Authors:G. Lizia Thankam, T.R. Neelakantan, and S. Christopher Gnanaraj
on fresh concrete properties (workability) as well as the mechanical properties (compressive strength, flexural strength, split tensilestrength) of hardened concrete. 2 Materials and test procedures F-GFA is used as fine aggregate throughout this
In this work thermal stability and tensile strength of polyurethanes obtained from glycolysates was investigated. The glycolysates
were produced via glycolysis of waste polyurethane foam (PUR) in the reaction with 1,3-propylene glycol (PG). Polyurethanes
were synthesized from the obtained intermediates by the prepolymer method using diisocyanate (MDI) and glycolysis product
of molecular mass ranging from 700 to 1000, while 1,4-butylene glycol (BDO) was used as a chain elongation agent. The influence
of NCO group concentration in prepolymer on tensile strength and elongation at break of polyurethanes was investigated using
Zwick universal tensile tester.
Thermal decomposition of the obtained glycolysates and polyurethanes was followed by TG coupled with FTIR spectroscopy. The
main products of thermal decomposition have been identified.
Authors:Z. Wu, A. Zhang, D. Shen, M. Leland, F. W. Harris, and S. Z. D. Cheng
Three aromatic polyimides based on 3,3′,4,4′-biphenyl-tetracarboxylic dianhydride (BPDA) and three different diamines 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (PFMB), 2,2′-dimethyl-4, 4′-diaminophenyl (DMB) or 3,3′-dimethylbenzidine (OTOL) have been synthesized. These polyimides are soluble in hotp-chlorophenol,m-cresol or other phenolic solvents. Fibers have been spun from isotropic solutions using a dry-jet wet spinning method. The as-spun fibers generally exhibit low tensile properties, and can be drawn at elevated temperatures (>380° C) up to a draw ratio of 10 times. Remarkable increases in tensile strength and modulus are achieved after drawing and annealing. The crystal structures of highly drawn fibers were determinedvia wide angle X-ray diffraction (WAXD). The crystal unit cell lattices have been determined to be monoclinic for BPDA-PFMB and triclinic for both BPDA-DMB and BPDA-OTOL. Thermomechanical analysis (TMA) was used to measure thermal shrinkage stress and strain. A selfelongation has been found in the temperature region around 450°C. This phenomenon can be explained as resulting from the structural development in the fibers as evidencedvia WAXD observations.
Authors:F. Khalfallah, Z. Boumerzoug, S. Rajakumar, and E. Raouache
that friction time, friction pressure, and forging pressure have a strong effect on tensilestrength, microstructures, and hardness of joints. In addition, Alves et al. [ 18 ] studied the rotary friction welding of AA 1050 aluminum alloy to AISI 304
Authors:Wisdom Okechukwu Egbujuo, Placid Ikechukwu Anyanwu, and Henry Chinedu Obasi
-reinforcing fillers. The reinforcing fillers are those which when introduced into rubber matrix will improve the tensilestrength, tear strength, abrasion resistance and other mechanical properties of the rubber vulcanizate, whereas non-reinforcing fillers are added
Authors:Laith Sh. Rasheed, Laith Mohammed Ridha Mahmmod, Sara Alaa Abed Alameer, and Abdulrasool Thamer Abdulrasool
supplied by IC particles sustain hydration process of cement as long as possible led to significantly improving the compressive strength of concrete. Fig. 3. Effect of internal curing on compressive strength relationship 3.2 Splitting tensilestrength The
Authors:Tapas Mitra, G. Sailakshmi, A. Gnanamani, and A. B. Mandal
resistance and high mechanical (tensilestrength) properties. But, during the course of extraction of collagen and reconstitution, the expected stability and strength could not be achieved. Thus it is often necessary to confer mechanical firmness and