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The subject of this study was the application of a novel CO2-based low-molecular weight poly (propylene carbonate) diol (PPCD) in the field of adhesive. Two-component polyurethane adhesive (PPCD-PU) was prepared with PPCD and polymethylene polyphenyl polyisocyanate (PAPI) as raw materials, propylene carbonate diol (PCD-EDA) as extender. The effects of the molecular weight, carbonate linkage content of PPCD and content of PCD-EDA on the properties of PPCD-PU were also investigated. The results showed that the novel CO2-based low-molecular weight poly (propylene carbonate) diol had higher carbonate linkage content (35%). The PPCD-PU synthesized by the PPCD had good adhesion performance, and the lap shear strength reached to 15 MPa. The addition of PCD-EDA not only improved the bonding properties of the adhesive, but also made PPCD-PU adhesive achieved higher lap shear strength in a shorter curing time. When the amount of PCD-EDA was 20 wt.%, the lap shear strength increased to 17 MPa, and the lap shear strength increased significantly from 3.7 to 10.6 MPa after curing at 80 °C for 30 min. Water absorption rate of PPCD-PU film was about 1.7%, and the lap shear strength was almost unchanged after 24 h of immersion in water. The temperature of 5%-weight loss of PPCD-PU was 284 °C, and the glass transition temperature was 79.3 °C. All the polyurethane adhesives obtained performed good heat and water resistance. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced plastics (CFRP) is widely used in the aerospace and automotive industries due to their light weight and high strength. The effective joining method of CFRP is bonding, and the surface state of CFRP is the main reason that affects the shear strength of the bonded joints. In order to improve the surface state of CFRP and shear strength, this paper systematically studied the effects of different power (80 W, 120 W, 180 W) laser treatment on the surface characteristics and bonding performance of CFRP and compared with the mechanical treatment (alcohol ultrasonic cleaned, sandpaper sanding). Four different adhesives were used in the adhesive joints, which were performed lap-shear tests. The SEM, XPS and contact angle measuring instrument were used to analyze the changes of physicochemical properties of CFRP after different surface treatment. The results showed that compared with alcohol cleaned and sandpaper sanding, 120 W laser treatment greatly improved the surface roughness of CFRP and formed micron-sized gaps. The water contact angle was reduced from 85° to 59.5°, and the surface energy increased from 25.6 mJ/m2 to 62.7 mJ/m2. The lap-shear results showed that the shear strength of the epoxy joints was improved after laser treatment, and the failure type was changed from interface failure to substrate failure. The polyurethane joint shear strength was not obviously improved and the combination failure of interface and cohesion was transformed into a pure interface failure after surface treatment. [ABSTRACT FROM AUTHOR]

Banana pseudo-stem was liquefied in the mixture of polyhydric alcohols of polyethylene glycol (PEG400) and glycerol. Hydroxyl value of liquefied products ranged from 294.8 to 370.2 mg KOH/g and M¯n was about 430. Liquefied products (LBPP) could be used as raw materials for polyurethane by reacting with 4, 4'-diphenylmethane diisocyanate (4, 4'-MDI) and PEG400 to synthesize liquefied product-based polyurethane (LBPP-PU) adhesive. To analyze in depth the creation of urethane linkage among LBPP, PEG400 and 4, 4'-MDI, factors which had effects on the residue content were all investigated. They were characterized by FT-IR and TG. The shear strength of LBPP-PU adhesive was improved when decreasing the percentage of the substitution of PEG400 by LBPP. The adhesive strength was obtained from T-peel of aspen/polyurethane adhesive joints, and the maximum lap shear strength (4.40 MPa) was obtained when 16.70% of LBPP was added to the LBPP & PEG400 system. [ABSTRACT FROM AUTHOR]

This investigation was conducted to determine the feasibility of using a two-component polyurethane (PUR) adhesive, with special waterproof properties, in constructing wooden structures. We designed and conducted tests to compare the shear strength and adhesion performance of PUR with polyvinyl acetate (PVAc) adhesive on block-shear specimens constructed of oriental beech ( Fagus orientalis L.), fir ( Abies alba Mill.), poplar ( Populus deltoides Bartr.), white oak ( Quercus alba L.), sycamore ( Platanus orientalis L.) and white walnut ( Juglans cinerea L.). The values of the percentage of wood failure were also determined in specimens constructed with each adhesive. The highest shear strength values of both adhesives were obtained in specimens constructed of beech, while the lowest shear strength values were obtained in fir and poplar specimens. Average shear strength of the PUR adhesive was 16.5% higher than that of the PVAc adhesive. Specimens constructed of fir, poplar and sycamore were characterised by the highest percentages of wood failure, whereas the lowest average percentages of wood failure were obtained in beech and oak specimens. With the exception of oak specimens, there was no statistically significant difference between percentage of wood failure among the PUR and PVAc adhesives. Generally, the PUR adhesive showed an acceptable adhesion performance on wood materials used in our study. [ABSTRACT FROM AUTHOR]

The article discusses the technological and strength properties of newly developed elastic coldcuring polyurethane adhesives PU-ELBO. Examples are given of applying adhesives in the units and assemblies of electric and radio components that operate under increased humidity, cyclic variations of temperature, and vibration loads. It is noted that, in a cured state, the developed PU-ELBO adhesive is characterized by minimal levels of gas emissions in vacuum and at high temperatures. [ABSTRACT FROM AUTHOR]

In order to identify damping characteristics (loss factors in bending and shear modes versus frequency) of an adhesive material, modal based direct model updating method used in previous paper (Jahani and Nobari, Exp Mech, 48:) is modified here. Two approaches adopted in the identification process. In the first one, the pre identified moduli from undamped model were used in identification of loss factors and in the second approach loss factors and moduli are identified simultaneously. The loss factors of a typical adhesive were identified using both approaches leading to acceptable results in both cases. The results show that loss factors and Young’s and shear moduli of adhesive are frequency dependent. All experiments and subsequent identifications are conducted both in bending and shear modes. The repeatability and consistency of method is proved by repeating the identification process for several times. [ABSTRACT FROM AUTHOR]

The aging behavior of polyurethane adhesive in medium was investigated and compared by means of scanning electronic microscopy(SEM), infrared spectroscopy(IR), interface analysis and shearing strength test. The experimental results show that the shear strength of polyurethane adhesive in salt water is decreased more quickly than that in water. Na+ and Cl− ions could make the polyurethane adhesive age faster and the interface metal corrosion. The high temperature accelerates the diffusion of water molecule, Na+ and Cl− ions and the degradation of the giant molecule. [ABSTRACT FROM AUTHOR]

Polyester polyols were synthesized using vegetable oil fatty acids having different characteristics (mainly in terms of hydroxyl functionality) and epoxy resin, using triethylamine as a catalyst. Polyols were characterized by the FTIR spectroscopy. Polyurethane adhesives were synthesized from it and used in bonding rubber. Treatment of sulphuric acid on the non-polar styrene butadiene rubber (SBR) surface was studied for the bond strength improvement via an increase in wettability of the rubber surface. Wettability was found by measuring the contact angle using Goniometer. Bond strength was evaluated by a 180° T-peel test. The surface modification and mode of bond failure were studied by Scanning Electron Microscopy (SEM). The synthesized polyurethane adhesives were compared with the commercial adhesive. [ABSTRACT FROM AUTHOR]

General information on polyurethane adhesives is outlined. Polyurethane adhesive is presented that was developed by ZAO Novbytkhim mainly for applications in footwear and the production of leather goods to join materials such as leather, fabric, polyurethane, resin, and some types of plastics. [ABSTRACT FROM AUTHOR]

The possibility of applying single-component polyurethane adhesive in the binding of printing materials during the manufacturing of books (that have cover paper with polymer coating) with different kinds of bookend paper is shown. This adhesive is greatly superior to polyvinyl acetate emulsions in its adhesive properties. [ABSTRACT FROM AUTHOR]