The objective of this study is to develop a fast curing phenolic formaldehyde (PF) and polymeric diphenyl methane isocyanate (MDI) based hybrid resin system for wood products applications. Various formulas of PF resins were synthesized with different formaldehyde to phenol ratio, sodium hydroxide to phenol and isocyanate group (-NCO) to hydroxyl group (-OH) molar ratios. The shear bonding strength property was used to evaluate and optimize the formulations by appropriate sample preparation. The optimized resins were characterized by rheometer, Fourier transform infrared spectroscopy (FTIR) and other methods. In order to eliminate the influence of hydroxyl groups from water in the PF resin, a frozen dried method was applied to remove the water while keeping PF resin in liquid state. Acetone was used to disperse the hybrid co-polymer to improve the mobility of the mixture of frozen dried PF resins and MDI. An unexpected phenomenon was observed when the two resins were mixed in acetone and a sharp reaction occurred. This led to an assumption that acetone promoted the curing of hybrid resin. The effect of acetone on the curing behavior of hybrid resin was studied by differential scanning calorimetry (DSC), confocal laser scanning microscope (CLSM) and other techniques. It was confirmed that acetone promoted the curing of the co-polymer system. The gel time of hybrid resin with acetone decreases sharply compared to that of pure phenolic resin and original hybrid resin. Acetone also helped the hybrid resin to have better penetration behavior by improving the mobility and this also resulted in less variation of the strength distribution. Finally, lap shear samples were prepared at room temperature curing commercial polyurethane (PU), phenol-resorcinolormaldehyde resin (PRF) and laboratory made hybrid resins based on PF and MDI to compare the shear strength of different resins under different application conditions. The strength reduction of frozen dried PF with acetone/MDI is the lowest in humidity, temperature and humidity-temperature conditions. With just humidity condition, its shear strength reduction is significantly lower than that of any other resins including the solid wood control.

<p> Various low-lying electronic states of formaldehyde and acetone have been investigated, using molecular orbital calculations, to determine their involvement in the photochemical system. The potential energy surfaces of these states were calculated using the CND0/2. </p> <p> The results of this study show that the decomposition of formaldehyde to molecular products H2 and CO (process II) occurs via the ground state; the potential surface of this process was studied using configuration interaction methods. </p> <p> The process leading to radical products in both acetone and formaldehyde (process I) can arise either directly from the singlet and triplet (n,π*) states via a reaction path of no symmetry, or by crossing to the 3 (π,π*) state should Cs symmetry be maintained. The ground state is the only other state correlating with radical products. </p> / Thesis / Master of Science (MSc)

No description available.

Master of Science

Formaldehyde, an important feedstock in industrial processes and manufacture, is widely present in numerous consumer products. Emitted by many types of consumer products and indoor materials, indoor air can contain high concentrations of formaldehyde. Exposure to formaldehyde is hazardous to human health. Thus knowledge of formaldehyde mass-transfer properties is critical to efforts to reduce formaldehyde emissions and establish related standards and regulations. The primary objectives of this project include: 1) documenting and validating procedures and methods for analyzing and measuring formaldehyde mass-transfer characteristics; 2) evaluating and comparing formaldehyde mass-transfer properties in different materials using micro-balance sorption/desorption tests; 3) investigating observed formaldehyde mass-transfer irreversibility and the recently developed formaldehyde polymerization theory. The procedures and methods for analyzing and measuring formaldehyde mass-transfer characteristics were developed in an effort to minimize experimental variability and were strictly followed during the research. The formaldehyde mass-transfer properties of five polymer materials (polycarbonate, polystyrene, poly(methyl methacrylate), polyethylene and polypropylene) were measured through sorption/desorption testing. Results indicated that formaldehyde solubility was highest in polyethylene while the rate of diffusion was the highest in polypropylene. Results also showed that the diffusion process in the selected polymer materials was irreversible in all cases. Furthermore, additional testing showed no detectable polyformaldehyde formation on polymer surfaces after exposure to formaldehyde. The causes of observed mass-transfer irreversibility need further study. / Master of Science

This work addresses biogenic formaldehyde (CH₂O) generated by wood during the manufacture of non-structural wood-based composites, from which CH₂O emissions are regulated. The target for regulation has been anthropogenic CH₂O released from hydrolytically unstable amino resins like urea-formaldehyde. However, current regulations (the Formaldehyde Standards for Composite Wood Products Act, signed into law in 2010 and implemented in 2016) restrict allowable emissions to such low levels that biogenic CH₂O may affect regulation compliance. The industry has met the latest regulations with new amino resin technologies. Nevertheless persistent anecdotal reports suggest that biogenic CH₂O complicates regulation compliance. This work represents an industry/university cooperation to seek a more thorough understanding of biogenic CH₂O, to begin documentation of biogenic CH₂O levels in wood, and to study the conditions and chemical mechanisms of its formation. Efforts began by establishing CH₂O analysis using the fluorimetric acetylacetone determination. A custom 12-liter chamber with controlled temperature and relative humidity, and "ultrapure" nitrogen (N₂) ventilation was created to measure CH₂O emissions from flakes sampled from four Virginia pine (Pinus virginiana) trees. Emissions from never-heated specimens varied significantly among the four trees, ranging from 0.02 – 0.19 µg CH₂O/m³g dry wood. Heating (200°C, 1 hour), followed by chamber equilibration, resulted in significantly increased emissions on the order of 50%. Sequential heating, followed by chamber equilibration (in other words, heat/equilibrate/measure emission/repeat), resulted in declining emissions suggesting that a finite chemical source of CH₂O was being depleted by the sequential heat treatment. Flake specimens were stored in the open laboratory, and over 2-3 months laboratory storage, initially high emitting specimens gradually emitted less CH₂O, and initially low emitters gradually emitted more CH₂O. Concerns over laboratory contamination were perhaps allayed when background levels of laboratory CH₂O were determined to be similar to the background levels in the ultrapure N₂ used to ventilate the chamber. Measurement of emissions was abandoned, and thereafter a simple water extraction technique (~ 94% CH₂O recovery) was used to measure the CH₂O content of never-heated and heated wood specimens, where the difference was identified as CH₂O generated due to heating. Increment cores from living Virginia pine (Pinus virginiana), yellow-poplar (Liriodendron tulipifera), and radiata pine (Pinus radiata) trees were used to measure CH₂O content and CH₂O generation due to heating (200°C, 10 min). Significant variations within and between trees of the same species were observed. Tissue types (juvenile/mature, heartwood/sapwood) sometimes correlated to higher CH₂O contents and greater heat-generation potential; but sometimes not depending upon species. Heating increased CH₂O levels 3-60 fold. Heating with high moisture levels caused greater CH₂O generation than for dry specimens. This moisture effect and a separate serendipitous observation suggested that CH₂O generation is acid catalyzed. Radiata pine generated extraordinarily high CH₂O levels when heated, far exceeding the other two species. It was suggested that pine extractives might catalyze CH₂O generation, perhaps in lignin. Pinus virginiana wood was heated (200°C, 10 or 60 min) while dry or after aqueous/acid or base pretreatment in order to reveal mechanisms of formaldehyde (CH₂O) generation. Among wood structural polymers, lignin was the overwhelming source of biogenic CH₂O, consistent with prior reports. The effects of wood extractives are mentioned below. The selection of acid catalyst strongly affected CH₂O generation as predicted in the acidolysis literature of lignin model compounds and isolated lignins. Lignin methoxyl cleavage was also observed, but was considered an unlikely source of thermochemical CH₂O. Alkaline pretreatments suppressed CH₂O generation. Regarding wood-based composite manufacture, the implications are that lignin reactions can be manipulated during hot-pressing. Potential benefits include reduced product emissions, and/or novel crosslinking strategies using biogenic CH₂O. Heat generation of CH₂O in Virginia pine and radiata pine was substantially reduced by extractives removal, but there was no such effect in yellow-poplar wood. Results suggested that pine extractives promote CH₂O generation by catalyzing or otherwise promoting C2 cleavage (acidolysis) in lignin. Thioacidolysis demonstrated that pine lignin reactions were strongly dependent upon the presence or absence of the extractives. When present, pine extractives seemed to promote C2 cleavage (CH₂O generation), but otherwise reduced the overall extent of lignin degradation. When pine extractives were removed, lignin suffered substantial degradation, but apparently less C2 cleavage since CH₂O generation was reduced. In contrast, thioacidolysis showed that yellow-poplar extractives appeared to promote lignin degradation, but extractives removal had no detectable impact on CH₂O generation. Implications exist for biorefinery research because it was shown that lignin reactions can be strongly affected by wood extractives. Two dimensional, proton-carbon, correlation NMR spectroscopy (2D NMR), and solvent submersion dynamic mechanical analysis (DMA) was used to investigate wood changes caused by heating in the presence or absence of external acid catalysis. 2D NMR was relatively insensitive to fine lignin changes that were detected using thioacidolysis. 2D NMR was effective for observing lignin changes under more extreme heating conditions, and evidence was found for lignin crosslinking reactions that probably occurred through substitution into lignin aromatic rings. DMA showed that most heating conditions caused an increase in the lignin glass transition temperature (Tg), consistent with heat-induced lignin crosslinking. Under one experimental condition of wood heating, DMA showed a reduction in the lignin glass transition temperature (Tg). This suggested that lignin cleavage without subsequent repolymerization might be promoted by carefully controlled conditions, and this has implications for biorefinery research where lignin repolymerization can be problematic. Finally, this work strongly supported the hypothesis that lignin generates CH₂O through well-known acidolysis pathways where CH₂O is borne from the lignin gamma-methylol group. Therefore, it was predicted that upon heating corn (Zea mays L.) stalk should generate less CH₂O than wood because corn stalk lignins exhibit a high degree of coumaric acid esterfication at the gamma-methylol group. This hypothesis was perhaps verified- it was found that in 4 out of 6 experimental heating conditions that corn stalk generated significantly less CH₂O than Virginia pine. / Ph. D.

A source-modulation microwave spectrograph was utilized to measure line width parameters for several spectral lines in the pure rotational spectrum of formaldehyde (H₂CO). The spectrograph featured high-gain ac amplification and phase-sensitive detection, and was capable of measuring microwave lines having absorption coefficients as small as 10⁻⁷ cm⁻¹ with a frequency resolution on the order of 30 kHz. Center frequencies of the measured lines varied from 4,830 MHz to 72,838 MHz; hence, most of the observations were made on transitions between K-doublets in the rotational spectrum. Corrections were applied to the measured line width parameters to account for Doppler broadening and, where possible, for deviations due to magnetic hyperfine structure in some of the K-doubled lines. Low modulation voltages and low microwave power levels were used to minimize modulation and saturation broadenings; other extraneous broadenings were found to be insignificant. The primary broadening mechanism at low gas pressure is pressure broadening, and a review of this topic is included. Line width parameters for the several observed transitions were determined by graphing half-widths versus pressure for each spectral line, and performing a linear least-squares fit to the data points. Repeatability measurements indicated the accuracy of the line width parameters to be better than ±10 percent. The reasons for this repeatability spread are discussed, Broadening of each line was measured for self- and foreign-gas broadening by atomic helium and diatomic hydrogen. Effective collision diameters were calculated for each broadening interaction, based on the observed rates of broadening.

Submitted by RAFAEL AUGUSTO PINHOLATI EUGENIO null (rafael.pinholati@duratex.com.br) on 2016-12-06T23:33:20Z No. of bitstreams: 1 DISSERTAÇÃO RAFAEL - MESTRADO Rev 4.pdf: 3957807 bytes, checksum: 74c157bc6d300c719cca57459b4455da (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-12-09T12:54:47Z (GMT) No. of bitstreams: 1 eugenio_rap_me_bauru.pdf: 3957807 bytes, checksum: 74c157bc6d300c719cca57459b4455da (MD5) / Made available in DSpace on 2016-12-09T12:54:47Z (GMT). No. of bitstreams: 1 eugenio_rap_me_bauru.pdf: 3957807 bytes, checksum: 74c157bc6d300c719cca57459b4455da (MD5) Previous issue date: 2016-12-02 / O trabalho consistiu na produção de painéis de MDF (Medium Density Fiberboard) em escala laboratorial utilizando o adesivo PVA (Poliacetato de Vinila), variando suas concentrações e realizando misturas com a resina comumente empregada neste processo, o adesivo a base de uréia-fomaldeído, onde foi avaliado além das características físicas e mecânicas dos painéis produzidos, também teve o intuito de verificar o desprendimento de formaldeído para o ambiente quando aplicado juntamente com a resina uréia-fomaldeído, e a avaliação dos perfis de densidades dos traços. As amostras foram confeccionadas com fibra de eucalipto, onde as dosagens do adesivo PVA seguiram as seguintes proporções: 30%, 50% e 70%, e para efeito de comparação com as amostras produzidas com a mistura de PVA foram fabricadas provas em branco com 100% uréia-formaldeído. No total foram produzidas 16 amostras, quatro painéis de cada traço, e retirados os corpos de prova que posteriormente foram avaliados conforme a NBR 15316-2:2015 para as condições secas. Todos os insumos foram fornecidos pelo fabricante de painéis Duratex SA, e os testes foram realizados nos laboratórios da empresa. O adesivo PVA mostrou-se bastante favorável, apresentando grande compatibilidade com os demais componentes da formulação, apresentando potencial para fabricação de MDF. Diversos traços conseguiram atender os requisitos da norma, com destaque para módulo de ruptura (MOR), módulo de elasticidade (MOE), obtidos atraves do ensaio de flexão estática, e o teor de umidade. Houve também uma discreta redução na emissão de formol em dois traços (T3 e T4), e na avaliação dos perfis de densidade foi constatado que a formulação dos traços não impactou nas densidades médias da espessura dos painéis. / The work consisted in the production of MDF (Medium Density Fiberboard) in laboratory scale using PVA adhesive (Polyacetate Vinyl Chloride), varying their concentrations and performing mixtures with commonly used resin in this process, the adhesive base of ureafomaldehyde, which was evaluated in addition to the physical and mechanical characteristics of the panels produced, also aimed to check the formaldehyde release to the environment when applied together with resin urea-fomaldehyde, and evaluation of the densities of the features profiles. The samples were made from eucalyptus fibers where PVA adhesive doses followed the following proportions: 30%, 50% and 70%, and for the purpose of comparison with the samples produced with the mixture of PVA blank tests were made with 100 % ureaformaldehyde. In total, we produced 16 samples, four panels of each stroke, and removed the specimens which were then evaluated according to NBR 15316-2: 2015 for dry conditions. All inputs were provided by the panel manufacturer Duratex SA, and the tests were performed in the company's laboratories. PVA adhesive proved to be very favorable, with high compatibility with the other components of the formulation, with potential for the production of MDF. Many features were able to meet the standard requirements, particularly modulus of rupture (MOR), modulus of elasticity (MOE), obtained through the bending, and moisture content test. There was also a slight reduction in formaldehyde emissions by two dashes (T3 and T4), and evaluation of density profiles was found that the formulation of the traits did not affect the average thickness of the thickness of the panels.

In this study southern pine scrim was treated with low molecular weight melamine formaldehyde (MF), phenolic formaldehyde (PF), and furfuryl alcohol (FA) at different loadings and formed into 25-mm thick panels. Mechanical, dimensional and biological properties were evaluated. Results showed that samples treated with 5 percent MF had the highest MOE, MOR and work to maximum load values (15.3 GPa, 54.2 MPa and 25.4 KJ/m3, respectively), while those treated with 10 percent MF had the highest internal bond and edgewise toughness values of 390 kPa and 12 N•m, respectively. With respect to dimensional stability, samples treated with 20 percent FA had the lowest swelling value (ASE = 36.8 percent), and the lowest water absorption value (27.5 percent). Dynamic swelling test revealed much higher ASE value (> 45 percent) for furfurylated samples. As for termite resistance, both untreated and treated samples had little weight loss (1.10-1.56 percent), high visual rating (8-9.3/10), and 100 percent mortality in laboratory test.

Formaldehyde is widely used fixative. Its advantages are low cost, simplicity of use and good fixation traits, which are fast tissue penetration, good preservation of morphological structures and compatibility with downstream histological applications. Formaldehyde disadvantages are negative effects on nucleic acids. Formaldehyde solutions modify primary structure of deoxyribonucleic acid (DNA), fragment DNA and create protein- DNA covalent bonds that hinder DNA isolation procedures. Level of negative effects of formaldehyde is dependent on many factors. Effect of formaldehyde chemical composition (formaldehyde dilution, presence of buffer or formic acid) and effect of fixation length were studied in this work. On DNA extracted from fixed tissues, DNA quantity and level of DNA fragmentation were studied by quantitative polymerase chain reaction, fluorescence assay for DNA quantification and by on-chip electrophoresis on bioanalyzer Agilent 2100. Quality and quantity of acquired DNA were tested by DNA profile determination for identification purposes using STR (short tandem repeats) analysis. Results show that of all tested fixatives, buffered 4% formaldehyde is the most suited solution in regards of sufficient amount of DNA and sufficient DNA quality. Other formaldehyde variants (non-buffered 4%...