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In search of “inks” for additive manufacturing of silicone rubber parts, three different types of “all-in-one” pastes with suitable rheological flow properties, ultraviolet (UV)-activated fast cros...

Homopolymerization of octamethylcyclotetrasiloxane, D4, and two copolymerizations of this monomer with octaphenylcyclotetrasiloxane, D4Ph2, and hexaethylcyclotrisiloxane, D3Et2, were investigated b...

While incorporation of only a few mol % of diphenylsiloxy-, DiPhS, repeat units into polydimethylsiloxane, PDMS, chains is enough to completely suppress their crystallization, it also leads, in polymers obtained by silanolate-initiated ring-opening polymerization, to a puzzling and yet unexplained chain branching which significantly distorts polymer molecular weight distributions and affects their chain conformation. In contrast to this, we found that introduction of comparable amounts (ca. 5 mol %) of diethylsiloxy-, DiEtS, units into the same type of polymers also suppresses polymer crystallization but does not lead to any detectable branching, yielding polymers with the most probable molecular weight distribution and typical random coil conformation in a thermodynamically good solvent, such as toluene. On the basis of the results of a 29Si NMR and SEC-MALS study, we propose that branching in DiPhS-containing polymers is caused by a nucleophilic attack of initiating silanolate anions on their Si–CAr sid...

Novel high hydroxyl number and high functionality polyols were developed using thiol-ene reaction of castor oil with mercaptoethanol or mercaptanized castor oil with allyl alcohol (by photochemical reaction) and 2-hydroxyethyl acrylate (by Michael thiol-ene reaction). The polyols had OH numbers of 220–295 mg KOH/g and functionalities close to 6. Cast polyurethane resins were prepared with methylene diphenyl diisocyanate (MDI), dicyclohexylmethane-4,4′-diisocyanate (HMDI) and m-xylylene diisocyanate (XDI). XDI gave rubbery to leathery polyurethanes with all three polyols, while MDI and HMDI gave amorphous glasses with good mechanical properties. Rigid polyurethane foams of good properties were made with MDI and three castor oil-based polyols.

New polyols with isocyanuric structure were synthesized by thiol-ene “click” chemistry of triallyl isocyanurate with 1-thioglycerol and 2-mercaptoethanol. The synthesized polyols, prepared with high reaction rates and in very high yields, were chemically and structurally characterized. These polyols were used for the preparation of rigid polyurethane foams with excellent physical–mechanical properties and inherent flame retardancy. By alkoxylation of isocyanuric polyols with propylene oxide and/or ethylene oxide in a self-catalytic process, odorless polyols with lower hydroxyl numbers and lower viscosities were obtained, leading to PU foams with good properties, but without inherent flame retardancy. The synthesized polyols with isocyanuric structure are suitable for the preparation of all types of rigid polyurethane foams, including thermoinsulation of freezers, buildings, storage tanks and pipes for the food and chemical industry, for packaging, and as wood substitutes.

Rubber seed oil having high free fatty acid content and high unsaturation was used to obtain high quality polyurethane resins through epoxidation and ring opening with methanol and free fatty acids. Two polyols prepared with free fatty acids and without were cured with modified methylene diphenyl diisocyanate to obtain strong, high modulus glassy polyurethanes. The effect of structure on thermal and mechanical properties was analyzed. This showed that the polyol with free fatty acid utilized to obtain a branched structure gave superior crosslinking density and mechanical properties. © 2016 Society of Chemical Industry

Rigid thiourethane foams were prepared from vegetable oil-based polythiols (polymercaptans) and compared with soy- and castor oil-based polyurethane reference foams. Three types of polymercaptans were tested, soybean oil-based one with thiol groups only, epoxidized soybean oil-based with vicinal thiol and hydroxyl groups and castor oil-based with hydroxyl and thiol groups separated with several methylene units. Physical, mechanical, and thermal characteristics of polyol- and thiol based foams were similar to petrochemical foams used as heat insulation materials in construction, appliances, etc.

Effects of molecular weight of methylphenyl-containing vinylsiloxy-functionalized terpolysiloxanes on their UV-activated crosslinking by hydrosilylation at room temperature in air, shelf life stability of "all-in-one" pastes prepared from them for additive manufacturing, and mechanical properties of the resulting crosslinked elastomers, are investigated. It is found that while rheology of pastes containing base polymers, trimethylsilylated silica fillers, and thixotropic additives is not significantly affected by the base polymer molecular weight but is dominated by the filler concentration, the pastes based on higher molecular weight polymers exhibit faster crosslinking (corresponding to higher catalyst turnover numbers) and their crosslinked elastomers show transient strain-induced crystallization. The latter appears in networks from terpolymers with degrees of polymerization (DP) of 240 and above (corresponding to about one half of the critical polydimethylsiloxane chain length for entanglement formation of DP = 460), within the temperature range of -80 to -30 °C, characteristic for polydimethylsiloxane melting transition. It is believed that this is the first time an observation of this chain length effect is reported for polysiloxane elastomers and that the properties reported herein can be expected to have major implications on the application potential of these polymers in both additive manufacturing and performance of their elastomers at sub-ambient temperatures.

The reactivity of internal epoxides, as in epoxidized fatty acids, with primary amines was investigated using primary amines and a model epoxide compound, which was a mixture involving cis- and trans-isomers of 9,10-epoxyoctadecane.The reactions were carried out at 100, 170, and 200°C for 24 h. It was observed that the reaction of an amine with an internal epoxide does not proceed to any significant extent even at 200°C in the absence of catalysts. Practical applications: The model reaction of an amine with 9,10-epoxyoctadecane is helpful to understand the reaction of amines with epoxidized vegetable oils. It revealed that the key step in the reaction of amine with epoxidized vegetable oils, in the absence of a catalyst, is amidation. Model compound, 9,10-epoxyoctadecane (E-OCD), was prepared and reacted with n-octylamine and ehtanolamine without catalysts. GPC showed that in the absence of catalysts, ring opening of an internal epoxide with amine does not take place to any significant extent. While ring opening in the presence of OH groups happens to a higher extent. OH groups could act as reactants or catalysts.

A range of vegetable oil derivatives with hydroxyl, amine, isocyanate, isothiocyanate, epoxy and silane terminal groups, useful for making new bio-based polymers, were synthesized from mercaptanized oils and different allyl organic compounds by thiol-ene reaction. All products were low viscosity liquids of light yellow color except amine containing oil, which was a low melting solid. Novel functionalized oils had 3–6 functional groups per mole and were suitable for rigid and flexible polymer products.

A novel bio based Mannich polyol using limonene was synthesized. Mannich polyols are a group of amino polyols with aromatic structure which provide fire resistance, good thermal and superior physico-mechanical properties. The synthesized Mannich polyol was structurally characterized using wet methods (hydroxyl number, acid value and viscosity), gel permeation chromatography, and FT-IR spectroscopy. The Mannich polyol was successfully used for preparation of rigid polyurethane foams. Thermal analysis of the rigid polyurethane foams indicated that they were thermally stable up to 250 °C. Studies based on dynamic mechanical analyses indicated that these rigid polyurethane foams have high glass transition temperature (~200 °C). These foams have also high compressive strength and very regular cell structure with uniform size distribution. The closed cell content of these foams was higher than 90 %. The synthesized Mannich polyol based on limonene was very reactive, indicating that it is very suitable for preparation of rigid polyurethane foams using “spray” process.

Alkynated and azidated octadecane, synthesized from 9-octadecene, were used as model compounds for alkynated and azidated vegetable oils to study the kinetics of thermal Huisgen 1,3-dipolar cycloaddition. Alkyne and azide groups of alkynated and azidated octadecane possess low reactivity as they are branched in the middle of an 18-carbon chain. Reaction kinetics was studied by GPC, 1H NMR, and DSC. Detailed kinetic analysis revealed that the reaction of alkynated and azidated octadecane required 24 h to reach 90% conversion at 100°C. The activation energy of the reaction is 55 kJ/mol. Practical applications: The kinetics study of this model reaction is necessary for estimating the extent of reaction and necessary curing time of the thermal polycycloaddition of alkynated and azidated vegetable oils whose main components are triglyceride-containing aliphatic chains of 16–22 carbons. Kinetics of thermal Huisgen 1,3-dipolar cycloaddition of alkynated and azidated octadecane (A-OCD and Az-OCD) as model compounds for alkynated and azidated vegetable oils was studied by GPC, DSC, and spectroscopic methods.

We propose a 2D shape deformation method to fit technical drawings of garments (“flats”) to body figure drawings with a diversity of fashion poses. We first dress a flat onto a body figure in a standard standing pose using Radial Basis Function (RBF) mapping. For different types of clothing, we suggest two levels of treatment to determine handles automatically. We deform the flats using the selected handles to create realistic fashion sketches that fit the garments onto fashion figures in different poses. Shape deformation is performed to minimize the distortion of all the triangles of the garment mesh and preserve garment properties in the deformation. Finally, the garment details, such as style lines and seams, are deformed accordingly for realistic deformation results. Experimental results have shown that our method can deform various garment flats to fit fashion figures in different poses.

Novel renewable polyols based on limonene were synthesized using thiol-ene “click” chemistry. These limonene based polyols were structurally characterized using wet methods (hydroxyl number, acid value and viscosity), gel permeation chromatography and spectroscopic methods. The results indicated that high yield of polyols from limonene based materials can be obtained using thiol-ene reaction. These limonene based polyols were used successfully for preparation of rigid polyurethane foams. These foams had regular shape cells and uniform cell size distribution. Thermal studies on these foams indicated that foams were thermally stable up to 250 °C. The glass transition temperature of the foams was higher than 200 °C. These rigid polyurethane foams had high compressive strength and the highest compressive strength of 195 kPa was observed. These foams have good physical–mechanical characteristics and could be suitable for all the applications of rigid polyurethane foams such as thermal insulation of freezers, storage tanks for the chemical and food industries, and packing materials for food industries.

The composition of crude algal oil was analyzed and determined by several methods. Oil was converted to polyols by ozonolysis, epoxidation, and hydroformylation. Ozonolysis gave a polyol with lighter color but a low OH number and was unsuitable for polyurethane applications. Epoxidation also improved the color and gave a polyol with an OH number around 150 mg KOH/g, which with diphenylmethane diisocyanate gave a homogeneous, rubbery, transparent sheet. Desirable rigid foams were prepared with the addition of water to the formulation. Hydroformylation was carried out successfully giving an OH number of about 150 mg KOH/g, but the polyol was black. Casting the polyurethane sheet was difficult due to the very high reactivity of the polyol. Polyurethane foam of lower quality than from epoxidation polyol was obtained. More work on optimization of the foaming system would improve the foam. Crude algal oil is a viable starting material for the production of polyols. Better results would be obtained from refined algal oils.

A geodesic distance-based approach synthesizes natural facial animations using radial basis function (RBF) interpolation. The approach consists of two parts: the geodesic distance calculation and the geodesic distance-based RBF interpolation. The method works in real time, which is important in computer games and online chatting.

Cashew nut shell liquid (CNSL) is a natural aromatic oil consisting of a mixture of phenolic structures with a carboxyl group in ortho position and substituted in meta position with a hydrocarbon chain of 15 carbon atoms. The major component of CNSL is anacardic acid (90 %), which is easily decarboxylated to cardanol by distillation. The present work describes the synthesis of new biobased Mannich polyols for rigid polyurethane foams in two steps: synthesis of Mannich bases by reacting phenolic ring of cardanol with N-(2-hydroxyethyl)-1,3-oxazolidine followed by alkoxylation reactions. The polyols were characterized by wet methods (hydroxyl numbers, viscosity, acid value, density, water content, iodine value etc.), spectroscopic methods (FT-IR, 1H NMR and 13C NMR) and by Gel Permeation Chromatography. The Mannich polyols from cardanol are excellent replacements for petrochemical derived Mannich polyols based on nonyl phenol. Cardanol-based polyols were used successfully for the preparation of rigid polyurethane foams of good physical–mechanical and fireproofing properties.

Novel bio-based polyols were prepared from hydroformylated oleic acid (9/10-hydroxymethyl-octadecanoic acid) methyl esters (HFME) and trimethylolpropane by transesterification. Hydroformylation produces primary hydroxyls, which allow relatively lower transesterification temperatures and better yields than hydroxy fatty acids with secondary hydroxyl groups. These non-crystallizing polyols have no double bonds and their viscosities are acceptable. Polyurethane (PU) elastomers prepared by reaction of these polyols with diphenylmethane diisocyanate had glass transition temperatures from -33 to -56 °C, depending on the molecular weight of the triols. Tensile strength and Shore A hardness were higher, and elongation, swelling and sol fraction lower than those of corresponding networks from polyricinoleic acid polyols. The plasticizing effect of longer dangling chains in HFME-based PU compensated, to a degree, the presence of double bonds in ricinoleic acid, effectively resulting in similar glass transitions between the two families of polyols.

Polyurethanes are obtained by reacting polyols with polyisocyanates. The primary hydroxyl content is a very important characteristic of polyols because it affects their reactivity. Typically primary hydroxyls are approximately threefold more reactive than the secondary hydroxyls when reacting with aromatic isocyanates. This paper presents a simple and convenient kinetic method for determining the primary hydroxyl content in soybean polyols, based on the difference in reactivity of primary and secondary hydroxyls with phenyl isocyanate (PI). The reaction kinetics were studied by following the disappearance of the NCO band at 2260 cm−1 with time in the infrared spectra. The reaction of PI with soybean polyols was carried out in a toluene:dimethylformamide (9:1, v/v) mixture. The relative error of the method is in the range of ±5%. The method is characterized by simplicity and good reproducibility, and it can be applied to all soybean polyols irrespective of their structure.

Received 12 August 2007; accepted 22 October 2007DOI 10.1002/app.27783Published online 23 January 2008 in Wiley InterScience (www.interscience.wiley.com).ABSTRACT: Triols of molecular weights (MWs) 1000–4000, suitable for flexible foams, were prepared by transes-terification of methyl esters of ricinoleic acid with trime-thylol propane. These polyols were noncrystallizing, rela-tively low-viscosity liquids. They were reacted with diphe-nylmethane diisocyanate (MDI) to obtain elastomershaving glass transition temperatures below 2608C. Poly-mer networks from high-MW polyols exhibited relativelyhigh sol fractions suggesting that some cyclization oc-curred during polyol preparation. The low Shore hardness,relatively low strength and modest elongation of the elas-tomers were attributed to the specific structure of polyrici-noleic chains and the presence of dangling chains, servingas plasticizers.

Soybean polyols prepared by ring opening reactions of epoxidized soybean oil with hydrogen active compounds (water, alcohols, organic or inorganic acids, thiols, hydrogen etc.) have a low reactivity in the reaction with isocyanates because the hydroxyl groups are secondary. This paper presents a simple and convenient method to increase the reactivity of soybean polyols with secondary hydroxyl groups by ethoxylation reactions with the preservation of triglyceride ester bonds. The method uses mild reaction conditions: low alkoxylation temperature of 35–45 °C, low pressure of 0.1–0.2 MPa (15–30 p.s.i.) and a superacid as catalyst (HBF4). The new soybean polyols have a higher reactivity toward isocyanates in polyurethane formation due to the high percentage of primary hydroxyl groups. The primary hydroxyl content was determined by the second order kinetics of polyol reaction with phenyl isocyanate.

New monomers were prepared by introducing the azide groups in castor, canola, corn, soybean, and linseed oils. Polymerization of the azidated oils with alkynated soybean oil under thermal "click" chemistry conditions (without using a solvent or a catalyst) yielded fully cross-linked elastomers (1-5) of almost the same density (1.05 × 10(-3) kg/m(3)). The degree of cross-linking gradually increased from the castor-derived polymer (220 mol/m(3)) to the linseed-derived polymer (683 mol/m(3)). A systematic correlation between the degree of cross-linking and the thermal and mechanical properties was observed in these biopolymers. Tensile strength (0.62-3.39 MPa) and glass transition temperature (-5 to 16 °C) increased and the linear thermal expansion coefficient decreased in the series from the canola-derived polymer (2) to the linseed-derived polymer (5). The castor-derived polymer (1) that possesses an additional hydroxyl group per fatty acid chain behaved differently.