Urea-formaldehyde Foam Research Articles

Impact of Location and Insulation Material on Energy Performance of Residential Buildings as per Saudi Building Code (SBC) 601/602 in Saudi Arabia

In hot and humid climates, a significant part of the energy is used to cool the building. There are several ways to reduce this air conditioning load, but one standout is through the selection and design of the right building envelope and its components. The thermal characteristics of the building envelope, in particular the thermal resistance of the insulation used, have an impact on the thermal and energy performance of building structures. Thermal conductivity, which indicates the ability of heat to move through a material given a temperature difference, is the primary factor affecting the performance of a thermal insulation material. Both temperature and humidity changes can affect a material's thermal conductivity value, which can then change. In fact, due to the fluctuating ambient air temperature and solar radiation, thermal insulation in buildings is susceptible to significant and continuous temperature variations. Thermal insulation used in building walls and roofs helps to reduce the energy demand of the building. It improves thermal comfort and, if used correctly, reduces the operational cost of the building. The present study has focused on the effects of location and insulation material on the energy performance of a residential building by considering five climatic locations in the Kingdom of Saudi Arabia (KSA). Five commonly used insulation materials with different thermal characteristics, namely polyurethane board (PU), expanded polystyrene (EPS), glass wool (GW), urea-formaldehyde foam (UFF), and expanded perlite (EP), were analyzed under various climatic zones as per the Saudi Building Code 601/602. The selected cities were categorized based on cooling degree days (CDD) and outdoor dry bulb temperature (DBT) as hot, very hot, and extremely hot climatic zones. Insulation improves thermal comfort and, if used correctly, reduces running costs. Experiments were conducted to determine the thermal conductivity, and the energy simulation was performed by employing IES-VE software for various insulation options. The findings indicate that the location has a significant impact on the energy performance of the insulating materials. The energy saving potential of polyurethane board (PU) insulation is more attractive in cities with higher DBTs and CDDs than in cities with lower DBTs and CDDs. The benefit of installing insulation ranged from a 2 to 14% decrease in energy demand for the climate zones studied. The sensitivity analysis showed that the energy saving potential of the insulation materials is sensitive to the set-point temperature (ST) band.

In situ preparation of intrinsic flame-retardant urea formaldehyde/carbon nanotubes nanocomposite foam: structure and reinforcing mechanism

ABSTRACT Urea-formaldehyde (UF)/carboxylated carbon nanotubes (CNTs-COOH) nanocomposite foams were prepared via in-situ polymerization. Chemical bonding and hydrogen bonding interactions formed between CNTs-COOH and UF matrix. UF resin adhered onto the ektexine of CNTs-COOH and grafting ratio of 496.41% was achieved. UF/CNTs-COOH foam showed smaller cell size, narrower cell size distribution and lower water absorption compared with UF foam. Introduction of 0.25 wt% CNTs-COOH resulted in 58.43% increase in compressive strength. CNTs-COOH were pulled out with surface covered with UF resin under stress and the failure mode was the destruction of matrix around interfacial layer. UL-94V-0 rating was achieved for the composite foams.

Facile construction of robust super-hydrophobic coating for urea-formaldehyde foam: Durable hydrophobicity and Self-cleaning ability

A robust super-hydrophobic coating was constructed on the surface of urea–formaldehyde (UF) foams through a facile immersion process in SiO2 nanoparticle-dispersed ethanol solution with dodecyltrimethoxysilane (DTMS) as compatibilizer. By introduction of DTMS, strong hydrogen bonding interaction formed between SiO2 coating and UF foam. The UF-g-SiO2/DTMS foam showed a water contact angle (CA) of 157.2° and a sliding angle (SA) of 3°, and after long-term immersion, very slight change of CA and SA was observed, while the water absorption ratio was 36.89% lower than that of pristine sample, displaying durable super-hydrophobicity. The UF-g-SiO2/DTMS foam showed excellent self-cleaning ability. Introduction of DTMS improved the dispersion of SiO2 in solution and thus lots of bamboo shoot-shaped granular protrusions of SiO2 nanoparticles at micro/nano-scale formed on the foam surface during treatment process, while the strong interfacial interaction prevented SiO2 nanoparticles from falling off the foam after long-term immersion, and thus durable hydrophobicity was achieved.

Prefabricated Dome Structures with Walls Made of Soil Composites and Urea-Formaldehyde Foam Insulation (UFFI) as a Way to Solve Transport Infrastructure Problems in Permafrost Regions

The territory of Russia extends from West to East for more than 10 thousand kilometres. Recently, this land has become of strategic importance on the international arena. The future development of Russia and its international situation will largely depend on the timely development of these territories. The development of infrastructure in permafrost regions requires the use of not only special construction technologies and materials, but also special design solutions that can reduce further operating costs, while maintaining the most comfortable conditions for human life and activities

Reactive toughening of intrinsic flame retardant urea-formaldehyde foam with polyether amine: Structure and elastic deformation mechanism

Polyether amine (PEA) was chemically introduced onto urea-formaldehyde (UF) chains for the purpose of toughening UF foams via reactions of PEA involved hydroxymethylation and condensation in UF system. Through introduction of PEA component, the curing process of UF-b-PEA proceeded within a broader temperature range, and the curing peak shifted to a higher temperature. Compared with neat UF foam, UF-b-PEA foams exhibited polygonal open cells with larger cell size, longer strut length and higher open porosity. During cyclic compression, the Mullins effect and the area in the hysteresis loop were reduced for UF-b-PEA foam, indicating outstanding compression resilience and compressive stability of the foam. Due to the open-cellular structure of foam and excellent flexibility of PEA component, the critical force of Euler buckling (Fc) decreased obviously, indicating the deformability of UF-b-PEA foams was improved without fracture of strut during reversible deformation. Besides, UF-b-PEA foams showed outstanding flame retardancy.

Construction of robust siloxane coating for urea-formaldehyde foam and durable hydrophobic mechanism

Urea-formaldehyde (UF) foams with robust siloxane coating were successfully prepared by grafting 3-aminopropyl-terminated poly-(dimethylsiloxane) (APDMS) and using 1, 6-hexanediol diglycidyl ether (HDE) as the bridging molecule. Compared with pristine UF foam and UF-g-APDMS foam, after immersion in water for 7 days, the UF-g-HDE-APDMS foam showed higher durable hydrophobicity with lower water absorption ratio and more integral cell structure. Moreover, for UF-g-HDE-APDMS foam, a large amount of APMDS molecules were grafted uniformly and tightly both on the surface and inside of the foam via strong interfacial interactions promoted by HDE, which prevented the APDMS molecules from falling off UF matrix. Such robust APMDS layer can act as a barrier to retard the water, and thus higher water contact angle and lower sliding angle can be kept during long term immersion for the foam, which was beneficial for reducing the destruction of the cell walls and keeping its structural integrity.

Obtaining urea-formaldehyde foam materials with improved mechanical properties

Obtaining urea-formaldehyde foam materials with improved mechanical properties

Preparation, characterization and thermal analysis of urea-formaldehyde foam

Urea formaldehyde foam (UFF) possesses outstanding properties of fire resistance, low smoke emission, low toxicity, and excellent insulation.

Preparation and properties of a polyvinyl alcohol toughened urea-formaldehyde foam for thermal insulation applications

Urea-formaldehyde (UF) foam exhibits excellent flame-retardant properties and low thermal conductivity. These properties make it suitable for thermal insulation in buildings. However, the brittleness of this material is its biggest disadvantage. In this study, polyvinyl alcohol (PVA) was used to improve the toughness of UF foam. The effect of the amount of PVA addition on the properties of the UF foam, such as the apparent densities, foaming ratio, compression strength, microstructure, fragility, limited oxygen index and thermal conductivity, were studied. The best performance was obtained for PVA modified UF foam with 1.5wt.% added PVA. The pyrolysis characteristics of the 1.5wt.% PVA modified UF foam were investigated using thermogravimetric analysis coupled with Fourier transform infrared spectroscopy. Emissions of CO2, ammonia and isocyanic acid were identified during pyrolysis. By comparing the combustion and pyrolysis derivative thermogravimetry (DTG) curves, the effects of the presence of oxygen on the thermal decomposition were observed.

Effects of surfactants on the mechanical properties, microstructure, and flame resistance of phenol–urea–formaldehyde foam

To study the effect of surfactants on the foaming behavior of phenol–urea–formaldehyde foam, silicone oil (Dow Corning DC-193) and Tween-80 surfactants were selected to study their effects on the mechanical properties, microstructure, and combustion characteristics of the foams. The results show that the surface tension of the phenol–urea–formaldehyde resins decreased with increasing surfactant concentration. Both the foaming temperature and foaming capacity of the phenol–urea–formaldehyde foam first increased and then decreased with increasing surfactant concentration. The compressive strength and oxygen index of the phenol–urea–formaldehyde foam first decreased and then increased with increasing surfactant concentration, which is probably related to the foaming capacity of the foam. The microstructure of the foams showed that the average pore diameters first increased and then decreased with increasing surfactant concentration. The combination of DC-193 and Tween-80 surfactants significantly improved the compressive strength, uniformity of the cells, and the number of closed cells in the final foam product.

Novel recycling of nonmetal particles from waste printed wiring boards to produce porous composite for sound absorbing application

Nonmetal materials take up about 70 wt% of waste printed wiring boards (WPWB), which are usually recycled as low-value fillers or even directly disposed by landfill dumping and incineration. In this research, a novel reuse of the nonmetals to produce porous composites for sound absorbing application was demonstrated. The manufacturing process, absorbing performance and mechanical properties of the composites were studied. The results show that the high porous structure of the composites leads to an excellent sound absorption ability in broad-band frequency range. Average absorption coefficient of above 0.4 can be achieved by the composite in the frequency range from 100 to 6400 Hz. When the particle size is larger than 0.2 mm, the absorption ability of the composite is comparable to that of commercial wood-fibre board and urea–formaldehyde foam. Mechanical analysis indicates that the porous composites possess sufficient structural strength for self-sustaining applications. All the results indicate that producing sound absorbing composite with nonmetal particles from WPWB provides an efficient and profitable way for recycling this waste resource and can resolve both the environment pollution and noise pollution problems.

Effect of polyethylene glycol on the mechanical property, microstructure, thermal stability, and flame resistance of phenol–urea–formaldehyde foams

In this study, polyethylene glycol (PEG) was added to phenol–urea–formaldehyde foam to improve its toughness, and the effects of PEG, with different molecular weights and dosages, on the mechanical property, microstructure, thermal stability, and flame resistance of phenol–urea–formaldehyde foam were studied. The addition of PEG significantly increased the toughness and impact strength and decreased the pulverization rate of the foam. The compression strength of the foam first increased and then decreased with increasing amounts of PEG. When 2 wt% PEGs were added, the compression strength of foams was the highest. The addition of PEG significantly influenced the microstructure of phenol–urea–formaldehyde foams, in which the cell diameter decreased and wall thickness increased with increasing amount and molecular weight of PEG. The addition of PEG also slightly decreased the thermal stability of phenol–urea–formaldehyde foams, and increased the heat release rate, total heat release, and total smoke release of the foams.

Preparation and Characterization of Melamine Modified Urea-Formaldehyde Foam

Abstract Melamine-urea-formaldehyde (MUF) foam was prepared using melamine modified urea formaldehyde resin. The effects of blowing agent, curing agent and surfactant on the properties of MUF foam such as apparent densities, compression strength, microstructure, fragility, limited oxygen index, thermal conductivity and formaldehyde emission were investigated. The best performance of MUF was obtained as the composition of blowing agent, curing agent and surfactant were 2.5%, 18% and 12% respectively. The water resistance of MUF foam, contents of foam's burning gas, curing mechanism and physical properties were also studied by Contact angle analyzer, TGA-FT-IR, FT-IR and 13C NMR.

Indoor Air Pollution: An Old Problem with New Challenges

Hazards in our indoor environments have been recognized since biblical times. The advice in Leviticus 14:33–48 for treating mold infested houses has contemporary meaning in the recent World Health Organization (WHO) document on damp and moldy indoor spaces [1]. In the developed world, faulty combustion, carbon monoxide from coal gas, lead paint, poor ventilation of tenement housing and hospitals have been recognized for decades as unhealthy. Indoor air quality, however, was not appreciated as an important component of public health until the proliferation of sealed buildings, energy conservation programs (urea formaldehyde foam insulation), new products, and the recognition of the health effects of radon, asbestos and latex. [...]

Agronomical Response and Water Use Efficiency of Sweet Pepper Plants Grown in Different Greenhouse Substrates

An experiment was carried out to assess the influence of three types of substrate on the growth and yield of sweet pepper (Capsicum annuum L.). Plants were grown during three cycles (2005, 2006, and 2007) in coconut coir dust (CC), urea formaldehyde foam (UF), and rice hull (RH) amended with polyacrylamide gel (water absorber). Growth parameters, dry weight (DW) of vegetative and generative parts, intercepted radiation, water uptake, total fruit yield, and quality parameters were analyzed. Plant height, total leaf fresh weight, and stem diameter were higher in CC and lower for the RH substrate, which also showed lower yields and fruit quality. Accumulated dry matter was modeled according to water uptake and substrate using a linear function. Upper and lower limits in water use efficiency, between 2.5 and 5.7 g DW/L, are linked to the irrigation strategies and crop seasons. Light use efficiency (LUE) under different conditions was also determined to predict plant dry matter and a unique value was obtained for the three substrates (LUE = 0.91 g/MJ). Three different irrigation strategies were proposed for each substrate as a function of intercepted radiation and defining an α coefficient (expressed in mm/m2/MJ) that coupled crop and climate components. These crop characterization and prediction tools could help to optimize plant growth and yield for environmentally friendly substrates.

Effects of urea formaldehyde foam soil amendment on growth and response to transient water deficit stress of potted Flindersia schottiana saplings

Hydrocell™is a urea formaldehyde resin foam (UFRF) product used as a soil amendment. It is proposed to improve the physicochemical properties ( viz. water relations and aeration) of the plant root zone. Flindersia schottiana is a tree species used in the ornamental horticulture industry. This study investigated the potential of Hydrocell™ [0–50% (v/v) incorporation rates] to promote growth of F. schottiana saplings during containerized nursery production in composted pine bark medium. The growth response of the potted saplings to transient water stress was also assessed. In addition, growth of F. schottiana saplings potted into three different soil types (sand, loam, clay) was assessed in the presence and absence of 30% (v/v) Hydrocell™. Under well-watered conditions in composted pine bark, Hydrocell™ treatments enhanced sapling leaflet numbers, with 30% (v/v) being the most beneficial treatment. However, no consistent significant differential effects of incorporation rate on either plant height or stem diameter were recorded. Extended time to wilting upon withholding irrigation was achieved, with the optimum Hydrocell™ rate being 10% (v/v). Among the three soil types compared, use of 30% (v/v) Hydrocell™ resulted in improved growth of potted F. schottiana saplings in the sand and loam soils, but not in the clay soil. These findings suggest that the UFRF, Hydrocell™, holds limited promise as a soil amendment for trees in the nursery phase. Optimum incorporation rates (v/v) would need to be determined for individual media types, specific irrigation regimes and individual taxa.

Better Bonding with Beans

Formaldehyde is an extremely useful industrial chemical but also one that has long been known to cause environmental health problems in some circumstances. A major route for human exposure is inhalation of formaldehyde gas emitted from urea- and phenol-formaldehyde resins used as adhesives in engineered woods such as plywood and particleboard. Industrial workers are exposed to significantly higher amounts of formaldehyde than the general public, although residents of new homes built with engineered wood materials often experience symptoms, especially soon after moving in. Formaldehyde concentrates in indoor air, with known and suspected human health effects ranging from eye irritation to cancer. Now a new adhesive using soy protein, processed to resemble the protein that allows mussels to cling to rocks, is enabling some manufacturers to make formaldehyde-free engineered woods. Developed by Kaichang Li, an associate professor in the wood science and engineering department at Oregon State University in Corvallis, the soy adhesive is being hailed by many as a nontoxic, economically attractive, and renewable solution to a long-standing environmental health issue.

Substrate temperature fluctuation and dry-weight partitioning of Lantana grown in four green roof growing media

SummaryFour potential green roof substrates were evaluated in a field study for their thermal characteristics and their impact on Lantana camara dry-weight accumulation. The substrates were a) a sandy loam soil (S), b) the sandy loam soil amended with urea formaldehyde resin foam (S:F) at a proportion of 60:40 v/v, c) the sandy loam soil mixed with peat and perlite (S:P:Per) at a proportion of 50:30:20 v/v, respectively and, d) peat amended with urea-formaldehyde resin foam (P:F) at a proportion of 60:40 v/v. Measurements included the monitoring of the substrate temperature and the determination of the dry-weight accumulation rhythm of shoots, leaves and roots. In addition, the lateral spreading of the roots was recorded and the shoot/root ratio determined. Temperature fluctuation within the substrates was found to depend on the type of the substrate, plant growth, and season. Temperature fluctuation was high in S, moderate in S:F and S:P:Per and low in P:F. Shoot and root dry-weight accumulation was reduced in P:F, while root growth was promoted in S substrate. Differences in dry-weight accumulation and the lateral spreading of the roots were affected more by the water holding capacity of the substrate than by the substrate temperature.

Reducing formaldehyde exposure in office environments using plants.

Formaldehyde is a toxic substance with adverse health effects detectable at low concentrations. Formaldehyde causes irritation of the eyes, skin and respiratory tract, wheezing, nausea, coughing, diarrhoea, vomiting, dizziness and lethargy at levels as low as 50 parts per billion (ppb) (0.05 ppm) (Horvath et al, 1988). Formaldehyde has also been associated with aggravation of asthma, emphysema, hayfever and allergy problems at low levels (EPA, 1987). Formaldehyde is currently considered a potential carcinogen to humans (EPA, 1987). Formaldehyde is a ubiquitous gas found in elevated concentrations in indoor environments. Concentrations of formaldehyde are typically an order of magnitude greater inside buildings compared to outdoor air (Godish, 1990). Formaldehyde concentrations are particularly high in portable buildings due to the presence of more formaldehyde emitting materials and the relatively smaller interior volumes of air (Sexton et al, 1983). Major sources of formaldehyde indoors are pressed wood products, such as particle board and plywood (Elbert, 1995: Myer and Hermans, 1985), and urea formaldehyde foam insulation (Spengler and Sexton, 1983). Other sources include carpets, curtains, floor linings, paper products, cosmetics and soaps, tobacco smoke and gas combustion (Spengler and Sexton, 1983: Godish, 1990). Methods to reduce indoor formaldehyde include source removal or use of non- polluting materials, emission reduction through physical or chemical treatments and dilution through ventilation and air purification. While most solutions involve dilution through ventilation, increased interest in the scientific literature (Wolverton et al, 1989: Godish and Guindon, 1989) as well as in the popular media has been given to the use of plants to purify air in buildings . Most studies however, have been conducted in the laboratory (Levin J, 1992: Godish T and Guindon C, 1989) and are difficult to extrapolate to real life situations (Wolverton et al, 1989: Godish and Guindon, 1989).

Environmental exposure unit: a system to test anti-allergic treatment.

Reading this article will enable readers to recognize the Environmental Exposure Unit (EEU), its historic development and its current role as a system to test anti-allergic treatment; to recognize clinical relevance of this test system and its relationship with other pollen challenge methods of evaluation of anti-allergic medication; and, to recognize variables associated with standard clinical studies of anti-allergic medication. Readers will review four studies of antihistamines tested in the Environmental Exposure Unit, three studies on nasal corticosteroids, one on topical eye drops and one on immunotherapy conducted in the EEU. The EEU has been in operation since 1985 preceded by a prototype challenge system to assess respiratory effects of urea formaldehyde foam insulation. A number of studies on the onset of action and efficacy of different antihistamines and nasal corticosteroids as well as other treatments have been completed producing accurate and consistent results influenced to some extent by study designs. Studies of commonly used antihistamines and nasal corticosteroids are discussed in detail and represent several of the studies undertaken to date in the EEU. Controlled ragweed pollen exposure using the EEU has shown that some antihistamines demonstrate an onset of action within 30 minutes while others have taken up to 3 hours to produce significant effect. Nasal corticosteroids evidenced the onset of clinical improvement at 5 to 6 hours with significance over placebo between 6 and 12 hours depending on dose. The EEU is an effective pollen delivery system that accurately and consistently determines the onset of action and efficacy of anti-allergic treatment in large groups of subjects. It eliminates variables associated with various other methods of evaluation of these medications but does not supplant the need for such evaluations.