Polymer foams have low density, good heat insulation, good sound insulation effects, high specific strength, and high corrosion resistance, and are widely used in civil and industrial applications. In this paper, the classification of polymer foams, principles of the foaming process, types of blowing agents, and raw materials of polymer foams are reviewed. The research progress of various foaming methods and the current problems and possible solutions are discussed in detail.

https://www.mdpi.com/2073-4360/11/6/953/pdf

Recent Trends of Foaming in Polymer Processing: A Review.

This research is a comprehensive review of the sustainability of additive manufacturing, from the circular economy and recycling of materials to other environmental challenges involving the safety of materials and manufacturing. There has been important progress in this area, with an increasing number of papers that cover diverse environmental aspects, including the circular economy, recycling and the life cycle assessment of materials. This increase is due to the importance that scientists, industry, government and society are now giving to these topics. This review seeks to develop a greater awareness in relation to the possibilities and implications in the use of the AM, as well as to encourage sustainable development by raising awareness in relation to the taking of necessary actions to achieve compliance of the Sustainable Development Goals. Similarly, current trends are examined in relation to the practices that are currently being adopted in order to ensure that AM is consolidated as a sustainable and convenient practice in the economic, social and environmental spheres. In general, polymers, ceramics, metals and composite materials are now undergoing intensive research to improve their use. Although this research shows that significant progress has been made on several relevant issues, using materials optimization to minimize energy and waste is still far from a global solution.

Sustainability of additive manufacturing: the circular economy of materials and environmental perspectives

Polyurethanes from seed oil-based polyols: a review of synthesis, mechanical and thermal properties.

Effect of walnut shells and silanized walnut shells on the mechanical and thermal properties of rigid polyurethane foams

Biomass type effect on biochar surface characteristic and adsorption capacity relative to silver and copper

This article presents the results of research on obtaining new polyurethane materials modified by a by-product from vegetable oils industry—rapeseed cake. The chemical composition of rapeseed cake was examined. Rigid polyurethane-polyisocyanurate (RPU/PIR) foams containing a milled rapeseed cake in their composition were obtained as part of the conducted research. Biofiller was added in amount of 30 wt.% up to 60 wt.%. Effects of rapeseed cake on the foaming process, cell structure and selected properties of foams, such as apparent density, compressive strength, brittleness, flammability, absorbability, water absorption, thermal resistance and thermal conductivity are described. The foaming process of RPU/PIR foams modified by rapeseed cake was characterized by a lower reactivity, lower foaming temperature and decrease in dielectric polarization. This resulted in a slowed formation of the polyurethane matrix. Apparent density of RPU/PIR foams with biofiller was higher than in unmodified foam. Addition of rapeseed cake did not have a significant influence on the thermal conductivity of obtained materials. However, we observed a tendency for opening the cells of modified foams and obtaining a smaller cross-sectional area of cells. This led to an increase of absorbability and water absorption of obtained materials. However, an advantageous effect of using rapeseed cake in polyurethane formulations was noted. Modified RPU/PIR foams had higher compressive strength, lower brittleness and lower flammability than reference foam.

/pdf/the-use-of-waste-from-the-production-of-rapeseed-oil-for-3k0o3cr5zi.pdf

The Use of Waste from the Production of Rapeseed Oil for Obtaining of New Polyurethane Composites

The article presents the results of research on the synthesis of a new biopolyol based on evening primrose oil, and its use in the production of rigid polyurethane–polyisocyanurate foams intended for thermal insulation. The obtained biopolyol was subjected to analytical, physicochemical, and spectroscopic tests (Fourier transform infrared (FTIR), 1H NMR, 13C NMR) to confirm its suitability for the synthesis of polyurethane materials. Then, it was used for the partial replacement of the petrochemical polyol in the polyurethane formulation. Obtained rigid polyurethane–polyisocyanurate foams are characterized by a lower apparent density, brittleness, water absorption, and thermal conductivity coefficient λ. In addition, foams modified by biopolyols had a higher content of closed cells and higher aging resistance. The results of the conducted research showed that the use of the biopolyol based on evening primrose oil may be an alternative to petrochemical polyols. The research presented herein is perfectly consistent with the trends of sustainable development and the philosophy of green chemistry.

/pdf/effect-of-evening-primrose-oil-based-polyol-on-the-2kgqrbtv3b.pdf

Effect of Evening Primrose Oil-Based Polyol on the Properties of Rigid Polyurethane⁻Polyisocyanurate Foams for Thermal Insulation.

Synthesis and application of new bio-polyols based on mustard oil for the production of selected polyurethane materials

Four types of rigid polyurethane-polyisocyanurate foams (RPU/PIR) were obtained. Three of them were modified by powder fillers, such as cinnamon extract (C10 foam), green coffe extract (KZ10), and cocoa extract (EK10) in an amount of 10 wt %. The last foam was obtained without a filler (W foam). The basic properties and thermal properties of obtained foams were examined. All foams were subjected to degradation in the climatic chamber acting on samples of foams in a defined temperature, humidity, and UV radiation for 7, 14, and 21 days. The physico-mechanical properties of foams were tested. The compressive strength of degraded foams after 7, 14, and 21 days was compared with the compressive strength of nondegraded foams (0 days). The chosen properties of degraded foams, such as cellular structure by scanning electron microscopy (SEM) and changes of chemical structure by FTIR spectroscopy were compared. The obtained foams were also subjected to degradation in a circulating air dryer in an increased temperature (120 °C) for 48 h. Additionally, W, C10, ZK10, EK10 foams were placed in a soil environment and subjected to 28 days biodegradation process. The biochemical oxygen demand (BOD), the theoretical oxygen demand (TOD), and the degree of biodegradation (Dt) of foams were determined in this measurment. Test results showed that the compressive strength of foams decreased with the longer time of foam degradation in the conditioner. The foam subjected to degradation darkened and became more red and yellow in color. The addition of natural compounds of plant origin to foams increased their susceptibility to biodegradation.

/pdf/assessment-of-photodegradation-and-biodegradation-of-rpu-pir-1nrq6d4zkl.pdf

Assessment of Photodegradation and Biodegradation of RPU/PIR Foams Modified by Natural Compounds of Plant Origin

Two series of rigid polyurethane-polyisocyanurate foams (RPU/PIR) modified by cinnamon extract (series C_0t and CU_0t) were obtained. One RPU/PIR series contained a commercial flame retardant (C_0t) in the formulation. The other was produced without its participation (CU_0t). The basic properties of obtained foams, e.g., apparent density, brittleness, water absorption, compressive strength, flammability were examined. Afterwards, both series of foams (C_0t and CU_0t) were subjected to degradation in the climatic chamber, acting on samples of foams a defined temperature, humidity and UV radiation for a seven days. In this way, two successive series of RPU/PIR foams were obtained, which were designated, respectively, C_1t and CU_1t, Chosen properties of degraded foams such as: compressive strength, cellular structure by scanning electron microscopy (SEM) and changes of chemical structure by FTIR spectroscopy were determined. Compressive strength and the aging resistance was also determined (against the coefficient of compressive strength variation (CV). The possible replacement of a commercial flame retardant in polyurethane formulations by the antioxidant raw material (cinnamon extract) was evaluated.

Marek Isbrandt

Papers

The Use of Waste from the Production of Rapeseed Oil for Obtaining of New Polyurethane Composites

Effect of Evening Primrose Oil-Based Polyol on the Properties of Rigid Polyurethane⁻Polyisocyanurate Foams for Thermal Insulation.

Synthesis and application of new bio-polyols based on mustard oil for the production of selected polyurethane materials

Assessment of Photodegradation and Biodegradation of RPU/PIR Foams Modified by Natural Compounds of Plant Origin

The Effect of Accelerated Aging Conditions on the Properties of Rigid Polyurethane-Polyisocyanurate Foams Modified by Cinnamon Extract