Hygroscopicity of resorcinol-formaldehyde resin and aqueous vinyl polymer-isocyanate resin in high humidity

Holzforschung ◽  
2005 ◽  
Vol 59 (3) ◽  
pp. 342-346 ◽  
Author(s):  
Junko Miyazaki ◽  
Takato Nakano

Abstract The hygroscopicity and hygro-mechanical properties of the adhesives, resorcinol-formaldehyde (RF) resin and aqueous vinyl polymer-isocyanate (API) resin have been examined. Adsorption isotherms for cured RF and API resins with various degrees of crosslinking showed that the hygroscopicity of both resins decreased as the curing reactions proceeded, although the mechanisms for these decreases differed. In RF resins cured with a large amount of hardener, a highly crosslinked structure is formed, so swelling is limited by the network. Thus, the hygroscopicity of cured RF resins decreases due to the restricted swelling, while the number of hydroxyl groups, another source of hygroscopicity, are not changed by the curing. On the other hand, swelling in API resins cured with a large amount of hardener is not completely inhibited because of long segments between the crosslinks. The hygroscopicity of cured API resins is lowered as the curing extent increased, since this reaction decreases the number of hydroxyl groups.

e-Polymers ◽  
2003 ◽  
Vol 3 (1) ◽  
Author(s):  
Koh-hei Nitta ◽  
Yoshikazu Yamamoto

Abstract We examined mechanical and morphological properties of fully transcrystalline polypropylene grown from the surface of poly(tetrafluoroethylene) sheets. Comparison of mechanical properties between transcrystalline and spherulitic polypropylenes demonstrated that Young’s modulus is dependent on the crystallinity and independent of the supermolecular structure. On the other hand, the mechanical yielding process was predominantly affected by the supermolecular structure, and the mechanical energy required for yielding of transcrystalline sheets was greater than that of the spherulitic morphology. In addition, it was found that mechanical necking is required for the alignment of lamellae in the stretching direction. This means that the unfolding process of lamellae orienting in the stretching direction is associated with necking and ductility.


1931 ◽  
Vol 4 (1) ◽  
pp. 54-63
Author(s):  
H. Mark ◽  
E. Valko

Abstract It is only during recent years that it has become possible by the use of new technic to detect molecular phenomena produced in the mechanical deformation of substances. As far as metallic substances are concerned, and crystalline substances in particular, the problem has already been solved for the most part. On the other hand, in spite of considerable progress during recent years the study of the deformation of organic substances and of fibers in particular, in which group rubber is included, has not yet been carried on. The mechanical properties of a crystalline system vary according to whether there is a single crystal or an aggregate of crystals. However, in both cases the extensibility of the products originates in a displacement of parallel layers, i. e., a sliding of the parts of the crystal along definite crystalline planes, this phenomenon of sliding being irreversible in these substances. In fact, in these cases the reversible part of the elongation is very weak, and amounts to only a few thousandths of the entire phenomenon. In brief, the phenomena of hardening brought about by deformation (sometimes observable) are due to disturbances of the regular lattice. In particular, the displacement of the atom and the change from its normal position can cause the appearance of irregularities on the surface of sliding.


2014 ◽  
Vol 699 ◽  
pp. 169-174
Author(s):  
Achmad Zubaydi ◽  
Nurul Muhayat ◽  
Budie Santosa ◽  
Dony Setyawan

Double sided friction stir butt welds on 6 mm thick of 5083 aluminum alloy were produced. Two variants of the weld side combination, different weld side (DS) and same weld side (SS), have been made to investigate the effect of the weld side on mechanical properties.The SS is a double sided welding process that produces advancing side in one plate and retreating side in the other one. On the other hand, the DS is a double sided welding process that causes advancing side and retreating side in each plate. Tensile properties of the joints were evaluated and correlated with macrostructure and hardness. The weld side influenced the macrostructure and mechanical properties of welded joints. The different weld side (DS) had better mechanical properties than the same weld side (SS).


2015 ◽  
Vol 815 ◽  
pp. 164-169
Author(s):  
Ng Hooi Jun ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Kamarudin Husin ◽  
Soo Jin Tan ◽  
Mohd Firdaus Omar

Utilization and suitability of bottom ash in Portland cement have been increasing significantly in recent year. Bottom ash has substantial effects on mechanical properties with different composition of replacement in mixture of bottom ash and Portland cement. Bottom ash was used to determine the feasibility of the substitution as recycling product from industry depending on the percentage of the bottom ash. On the other hand, bottom ash offers a better solution for maintaining materials characteristic of Portland cement mortar and also provide beneficial mechanical performance. The result of using bottom ash in Portland cement mortar showed that it could make better the mechanical properties and hence disposed bottom ash wastes safely in technical, economic and environmental methods.


2018 ◽  
Vol 56 (2A) ◽  
pp. 63-68
Author(s):  
Le Thi Bang

Bis-3,4- dimethyldibenzylidene sorbitol (DMDBS); bis-p-methylbenzylidene sorbitol (MDBS) and the mixture of DMDBS/MDBS (50/50) were studied through optical, thermal, mechanical properties and surface morphology. With the same amount of additive (DMDBS/MDBS mixture and DMDBS) in the material, the results are similar. On the other hand, using an additive mix reduces the cost of production due to MDBS. Furthermore, the additive mixture is used without producing odours. Therefore, the mixture of DMDBS/MDBS (50/50) is chosen.


Holzforschung ◽  
2011 ◽  
Vol 65 (6) ◽  
pp. 835-844 ◽  
Author(s):  
Sebastian Clauß ◽  
Joseph Gabriel ◽  
Alexander Karbach ◽  
Mathias Matner ◽  
Peter Niemz

Abstract Only small amounts of additives are needed to formulate one-component polyurethane (1C PUR) adhesives for various applications. The current study illuminates the effects of the formulation on the mechanical properties of pure adhesives, on the one hand, and their performance in bonded wood joints on the other. Tensile shear tests on bonded wood joints, tensile tests on adhesive films, and nanoindentation measurements in the interphase region of the bond were performed. Analyses by means of infrared, atomic force, and electron microscopy provided the explanatory basis for the results obtained. Additionally to laboratory made 1C PUR, unmodified commercial 1C PUR, melamine-urea-formaldehyde (MUF), and phenol-resorcinol-formaldehyde (PRF) were tested for comparison. The results obtained confirm that the mechanical properties of 1C PUR adhesives are significantly affected by their prepolymer composition. The adhesive formulation by means of additives, on the other hand, does not affect the mechanical properties but is to a large extent responsible for the bonding performance.


2011 ◽  
Vol 250-253 ◽  
pp. 480-484 ◽  
Author(s):  
Miao Zhou Huang ◽  
Tao Meng ◽  
Xiao Qian Qian ◽  
Jin Jian Zhang

The flow ability, mechanical properties and microstructure of concrete with different strength grades affected by nano-SiO2and nano-CaCO3was studied. The experiment results showed that the strength of concrete at early age was increased by adding the nano-materials if the strength grade of concrete was not high. But the strength at the age of 28 days was not affected a lot by adding these nano-materials. On the other hand, it was not useful to the strength if the strength grade of concrete was high.


The author points out what he considers to be important errors in the series of papers by Dr. Martin Barry, which have lately appeared in the Philosophical Transactions, and are entitled, “ On the Corpuscles of the Blood ," and “ On Fibre ." He alleges that Dr. Barry has generally confounded the colourless corpuscles contained in the blood with the red corpuscles of the same fluid; each of which latter kind consists of a vesicle or cell, with thick walls, but in a collapsed and flattened state, and having therefore a biconcave form, and in consequence of its thick wall being doubled on itself, presenting under the microscope a broad circumferential ring, which is illuminated or shaded differently from the depressed central portion, according to the focal adjustment of the instrument: while the colourless corpuscles, on the other hand, are of a globular shape, strongly refractive of light, and granulated on their surface, and are of less specific gravity and of somewhat larger size than the red corpuscles. The author quotes various passages from Dr. Barry’s papers in proof of his assertions, and refers particularly to fig. 23 of his second paper on the corpuscles of the blood. He farther states, that Dr. Barry’s description of the appearances of what he terms the red corpuscles, in paragraphs 53, 68, and 76 of his second paper, can, in fact, apply only to the colourless corpuscles: and he observes, that even when Dr. Barry does, at last, in his “Additional Observations,” advert to the distinction between the red and the colourless globules, he considers the latter as being merely “the discs” contained in the red globules appearing under an altered state. The author regards as wholly erroneous the notion which Dr. Barry entertains that a fibre exists in the interior of the blood-cor­puscle; and that these fibres, after their escape from thence, constitute the fibres which are formed by the consolidation of the fibrin of the liquor sanguinis . The beaded aspect presented by the double contour of the thick wall of the red corpuscle when it has been acted upon either by mechanical causes or by chemical reagents, of which the effect is to corrugate the edge, and to bend it alternately in opposite directions, has, in the opinion of the author, given rise to the illusive appearance of an internal, annular fibre. The appearance of flask-like vesicles presented by some of the red corpuscles, with the alleged fibre protruding from their neck, the author ascribes altogether to the effects of decomposition, which has altered the mechanical properties of the corpuscle, and allowed it to be drawn out, like any other viscid matter, into a thread.


2008 ◽  
Vol 584-586 ◽  
pp. 547-552 ◽  
Author(s):  
Daisuke Terada ◽  
Toshiaki Masui ◽  
Naoya Kamikawa ◽  
Nobuhiro Tsuji

Effect of solid solution elements on microstructure evolution and mechanical properties was investigated using a high purity Al (purity 99.99%) and Al-0.5 at.% X ( X = Si, Ag, Mg ) alloys deformed by accumulative roll bonding (ARB) process up to 7 cycles (equivalent strain of 5.6) at ambient temperature. The ARB-processed high purity Al showed the equiaxed microstructure having mean grain size of 750 nm. On the other hand, the microstructure of the ARB-processed Al-0.5at.%X alloys showed lamellar boundary structures elongated along RD. The mean lamellar boundary spacing significantly differed depending on the alloying elements, which suggested that solute atoms had a significant effect on microstructure evolution. The difference in the grain size was regarded to be caused by the difference in recovery processes in the alloys. The tensile strength of the alloys increased with increasing the number of ARB cycles. In the Al-Si and Al-Ag alloys, the post-uniform elongation increased with increasing the number of the ARB cycles. On the other hand, the elongation of the Al-Mg hardly changed during the ARB process.


1937 ◽  
Vol 10 (3) ◽  
pp. 556-563
Author(s):  
Shohei Saito ◽  
Katsumi Ishiguro

Abstract Experiments were carried out to determine the resistance of rubber products to vibration. There were no essential changes in mechanical properties as a result of vibration for 50 to 100 hours. There were on the other hand considerable changes in electrical properties, e. g., the insulation resistance decreased with increase in time of vibration. Further experiments in connection with this problem will be carried out to obtain data on the effects of vibration for prolonged periods. The authors wish to thank Messrs. Endo, Taguma, Hamono, and Wada for their aid in the experimentation.


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