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Polyvinyl Alcohol and Polyvinyl Acetate
Published in Abdullah Al-Mamun, Jonathan Y. Chen, Industrial Applications of Biopolymers and their Environmental Impact, 2020
One of the most traditional applications of PVA is found in fiber production, of which the first example is polyvinyl formal from PVA and formaldehyde developed in Japan by Sakurada et al. in 1939 and then Kurashiki Rayon Co., Ltd., started commercial production in 1950, which is often called as vinylon [31]. PVA fiber is not suited for clothing application. However, superiorly strong mechanical properties can be gained by orientation of polymer chains during drawing or stretching, owing to high crystallinity by pendent hydroxyl groups, which leads to high resistance to water and chemicals, including alkali and natural conditions. Therefore, PVA fiber is now composed of PVA homopolymer and the name of vinylon often indicates the PVA fiber.
Dispersions of Rigid Nonspherical Particles
Published in Rajinder Pal, Rheology of Particulate Dispersions and Composites, 2006
Suspensions of nonspherical (anisometric) rigid particles in liquids are ubiquitous in many industries, such as printing and papermaking, petroleum, polymer, aerospace, bioengineering, construction, ceramics, coal, magnetic media, pharmaceutical, and food [1–10]. Slurries of nonspherical particles (such as calcium carbonate, kaolin clay, titanium dioxide, talc) and water are widely used in the paper-coating process. Clay particles used in drilling muds are nonspherical in shape; the particles of bentonite and hectorite clays are platelike, whereas the particles of attapulgite and sepiolite clays are rod shaped. Platelike particles of mica, aluminum, magnesium hydroxide, and talc are commonly used as fillers/reinforcing agents in plastics to enhance stiffness [5]. Many polymeric composites are manufactured from suspensions of rodlike fibers in polymer melts. Fibers of rayon, vinylon, glass, nylon, and carbon materials are often utilized [8]. The solid propellants commonly used in aerospace propulsion are prepared from dispersion of nonspherical solid particles (oxidizer particles) in a rubbery matrix. Blood is a suspension of red blood cells (erythrocytes), white blood cells (leukocytes), and platelets in plasma [11]. Red blood cells are biconcave disks about 8 μm in diameter and 1 μm in thickness at the center. White blood cells are generally spherical with a mean diameter of about 7 μm. Platelets are irregularly oval or spherical bodies without any nucleus. Suspensions of acicular (needle or cigar shaped) magnetic particles are commonly used in the manufacture of digital tapes and magnetic recording media [6]. Molten chocolate is a suspension of solid nonspherical particles (mostly sugar granules and crushed cocoa beans) in cocoa butter [4]. Other examples of suspensions of nonspherical particles include suspensions of mineral pigments, cement, concrete, coal, starch, and insoluble drugs.
THz spectra of drawn and undrawn fibers measured on fiber shape samples
Published in The Journal of The Textile Institute, 2021
Shouhei Koyama, Toru Kurabayashi, Riko Tamura, Itsuki Okada
Many research groups have reported THz spectra of textile products. Tong et al. measured THz spectra of terylene (polyethylene terephthalate fiber), polyamide (Nylon fiber), and vinylon (Polyvinyl alcohol fiber), and reported that each had a characteristic absorption peak around 1 THz (Tong et al., 2012). Yan et al. measured THz spectra of ramie and bamboo fibers; they detected changes in the absorption spectrum due to intermolecular modes, making it possible to distinguish the two fibers (Yan et al., 2013). Naftaly et al. reported THz spectral measurements of woven wool, cotton, linen, silk, and mixed-fiber fabrics (Naftaly et al., 2013). Kurabayashi et al. clarified the method of using THz spectroscopy to identify cellulosic fibers commonly used in clothes and reported that the mixing ratio could be quantitatively evaluated within a few percent (Kurabayashi et al., 2017). Kim et al. reported a method for detecting damage in glass fiber reinforced plastic (GFRP) using THz spectroscopy (Kim et al., 2017). These researches have mainly focused on single fiber THz spectral measurements, not on changes in the internal molecular structure of the same type of fiber. In some research reports, THz spectrum was measured by freeze-crushing the sample and processing it into a pellet mixture of sample and polyethylene powders. Many fiber products are organic substances, it is possible that the molecular structure inside the fiber may be changed by freeze-crushing.
Preparation of isocyanate microcapsules by interfacial polymerization/in-situ polymerization and their application in wood adhesives
Published in The Journal of Adhesion, 2022
Yangbao Ma, Jixuan Song, Yan Jiang, Yanhua Zhang, Jiyou Gu
Polymeric Methylene Diphenylmethane Diisocyanate (PAPI, 44V20,∼30%, ≥99.8%) was obtained from Covestro (Germany). Urea (≥98.0%) was purchased from Heilongjiang Heihua Co., Ltd. (Heilongjiang, China). Formaldehyde (≥35.8%) was obtained from Harbin Juye Reagent Co., Ltd. (Harbin, China). Gum Arabic powder (GA, AR), Acetone (AR), Triethanolamine (AR), Dibutylamine (AR) were purchased from Tianjin Xingfu Fine Chemical Co., Ltd. Butyl acetate (AR), Hydrochloric acid (AR), Sodium hydroxide (AR) were purchased from Tianjin Fuyu Fine Chemical Co., Ltd. Polyvinyl Alcohol 1788 (PVA-1788, ≥93.5%) was purchased from Sinopec Sichuan Vinylon Works. All chemicals in this study were used as received without further purification.
Synthesis of isocyanate microcapsules as functional crosslinking agent for wood adhesive
Published in The Journal of Adhesion, 2021
Yangbao Ma, Yanhua Zhang, Xinwei Liu, Jiyou Gu
Polymethylene polyphenyl polyisocyanate (PAPI, 44V20, -NCO ~30%, ≥99.8%) was obtained from Bayer (Leverkusen, Germany). Polyvinyl Alcohol 1788 (PVA-1788, ≥93.5%) was purchased from Sinopec Sichuan Vinylon Works, Urea (≥98.0%) was purchased from Heilongjiang Heihua Co., Ltd. (Heilongjiang, China). Formaldehyde (≥35.8%) was obtained from Harbin Juye Reagent Co., Ltd. (Harbin, China). hydrochloric acid (HCl, 36%~38%), dichloromethane (DCM, ≥99.5%) and triethanolamine (TEOA, ≥99.5%) were obtained from Tianjin Fuyu Fine Chemical Co., Ltd. (Tianjin, China). All chemicals in this study were used as received without further purification.