Polyurethane coatings are widely used to prevent corrosion. TiO2/Polyurethane composite coatings with 1 – 5 wt% TiO2 compositions were produced, and the barrier properties were assessed. Techniques including the accelerated cyclic electrochemical technique (ACET), water contact angle measurements, scanning electron microscopy (SEM), and pull-off adhesion testing were employed to characterize the coating barrier properties. The results showed that the addition of TiO2 to polyurethane coatings in the amount of 1 – 3 wt% improved barrier properties - corrosion resistance, water contact angle, and pull-off adhesion - compared to polyurethane alone. Of these composites, the 3 wt% was the optimal TiO2 composite to achieve the best barrier properties. Conversely, the 4 wt% and 5 wt% composites were found to provide minimal improvement in water contact angle and pull-off adhesion as well as reduced performance in corrosion resistance compared to polyurethane alone. The reduced performance of the 4 wt% and 5 wt% composite coatings was attributed to coating cracking and particle agglomeration caused by the overabundance of TiO2 within the coating.

Biodiesel is an environmentally friendly alternative to petroleum diesel. It is biodegradable, nontoxic and has lower greenhouse gas emission profiles compared to petroleum diesel. Polyurethane (PU) products such as PU foams and PU coatings are widely used in many aspects of our life. Traditionally, the PU industry is heavily petroleum dependent because both the feedstocks - isocyanates and polyols - are petrochemical products. Bio-based PU products became a very promising research field due to concerns about the environment and the depletion of petroleum resources. Waste cooking oil (WCO), which is abundantly available and about 2 or 3 times cheaper than virgin vegetable oil, is considered a good source for production of biodiesel. Also, post-consumer PET bottles contribute a large volume fraction in the solid waste stream and their non-biodegradability has caused concern. In this study, a sustainable process of value-added utilization of wastes, specifically WCO and post-consumer PET bottles for the production of biodiesel and PU foams, respectively, was developed. WCO collected from campus cafeteria was firstly converted into biodiesel, which can be used as vehicle fuel. Then crude glycerol (CG), a byproduct of the above biodiesel process, was incorporated into the glycolysis process of post-consumer PET bottles collected from campus to produce polyols. Thirdly, PU foams were synthesized through the reaction of the above produced polyols with isocyanate in the presence of catalysts and other additives. The characterization of the produced biodiesel demonstrated that its properties meet the specification of the biodiesel standard. The effect of CG loading on the properties of polyols and PU foams were investigated. With the increase of CG loading from 0% -15%, the hydroxyl value increased from 478 mg KOH/g to 592 mg KOH/g. This is most likely due to the high hydroxyl value of glycerol (1829 mg KOH/g). The PU foams produced showed density of 46.03-47.66 kg/m3 an (open full item for complete abstract)

Abstract This study focused on the development of bio-based polyols and polyurethanes (PU) from biodiesel-derived crude glycerol and lignocellulosic biomass. Polyols were produced via liquefaction of lignocellulosic biomass using crude glycerol as a liquefaction solvent. The polyols produced were used directly to prepare PU foams. The effects of liquefaction parameters on the properties of polyol and PU foams were investigated. Under optimal liquefaction conditions, the polyols and PU foams produced had properties comparable to their analogs derived from petrochemical solvent-based liquefaction processes. Certain impurities in crude glycerol are critical for the improvement of polyol and PU foam properties. The composition of five representative biodiesel-derived crude glycerol samples was determined to identify their components. All crude glycerol samples contained glycerol, soap, methanol, FAMEs (methyl esters of fatty acids), water, glycerides, FFAs (free fatty acids), and ash, but their proportions varied widely with the origins of crude glycerol. The effects of crude glycerol impurities on the properties of polyols and PU foams derived from base- and acid-catalyzed biomass liquefaction processes were studied. For both liquefaction processes, increasing levels of organic impurities (i.e. FFA, FAMEs, and glycerides) in crude glycerol decreased biomass conversion and polyol hydroxyl numbers and increased polyol molecular weight. The presence of suitable amounts of organic impurities, especially FFA and FAMEs, in crude glycerol improved the properties of polyols and PU foams produced. For both processes, valid regression models (R2=0.99) were developed to predict the hydroxyl numbers of polyol from the contents of organic impurities in crude glycerol. In contrast to their negligible effects on the base-catalyzed process, inorganic salts, including NaCl and Na2SO4, negatively affected the properties of polyols produced from the acid-catalyzed process. A two-ste (open full item for complete abstract)

This work deals with the development of a non-chromate, one-step finishing system for corrosion protection of hot-dip galvanized steel. Environmental regulations demand that chromate pretreatments and chromate pigments used in primers be replaced. In this project a pretreatment-free, chromate-free one-step finishing system was needed for hot-dip galvanized steel used in automotive coils in cars. Pretreatments act as adhesion-promoters and bind coatings to metals and since silanes, especially systems using bis-amino silane and bis-sulfur silane, have been shown as excellent adhesion-promoters by this lab, the idea of incorporating silanes in primers for obtaining adhesion to metals emerged. Whether this also meant increased corrosion protection was investigated. It was clear from the performance results and characterization experiments that silanes perform positively, in terms of enhanced corrosion protection of the metal substrate and adhesion. The polyurethane network resulted from the curing agent-resin reaction. A chromate-free, one-step finishing system without need for pretreatment and exhibiting enhanced corrosion protection and adhesion to metal was developed.

This research aimed to develop hydrogels for agricultural and horticultural application. The most remarkable characteristic of hydrogels is their ability to absorb large amounts of aqueous solutions, such as pure water and nutrient solution. They could make plants grow at optimal environments as the release of water and nutrients is controlled into soils. The advantages not only keeps continuous optimal environment but also reduces the use of freshwater and associates labor cost, being compared to directly sprinkling water to plants. Currently, commercial hydrogels are being produced from these hydrogel advantages. However, there are a few drawbacks. Firstly, while these hydrogels can rapidly absorb large amounts of water, they also dehydrate very rapidly in a matter of hours. Secondly, they are fragile and break apart easily losing their water retention properties. In this study, we tried to overcome the weakness of commercial hydrogels. We researched the dehydration and mechanical characteristics of various types of hydrogels, such as pure hydrogels and ionic hydrogels. Based on these studies, we designed a double layer PAAm-based hydrogel to overcome the inherent weakness of pure and ionic hydrogels which are kinds of commercial hydrogels. The inner layer gel consists of soft, low crosslinked PAAm which retains the high water absorbing property, ensuring its ability is to supply sufficient water, while the outer layer is made up of either highly crosslinked PAAm or polyurethane (PU), providing low aqueous permeability and high mechanical strength. The dehydration rates of PU-PAAm double layer hydrogels could be controlled by the pore sizes of PU coating layer determined by the molecular weight of polyethylene glycol and by the thickness of coating layer. In addition, the cross-linking density of inner gel and the temperature of coating solution affected the dehydration rate of PU-PAAm double layer hydrogels. Such a double layer design resulted in mechanical sta (open full item for complete abstract)

Polyesters are a class of polymers widely used in organic coatings applications. In this work, four types of organic coatings based on polyester polyols were prepared: UV-curable polyester/poly(meth)acrylate coatings, thermal curable polyester polyurethane-urea coatings, thermal curable non-isocyanate polyurethane coatings, and UV-curable non-isocyanate polyurethane coatings. Polyester/poly(meth)acrylate block copolymers are synthesized using a combination of polycondensation and Atom-Transfer Radical Polymerization (ATRP). All block copolymers are characterized by means of Nuclear Magnetic Resonance (NMR) and Gel Permeation Chromatography (GPC). In the case of unsaturated-polyester-based block copolymers the main chain double bond in the polyester backbone remains almost unaffected during ATRP. The unsaturated block copolymers are crosslinkable and can form networks upon photo-irradiation in the presence of a suitable photoinitiator. These copolymers might be interesting candidates for coatings with better overall properties than those based on neat polyesters. Thermal curable polyester polyol based Polyurethane-Urea (PUU) coatings were formulated using Partially Blocked HDI isocyanurate (PBH), Isophorone Diamine (IPDA), and polyester polyol. As a comparison, the polyurethane coatings (PU) without adding IPDA were also prepared. The mechanical and viscoelastic properties of the PUU and PU coating were investigated by using tensile test and Dynamic Mechanical Thermal Analyzer (DMTA). It was found that PUU coating exhibited higher crosslink density, Tg, tensile modulus and strength than the corresponding PU coating. Thermal curable non-isocyanate polyurethane coatings were prepared by using polyamine and cyclic carbonate terminated polyester. Cyclic carbonate terminated polyester was synthesized from the reaction of the carbon dioxide and epoxidized polyester which was prepared from the polyester polyol. The properties of the epoxidized and cyclic carbonate terminat (open full item for complete abstract)