Adhesives preparation from starch

Current corrugated board adhesives are prepared from starch that has a much higher molecular weight (> 100,000 mass units). The largest portion of starch in the commercial adhesive preparation is in an undissolved (i.e., kernel)... 

Starch polyurethane foams could be converted into sorbents for water when starch-acrylonitrile or starch-methacrylonitrile graft copolymers were crosslinked with diisocyanates.2655 2656 Such polyurethanes have been proposed as occlusive wound dressings,2657 as well as sizes for cotton yams.2658 Starch polyurethanes for reinforced paper were produced in reaction of iV-chlorocarbamoylethyl starch with cresol or thiolignin.2659 The addition of mineral salts to polyurethanes prepared from starch and urea improved their performance as adhesives.570... 

The reaction of starch with bis(hydroxymethyl)ethyleneurea condensed with cationic poly(urea amides) and cationic polyamides was used to produce paper sizes, adhesives, and textile-finishing agents.2616 Cationic starch that has been prepared from starch and cyanamide was patented for sizing wood and for synthetic wool fibers and fabrics.2296,2298,2662 Reaction of starch urethanes with alkylene oxides and aldehydes was reported for use as hardenable compounds in waterproof films, coatings, and adhesives.2663... 

In industrial production of acid-modified starches, a 40% slurry of normal com starch or waxy maize starch is acidified with hydrochloric or sulfuric acid at 25—55°C. Reaction time is controlled by measuring loss of viscosity and may vary from 6 to 24 hs. For product reproducibiUty, it is necessary to strictly control the type of starch, its concentration, the type of acid and its concentration, the temperature, and time of reaction. Viscosity is plotted versus time, and when the desired amount of thinning is attained the mixture is neutralized with soda ash or dilute sodium hydroxide. The acid-modified starch is then filtered and dried. If the starch is washed with a nonaqueous solvent (89), gelling time is reduced, but such drying is seldom used. Acid treatment may be used in conjunction with preparation of starch ethers (90), cationic starches, or cross-linked starches. Acid treatment of 34 different rice starches has been reported (91), as well as acidic hydrolysis of wheat and com starches followed by hydroxypropylation for the purpose of preparing thin-hoiling and nongelling adhesives (92). 

US 5,204,399 (American) 1991 Thermally conductive thermoplastic polyimide film die attach adhesives and their preparation National Starch and Chemical Investment Holding Corp. R Edelman Adhesive formulations having excellent die shear strength A polyimide-siloxane was prepared from aromatic amines, bis aminophe-noxybutylsiloxane and aromatic dianhydrides... 

The hemicellulose adhesives were evaluated on 50- by 100-mm2 A-flute corrugated board samples. Commercial single-faced board (125 to 160 g/m2) bonded with a maize starch adhesive and liner (160 g/m2) was obtained. The liner and fluting material were prepared from virgin kraft pulp and were not surface-sized with starch. The single-faced material was cut into samples (50 x 100 m2) with the flutes in the 50-mm direction. Liner samples were cut in 60- by 110-m2 samples. 

Epichlorohydrin is usually prepared from propene and is mainly used in the manufacture of glycerol and epoxy resins. It is also used in the manufacture of elastomers, glycidyl ethers, cross-linked food starch, surfactants, plasticizers, dyestuffs, pharmaceutical products, oil emulsifiers, lubricants, and adhesives as a solvent for resins, gums, cellulose, esters, paints, and lacquers and as a stabilizer in chlorine-containing substances such as rubber, pesticide formulations, and solvents. 

Mondragon et al ° reported that unmodified and modified NR latex were used to prepare thermoplastic starch/NR/MMT nanoeomposites by twin-screw extrusion. After drying, the nanoeomposites were injection moulded to produce test specimens. SEM of fractured samples revealed that chemical modification of NR latex enhanced the interfacial adhesion between NR and thermoplastic starch (TPS), and improved their dispersion. X-ray diffraction (XRD) showed that the nanoeomposites exhibited partially intercalated/exfoKated structures. Surprisingly, transmission electron microscopy (TEM) showed that clay nanoparticles were preferentially intercalated into the rubber phase. Elastic modulus and tensile strength of TPS/NR blends were dramatically improved from 1.5 to 43 MPa and from 0.03 to 1.5 MPa, respectively, as a result of rubber modification. 

In recent years, soy products such as soy whole flour (SF), soy protein concentrate (SPC), and soy protein isolate (SPI) have been considered as alternatives to petroleum polymers because of their abundance, low cost, perfect adhesion, and good biodegradability (Maruthi et al. 2014). SF contains about 40-60 % protein, combined with fats and carbohydrates. Soy protein concentrate contains about 60-70 % protein. SPI contains more than 90 % of protein and is the most widely used soybean product for film processing (Ciannamea et al. 2014). Moreover, SPI-based films are clearer, smoother, and more flexible compared to other plant protein-based films, and they have impressive gas barrier properties compared to those prepared from lipids and polysaccharides. When SPI films are not moist, their O2 permeability was 500, 260, 540, and 670 times lower than that of films based on low-density polyethylene, methylceUulose, starch, and pectin, respectively (Song et al. 2011). Thus, in addition to their large availability, soy protein-based materials have interesting barrier and release properties ideal for packaging applications. 

Starch adhesives are derived primarily from the cassava plant, although other starch sources may be used. Starch is usually heated in alkaline solutions, such as NaOH, followed by cooling to room temperature to prepare the dispersions. After cooling, they are applied as cold-press adhesives. They develop their strength by loss of water into a wood substrate. Tack is developed rapidly normal wood processing takes 1-2 days at room... 

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