Study on the Pyrolysis Behaviors of Urea-Formaldehyde Resin and Rice Straw Mixed Pellets

In order to study the effect of biomass on the pyrolysis characteristics of urea-formaldehyde resin, the thermogravimetric experiments were carried out respectively using urea-formaldehyde resin (UF), rice straw (RS), and their mixed pellets with different proportions. The pyrolysis kinetics analysis was conducted. The results showed that the pyrolysis process of UF resin and mixed pellets could be divided into three stages: the drying and dehydration of the material, the rapid decomposition of volatile matter, and residue decomposition. The reaction order of UF resin and mixed pellets was discussed using the Coats–Redfern method, the activation energy of UF resin was 54.27 kJ/mol, and this value decreased with the addition of rice straw. As the mass ratio of UF resin to rice straw was 3:1, the activation energy achieved the lowest value, which means that the addition of rice straw was beneficial to the pyrolysis process of UF. In the process of pellet preparation, the falling strength and compressive strength of UF resin pellets can be improved by adding an appropriate proportion of rice straw. In this test, the yield of pyrolytic carbon reached the highest value of 23.93%, as the mass ratio of UF resin to rice straw was 3:2. When the mass ratio was 4:1, the highest liquid product yield of 43.21% was achieved.

Synthesis of Organosilicon Polymers Based on Carbamide Formaldehyde Resin

The article presents the synthesis of organosilicon compounds based on industrial secondary raw materials of urea-formaldehyde resin and tetraethoxysilane. The structural characteristics of the synthesized hydrophobic polymer have been studied. Compositions of hydrophobic compositions based on synthesized poly (oligomers) have been developed and tested in concrete mixtures.

Carbon-Carbon Composite Materials Based on Low Modulus Fabrics

Scientific research and the search for new technologies to increase the level of mechanical and high-temperature properties are ongoing. The article discusses the technology of using carbon materials, pyrolysis and impregnation with phenol-formaldehyde resins. It is shown that the proposed technology makes it possible to achieve a sufficient level of mechanical properties when using low-modulus carbon fabrics after pyrolytic treatment as a prepreg at a temperature treatment no higher than 900 K. Pillowcase and resole phenol-formaldehyde resins were used to impregnate the prepreg. The proposed technology also allows the introduction of alloying additives into the system to improve the properties. An example of the introduction of nitrogen into a composite by adding urotropine to a phenol-formaldehyde resin, which was used to impregnate the composite, is considered.

Process optimization and removal of phenol formaldehyde resin coating using mechanical erosion process

Consumption of coated abrasive discs in various automobile and pipe fitting application is increasing, due to its good surface finish. Coated abrasive disc consists of single layer of abrasive grain bonded to a fibre backing. The major portion of the disc is comprised of fibre backing. But the sustainability of the fibre backing is low and is dumped as waste after usage. The present work deals with the removal of resin coating and recovery of fibre backing from the spent coated abrasive discs using physical separation process such as sand blasting technique. Initially, the recovery experiment was carried out based on L16 orthogonal array. The factors and levels chosen for the experiments were erodent pressure (0.2, 0.4, 0.6 and 0.8 MPa), erodent size (36, 60, 80 and 120 grit), disc orientation (30, 45, 60 and 75°) and number of times flexing (5, 10, 15 and 20). The experimental result shows that erodent size and erodent pressure have a major impact on recovery of the fibre backing. The surface structure of the recovered backing was analysed using scanning electron microscopy and optical microscopy. The recovered backing was very much useful for the coated abrasive industry as the flexible backing and support material for abrasive grain coating.

Research Progress of Wood-Based Panels Made of Thermoplastics as Wood Adhesives

When thermoplastic resins such as polyethylene (PE) and polypropylene (PP) are selected as wood adhesives to bond wood particles (fibers, chips, veneers) by using the hot-pressing technique, the formaldehyde emission issue that has long existed in the wood-based panel industry can be effectively solved. In this study, in general, thermoplastic-bonded wood-based panels presented relatively higher mechanical properties and better water resistance and machinability than the conventional urea–formaldehyde resin-bonded wood-based panels. However, the bonding structure of the wood and thermoplastic materials was unstable at high temperatures. Compared with the wood–plastic composites manufactured by the extruding or injection molding methods, thermoplastic-bonded wood-based panels have the advantages of larger size, a wider raw material range and higher production efficiency. The processing technology, bonding mechanism and the performance of thermoplastic-bonded wood-based panels are comprehensively summarized and reviewed in this paper. Meanwhile, the existing problems of this new kind of panel and their future development trends are also highlighted, which can provide the wood industry with foundations and guidelines for using thermoplastics as environmentally friendly adhesives and effectively solving indoor pollution problems.

Formaldehyde Levels in Fabrics on the Ghanaian Market

Background: Formaldehyde is a chemical used in several textile production processes, such as hardening of fibers and antimold finishing. However, it has varying effects on humans, such as irritation of the eyes, nose, throat, wheezing, chest pains and bronchitis. In the midst of COVID-19, individuals are using various fabrics for face mask production, which may be containing levels of formaldehyde that can negatively affect their health. Methods: This study investigated formaldehyde levels in fabrics on the Ghanaian market to determine compliance to standards set by the Ghana Standards Authority (GSA) with the aid of experimental procedures. Thirty-two (32) different brands of fabrics were selected for the investigation. Formaldehyde levels were determined using a spectrophotometer (DR6000). Data were analyzed using the Statistical Product and Service Solutions (SPSS) for Windows version 22. The mean performance attributes and the formaldehyde levels of the sampled fabrics were determined before and after washing. Inferential statistics (Analysis of Variance and Paired Samples t-test) at 0.05 alpha levels were used to determine significant differences between and among the groups involved. Results: The fabric samples tested positive for formaldehyde before and after washing, with some exceeding the standard limits set by the GSA before washing. Significant differences existed between and among the samples with regard to formaldehyde levels as well as weight and weave types of the samples and formaldehyde levels. Conclusion: Washing significantly reduced the formaldehyde levels in the fabrics. It is recommended that Ghana standards authority takes a further look at the fabrics on the Ghanaian market to ensure manufacturers comply with set standards and consumers are also advised to wash their clothes at least once before use to reduce the level of impact formaldehyde resin may have on them.