Apparent Strength Research Articles

The interplay of excitonic delocalization and vibrational localization in optical lineshapes: A variational polaron approach.

The dynamics of molecular excitonic systems are complicated by a competition between electronic coupling (which drives delocalization) and vibrational-electronic (vibronic) interactions (which tend to encourage electronic localization). A particular challenge of molecular systems is that they typically possess a large number of independent vibrations, with frequencies often spanning the entire spectrum of relevant electronic energy gaps. Recent spectroscopic observations and numerical simulations on a water-soluble chlorophyll-binding protein (WSCP) reveal a transition between two regimes of vibronic behavior, a Redfield-like regime in which low-frequency vibrations respond to a delocalized excitonic state, and a Förster-like regime where high-frequency vibrations act as incoherent excitations on individual pigments. Although numerical simulations can reproduce these effects, there is a need for a simple, systematic theory that accurately describes the smooth transition between these two regimes in experimental spectra. Here we address this challenge by generalizing the variational polaron transform approach of [Bloemsma et al., Chem. Phys. 481, 250 (2016)] to include arbitrary bath densities for systems with or without symmetry. We benchmark this theory against both numerical matrix-diagonalization methods and experimental 77K fluorescence spectra for two WSCP variants, obtaining quite satisfactory agreement in both cases. We apply this theory to offer an explanation for the large loss in apparent electronic coupling in the WSCP Q57K mutant and to examine the likely impact of the interplay between excitonic delocalization and vibrational localization on vibrational sideband shapes and apparent coupling strengths in high-resolution optical spectra for chlorophyll-protein complexes such as WSCP.

Electrospun "Hard-Soft" Interpenetrating Nanofibrous Tissue Scaffolds Facilitating Enhanced Mechanical Strength and Cell Proliferation.

"Soft" hydrogel-based macroporous scaffolds have been widely used in tissue engineering and drug delivery applications due to their hydrated interfaces and macroporous structures, but have drawbacks related to their weak mechanics and often weak adhesion to cells. In contrast, "hard" poly(caprolactone) (PCL) electrospun fibrous networks have desirable mechanical strength and ductility but offer minimal interfacial hydration and thus limited capacity for cell proliferation. Herein, we demonstrate the fabrication of interpenetrating nanofibrous networks based on coelectrospun PCL and poly(oligoethylene glycol methacrylate) (POEGMA) nanofibers that exhibit the mechanical benefits of PCL but the interfacial hydration benefits of hydrogels. The electrospinning process results in partially aligned but interpenetrating fiber network with minimal internal phase separation, leading to anisotropic but strong mechanical properties even in the hydrated state; apparent ultimate tensile strengths of the swollen scaffolds ranged from 429 ± 39 kPa in the direction of fiber alignment (longitudinal) to 86 ± 25 kPa perpendicular to fiber alignment (cross-longitudinal), typical of PCL-based scaffolds and enabling efficient suture retention in different directions. However, contact angle measurements indicate hydrogel-like interfacial properties due to the presence of the interpenetrating POEGMA network. C2C12 myoblast proliferation in the PCL-POEGMA scaffolds was 50% higher than that observed on PCL-only scaffolds, a result attributed to the presence of the more hydrophilic POEGMA interpenetrating nanofiber network. Overall, this method is demonstrated to represent a facile single-step strategy to fabricate strong macroporous but still interfacially hydrophilic scaffolds for tissue engineering applications.

Porosity of green body: A potential essential factor regulating the making of sintered ceramsite from aluminum-based drinking water treatment residuals

Ceramsite is commonly applied in filtration systems for water treatment and aluminum (Al)-based drinking water treatment residue (DWTR) has been widely reported to have high potential to be recycled as main ingredient to make the sintered ceramsite. Various key factors affecting ceramsite making (e.g., composition and sintering temperature) have been identified to promote the beneficial recycling; however, according to sintering processes, this study hypothesized that porosity of green body was also a potential key factor, and then moisture content of green body (33 %-40 %) and particle size of DWTR (< 425 μm), which were the parameters initially considered for ceramsite making, were adopted to regulate the porosity for affecting characteristics and mechanisms investigation. The results verified the hypothesis and showed that increasing moisture content tended to decrease loss on ignition, apparent density, and bulk density, to increase water absorption, and to cause rougher surface of ceramsites, promoting the maximum Cu adsorption capacity of the ceramsite (estimated by Langmuir model); while at medium level of moisture content (e.g., 35 %), a relatively high compressive strength, strong Cu adsorbability (evaluated by Freundlich model), and low solubility in hydrochloric acid were found. Moreover, larger sized DWTR tended to increase loss on ignition, broken rate, solubility in hydrochloric acid, silt content, and water absorption, to reduce apparent density and compressive strength, and to cause rougher surface of the ceramsite, promoting the maximum adsorption capacity and decreasing the adsorbability of Cu. Further analysis suggested that moisture content was mainly through regulating total volume of voids and amount of raw materials to affect sintering, while particle size was mainly through regulating the contacting of particles. These results demonstrated the importance of the moisture contents of green body and the particle size of DWTR on affecting sintered ceramsite making, and porosity of green body was recommended to be taken as an essential factor when determining the optimal condition to make sintered ceramsite making.

Investigation of pull-out and mechanical performance of fibre reinforced concrete with recycled carbon fibres

This paper presents the pull-out bonding behaviour and mechanical performance of recycled carbon fibre (rCF) reinforced concrete based on the recent investigation of fibre reinforced concrete (FRC) with rCF recovered from pyrolysis. Single fibre pull-out tests have been carried out to identify the apparent interfacial shear strength of different types of rCF and virgin carbon fibre (vCF) to identify the fibre matrix connection. Furthermore, a series of tests have been carried out to identify the workability, compressive strength and tensile strength of FRC. Besides rCF, also vCF and steel fibre were used for fabrication of FRC test specimens. rCF have shown the same adhesion behaviour and strength like vCF. Furthermore, the use of unsized or acrylate-based sized rCF creates an adhesion between fibre and matrix material. During the pull-out tests, the failure does not occur as an adhesive crack between fibre and cement matrix, but as a cohesive crack in the cement matrix. The mechanical performance of FRC with rCF was compared with mortar and FRC with vCF and steel fibres. The results of compressive test conducted for FRC with vCF and rCF indicated that the influence of vCF and rCF on the compressive strength of FRC was insignificant. On the other hand, the results of tensile test conducted for FRC with vCF and rCF indicated that the tensile strength of FRC with rCF was at least 14.9% greater than that of FRC with vCF.

Influence of aluminum waste, hydrogen peroxide, and silica fume ratios on the mechanical and thermal characteristics of alkali-activated sustainable raw perlite based geopolymer paste

Geopolymer concretes have great potential in the sustainable construction industry in the future, as they can be produced without using cement and waste materials can be used as binders. This paper explores the use of sustainable, lightweight geopolymer pastes as construction materials using raw perlite as the primary ingredient. It achieves this by alkaline activation with additives such as waste aluminum lathe (Al), Hydrogen peroxide (H2O2) and silica fume (SF). The experiments were conducted in four groups: Al added in the 1st group, Al + Silica fume (SF) in the 2nd group, H2O2+SF in the 3rd group, and Al + H2O2 in the 4th group. Apparent density, compressive strength, flexural strength, and thermal conductivity tests were performed at 7, 14, and 28 days. SEM and EDX analyses were also conducted. The results showed that as the ratio of Al and H2O2, which have a aerating effect, increased, decrease in apparent density and strength was observed. However, when Al + SF were added together, significant improvements of 10%–20% were observed in compressive and flexural strengths, as well as apparent density. 35% water/pearlite ratio and 0.50% Al addition reduced compressive strength by 5% and lightened apparent density by 15%. At 40% water/pearlite ratio, 0.50% Al addition reduced compressive strength by 10% and lightened apparent density by 5%. According to these results, the best performance is obtained with 35% water/pearlite ratio and 0.50% Al addition Furthermore, the addition of lightweight SF resulted in good geomerization and reduced crack formation. This effect was evident in the internal structure based on SEM analysis. Interestingly, despite aluminum's overall high thermal conductivity, its incorporation into raw perlite-based pastes resulted in reduced thermal conductivity.

Material Compatibility in 4D Printing: Identifying the Optimal Combination for Programmable Multi-Material Structures.

This study identifies the optimal combination of active and passive thermoplastic materials for producing multi-material programmable 3D structures. These structures can undergo shape changes with varying radii of curvature over time when exposed to hot water. The research focuses on examining the thermal, thermomechanical, and mechanical properties of active (PLA) and passive (PRO-PLA, ABS, and TPU) materials. It also includes the experimental determination of the radius of curvature of the programmed 3D structures. The pairing of active PLA with passive PRO-PLA was found to be the most effective for creating complex programmable 3D structures capable of two-sided transformation. This efficacy is attributed to the adequate apparent shear strength, significant differences in thermomechanical shrinkage between the two materials, identical printing parameters for both materials, and the lowest bending storage modulus of PRO-PLA among the passive materials within the activation temperature range. Multi-material 3D printing has also proven to be a suitable method for producing programmable 3D structures for practical applications such as phone stands, phone cases, door hangers, etc. It facilitates the programming of the active material and ensures the dimensional stability of the passive components of programmable 3D structures during thermal activation.

Atmospheric-pressure plasma jet texturing of C/C composites for improved joint strength

This study explores the use of air-fed atmospheric pressure plasma jets (APPJs) as a pre-joining treatment for 3D carbon fiber-reinforced carbon matrix composites (C/C) with the aim of both creating a textured surface that resembles a brush structure and improving the joint strength.The effects of various treatment time lengths on the mass loss, etching depth, and surface texture were investigated using SEM and confocal microscopy. An optimal process time of 30 s was selected, while keeping the other process parameters fixed (air flow of 1750 l/h and nozzle-sample distance of 5 mm). Wetting tests were conducted at 1000 °C, on both untreated and pre-treated C/C surfaces by means of liquid TiCuNi brazing alloy, and low contact angles of about 20° were measured. C/C–TiCuNi–C/C and C/C–TiCuNi–Cu joints were then produced, and their interfacial reactivity was evaluated. The apparent shear strength measured for the APPJ-treated C/C–Cu joints was 140 % higher than the value recorded for the untreated joints, thus confirming the effectiveness of the treatment.Even though a further investigation is needed in which an optimization of the process parameters should be included, this preliminary study has revealed the viability of APPJ as a promising technique to enhance the bonding of C/C composites in dissimilar assemblies and to improve the joint quality.

Compressive failure and fragmentation of fused silica glass under quasi-static loading

This paper investigates the failure and post-failure fragmentation processes of fused silica glass cylinders under quasi-static compression, addressing the effects of surface finish on apparent strength. The compressive strengths of cylinders with side-polished sides under dry friction conditions (PSG-D) or lubricated conditions (PSG-L) were 2.52 GPa and 2.32 GPa, respectively. In situ observations showed that these specimens fractured from either the top or bottom contact surfaces, and that friction between the specimen and the loading anvil delayed the development of surface cracks. The unpolished rough side specimens (RSG-D) under dry friction conditions failed at a much lower level of 1.54 GPa, initiated by defects in the side surfaces. Specimens "explosively" fragmented upon failure. The propagation speed of the failure front ranged from 1800 to 2800 m/s. The average sizes and distributions of the fragments were determined through statistical analysis, with results showing reasonably close agreement with theoretical estimations.

Sustainable valorization of mining waste: Phosphate sludge repurposing for advanced ceramic production

Managing the vast quantities of waste constantly generated by mining activities is one of the major environmental and economic problems facing mankind today. Fluorapatite is separated from the associated gangue minerals by a series of crushing and screening, washing, and flotation processes. These processes produce a significant amount of phosphate sludge, which is stored on the mine site in drift rock and large surface ponds. One possible environmental option is to reuse it as an alternative raw material in ceramics and building materials. Consequently, two phosphate sludges from two different Moroccan towns, Youssoufia and Khouribga, were studied. Due to the complexity of these raw materials resulting from long geological processes, in-depth physical, chemical, mineralogical, and thermal characterization is required. Dry compressed powder pellets were sintered at 900 °C, 1000 °C, and 1100 °C for 2 h. The study focuses on the effect of sintering temperature on mineralogical transformations and ceramic properties such as apparent porosity, water absorption, and mechanical strength. At 1100 °C, a slight increase in density was observed for both phosphate sludges. Water absorption was reduced by 2.51 % in both sludges for pellets sintered at 1100 °C compared to those sintered at 900 °C. Mechanical strength improved significantly, with an increase of about 60 % for samples sintered at 1100 °C, recording 227 N for Youssoufia sludge and 247 N for Khouribga sludge. This work has provided new data on the physical, chemical, mineralogical, and thermal changes in ceramics as the sintering temperature increases. These data will be useful for the manufacture of high-value ceramics.

Study of Concrete Properties of Recycled Glass Fibres from Decommissioned Wind Turbine Blades

As an environmentally friendly and renewable energy solution, wind power is rapidly gaining favour worldwide due to its gentle impact on the environment. Nevertheless, the potential environmental risks posed by discarded wind turbine blades still need to be brought to our attention. Therefore, exploring ways to recycle and reuse discarded wind turbine blades has become an urgent task in the field of environmental protection. This study focuses on the incorporation of recycled glass fibres from crushed wind turbine blades into concrete to assess their benefits in engineering practice. In this study, we used four different particle sizes of recycled glass fibres, 0-5mm, 5-10mm, 10-15mm and 15-20mm, and incorporated them into the concrete at four different admixture levels of 0.2%, 0.4%, 0.6% and 0.8%. By comprehensively examining its workability, mechanical properties and microstructure, we found that although the incorporation of glass fibres reduced the apparent density, slump and compressive strength of the concrete to a certain extent, it significantly improved the split tensile and flexural strengths of the concrete, as well as effectively improved the brittleness of the material and enhanced its toughness. These findings reveal the feasibility of recycling glass fibres from decommissioned wind turbine blades and applying them to concrete. This study not only opens up a new path for environmentally friendly recycling and reuse of wind turbine blades, but also provides a valuable reference for practical engineering applications, with significant social and economic benefits.

Improvement of apparent IFSS and specific modulus of CNT yarns

Due to the high strength of carbon nanotubes (CNTs) significant effort has been devoted to incorporating them into fibers and composites. To maximize their potential in these areas, there must be strong interactions between the CNT structures and the matrix of the composite. For CNT yarn, progress in this area has been limited. In this work, we present a method for modifying CNT yarn which improves the apparent interfacial shear strength (IFSS) by up to 45 %, as measured by single yarn pullout testing. An ammonium peroxide mixture (APM) treatment method is used to modify the yarn, and this is followed by treatment with commercial sizing agents. A tensioned heat treatment method is also employed to limit the effect of APM treatment on strength and modulus. This method increased the specific modulus of CNT yarns by as much as 16 %. The combined heat and chemical treatments yield increases as high as 43 % in IFSS and 6 % in specific tensile modulus while tempering the decreases in specific tensile strength. The yarn is characterized by SEM, EDS and Raman spectroscopy to show surface carbon being removed from the yarn, seemingly without damaging the CNT structures in the yarn. The main mechanism for IFSS increase appears to be removal of non-graphitic material from the yarn and slight oxidation of the yarn surface. The increase seen in IFSS has the potential to improve the performance of CNT yarn/polymer matrix composites for aerospace applications.

Elastic response of trabecular bone under compression calculated using the firm and floppy boundary lattice element method

Micro-Finite Element analysis (μFEA) has become widely used in biomechanical research as a reliable tool for the prediction of bone mechanical properties within its microstructure such as apparent elastic modulus and strength. However, this method requires substantial computational resources and processing time. Here, we propose a computationally efficient alternative to FEA that can provide an accurate estimation of bone trabecular mechanical properties in a fast and quantitative way. A lattice element method (LEM) framework based on the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) open-source software package is employed to calculate the elastic response of trabecular bone cores. A novel procedure to handle pore-material boundaries is presented, referred to as the Firm and Floppy Boundary LEM (FFB-LEM). Our FFB-LEM calculations are compared to voxel- and geometry-based FEA benchmarks incorporating bovine and human trabecular bone cores imaged by micro Computed Tomography (μCT). Using 14 computer cores, the apparent elastic modulus calculation of a trabecular bone core from a μCT-based input with FFB-LEM required about 15 min, including conversion of the μCT data into a LAMMPS input file. In contrast, the FEA calculations on the same system including the mesh generation, required approximately 30 and 50 min for voxel- and geometry-based FEA, respectively. There were no statistically significant differences between FFB-LEM and voxel- or geometry-based FEA apparent elastic moduli (+24.3% or +7.41%, and +0.630% or -5.29% differences for bovine and human samples, respectively).

Risk Controls Identified in Action Plans Following Serious Incident Investigations in Secondary Care: A Qualitative Study.

The impact of incident investigations in improving patient safety may be linked to the quality of risk controls recommended in investigation reports. We aimed to identify the range and apparent strength of risk controls generated from investigations into serious incidents, map them against contributory factors identified in investigation reports, and characterize the nature of the risk controls proposed. We undertook a content analysis of 126 action plans of serious incident investigation reports from a multisite and multispeciality UK hospital over a 3-year period to identify the risk controls proposed. We coded each risk control against the contributory factor it aimed to address. Using a hierarchy of risk controls model, we assessed the strength of proposed risk controls. We used thematic analysis to characterize the nature of proposed risk controls. A substantial proportion (15%) of factors identified in investigation reports as contributing to serious incidents were not addressed by identifiable risk controls. Of the 822 proposed risk controls in action plans, most (74%) were assessed as weak, typically focusing on individualized interventions-even when the problems were organizational or systemic in character. The following 6 broad approaches to risk controls could be identified: improving individual or team performance; defining, standardizing, or reinforcing expected practice; improving the working environment; improving communication; process improvements; and disciplinary actions. The identified shortfalls in the quality of risk controls following serious incident investigations-including a 15% mismatch between contributory factors and aligned risk controls and 74% of proposed risk controls centering on weaker interventions-represent significant gaps in translating incident investigations into meaningful systemic improvements. Advancing the quality of risk controls after serious incident investigations will require involvement of human factors specialists in their design, a theory-of-change approach, evaluation, and curation and sharing of learning, all supported by a common framework.

A constitutive model for rate-dependency analysis of open hole woven composites under compression loading

The mechanical performance of composite materials under impact phenomena is of interest for several industries. Although the effect of the strain rate on composites significantly affects the behaviour of these materials, most studies describe the mechanical behaviour of CFRP laminates neglecting the strain rate dependence. This work presents a new constitutive model to numerically implement the change of in-plane properties of an plain weave CFRP (AGP193) over a wide range of strain rates (up to 500 s−1). Open hole compression tests are used to validate the model under quasi-static and dynamic loading. The importance of implementing the influence of strain rate on mechanical properties is illustrated by the maximum strength plot and the stress–strain history, both of which would be underestimated without the inclusion of strain rate in the model. The strain rates at the edge of the hole greatly exceed the average values in the sample, leading to an underestimation of the apparent strength up to 100% if the strain rate effect is not taken into account.

Preparation of barium alumino-silicate based ceramsite from bauxite, coal gangue and barite: Physical properties, microstructure, and γ-ray shielding behavior

Improving the strength of radiation shielding concrete and the safety of corresponding structures is crucial. However, radiation shielding ultra-high performance concrete (RS-UHPC) often faces the issues of high volume shrinkage and easy cracking. Using barium alumino-silicate-based ceramic as aggregate in concrete is a promising solution for its internal curing effect and excellent radiopacity. In this study, a barium alumino-silicate-based ceramsite (BASC) was developed using bauxite, coal gangue, and barite. The effects of boric anhydride (2 %, 5 %, 8 %), barite powder dosages (20 %, 40 %, 60 %, 80 %), and sintering temperature (1260°C, 1280°C, 1300°C, 1320°C) on the apparent density, compressive strength, and water absorption of the ceramsite were investigated. The microstructure and reaction mechanism of the BASC were analyzed using TG-DSC, XRD, SEM-EDS, and low-field NMR techniques. The results showed that the addition of barite increases the apparent density of ceramsite but decreases its strength. The ceramsite with 60 % barite calcined at 1320°C has a density of 3120 kg/m3, water adsorption of 11.19 %, and a cylinder compressive strength of 11.2 MPa. The prepared BASC ceramsite exhibits a highly connected pore structure and good water retention capacity at this temperature. The ceramsite has many closely packed celsian and corundum crystallites, which give it good mechanical strength. Finally, the gamma-ray attenuation and autogenous shrinkage of UHPC prepared with this ceramsite was tested. The linear attenuation coefficient of the BASC-UHPC is 0.176 cm−1, comparable to UHPC prepared with lead glass. The BASC replacement for quartz sand reduces the 28d autogenous shrinkage of UHPC by 55.0 %. The research results can guide the application of BAS-based ceramsite in radiation-shielding ultra-high performance concrete.

Mechanical characterization of ultrasonically welded CF/PEEK laminates by short beam shear test

Bond strength between composite plates has often been evaluated using single-lap shear tests, with the difficulty of having the characteristics of the entire bond area reflected in the results. To overcome this limitation, a short-beam shear test was performed in this study. The specimens were fabricated by ultrasonic welding using carbon fiber reinforced polyether ether ketone laminates as the adherend and a resin mesh. The effect on mechanical characterization was investigated by varying the thickness and stacking configuration of the adherend and the welding energy. The highest apparent interlaminar shear strength was observed when an approximately 3 mm thick adherend of the quasi-isotropic laminate was welded, and the strength was approximately 17% lower than that of non-welded laminates.

Production of Glass Foam in a Microwave Oven Using Agro-Industrial Waste as Raw Material

Climate change is characterized by shifts in temperature and climate patterns. Constructing new high-rise environments using materials that incorporate agro-industrial waste can help mitigate this impact without compromising technological properties. This study produced vitreous foams intended to replace natural aggregates in lightweight concrete partially. These foams were sintered in a microwave oven at temperatures of 750 °C, 800 °C, and 850 °C, utilizing glass powder and sugarcane bagasse ash as raw materials. The homogenization and preparation of these materials were conducted through a mechanical pelletization process, employing a constant rotation engine at approximately 40 rpm. The efficacy of microwave sintering was assessed by comparing the outcomes with those from sintering in a conventional electric muffle furnace under identical conditions. The results indicated that the microwave-sintered vitreous foams exhibited the following values for apparent density (≤0.30 g/cm3), porosity (86% to 94%), and compressive strength (0.48 MPa to 0.58 MPa), which align with the global standards for commercial vitreous foams. The microwave sintering route proved to be economically feasible by reducing sintering time and, consequently, energy costs, without sacrificing technological properties. The materials produced in this study offer a promising solution to minimize the environmental impact associated with constructing new buildings, particularly tall structures. Additionally, they support the circular economy by converting waste into valuable by-products.

A round-robin study on the tensile characterization of single fibres: A multifactorial analysis and recommendations for more reliable results

In this benchmark, the tensile properties of three types of organic fibres – flax, hemp and aramid − were determined using single-fibre tensile tests performed by nine research groups. Flax and hemp were chosen due to their prevalence among European fibre plants. Aramid was selected for its synthetic nature and comparable dimensional properties. Due to the morphological complexity and variability of plant fibres, the scatter in the apparent tangent modulus and strength is more pronounced for flax and hemp compared to aramid. The primary source of scatter in the tensile properties results from human factors and experimental procedures, particularly regarding the fibre selection, the measurement of the fibre cross-sectional area and of the tensile strain. The post-processing procedure also turns out to be a key factor. Finally, recommendations and guidelines for best practices are proposed to reduce the main sources of dispersion associated with the reproducibility of single fibre tensile tests.

Nascent chains derived from a foldable protein sequence interact with specific ribosomal surface sites near the exit tunnel

In order to become bioactive, proteins must be translated and protected from aggregation during biosynthesis. The ribosome and molecular chaperones play a key role in this process. Ribosome-bound nascent chains (RNCs) of intrinsically disordered proteins and RNCs bearing a signal/arrest sequence are known to interact with ribosomal proteins. However, in the case of RNCs bearing foldable protein sequences, not much information is available on these interactions. Here, via a combination of chemical crosslinking and time-resolved fluorescence-anisotropy, we find that nascent chains of the foldable globin apoHmp1–140 interact with ribosomal protein L23 and have a freely-tumbling non-interacting N-terminal compact region comprising 63–94 residues. Longer RNCs (apoHmp1–189) also interact with an additional yet unidentified ribosomal protein, as well as with chaperones. Surprisingly, the apparent strength of RNC/r-protein interactions does not depend on nascent-chain sequence. Overall, foldable nascent chains establish and expand interactions with selected ribosomal proteins and chaperones, as they get longer. These data are significant because they reveal the interplay between independent conformational sampling and nascent-protein interactions with the ribosomal surface.

Cellulose-Based Polyurethane Foams of Low Flammability.

Decreasing oil resources creates the need to search for raw materials in the biosphere, which can be converted into polyols suitable for obtaining polyurethane foams (PUF). One such low-cost and reproducible biopolymer is cellulose. There are not many examples of cellulose-derived polyols due to the sluggish reactivity of cellulose itself. Recently, cellulose and its hydroxypropyl derivatives were applied as source materials to obtain polyols, further converted into biodegradable rigid polyurethane foams (PUFs). Those PUFs were flammable. Here, we describe our efforts to modify such PUFs in order to decrease their flammability. We obtained an ester from diethylene glycol and phosphoric(III) acid and used it as a reactive flame retardant in the synthesis of polyol-containing hydroxypropyl derivative of cellulose. The cellulose-based polyol was characterized by infrared spectra (IR) and proton nuclear magnetic resonance (1H-NMR) methods. Its properties, such as density, viscosity, surface tension, and hydroxyl numbers, were determined. Melamine was also added to the foamed composition as an additive flame retardant, obtaining PUFs, which were characterized by apparent density, water uptake, dimension stability, heat conductance, compressive strength, and heat resistance at 150 and 175 °C. Obtained rigid PUFs were tested for flammability by determining oxygen index, horizontal flammability test, and calorimetric analysis. Obtained rigid PUFs showed improved flammability resistance in comparison with non-modified PUFs and classic PUFs.