Phenolic Foam Research Articles

Light intensity and rooting substrates are important for rooting growth and development of Zabelia tyaihyonii cuttings

The Korean endemic species Zabelia tyaihyonii grows only in limited native areas of Chungcheongbuk-do and Gangwon-do provinces. This species is currently listed as an endangered taxon in the International Union for Conservation of Nature Red List, recommending conservation of its genetic resources. Few studies have addressed its asexual propagation. The effect of different light intensities (200, 300, and 400 μmol m−2 s−1 PPFD) and rooting substrates (phenolic foam, decomposed granite soil, and pearlite) on growth and development of Z. tyaihyonii cuttings was evaluated. The rooting percentage was the highest in phenolic foam with 300 μmol m−2 s−1 PPFD, but new shoots were formed in decomposed granite soil with 400 μmol m−2 s−1 PPFD, with positive growth and development compared with that in other planting conditions concerning rooting percentage, root length, number of roots, and fresh and dry mass of the shoots and roots. Thus, phenolic foam with 300 μmol m−2 s−1 PPFD can support good growth when propagating Z. tyaihyonii from cuttings, but decomposed granite soil with 400 μmol m−2 s−1 PPFD may be a more suitable choice for their efficient growth and development.

Lignin demethylation for modifying halloysite nanotubes towards robust phenolic foams with excellent thermal insulation and flame retardancy

AbstractThe demethylation of lignin was conducted under HBr catalysis and microwave irradiation resulting in a demethylation rate of 21.4% as calculated from1H NMR. The demethylated lignin (DL) was applied to modify halloysite nanotubes (HNTs) forming a nano‐hybrid containing 16.5 wt% of DL according to TGA results, and showing rough surfaces dotted with DL particles as observed through TEM. HNTs‐DL was introduced into resol resin synthesis where DL molecules participate in phenol‐formaldehyde polycondensation, functioning as a binder to connect the inorganic HNTs framework and the organic resol resin molecules, giving an increase in flow activation energy as calculated from rheological results. The prepared phenolic foam containing 0.4 wt% of HNTs‐DL shows a significant increase by 37.7% in compressive strength and a decrease by 27.3% in pulverization ratio compared to the neat phenolic foam, and exhibits uniform cells with the highest cell density as observed in SEM, explaining its improved performance in thermal insulation and flame retardancy.

Adopting combination of passive design strategies to optimize building energy needs

The paper’s main goal is to analyze the efficiency of roof and wall systems based on varying insulating material layers in the tropical climatic region of Vijayawada, Andhra Pradesh, India. This research is carried out on “e-QUEST” software for energy analysis which is determined on monthly basis and the results gave evidence about energy consumption of building envelope and its operational life cycle costing. The wall and roof system have been studied for computation of the operating energy requirements and its subsequent carbon footprints which comes under concept of sustainability of building. The materials identified for insulating roof are vacuum insulated panels, wool glass, phenolic foam, expanded polystyrene, polystyrene, and for wall are cellulose, fiber glass, mineral wool, polystyrene, aero gel. Due to both have insulation of wall and roof systems the passage a source of heat minimized because of which the cooling demand is reduced on building and ultimately leads to lowering of energy consumption. Hence this study is crucial to understand the resident indoor air comfort, environmental and long-term economic benefits.

Economic affordable carbonized phenolic foam anode with controlled structure for microbial fuel cells

In microbial fuel cells (MFCs), the anode electrode is a core structure as the catalytic area of exoelectrogens. The anode material for large-scale MFCs needs excellent bioelectrochemical performance and low fabrication costs. Herein, carbonized phenolic foam with controllable porous structures was developed as the bio-capacitor of MFCs. The proportion of sodium dodecylbenzene sulfonate (SDBS), which improved mixing and dissolution between the resin liquid and the foaming agent, was adjusted to form open pores on the foam film and skeletons, which promoted both the capacitance and biocompatibility of the anode. Within SDBS proportion from 0 to 1.2 wt%, the anode SPF-9 (0.9 wt%) obtained the best capacitance (37 ± 0.13 F g−1), electrochemical active surface area (87 ± 0.38 cm2) and hydrophilia (contact angle 79 ± 0.2°). The MFCs with SPF-9 obtained the highest power density of 3980 ± 178 mW m−2, while those of carbon-cloth anodes were 1600 ± 28 mW m–2. The biofilm of SPF-9 also demonstrated higher activity and obtained larger abundance of exoelectrogens (68 ± 0.38%). The increased capacitance and biocompatibility mainly resulted in the good performance of SPF-9. The carbonized phenolic foam anode material was worth considering for the future application of MFCs due to its superior electrochemical performance and large-quantity fabrication capability.

Plant growth regulators and rooting substrates affect growth and development of Salix koriyanagi cuttings

Salix koriyanagi is an endemic species with high conservation priority in Korea because of its isolated distribution. We evaluated the effects of plant growth regulators (PGRs), including 500 mg L-1 or 1000 mg L-1 IBA, 1000 mg L-1 or 2000 mg L-1 NAA and rootone, and rooting substrates such as phenolic foam, bonded medium, and perlite on the growth and development of S. koriyanagi cuttings. The highest percent rooting was observed in the cuttings treated with 500 mg L-1 IBA in phenolic foam. PGR treatment increased the number of roots on the cuttings, and the highest root fresh and dry weights were observed in the cuttings treated with 500 mg L-1 IBA in phenolic foam. These results suggest that treatment with 500 mg L-1 IBA in phenolic foam was the most effective for root initiation in this species and can be used for the mass production of Korean endemic S. koriyanagi through cuttings.

Flexible and double-layered photothermal material based on resorcinol-formaldehyde foam for solar assisted water desalination

Solar-assisted steam generation is considered as an environmental-friendly and feasible technology to effectively harvest solar energy, which has been widely in water purification, seawater desalination and steam sterilization. In this work, we demonstrated flexible and scalable double-layered photothermal material (named as ppy-RF) based on phenolic aldehyde foam and polypyrrole coating as a light adsorption layer for solar steam generation. The resulting ppy-RF foam possessed interpenetrated and macroporous network with high porosity (>86%), superhydrophilicity, low thermal conductivity (0.0396 W m-1 K-1) and almost 100% absorbance (500-2500 nm). These characteristics make ppy-RF foam rapid water transportation and steam generation with an energy conversion efficiency of 90% under solar illumination of 1 kW h-1. Furthermore, the ppy-RF foam exhibits outstanding salt-resistant performance and long-term stability for desalination even in high salinity brine (20 wt%). By combination of its porous, flexible and monolithic configuration obtained by a simple and scalable fabrication method with efficient solar-thermal conversion ability and salt-resistance, the ppy-RF foam shows great potential in the application of clean water production and brine desalination.

Progress in Bio‐Based Phenolic Foams: Synthesis, Properties, and Applications

AbstractPhenolic foams are widely used as insulation materials in construction, transportation, and spacecraft industries due to their flame retardancy, thermal stability, low toxicity, and low smoke generation. However, these foams are typically produced from non‐renewable resources. With increasing environmental pollution, volatility in petrochemical prices, and depletion of petroleum resources, the demand for polymeric materials produced from renewable resources is ever‐increasing. Numerous recent studies have introduced biomass as an alternative resource for petroleum‐based raw materials for producing phenolic foams. In addition to their environmental benefits, bio‐based phenolic foams exhibit properties similar or even superior to traditional phenolic foams. In this review, traditional phenolic foams are discussed. Recent progresses on synthesis of foams from bio‐based resources, modification of the bio‐alternatives, performance enhancements, and comparison with traditional phenolic foams are outlined. Challenges and methods to further improve performance characteristics of bio‐based phenolic foams and their expanding range of applications are highlighted.

Preparation of nano-TiN composite phenolic foam decoration materials

This paper takes nano-titanium nitride (TiN) composite phenolic foam decoration materials as the research object, aims to analyze and prepare the best performance insulation building decoration materials, and provides reference and reference for the improvement and development of building insulation decoration materials in my country. In this paper, the experimental method, comparative method, data analysis method and literature analysis method are used in this study. First, a brief overview of nano-TiN and phenolic foam materials, their application in various fields are introduced, and then nano-nitriding Preparation experiment of titanium composite phenolic foam decoration materials, discussed and analyzed the effects of nano-TiN, foam stabilizer, foaming agent and curing agent on the preparation of phenolic foam decoration materials, and finally compared phenolic foam decoration materials with traditional insulation decoration materials The difference between the advantages of phenolic foam decoration materials and traditional insulation decoration materials in the limit oxygen index and the maximum smoke density. The research results show that under the influence of nano-TiN, the thermal conductivity of phenolic foam material has decreased from 35.23 to 29.65, which greatly improves the thermal insulation and thermal insulation effect; when the amount of foam stabilizer and foaming agent is 5 wt% and 7 wt%, The foam material has the best water absorption effect; the addition of curing agent greatly improves the flame-retardant performance of the foam material; the limiting oxygen index and the maximum smoke density of the phenolic foam are 48.9% and 3.7%, respectively, which is better than traditional building insulation materials flame retardant and low smoke. It is believed that the composite phenolic foam decorative material based on nano-TiN will have a broader market application prospect.

An Investigation of Foam Concrete Usability as a Cavity Filler Material in Mining

Strength and deformability properties of different cavity filler materials of a phenolic foam, a polyurethane based foam and a foam concrete (FC) mix were investigated and compared in this study. Instead of using polymeric foam fillers, FC usage was found to supply better load bearing capacity and modulus of elasticity values. The fresh FC mixes consisting of cement, water and foaming agents are able to be filled into the mine cavities. In the cavity filling applications, typical polymer foams cause support reactions with low stiffnesses and let the rock mass at the roof to be loosened. A relatively stiff cavity filling material can help rock masses to bear itself by prevention of the loosening. To avoid excessive deformations of the rock masses, the deformation modulus is an important parameter as well as the strength property. The FC filler materials were found advantageous because of economical supply of improved load bearing capacities and stiffness values for controlling the rock mass convergences.

Production of tomato seedlings using seeds pelleted with Natrum muriaticum and submitted to saline stress

The development and yield of plants is directly related to the effects of salinity. There are several reports in scientific studies of significant reduction in the growth and production of tomato in soils with high electrical conductivity. The correction or recovery of salinized soils, although technically possible, is a slow and very expensive process, making it necessary to develop new technologies. The objective of this study is to evaluate the production of tomato (Solanum lycopersicon L.) seedlings using seeds pelleted with a homeopathic preparation of Natrum muriaticum (Nat-m) submitted to saline stress. The treatments consisted of the pelletization of tomato seeds with six dynamizations of Nat-m (3cH, 5cH, 7cH, 9cH, 11cH and 13cH). Coated or uncoated seeds (controls) were placed in phenolic foam blocks, kept in plastic trays previously moistened with 50 mM NaCl saline solution (2.922 g.L-1 of NaCl, electrical conductivity = 4.5 dSm-1) and nutrient solution (0.15 dS.m-1) at half the ionic strength, containing 4, 1, 2, 1, 0.5 and 0.5 mmol.L-1 of N, P, K, Ca, Mg and S, and 17.5, 9.5, 10.5, 2, 0.45 and 0.35 mmol.L-1 of Fe, Mn, Zn, Cu and Mo, respectively. The variables evaluated were germination percentage, germination speed index, shoot length, leaf area, number of leaves, root volume, root dry matter, and shoot dry matter. The treatments pelleted seeds/talc Nat-m 5cH and pelleted seeds/talc Nat-m 7cH increased all variables evaluated. They differed statistically from the controls, with a positive response for the development of tomato seedlings under disequilibrium conditions.

Growing Mediums for Medical Cannabis Production in North America

The production and use of cannabis for medical purposes has been legalized in Canada and several states in the USA. Due to the historically illegal nature of cannabis, there is very little information available in academic publications about appropriate growing media for growing cannabis. The purpose of this review is to provide an overview of the most commonly used growing media for the production of medical cannabis and to discuss their advantages and disadvantages. Based on current knowledge, there is a general agreement on the properties of a suitable growing medium within the cannabis industry. However, there is little consensus among growers on the best growing medium to grow cannabis. Different categories of growing media are widely used in North America. In this review, we classified them into several main categories principally based on the type of material used in their composition and the growth stages of the plant. The main categories include: coir-based, peat-based, rockwool, phenolic foam, and living soil. It is not easy to suggest the best growing medium for cannabis production. Each category of growing medium has its strengths and weaknesses. Overall, it seems that coir-based products are the intermediate substrates showing more advantages and less weakness; however, choosing any of these categories depends a lot on the growing technique and production system. Future research should focus on determining the optimal level of growing media properties to produce high yielding medical cannabis with the desired quality.

SEM morphology, porosity, swelling and hardness test of foam from dried albumin -gambier tannins

Phenolic foam is a product of natural albumin made from gambier tannins, water, and other additional substances. The interaction of albumin and tannin polyphenols can be considered as complex formation because of the secondary bonds that exist between them. Albumin-based foam is produced by a high-speed mixing system, therefore obtaining a homogeneous emulsion of gas dispersion in the oven-dried liquid. The aim of this study was to examine the morphological structure, porosity, swelling, and hardness of a foam made from several concentrations of dried albumin mixed with gambier tannins. The results showed that there werelarge, small, regular and cracked pore structures, with an average porosity of 73.16%, swelling of 45.55% and hardness of 22.09 (N/cm2) depending on albumin concentration used.

Effective Halogen- and Phosphorus-Free Polyphenylene Ether Resin-Based Flame-Retardant Foam.

A novel halogen- and phosphorus-free intrinsic flame-retardant foam is fabricated from curable phenol-terminated polyphenylene ether resin with a high molecular weight using phenol, formaldehyde, and diphenyl ether as starting materials. The limiting oxygen index (LOI) of the pure foam is 24.90% ± 0.28. When 0.5 wt % silica sol is added, the LOI of the foam (SPF-0.5) is up to 28.5% ± 0.15 and both the combustion heat release rate and total combustion heat are low. Moreover, the SPF-0.5 foam exhibits high carbon residue, high compressive strength, and low pulverization rate and is superior to some previously reported phenolic foam. The flame-retardant mechanism includes the condensed-phase flame retardation and the gas-phase flame retardation, with the former being the main step, which is based on the high cross-linking density, the higher strength and smaller size of foam cells, and the formation of a carbon–silicon compound in the foam. This halogen- and phosphorous-free flame-retardant foam is also environmentally benign.

Influential factors on thermal performance of energy slabs equipped with an insulation layer

The energy slab is a slab structure in a building that encases heat exchangers to utilize geothermal energy for heating and cooling of the building. In the energy slabs, the presence of thermal insulation layers is crucially important compared to those of the conventional Ground Heat Exchanger (GHEX). In this paper, a computational fluid dynamics (CFD) model was developed by calibrating with the result of the in-situ thermal performance test (TPT) to comprehensively assess the effect of influential factors on the thermal performance of energy slabs. Note that the thermal conductivity of ground formations and the flow rate of working fluid significantly influence the thermal performance of energy slabs. Especially in the energy slabs, the existence of a thermal insulation layer with appropriate thermal properties is significantly important to relieve the thermal interference induced by ambient air temperature. Considering the performance of thermal insulation and economic feasibility, a PF (phenol foam) board is found to be the suitable material for the energy slab considered in this paper.

Effect of Catalysts and Curing Temperature on the Properties of Biosourced Phenolic Foams

Biosourced phenolic foams (BPFs) based on lignin alkaline liquor and tannins were successfully synthesized without using formaldehyde and any blowing agent. The influence of three sorts of catalysis (acid, alkaline, and thermal) and different curing temperatures (80, 100, and 120 °C) on the final properties of the foams was investigated. Concerning foam morphology, scanning electron microscopy observations showed that a low-curing temperature could significantly reduce the cell size and improve the structural homogeneity of phenolic foams. It was also proved by Fourier transform infrared spectroscopy analysis that alkaline catalysis promotes aromatic functions, whereas the polycondensation reaction and ether linkages were dominant under acid catalysis. Thermogravimetric analysis, cone calorimetry, and Bunsen burner test revealed that the foams prepared under alkaline catalysis displayed the best thermal stability and fire resistance. The obtained BPFs exhibited a high compressive strength (0.11–1.65 MPa) and good thermal conductivity (41.5–50.55 mW/m·K), which are linearly proportional to the foam densities. Accordingly, they could be used as a thermal insulator for the construction or retrofitting of buildings.

Substantial emissions of nitrated aromatic compounds in the particle and gas phases in the waste gases from eight industries

Nitrated aromatic compounds, the ubiquitous nitrogen-containing organic pollutants, impact the environment and organisms adversely. As industrial raw materials and intermediates, nitrated aromatic compounds and their aromatic precursors are widely employed in the industrial production activities. Nevertheless, their emission from industrial waste gases has so far not been studied extensively. In this study, the concentrations of 12 nitrated aromatic compounds in the particle and gas phases downwind of 16 factories encompassing eight industries (i.e., pharmaceutical, weaving and dyeing, herbicide, explosive, painting, phenolic resin, paper pulp and polystyrene foam industries), were determined by ultra-high-performance liquid chromatography-mass spectrometry. Their concentrations in the particle and gas phases from different factories ranged from 114.7 ± 63.5 to 296.6 ± 62.5 ng m−3 and 148.7 ± 7.4 to 309.8 ± 26.2 ng m−3, respectively, thus, exhibiting significantly high concentrations as compared to the background sites. Among the 12 detected species, 4-nitrophenol, 5-nitrosalicylic acid, 3-nitrosalicylic acid and 4-methyl-2,6-dinitrophenol were observed to be the predominant species, with total fractions up to 47.9–72.3% and 63.1–70.3% in the particle and gas phases, respectively. Their emission profiles with respect to the industrial activities exhibited large discrepancies as compared to the combustion sources, thus, indicating different formation mechanisms. The emission ratios of particulate nitrated aromatic compounds owing to the industrial activities were estimated between 0.5 ± 0.2 and 4.3 ± 1.5 ng μg−1, which were higher than or comparable to those from various combustion sources. The findings from this study confirm the industrial emission to be an important source of nitrated aromatic compounds in the atmosphere. The substantial emissions of nitrated aromatic compounds from various industries reported in this study provide the fundamental basis for further emission estimation and pollution control.

Lignin-Based Phenolic Foam Reinforced by Poplar Fiber and Isocyanate-Terminated Polyurethane Prepolymer.

Phenolic foams (PFs) are lightweight (<200 kg/m3), high-quality, and inexpensive thermal insulation materials whose heat and fire resistance are much better than those of foam plastics such as polyurethane and polystyrene. They are especially suitable for use as insulation in chemical, petroleum, construction, and other fields that are prone to fires. However, PFs have poor mechanical properties, poor abrasion resistance, and easy pulverization. In this paper, a polyurethane prepolymer was treated with an isocyanate, and then the isocyanate-terminated polyurethane prepolymer and poplar powder were used to prepare modified lignin-based phenolic foams (PUPFs), which improved the abrasion resistance and decreased the pulverization of the foam. The foam composites were comprehensively evaluated by characterizing their chemical structures, surface morphologies, mechanical properties, thermal conductivities, and flame-retardant properties. The pulverization ratio was reduced by 43.5%, and the thermal insulation performance and flame-retardancy (LOI) were improved. Compared with other methods to obtain lignin-based phenolic foam composites with anti-pulverization and flame-retardant properties, the hybrid reinforcement of foam composites with an isocyanate-terminated polyurethane prepolymer and poplar powder offers a novel strategy for an environmentally friendly alternative to the use of woody fibers.

Preparation of carbon foam-reinforced carbon aerogels and their copyrolysis mechanism

This paper reports a copyrolysis strategy for preparing carbon foam-reinforced carbon aerogels with low thermal conductivity. Three types of precarbonized foams derived from commercial (0.03 g/cm 3 ), low-density (0.03 g/cm 3 ), and medium-density (0.06 g/cm 3 ) phenolic resin foams were impregnated with resorcinol-formaldehyde (RF) sol, aged at 50 °C, exchanged with ethanol, dried supercritically, and finally carbonized by copyrolysis at temperatures ranging from 600 to 900 °C. The linear shrinkage characteristics during the pyrolysis of the aerogels, foams, and composites at different temperatures were measured to analyze the formation process of the gap at the composite interface. The compressive strength of the composites was found to be higher than that of the carbon foam components. The thermal conductivity of the three composites was gauged at temperatures ranging from 25 to 1900 °C. The CCH-900 (commercial carbon foam-reinforced carbon aerogels after copyrolysis at 900 °C) composite exhibited the lowest high-temperature thermal conductivity (λ 1900 °C = 0.25 W/m·K). Finally, the copyrolysis mechanism of the RF aerogels and phenolic resin foams was analyzed through XPS, TG-MS, and Fourier transform infrared spectrometer. • A novel co-pyrolysis strategy is proposed to reduce the interfacial gap of carbon foam-reinforced carbon aerogel composites. • The composites constructed by the phenolic resin foams with wall film exhibit low high temperature thermal conductivity. • The co-pyrolysis mechanism between phenolic aerogels and phenolic resin foams are proposed.

Physical factors increased quantity and quality of micropropagated shoots of Cannabis sativa L. in a repeated harvest system with ex vitro rooting

Micropropagation is a preferred method to propagate clean, clonal stock plants. Subculture is labor intensive and costly. In vitro hedging can reduce hood labor and was demonstrated with cannabis (Cannabis sativa L. ‘US Nursery Cherry 1’) using both apical and nodal explants at four different photosynthetic photon flux densities (25–167 μmol m−2 s−1) in vessels with vented or non-vented closures. The numbers of harvested shoot tips from four repeated 3-wk cutting cycles without subculture and the quality of the harvested shoot tips during ex vitro rooting in phenolic foam plugs were observed. The number of shoot tips harvested in non-vented vessels increased over four repeated cycles; however, there was a decline in number of shoot tips harvested from vented vessels in the fourth cycle due to excessive drying and collapse of the agar matric. The number of shoot tips harvested through repeated cycles was increased with light intensity. Nearly 100% of the micro-cuttings from optimal light and ventilation rooted ex vitro. Most plantlets had roots that penetrated the exterior surfaces of the plug after 2 wk. The number of leaves per rooted plantlet ex vitro increased with light intensity in vitro. Micropropagation labor efficiency could be improved by using a multi-cycle cutting process which would allow the same material to be repeatedly cut from rooted bases instead of subcultured. In a system with strong apical dominance, enhanced axillary divisions of shoot tip explants over successive cycles of cutting, without the need of exogenous PGRs, were further increased by appropriate in vitro factors, light, and ventilation, presenting labor saving potential compared to standard, single-cut system in common use.

Climate Resilience of Internally-Insulated Historic Masonry Assemblies: Comparison of Moisture Risk under Current and Future Climate Scenarios

The conservation of cultural heritage built of historical brick masonry alongside meeting targets in energy reduction will most likely require widespread installation of internal wall insulation (IWI). In London, traditional buildings (pre-1919) make up 40% of the existing stock and insulating from the interior is a likely retrofit solution for solid brick walls. Adding insulation may introduce a higher risk to moisture accumulation and consequences such as mould growth and material decay. To investigate resilience to future moisture loads, three interior insulation assemblies (conforming to two U-value guidelines) were simulated in DELPHIN under reference, near-future (2040), and far-future climate (2080) scenarios. Calcium silicate, phenolic foam, and wood fibre assemblies were simulated. The reference year climate file was compiled from observed data and future files developed using the UK Climate Projections 2018 (UKCP18). Assemblies were evaluated for moisture accumulation, mould growth risk, and freeze-thaw (FT) risk. Results show low-to-medium risks in 2040 and high risks in 2080, assemblies of higher absorptivity and thinner insulation comparatively performing best. The calcium silicate assembly fared best for moisture performance; however, all assemblies will be subject to high moisture risk levels in the far future and responsible retrofits must take this and alternative design solutions into account.