Today, thermosetting polymer resins containing formaldehyde are mainly used in the production of plywood composites. These glues are toxic due to the generation of gaseous products, chiefly formaldehyde, during the production and exploitation of laminated materials, which pollute the environment. In order to decrease the emission of toxic products from these resins, natural product additives (lignins, tannins etc.) or fully biodegradable polymers such as starch, polylactides etc., are used. These glues are not toxic, but they have poor adhesion to wood, low water resistance and are more expensive. Our previous investigations have shown the possibility of using non-toxic virgin polyolefins as hot melts for plywood production. The aim of this work was to investigate the use of cheaper waste products, such as recycled thermoplastic polymers (polyolefins, polyamides), as glue hot melts for wood veneer bonding instead of traditional thermosetting resins, which are based on formaldehyde. Different recycled thermoplastic polymers produced from tetra package waste, domestic film waste, recycled polypropylene and recycled polyamide-6 were used as hot melts for birch wood veneer bonding. The content of the recycled adhesives was determined using differential scanning calorimetry (DSC) and the tetra package waste content of different types of polyethylenes, with additives of polypropylene and polyethylene terephthalate (PET), was fixed. Virgin high-density polyethylene and polypropylene were used as references. The fluidity of all the recycled materials, using melt flow index (MFI) measurements, was 1.96 g/10 min for polyethylenes and 1.94 g/10 min for polypropylene; this adhesive fluidity is sufficient to form full contact with the surface of the wood veneer sheets. Adhesive activity of the recycled hot melts was evaluated by preparing single overlap
The analysis of hemp cultivation and usage trends in the world and Europe shows that hemp cultivation and processing in Latvia has good perspectives. This paper presents the results of a first study about the usage of pectinase enzyme Beisol PRO (4% water solution) for Latvian hemp sort "Purini" retting at different time and temperatures conditions and treatment influence on obtained fibres quality. Gravimetrical examination of the quantity of fibres and sheaves after retting, physical-mechanical tests and TG analysis, colour properties, and selected samples microscopy evaluation show that enzyme treatment is not significant for fibre separation from stem as well as TG characteristics at investigated time and temperature conditions. Use of pectinase enzyme for hemp retting in some cases increases tensile strength of fibres and causes changes of colour characteristics.
In this research an effect of a flame-retardant coating with antimony trioxide (Sb2O3), commercial printing pastes Printperfec EX-TS, Tubvinyl 235MC and a pigment Bezaprint ROT KF onto a raw linen fabric and a bleached linen fabric has investigated. After the coating 5 washing cycles were applied to half of the fabrics. The burning test of the raw and the bleached linen fabrics and those coated with commercial printing pastes and antimony trioxide, as well as the washed fabrics was accomplished. The results of the test show, that the raw and the bleached linen fabric burns completely. The flame extinction was observed for coated fabrics and coated washed fabrics.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.