Orientador: Jaime Olbrich Neto / Resumo: Os cabelos são um importante componente de identidade social e sedução, favorece o mercado de cosméticos, notadamente o capilar, que busca inovações e novidades destinadas a obter um resultado desejado. Mulheres e homens dão importância para a saúde e aparência dos mesmos, empenhando cuidados que vão além dos habituais de higiene. A procura pelo cabelo ideal expõe a riscos de doenças, tanto os profissionais dos salões de beleza e como seus clientes. São doenças ocupacionais, em muitos casos, negligenciadas. Entre estes riscos encontra-se a dermatite de contato. No Brasil, a chamada escova progressiva é a mais conhecida e utilizada para alisamento. Neste processo o uso de formaldeído (FA) em concentrações não permitidas tem sido prática comum, expondo cabeleireiros e clientes a risco de doenças relacionadas ao contato com FA. O FA é permitido na concentração de até 0,2% como conservante de produtos. O presente estudo objetivou avaliar indivíduos expostos ao FA ao realizarem alisamento capilar, se estavam sensibilizados ao FA. Para identificar FA em produtos de alisamento capilar, usado pelos cabeleireiros participantes desta pesquisa, utilizou-se um kit comercialmente disponível. Foram incluídos profissionais expostos ao FA, clientes (esporadicamente expostos) e indivíduos nunca expostos. Foram realizados patch teste com a bateria brasileira para dermatite de contato, e um participante apresentou teste cutâneo positivo para formol, onze para bicromato de potássio e oito para s... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Hair is an important component of social identity and seduction, it favors the cosmetics market, notably the capillary, which seeks innovations and novelties designed to obtain a desired result. Women and men give importance to their health and appearance, engaging in care that goes beyond the usual hygiene. The search for the ideal hair exposes the risks of diseases, both the professionals of the beauty salons and their clients. Occupational diseases that are, in many cases, neglected. Contact dermatites is one of the risks. In Brazil, the so-called brazilian hair straightening is the preferred for straightening. In this process, the use of formaldehyde (FA) in unallowed concentrations has been common practice, exposing hairdressers and clients to the risk of diseases related to contact with FA. At a concentration of up to 0.2%, as a p preservative, FA is permitted. The present study aimed to evaluate individuals exposed to FA when performing hair straightening, and if they were sensitized to FA. To identify FA in hair straightening products, used by hairdressers participating in this research, a commercially available kit was used. Professionals exposed to the FA, clients (sporadically exposed) and individuals never exposed were included. Patch tests were performed with the Brazilian battery for contact dermatitis, and one participant presented a positive skin test for formaldehyde, eleven for potassium bichromate and eight for nickel sulfate. Clinical symptoms were more se... (Complete abstract click electronic access below) / Mestre

京都大学 / 新制・課程博士 / 博士(医学) / 甲第23372号 / 医博第4741号 / 新制||医||1051(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 滝田 順子, 教授 髙折 晃史, 教授 江藤 浩之 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Phenol-formaldehyde adhesives are important adhesives known to have superior water resistance capacity and high mechanical strength when utilized in wood-based applications. Due to unsustainability and environmental issues associated with the use of fossil fuels, there is an urgent need to look for alternative raw materials, which are renewable in nature. Pinyon-juniper biomass has been found to be a suitable replacement for petroleum-based phenol because it is renewable, abundant, and readily available. In this thesis, bio-oil produced from the pyrolysis of pinyon-juniper biomass using red mud alumina catalyst was used to produce wood adhesives. The characterization of pinyon-juniper bio-oil showed the presence of phenolics, aromatic hydrocarbons, aliphatic hydrocarbons, carboxylic acids, ethers, ketones, aldehydes, and aliphatic alcohols. Resol synthesis parameters such as formaldehyde-to-phenol molar ratio (1.8 and 2), catalyst loading (0.25, 0.63, and 1.25 g of NaOH), reaction time (60 minutes), and reaction temperature (95°C), were investigated in the production of pinyon-juniper adhesives. Based on the results obtained, the extent of phenol substitution with pinyon-juniper bio-oil was dependent on the amount catalyst used during the synthesis process. The maximum phenol substitution of 80% was achieved using a catalyst loading of 1.25 g of NaOH while the minimum phenol substitution of 50% was obtained at a catalyst loading of 0.25 g of NaOH. Dry shear strength (8.99 to 12.73 MPa) and wet shear strength of (5.16 to 7.36 MPa) for both pure phenol-formaldehyde resols and pinyon-juniper substituted resols were comparable and exceeded the minimum requirement of 0.66 MPa for plywood. Finally, the chemical structure of pure phenol-formaldehyde resols showed the presence of more phenolic OH groups compared to pinyon-juniper substituted resols. This observation was corroborated by the higher concentration of free phenol in pure phenol-formaldehyde adhesives compared to pinyon-juniper substituted resols.

Phenolic adhesives are widely used in the production of engineered wood products due to their exceptional moisture and thermal resistance, chemical stability, and bonding strength. The phenolic adhesive is currently produced through condensation polymerization of two fossil fuel-derived compounds: phenol and formaldehyde. However, due to fluctuations in the price of phenol and formaldehyde with the price of oil, environmental and health issues associated with using these compounds, there is a strong interest in finding alternative renewables feedstocks. Lignin is a natural polyphenolic compound with excellent potential to substitute phenol in phenolic adhesive formulations. Lignin is produced as byproducts during pulp and bioethanol processes. On the other hand, biobased aldehydes such as glyoxal have recently gained a lot of attention for replacing the toxic formaldehyde in production of environmentally friendly wood products. In this study, a wide range of lignin samples from different resources (hardwood, softwood, wheat straw, and corn stover), and isolated via various processes (kraft, organosolv, soda, sulfite, and enzymatic hydrolysis), were used to formulate 100% lignin-based phenolic adhesives. In a separate work, formaldehyderee phenolic adhesives were also developed using either glyoxal or gossypol (a dialdehyde from cotton seed) in combination with phenol. Chemical, physical, and thermal properties of lignin samples and developed phenolic resins and adhesive were measured using advanced analytical techniques and appropriate ASTM standard test methods. Based on two-way ANOVA analysis results of shear strength data, a biorefinery corn stover lignin that had the highest p-hydroxyphenyl and p-coumaric acid content was the most suitable lignin for replacing 100% of phenol in phenolic adhesive formulation. In addition, the developed lignin-based adhesive (formulated with biorefinery corn stover lignin) showed similar dry and wet adhesion strengths as that of commercially formulated phenol resorcinol formaldehyde (PRF) adhesive. On weight basis, the formaldehyde consumption in the developed lignin-based adhesive was 50% lower than the formaldehyde used in phenol formaldehyde (PF) resin. Moreover, two formaldehyderee formulated adhesives using glyoxal and gossypol (renewable feedstocks) had very similar physico-chemical properties to phenol formaldehyde adhesive.

Urea formaldehyde (UF) resins are widely used as adhesives for wood-based composites. These thermosetting polymers have advantages of relative low price, fast curing speed, and relative good bonding performance. However, UF resin bonded composites are designed for interior applications due to its weak water resistance. Moreover, traditional prevalent ways for recycling wood-based composites face problems caused by UF resins. In this project, the reuse of cured UF resins was systematically studied. The verification and characterization of crystalline structures in cured UF resins were conducted. The results showed that the crystalline regions were accounted for nearly 14.48% in a typical 1.2 formaldehyde to urea (F/U) molar ratio UF resin. The details of the resin crystalline regions, such as grain sizes and interplanar spacing (d-spacing), were characterized. The crystalline structures, nevertheless, did not affect the UF resin hydrothermal hydrolysis in this study. The reuse of cured UF resin was started with a hydrothermal hydrolysis. Under 140 °C and 2 h of hydrothermal process, 20 mL of 30 w.t. % formaldehyde water solution was able to depolymerize up to 1.7 g of cured UF resin. The hydrolyzed formaldehyde solutions were directly used as normal formaldehyde solutions for UF resin synthesis. The synthesized resin (named as UUF resin) contained about 6 w.t. % of cured UF resin and presented similar chemical structures and bonding performance as normal UF resins. Hybrid resins made of UUF resin and polymeric 4-4 diphenyl methane diisocyanate (pMDI) were prepared. The pMDI was found evenly dispersed in the hybrid resins by using acetone as its solvent. These hybrid resins resulted in faster curing and stronger bonding performance than pure UUF resins. Furthermore, the hybrid resin was used in a new bonding design, which used southern pine wood radial section features. This design generated finger joint like bonding interfaces by hot pressing two resin coated wood radial sections. The bonding strength and bond line stability were enhanced by this design.

Phenol formaldehyde (PF) is the oldest known synthetic polymer. This polymer has seen many applications throughout history, including jewelry, electric wire insulation, and resins used to make adhesives. Today, PF resins are still crucial components used in the wood products industry. These PF resins are formulated into adhesives used to make plywood and various other wood composite products. For example, in the United States, 90 % of the homes are still frame homes that use plywood for construction. The PF adhesives used to make these composites are formulated using agricultural waste products like walnut shells and corn-cob residue. These organic waste products act as fillers that reduce the cost, increase the viscosity, and affect the rheology of the fillers. Wheat flour is added as an extender to reduce cost and affect the tack of the adhesive. These organic fillers are lignocellulosic materials that are made of lignin, cellulose, and hemicellulose. Not much is known about the interactions of these organic fillers and the polymer resin. Rheological studies in our lab have shown that not all of the additions to the adhesive formulation are inert components in the adhesive. The steady-state flow curve analysis of PF adhesives revealed that there is a liquid structure change that occurs at high shear rate. This structure change is observed as a viscosity increase that occurs after applying a maximum shear rate of 4000 1/s. A rheological analysis was conducted to determine the source of this change, with individual components added to the resin. The PF base resin (with nothing added) has a Newtonian rheological behavior. When wheat flour is added to the resin, the overall viscosity increases, and shear thinning occurs at highe shear rates. There is no final viscosity change observed on with the addition of wheat flour. Adding corn-cob residue to the resin increased viscosity, led to some shear thinning at higher shear rates, and allowed the viscosity changes observed in the fully formulated adhesives. These experiments showed that the liquid structural changes that occur in the adhesives are attributed to the organic fillers. All organic fillers used in our studies, including corn-cob residue, walnut shell, almond shell, and Alder bark produce different levels of viscosity change in the PF adhesive formulations. These biomass materials have varying amounts of lignocellulosic content, particle size distributions, and particle shape. Among the fillers, corn-cob residue was shown to cause the most viscosity change compared to any of the fillers. Corn-cob residue is unique compared to the others because it has undergone acid digestion to convert its xylans to furfural. During the viscoelastic oscillation studies, the corn-cob residue filled adhesives showed that they developed network structures in response to a high shear rate that were not observed using the other fillers. With the discovery of these network structures, the next goal of this research was to correlate the effects observed on the rheometer to relevant adhesive application technology like high shear spraying. The corn-cob residue adhesive was sprayed at approximately 70,000 1/s compared to the 4000 1/s of rotational shear on the rheometer. The viscoelastic oscillation studies revealed that there was no network structure formation after high-shear spraying. Further, there was no change observed in the flow curve analysis after spraying the adhesive. This study showed that there are limitations when trying to correlate changes that happen in adhesives during spraying, where extensional forces dominate compared to shear forces. In future research, there is the opportunity to explore the effects of extensional deformation that occurs during the atomization of the adhesive, which will be more reflective of the changes that occur during spraying. / Doctor of Philosophy / Phenol-formaldehyde adhesives are crucial products in the home construction industry. These adhesives are used to make plywood that is used to build frame homes, which represent approximately 90 % of the homes in the United States. These phenol-formaldehyde adhesives are made using organic materials repurposed from agricultural waste products like corn cobs, walnut shells, almond shells, and tree bark. These products help to enhance the properties of the adhesive, reduce the cost, and reduce the amount of resin used. The goal of this research is to understand better the interactions between the adhesive and the organic fillers using rheology. Rheology is a field that studies how materials change and flow with applied external forces. This is an important field because it provides information on viscosity and viscoelastic behavior. Our research has shown that in response to high shear rates, the viscosity of these phenol-formaldehyde adhesives increases. Studying these changes can lead to a better understanding of how these materials change during industrial spraying. This understanding could lead to improved building adhesive materials in the home construction industry.

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This was a university/industry research cooperation with focus on how organic fillers affect the properties of phenol-formaldehyde resole (PF) resins that are formulated for veneer applications like plywood and laminated veneer lumber. The PF formulations studied in this work used fillers that were derived from walnut shell (Juglans regia), alder bark (Alnus rubra), almond shell (Prunus dulcis), and corn cob (furfural production) residue. The chemical composition of all fillers was measured and compared to published data. The basic rheological behavior of the formulations was determined and used to develop an adhesive tack measurement based upon lubrication theory. In this work, the probe-tack test was adapted to a typical stress-controlled rheometer by using the normal force and displacement system to compress the adhesive between parallel plates. By employing a simple power law to describe the complex rheology of adhesives and a lubrication approximation for the viscous force, squeeze flow of adhesives between two flat, impermeable steels and between steel and porous wood can be successfully modeled. However, deviations from theory were encountered as related to the method of adhesive application. Both meniscus force in consequence of the surface tension of adhesive pull around the edge of plate and viscous force due to the viscosity of adhesive operate inside the meniscus when adhesive was spread on the entire surface by a hard roller. manufacture where viscosity and surface tension effects were both involved. Last but not Such is probably the case when wood veneer is cold-pressed (pre-pressed) in plywood least, rheological behavior and alkali modification of wheat flour was determined by rheological and infrared studies, respectively. / Master of Science