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Synthesis and Characterization of Lignosulfonate-based Adhesive and Profragrance

Author: WangZuo
Tutor: ShenYouQing
School: Zhejiang University
Course: Chemical Engineering
Keywords: Lignosulfonate formaldehyde-free adhesive profragrance encapsulation sustained-release
CLC: TQ437
Type: Master's thesis
Year: 2014
Downloads: 2
Quote: 0
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Abstract


Various countries in the world are paying more attention to the research of developing low formaldehyde or formaldehyde-free wood adhesives. Research on formaldehyde-free wood adhesive which use natural renewable material as raw material has become a hotspot. Industrial lignin mainly consists of alkali lignin and lignosulfonate separated from wastewater of the pulp and paper industry. Molecular structure of lignin and its derivatives containing phenol hydroxyl, alcoholic hydroxyl, carboxyl, ether bond, carbon-carbon double bond and other functional groups and chemical bonds, so they can react with crosslinking agent such as aldehydes, polyol, maleic anhydride, amine to prepare adhesives. Meanwhile, for the reason that lignin and derivatives are well-sourced, non-toxic, diverse in molecular structure and easy to modify, lots of research work are focused on them.In the first part of this paper, we made use of lignosulfonate as polyol to prepare a novel lignosulfonate-based adhesive which is absence of formaldehyde. In the experiment, hydrogen peroxide and ferrous sulfate are used as a redox initiator. By initiating the copolymerization of acrylic acid (AA) and maleic anhydride (MA), polymer MA-co-AA system is obtained. The MA-co-AA, lignosulfonate and polyol are blended together and heated to occur the condensation polymerization reaction. The gel content is measured to determine the crosslinking density and the speed of curing reaction. By which, the factors that have impacts on the curing reactions can be analyzed, such as molecular weight and molecular weight and distribution functional groups of different lignosulfonates.Flavour plays an important role in consumer satisfaction and influences further consumption of products. Flavours are usually delicate and volatile. As a result of their high volatility, the smell of fragrances can only be perceived over a relatively short period, in particular in applications of functional perfumery. To increase the long-lastingness of perfumery ingredients in these applications, fragrance precursors, so-called profragrance, have been developed. Profragrance represent an attractive alternative to classical encapsulation techniques.They link fragrance molecules via a covalent bond to a suitable substrate to form a nonvolatile fragrance conjugate. The covalent bond is then cleaved in application under mild environmental conditions, such as variations of temperature, exposure to (day) light, easily accessible or ubiquitous reagents such as oxygen or water (including a change in the pH value), as well as different enzymes and microorganisms. Different sets of compounds were found to be the best performers for different types of applications.Thioethers were found to be suitable precursors to release the corresponding fragrances. A series of thioether profragrances was prepared by reaction of different mercaptoalkanoates with δ-damascone and tested for their release efficiency in a fabric softener and an all-purpose cleaner application. Bodycare and household products are aqueous surfactant formulations, the profragrances of8-damascone were added to a concentrated aqueous TEA-esterquat surfactant emulsion. Dynamic headspace analysis on dry cotton and on a ceramic plate showed that the performance of the different precursors depended on the precursor structure, but also on the particular conditions encountered in different applications.

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