Thermomechanical and Fire Properties of Polyethylene-Composite-Filled Ammonium Polyphosphate and Inorganic Fillers: An Evaluation of Their Modification Efficiency

Characterization of Microalgae Biomass-Based Composites Obtained through Rotational Molding

The wide range of applications and the numerous advantages of plastics have led to their excessive use, with subsequent damage to ecosystems. As an environmentally friendly alternative, biocomposites have gained much attention, and microalgae have become a potential source for their production. In this study, the use of washed and unwashed Spirulina in polyethylene-based composites has been evaluated as a way to prevent the thermooxidation of polyethylene, while at the same time, reducing the amount of virgin plastic used. Biocomposites were produced by rotomolding, testing different biomass contents and determining their mechanical and thermal performances as well as their water uptake level. Composites with up to 15% of biomass (by weight), a particularly high ratio for rotomolding, were satisfactorily produced. Using 5% of both biomasses did not significantly modify the behavior when compared with the neat PE samples' properties. For higher loadings, the use of non-washed biomass allowed us to obtain better properties, with added benefits related to using an unwashed biomass (less water consumption, lower costs and fewer environmental impacts). On the other hand, this study showed a promising beneficial effect on the thermooxidative resistance of composites, as the oxidation induction times were notably increased with biomass addition.

Comprehensive Analysis of the Influence of Expanded Vermiculite on the Foaming Process and Selected Properties of Composite Rigid Polyurethane Foams

This article presents the results of research on obtaining new polyurethane (PUR) foams modified with thermally expanded vermiculite. The filler was added in amount of 3 wt.% up to 15 wt.%. The additionally applied procedure of immersion the non-organic filler in H₂O₂ was performed to increase the exfoliation effect of thermally treated mineral and additional oxidation the surfaces. The effect of fillers on foaming process, cell structure, thermal insulation, apparent density, compressive strength, thermal properties, and flammability are assessed. The foaming process of PUR foams modified with vermiculite was comparable for all systems, regardless of the content of the filler. A slight increase in reactivity was observed, confirmed by a faster decrease in dielectric polarization for the system with modified vermiculite by H₂O₂. The modification of the reference system with the vermiculite increased the content of closed cells from 76% to 91% for the foams with the highest vermiculite content. Coefficient of thermal conductivity of reference foam and foams modified with vermiculite was in the range 24-26 mW/mK. The use of vermiculite up to 15 wt.% did not influence significantly on mechanical properties and flammability, which from an economic point of view is important because it is possible to reduce the cost of materials by introducing a cheap filler without deteriorating their properties.

Waste Eggshells as a Natural Filler for the Poly(Vinyl Chloride) Composites

The paper presents the characteristics of unplasticized PVC composites modified with biofiller obtained from the waste eggshells of hen eggs. The composites obtained by extrusion contained from 10 phr to 40 phr of biofiller. The filler was characterized using the SEM, TG, and sieve analysis methods. The influence of the filler on the processing properties was determined using plastographometric and MFR tests. Fundamental analysis of mechanical properties was also performed, i.e., Charpy impact strength and determination of tensile properties. The mechanical properties were supported with dynamical mechanical thermal analysis, time of thermal stability, and thermogravimetric analysis. Structure analysis was also performed using SEM and X-ray microcomputed tomography (micro-CT). The processing properties of the tested composites do not give grounds for disqualifying such material from traditional processing PVC mixtures. Notably, the biofiller significantly improves thermal stability. Ground eggshells (ES) work as scavengers for the Cl radicals released in the first stage, which delays the PVC chain’s decay. Additionally, a significant increase in the value of the modulus of elasticity and softening point (VST) of the composites concerning PVC was found. Ground hen eggshells can be used as an effective filler for PVC composites.

Comprehensive Enhancement of Prepolymer-Based Flexible Polyurethane Foams' Performance by Introduction of Cost-Effective Waste-Based Ground Tire Rubber Particles

Material innovations in polyurethane (PU) foams should ideally combine performance enhancement, environmental impact limitation, and cost reduction. These goals can be achieved by applying recycled or waste-based materials without broader industrial applications, implicating their low price. Herein, from 5 to 20 parts by weight of ground tire rubber (GTR) particles originated from the recycling of postconsumer car tires were incorporated into a flexible foamed PU matrix as a cost-effective waste-based filler. A two-step prepolymer method of foams manufacturing was applied to maximize the potential of applied formulation changes. The impact of the GTR content on the foams' processing, chemical, and cellular structure, as well as static and dynamic mechanical properties, thermal stability, sound suppression ability, and thermal insulation performance, was investigated. The introduction of GTR caused a beneficial reduction in the average cell diameter, from 263.1 µm to 144.8-188.5 µm, implicating a 1.0-4.3% decrease in the thermal conductivity coefficient. Moreover, due to the excellent mechanical performance of the car tires-the primary application of GTR-the tensile performance of the foams was enhanced despite the disruption of the cellular structure resulting from the competitiveness between the hydroxyl groups of the applied polyols and on the surface of the GTR particles. The tensile strength and elongation at break were increased by 10 and 8% for 20 parts by weight GTR addition. Generally, the presented work indicates that GTR can be efficiently applied as a filler for flexible PU foams, which could simultaneously enhance their performance, reduce costs, and limit environmental impacts due to the application of waste-based material.