Three higher hydrocarbon phase change materials (PCMs) with melting points of 25, 40 and 50°C were microencapsulated by in situ polymerization of amino-aldehyde resins. Trimethylolmelamine (TMM) and ...hexamethoxymethylolmelamine (HMMM) were studied as amino-aldehyde pre-polymers for microcapsule wall formation, in combination with emulsifying modifying agents based on styrene-malein anhydride copolymers (SMA) of different molecular weights and different styrene-maleic acid anhydride ratios. Microcapsule sizes, size distribution and wall permeability were analysed. A mathematical model was developed for comparing the mechanical resistance of different batches of microcapsules, produced at different TMM-SMA ratios. Larger microcapsules with thicker walls and larger pores (MLAR) expressed lower resistance to breakage than slightly smaller microcapsules with thinner walls and finer pore structure (MSMA). Mathematical data were confirmed by a smudging colouration test. Laboratory microencapsulation process parameters were optimized to obtain impermeable microcapsules with improved mechanical stability. The process was transferred into a 10 l pilot reactor for two PCMs with melting points of 25 and 40°C. Dry powder of microencapsulated PCMs was obtained by spray drying of aqueous microcapsule suspensions.
The microencapsulated animal repellent Daphne was prepared by in situ polymerization of melamine-formaldehyde prepolymer with styrene-maleic acid anhydride copolymer as a modifying agent. Pure Daphne ...(a mixture of essential oils and other volatile compounds) and Daphne (45wt%) diluted with isopropylmyristate (55wt%) were used as core materials. Three types of formulations were prepared: (1) aqueous suspension concentrates, tobe diluted for spraying, (2) thickened pastes with microcapsules for coating tree bark, and (3) textile, paper and metal strips, coated or impregnated with microcapsules. In field testing, all formulations with microcapsules showed a prolonged effect in comparison with non-encapsulated Daphne. The repelling effect on animals was stronger in summer and weaker in winter, when the pressure of the animals was much more intense, and diffusion of repellent from the microcapsules was reduced due tolow temperatures. However, pastes for the bark and non-woven textile strips impregnated with microencapsulated Daphne showed good repelling effect against deer and rabbits in the winter period.
Microcapsules on Woven and Non-woven Materials Knez, E.; Kukovič, M.; Pipal, V. ...
International journal of polymeric materials,
10/1/2000, Letnik:
47, Številka:
4
Journal Article, Conference Proceeding
Recenzirano
Properties of textiles can be improved or changed by applying a special finishing, which contains microcapsules and contributes to an antimicrobial, deodorising, medicinal or insect repelling effect. ...For the impregnation of woven and non-woven textiles, the compatibility of microcapsules with various water-based additives was tested: (1) water suspensions of binders based on latex (styrene-butadiene, polyvinylacetate, acrylate) with anionic and/or non-ionic emulsifiers, (2) binders based on solutions of water-soluble polymers (polyvinyl alcohol, carboxymethyl cellulose, modified starch, xanthanes), (3) finishing media based on urea- and melamine-forinaldehyde resins and dimethylolethylene urea. The suspension of microcapsules can be mixed with the above binders in all ratios. To determine the optimum conditions for the preparation of finishing formulations with microencapsulated ingredients, the coating system, the target effect of finishing, the textile properties and the target properties of the final product have to be defined.
The deer and rabbit repellent Daphne was microencapsulated by the in situ polymerization method and formulated into aqueous suspension formulations with polyvinyl alcohol and/or acrylate latex ...binders. The efficacy of formulations on Capreolus capreolus and Lepus europaeus was tested in 1 wt% concentration (sprays) and 50 wt% concentration (coatings) in the winter season with baits containing apple branches with leaves. Microencapsulated repellent in 50 wt% concentration showed a prolonged release and a statistically significant improved effect on C. capreolus in the second month of testing (days 30 and 49) and on L. europaeus in the third month (day 71), while 1 wt% concentrations had no statistically significant effects. Due to limited precipitation during the experiment, the differences in formulation efficacy regarding binder resistancy to rain were not expressed.
Ionic liquids as trihexyl-tetradecyl-phophonium-dicyanamide (Cyphos 105) and cocosalkyl-pentaethoxi-methyl-ammonium-methosulfate (Ammoeng 100) were applied for the esterification of stearic acid and ...glycerol using Candida antarctica lipase (Novozyme 435). When only ILs were applied as solvents at 1:15 initial substrate molar ratio the conversion was 76 and 78 % in the case of two kinds of ILs, respectively. Mixed the ILs and supercritical CO2 the conversion reached 79 and 86 %. The conversion was found highest in supercritical CO2, reached 90 %. Moreover formation of glycerol-di-stearate is much lower in the case of ILs comparing with SCCO2.
The minimal inhibitory concentration (MIC) of tobramycin for 8 strains of Pseudomonas aeruginosa was 0.075 μg/ml. using an agar-dilution technique. It was possible to develop a moderate degree (up to ...16-fold) of in vitro resistance in 5 of these 8 clinically isolated strains by exposing them to gradually increasing concentrations of tobramycin. Tobramycin-resistant strains exhibited cross-resistance to gentamicin and to a lesser degree to neomycin. Cross-resistance to kanamycin could not be detected. Resistant strains showed no significant loss of resistance after repeated (up to 20) transfers in antibiotic-free medium. La concentration inhibitoire minimale (CIM) de la tobramycine pour 8 souches de Pseudomonas aeruginosa était de 0.075 μg/ml. en employant un procédé de dilution agarique. On a pu déclencher une résistance modérée in vitro (jusqu'à 16 fois plus) dans 5 de ces 8 souches cliniquement isolées en les soumettant graduellement à des concentrations de plus en plus fortes de tobramycine. Les souches qui se sont avérées rebelles à la tobramycine témoignaient d'une résistance croisée à la gentamycine et aussi, dans une certaine mesure, à la néomycine. On n'a pu constater aucune résistance à la kanamycine. Les souches rebelles, soumises à des transferts répétés (jusqu'à 20 fois) dans un milieu dépourvu d'antibiotiques, ne témoignaient d'aucune perte de résistance appréciable.
The contribution presents the results of testing the efficacy of microencapsulated repellents, based on Psyadia punctulata leaf exudate, and Daphne repellent. The active compound of Daphne (Dragoco, ...Austria) is a mixture of more than twenty natural and synthetic volatile compounds, contributing to smell- and taste-based repellent effects against deer. Psiadia punctulata, a plant species from Eastern Africa, is known to be avoided by browsing herbivores, even during severe drought. Its extract, obtained by acetone extraction of a resinous surface leaf exudate, was tested as a taste-based repellent. A modified in situ polymerization method of aminoaldehyde resins with styrene-maleic acid anhydride modifier was used for the microencapsulation. The product was mixed with polyvinyl alcohol and acrylate binders into a suspension formulation. The efficacy of the repellent on roe deer (Capreolus capreolus Linne) in winter was tested with baits, containing one-year-old apple branches, on agricultural surfaces sown with wheat. The damage caused by browsing was evaluated at different time intervals. The results of testing showed that all microencapsulated repellent formulations exhibited a prolonged activity and improved efficacy in comparison with the standard non-encapsulated Daphne repellent.
