plasticizer migrates, and the hydrolytic media can diffuse inside the fibers [107]. Therefore, the hydrolytic degradation of fibers added with oils is more noticeable for longer times as evidenced in the morphological changes of the fibers.…”

Hybrid Epoxy Composites with Both Powder and Fiber Filler: A Review of Mechanical and Thermomechanical Properties

“…Polymer hybrid materials contain fillers or modifiers that have different functionalities, thanks to which they are characterized by unique usable, technological, and processing properties. Designing a composite material requires taking the processing technique, the susceptibility of all components to heat, mechanical treatment, durability, and the ability to create compounds into account [1][2][3][4][5]. Epoxy resins can be in the form of liquids, pastes, or powders, which significantly facilitates their modification by mixing with reactive or non-reactive additives [6][7][8].…”

The influence of oil content within lignocellulosic filler on thermal degradation kinetics and flammability of polylactide composites modified with linseed cake

“…This outcome is surprising, as the oil-rich samples presented higher thermal degradation temperatures. It may be suggested that the composites characterized by different morphology and crystallinity (as described in our previous article) [23] also present different thermal conductivity and specific heat, therefore, the needed energy is absorbed by the sample at different temperature. LC, a multicomponent filler, which comprises of cellulose, mucilage, proteins, and oil as well as mineral compounds, [51,52] which need different activation energy to decompose, as it is reflected by the shape of the E a vs α curve.…”

“…As a result, five grades of the filler characterized with the oil content of 0.9% to 39.8% were obtained: LC-0.9, LC-4.6, LC-17.7, LC-30.4, and LC-39.8, where the number is the oil content in weight percent, determined by a Büchi Universal Extraction System B811 using petroleum ether as a solvent, with extraction time of 150 minutes at a temperature of 100 C. A more detailed description of the filler preparation can be found in our previous article. [23]…”

“…As we showed in our previous research, the addition of oil-rich LC to polylactide causes an increase of crystallinity and elongation at break. [23,24] Nevertheless, the presence of the oil, apart from the aforementioned benefits, may cause serious problems, including lowered thermal stability of the composites. [25] Linseed oil is one of the so-called drying oils.…”