Thiolated Silicone Oils as New Components of Protective Creams in the Prevention of Skin Diseases

This work investigates the possibility of using thiolated silicone oils as new components in protective creams and their impact on the efficacy of these products. Thiolated silicone oils were synthesized by amide bond formation between primary amino groups of poly17dimethylsiloxane-co-(3-aminopropyl)-methylsiloxane] and carboxylic groups of thiol ligand (3-mercaptopropionic acid) with carbodiimide as a coupling agent. To evaluate and compare the properties of these kinds of thiomers, three different emulsion o/w types were obtained. Emulsion E1 contained methyl silicone oil, E2 poly[dimethylsiloxane-co-(3-aminopropyl)-methylsiloxane], and E3 thiolated silicone oil (silicone-MPA), respectively. Physicochemical properties, including pH, conductivity, droplet size distribution, viscosity, and stability, were assessed. The efficacy of barrier creams in the prevention of occupational skin diseases depends on their mechanical and rheological properties. Thus, the method which imitates the spreadability conditions on the skin and how structure reconstruction takes places was performed. We also investigated textural profile, bioadhesion, protection against water and detergents, and water vapor permeability. Emulsion E3 was characterized by beneficial occlusion, spreadability, and adhesion properties. These features with prolonged residence time on the skin can make designed barrier creams more preferable for consumers.

The Compatibility of Three Silicone Oils with Polydimethylsiloxane and the Microstructure and Properties of Their Composite Coatings

The compatibility of three types of silicone oil with polydimethylsiloxane, the phase separation of their mixture and the microstructure and properties of their composite coatings were investigated. The existing form of silicone oil in the coating and the precipitation behavior were also studied. The compatibility observed experimentally of the three silicone oils with PDMS is consistent with the results of the thermodynamic calculation. The silicone oil droplet produced by phase separation in the mixture solution can keep its shape in the cured coating, also affecting the microstructure and mechanical properties of the coating. It was found that methyl silicone oil and methyl fluoro silicone oil do not precipitate on the surface, and they have no effect on the surface properties of the coating. In contrast, phenyl silicone oil has obvious effect on the surface, which makes the water contact angle and diiodomethane contact angle of the coating decrease significantly.

The effect of oil heat treatment on biological, mechanical and physical properties of bamboo

Bamboo is now widely used in construction, papermaking, textile, furniture and other fields because of its renewable, fast-growing, high-strength, high-yield and easy processing. However, compared with wood, bamboo and bamboo products are more vulnerable to damage by fungi and pests. An effective and eco-friendly method is urgently needed to improve their physical and chemical properties, decay resistance and anti-mildew properties, and hydrophobic properties. Here, bamboo was heated with methyl silicone oil. The effect of different temperatures (140 °C–200 °C) and different times (2 h–6 h) on the properties of bamboo was studied systematically, including chemical composition, physical and mechanical properties, surface wettability, decay resistance and anti-mildew property. No starch granules were observed inside the parenchymal cell lumen of bamboo specimen heat treated at 200 °C for 6 h. And with the increase of heat treatment temperature and time, the content of cellulose and hemicellulose decreases gradually while relative content of lignin increases due to its better thermal stability. Accordingly, the surface wettability decreases due to the changes of the surface functional groups and micro-morphologies. Under the condition of oil heat treatment at 160 °C for 2 h, the compressive strength parallel to grain of bamboo samples reach the maximum of 109.52 MPa. With further increase of heating temperature, the corresponding compressive strength decreases. The resulted bending strength and MOE both display similar changing trend. However, the optimal parameter is at 180 °C for 2 h, with the highest bending strength and MOE values of 142.42 MPa and 12,373.00 MPa, respectively. Finally, the decay resistance and anti-mildew property are dramatically enhanced with increased heat treatment temperature and time. All the corresponding changing mechanisms are investigated in depth and in detail. Our results provide comprehensive process parameters and micro-mechanism for the performance of oil heat treatment of bamboo, which can be used to guide the actual production.

Preparation of Binary Thermal Silicone Grease and Its Application in Battery Thermal Management

To improve the problems of large interface thermal resistance and low heat dissipation efficiency in battery thermal management (BTM), this paper uses methyl silicone oil as the matrix, AIN, copper powder (CP), and carbon fiber (CF) as thermally conductive fillers, and acetone and stearic acid as particle surface modification components. A variety of binary thermal silicone greases (TSGs) with different compositions were prepared. Different instruments were used to test the material properties of TSGs, and a better TSG was selected to coat the interface between battery and phase change material (PCM) for battery charging and discharging experiments. Through the analysis of experimental data, it was found that among the TSGs made of three mixed fillers (AIN/CP, AIN/CF, CP/CF), the three TSGs had good thermal stability, and their thermal degradation temperature both exceeded 300 °C. As the ratio of thermally conductive filler was gradually changed from 5:1 to 1:5, the TSG containing CP/CF had higher thermal conductivity and lower volume resistivity, while the TSG containing AIN/CF had the least damage due to interface wear. The acidification treatment of thermally conductive filler can improve the adsorption and compatibility of thermally conductive particles and silicone oil, and reduce the oil separation rate of TSGs. The prepared expanded graphite (EG)/paraffin wax (PW) composite phase change material (CPCM) has a relatively large latent heat of phase change, which can effectively control the temperature of the battery, but coating TSG between the battery and the CPCM can further enhance the heat dissipation effect of the battery.

CARACTERIZACIÓN QUÍMICA DEL ACEITE ESENCIAL DE ORÉGANO COMO AGENTE BIOCONSERVADOR EN ALIMENTOS

Se ha analizado químicamente el aceite esencial de orégano cultivado en el cantón El Empalme en Ecuador para aplicarlo como agente bioconservador en alimentos. Para ello se empleó cromatografía de gases acoplada con espectrometría de masas. Se identificó como componente principal el carvacrol con 62,41%, seguido de β-cariofileno 8,84%, α-bergamoteno 6,75%, p-cimeno 6,24%, geraniol 4,29%; y α-humuleno, β-felandreno, 1-octen-3-ol, oxido de cariofileno, 4-terpineol, E-citral, γ-terpineno, z-citral en pequeñas cantidades. El Carvacrol le otorga al orégano múltiples propiedades antioxidantes, microbiológicas y conservantes de alimentos, además de potenciales aplicaciones en perfumería y cosmética. Palabras Clave: Orégano, aceite esencial, cromatografía de gases, espectrometría de masas. Referencias [1]J. Bruneton, Farmacognosia. Fitoquímica, Plantas Medicinales, Zaragoza: Acribia, 2001. [2]N. Rodríguez, « Uso de agentes antimicrobianos naturales en la consevacion de frutas y hortalizas,» Ra Ximhai, vol. VII, pp. 153-170, 2011. [3]S. Burt, «Essential oils: their antibacterial properties and potential applications in foods.,» Int J Food Microbiol, pp. 223-253, 2004. [4]J. Gutiérrez, G. Rodríguez, C. Barry-Ryan y P. Bourke, «Efficacy of plant essential oils against foodborne pathogens and spoilage bacteria associated whit ready-to-eat- vegetables: Antimicrobial and sensory screening.,» Journal of Food Protection, pp. 1846-1854, 2008. [5]R. Hulankova, G. Borilova y I. Steinhauserova, «Combined antimicrobial effect of oregano essential oil and caprylic acid in minced beef.,» Meat Science, pp. 190-194, 2013. [6]I. Fernández-Pan, M. Mendoza y J. Mate, «Whey protein isolate edible films essential oils incorporated to improve the microbial quality of poultry.,» Sci Food Agric, pp. 2986-2994, 2013. [7]L. Iturriaga, I. Olabarrieta y I. Maranon, «Antimicrobial assays of natural extracts and their inhibitory effect against Listeria innocua and fish spoilage bacteria, after incorporation into biopolymer edible films.,» Int J Food Microbiol, pp. 58-64, 2012. [8]C. Mera, V. Guerrón, S. Sánchez, J. Neira y R. Moreno, «Efecto del aceite esencial de orégano (Oreganum Vulgare L.) como agente antimicrobiano en la conservación de carne de dos especies de tilapia.,» Nutrición Clínica, Dietética y Hospitalaria, nº 39, pp. 35-36, 2019. [9]J. Soriano, Micotoxinas en alimentos, Ediciones Díaz de Santos: Madrid, 2007. [10]M. Pascual, K. Slowing, E. Carretero, M. Sánchez y A. Villar, « Lippia: Traditional uses, chemistry and pharmacology.,» Ethnopharmacol, pp. 201-214, 2001. [11]H. Peredo, E. Palou y A. López, «Aceites esenciales: métodos de extracción,» Temas selectos de ingeniería de alimentos, vol. 1, nº 3, pp. 24-32, 2009. [12]A. Kimbaris y N. D. D. Siatis, «Comparison of distillation and ultrasound - assisted extraction methods for the isolation of sensitive aroma compounds from garlic,» Ultrasonics Sonochemistry, vol. 13, pp. 54-60, 2006. [13]B. Bayramoglu, S. Shamin y G. Sumnu, «Solvent-free microwave extraction of essential oil from oregano,» Journal of food engineering, nº 88, pp. 535-540, 2008. [14]M. Golmakani y K. Rezaei, «Comparison of microwave-assisted hydrodistillation with the traditional hydrodistillation method in the extraction of essential oil from Thymus Vulgarus,» Food Chemistry, nº 101, pp. 1558-1564, 2008. [15]M. Ortuño, Manual práctico de aceites esenciales, aromas y perfumes, España: Aiyana, 2006. [16]A. Caldas, «Optimización, Escalamiento y Diseño de una Planta Piloto de Extracción Sólido Líquido,» Universidad de Cuenca , Cuenca, 2012. [17]M. Méndez, K. Bodero y S. Alvarado, «Biosíntesis de nanopartículas de hierro (FE3O4) en la remidacion de aguas contaminadas,» Universidad, Ciencia y Tecnología, vol. 24, nº 96, pp. 35-45, 2020. [18]J. Sercik, «Detector in gas chromatography,» Journal of Chromatography Library, vol. 4, pp. 34-42, 1975. [19]E. Gimeno, «Compuestos fenólicos. Un análisis de sus beneficios para la salud,» Offarm, vol. 23, nº 6, pp. 80-84, 2004. [20]J. Bello, Ciencia bromatológica: principios generales de los alimentos, Madrid: Díaz de Santos, 2000. [21]R. Fonnegra y S. Jiménez, «Plantas medicinales aprobadas en Colombia,» Universidad de Antioquia, Medellín, 2007. [22]N. Davies, «Gas chromatographoic retention indices of monoterpenes and sesquiterpenes on methyl silicone and carbowax 20 M. phases.,» Journal of Chromatography A, pp. 1-24, 1990.

Study on the Synthesis and Thermal Stability of Silicone Resin Containing Trifluorovinyl Ether Groups

Silicone resin is a high-temperature resistant material with excellent performance. The improvement of its thermal stability has always been the pursuit of researchers. In this paper, a sequence of silicone resins containing trifluorovinyl ether groups were prepared by the co-hydrolysis-polycondensation of methyl alkoxysilane monomers and {4-[trifluorovinyl(oxygen)]phenyl}methyldiethoxysilane. The structures of the silicone resins were characterized by FT-IR and 1H NMR. The curing process of them was studied by DSC and FT-IR spectra, and results showed that the curing of the resins included the condensation of the Si-OH groups and the [2 + 2] cyclodimerization reaction of the TFVE groups, which converted to perfluorocyclobutane structure after curing. The thermal stability and thermal degradation behavior of them was studied by TGA and FT-IR spectra. Compared with the pure methyl silicone resin, silicone resins containing TFVE groups showed better thermal stability under both N2 and air atmosphere. Their hydrophobic properties were characterized by contact angle test. Results showed that PFCB structure also improved the hydrophobicity of the silicone resin.

Effects of One-Step Hot Oil Treatment on the Physical, Mechanical, and Surface Properties of Bamboo Scrimber

Bamboo scrimber is a new type of bamboo-based panel that is prone to be affected by biological and service environments under outdoor conditions. In this paper, the physical and mechanical performance and the microchemical and surface properties of untreated and hot-oil-treated bamboo scrimber were analyzed to illustrate the processing mechanism of scrimber. Methyl silicone oil treatment was carried out at 120, 140, and 160 °C for 2, 4, and 6 h. The density, mechanical properties, air-dried moisture content, surface morphology, chemical structure, swelling properties, color, and contact angle of the bamboo scrimber were analyzed to evaluate the treatment effectiveness. Observation of the environmental-scanning electron microscope indicated that the glue layer of the bamboo scrimber was not significantly damaged after hot oil treatment. At low temperatures, the mechanical properties did not change significantly. Infrared-spectrum analysis showed a significant decrease in mechanical properties at higher temperatures and longer treatment time for the degradation of hemicellulose. The contact angle test and swelling properties test showed that the hot oil treatment improved the dimensional stability and reduced the wettability on the surface of the bamboo scrimber. The above analysis results show that the treatment at 140 °C for 2 h is most effective.

Evaluation of the contact angle and wettability of hydrophobised lightweight concrete with sawdust

The aim of the research presented in the paper was to evaluate the feasibility of using hydrophobic preparations based on organosilicon compounds for protection treatment on the lightweight concrete modified with sawdust. The experimental part of the work concerns the physical and mechanical properties of lightweight concrete and the influence of two hydrophobic agents on the contact angle of the material. Lightweight concrete contact angle (θw) was determined as a time function using one measuring liquid. Water repellent coatings in lightweight concrete structure with the coarse aggregate sawdust (CASD) using electron microscopy were presented. The effectiveness of hydrophobisation of porous lightweight concretes was determined on the basis of the research. For the hydrophobic surface, the contact angle decreased and it depended on the used agents. The lowest contact angle of 40.2° (t=0) was obtained for reference concrete before hydrophobisation and 112.2° after hydrophobisation with a methyl-silicone resin based on organic solvent. The results of scientific research confirm the possibility to produce lightweight concretes modified with CASD with adequate surface protection against external moisture.

Preserving Softness and Elastic Recovery in Silicone-Based Stretchable Electrodes Using Carbon Nanotubes

Soft electronics based on various rubbers have lately been needed in many advanced applications such as soft robotics, wearable electronics, and remote health monitoring. The ability of a self-sensing material to be monitored in use provides a significant advantage. However, conductive fillers usually used to increase conductivity also change mechanical properties. Most importantly, the initial sought-after properties of rubber, namely softness and long elastic deformation, are usually compromised. This work presents full mechanical and electro-mechanical characterization, together with self-sensing abilities of a vinyl methyl silicone rubber (VMQ) and multi-walled carbon nanotubes (MWCNTs) composite, featuring conductivity while maintaining low hardness. The research demonstrates that MWCNT/VMQ with just 4 wt.% of MWCNT are as conductive as commercial conductive VMQ based on Carbon Black, while exhibiting lower hardness and higher elastic recovery (~20% plastic deformation, similar to pure rubber). The research also demonstrates piezo-resistivity and Raman-sensitivity, allowing for self-sensing. Using morphological data, proposed mechanisms for the superior electrical and mechanical behavior, as well as the in-situ fingerprint for the composite conditions are presented. This research novelty is in the full MWCNT/VMQ mechanical and electro-mechanical characterization, thus demonstrating its ability to serve as a sensor over large local strains, multiple straining cycles, and environmental damage.