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Shore A Hardness (shore a + hardness)
Selected AbstractsEffects of ultraviolet irradiation on the static and dynamic properties of neoprene rubbersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Hsoung-Wei Chou Abstract Rubbers deteriorate when they are exposed to ultraviolet irradiation for long periods of time. By conducting a series of hardness measurements and simple tension tests, the static properties of neoprene rubbers before and after exposure to various durations of ultraviolet irradiation were first measured. It is found that the Shore A hardness and tensile modulus of neoprene rubbers after exposure to ultraviolet irradiation are increased but their elongation at break, tensile strength, and energy to break are significantly decreased. On the basis of a complex spring model of a vibration system, the dynamic shear properties of neoprene rubbers before and after exposure to different durations of ultraviolet irradiation were then determined from the experimental results of dynamic transmissibility tests. It is also found that the storage modulus, loss modulus, and loss factor of neoprene rubbers are drastically affected by the duration of ultraviolet irradiation they experienced. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Conductive Composites of Polyurethane Resins and Ionic LiquidsMACROMOLECULAR MATERIALS & ENGINEERING, Issue 5 2008Belinda Berns Abstract Composites of PUR and IL were prepared and specific conductivities and Shore A hardness were determined. IL were based on 1-alkyl-3-methylimidazolium salts with counterions BF, PF, triflate, or ethylsulfate. Presence of IL increased the conductivity by five orders of magnitude. Variation of alkyl chain length and nature of counterions only had little effect on the conductivity. Presence of IL had a plasticizing effect, which was most pronounced for the IL with dodecyl groups and PF as counterion. In broadband dielectric measurements, the complex conductivity showed a characteristic dispersion that is caused by the interplay between (hopping) transport of charge carriers and electrode polarization. [source] Thermal and mechanical properties of dough modeling compound reinforced ethylene propylene diene monomer/silicon rubber compositesPOLYMER COMPOSITES, Issue 6 2006Weili Wu Ethylene propylene diene monomer (EPDM)/silicon rubber composite was prepared by adding dough-modeling compound (DMC). EPDM/silicon rubber is the matrix of the composite, and DMC is a disperse phase (reinforced phase). The morphology of the composite was studied by scanning electron microscopy, and it was found that the compatibility of DMC/EPDM/silicon rubber composite was good. The influence of the DMC and peroxide curing agents on the mechanical and thermal properties were studied. The results showed that the mechanical and thermal properties of the composite were best, when DMC/EPDM/silicon rubber was 80/25/75. The thermal properties of the composite prepared with added equivalent dicumyl peroxide was better than those with added benzoperoxide, but Shore A hardness and elongation at break are unchangeable. The integral properties of DMC reinforced EPDM/silicon rubber composite was much better than three raw materials. POLYM. COMPOS. 27:621,626, 2006. © 2006 Society of Plastics Engineers [source] Preparation and properties of transparent thermoplastic segmented polyurethanes derived from different polyolsPOLYMER ENGINEERING & SCIENCE, Issue 5 2007Da-Kong Lee Various segmented polyurethanes of different soft segment structure with hard segment content of about 50 wt% were prepared from 4,4,-diphenylmethane diisocyanate (MDI), 1,4-butanediol and different polyols with a Mn of 2000 by a one-shot, hand-cast bulk polymerization method. The polyols used were a poly(tetramethylene ether)glycol, a poly(tetramethylene adipate)glycol, a polycaprolactonediol and two polycarbonatediols. The segmented polyurethanes were characterized by gel permeation chromatography (GPC), UV-visible spectrometry, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), X-ray diffraction, and their tensile properties and Shore A hardness were determined. The DSC and DMA data indicate that the miscibility between the soft segments and the hard segments of the segmented polyurethanes is dependent on the type of the soft segment, and follows the order: polycarbonate segments > polyester segments > polyether segments. The miscibility between the soft segments and the hard segments plays an important role in determining the transparency of the segmented polyurethanes. As the miscibility increases, the transparency of the segmented polyurethanes increases accordingly. The segmented polyurethanes exhibit high elongation and show ductile behavior. The tensile properties are also affected by the type of the soft segment to some extent. POLYM. ENG. SCI., 47:695,701, 2007. © 2007 Society of Plastics Engineers. [source] Viscoelastic and damping characteristics of poly(n -butyl acrylate)-poly(n -butyl methacrylate) semi-IPN latex filmsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 5 2007K. I. Suresh Abstract This article reports the synthesis, characterization, and damping characteristics of semi-interpenetrating (semi-IPN) latex systems composed of poly n -butyl acrylate (PBA) core and poly n -butyl methacrylate (PBMA) shell. The IPN's were prepared by seeded emulsion polymerization using crosslinked PBA seeds with varying crosslinker (m -diisopropenyl benzene) concentration. The polymer weight ratio in the first and second stage polymerization is maintained at 1:1 in all the cases. The particle size determined by dynamic light scattering shows a decrease in the shell thickness with increasing crosslinker concentration of the seed. The mechanical properties, like Shore A hardness of the films, increased from 18 to 65 when the crosslinker concentration is increased from 0 to 4.8,mol%. The dynamic mechanical studies show that the modulus value of the IPN's is below that of non-crosslinked films, and the value depends upon the crosslink density of the seed. Mechanical models, such as the Kerner's model and the Takayanagi's model, were used to explain the variation in the dynamic mechanical properties with the degree of seed crosslinking. The study indicates lower bound (rubbery) behavior for the films with lightly crosslinked cores. The study also shows that, at lower crosslinker concentration enhanced phase separation and better damping properties are achieved but at higher cross linker concentration (>2,mol%) greater interpenetration of the shell monomer to the cores takes place and tough films, with reduced damping properties are formed. Copyright © 2007 John Wiley & Sons, Ltd. [source] | ||||||||||