Shrinkage Loss Research Articles

Influence and Mechanism of Polymer Coating on Shrinkage of Cement-Based Materials

The influence of polymer coating on the shrinkage of cement-based materials is comparatively analyzed in this paper. First of all, the relationship between cement-based materials shrinkage and water loss is discussed. Furthermore, some surface topography differences and pore structure changes of cement-based materials causing by polymer coating are investigated. At last, the affecting mechanism of polymer coating on reducing cement-based materials shrinkage is investigated. The results show that polymer coating can significantly reduce the shrinkage of cement-based materials. A more thick coating gets a higher shrinkage reducing ratio. There is a close relationship between cement-based materials water loss ratio and shrinkage ratio. Polymer coating can make the micro-crack on cement-based materials surface disappear. The cement-based materials coated with polymer have a lower surface layer cumulative average porosity than blank control group. The evaporation of capillary water and the development of negative capillary pressure in cement-based materials are controlled by polymer coating, thus the shrinkage becomes small.

Effect of Skimmed Milk Powder Incorporation on the Physico-chemical and Sensory Characteristics of Restructured Buffalo Meat Blocks

Kumar, S. and Sharma, B.D. 2003. Effect of skimmed milk powder incorporation on the physico-chemical and sensory characteristics of restructured buffalo meat blocks. J. Appl. Anim. Res., 23: 217–222. Restructuring of meat from spent animals brings about convenience in product preparation, besides enhancing tenderness and value addition. Milk proteins have been shown to offer added functionality and nutritional properties in some meat products. This study was undertaken to evaluate the incorporation of skimmed milk powder (SMP) at 0, 2, 4 and 6 per cent levels replacing lean meat in prestandardized restructured buffalo meat blocks. There was a progressive improvement in the cooking yield, protein, shrinkage, binding strength and sensory characteristics of the meat blocks with increasing levels of skimmed milk powder incorporation. At 2 per cent SMP incorporation, most of the physico-chemical and sensory characteristics of the product were found to be comparable to control and 4per cent SMP products. However, incorporation of 6 per cent skimmed milk powder in the product brought about a significant (P<0.05) improvement in protein, flavour, binding strength and overall acceptability as compared to control. Shrinkage loss was also significantly reduced.

Electrical properties of polycrystalline ZnO:Cu obtained from freeze-dried ZnO + copper(II) acetate powders

Highly homogeneous mixtures of powders containing ZnO and monohydrated copper(II) acetate, (CH3COO)2CuċH2O, AcCuH2O were obtained by freeze drying. Thermal analysis and high-temperature X-ray diffraction showed that pure freeze-dried AcCuH2O powder decomposed to CuO, in air, at temperatures above 325 °C. Due to the polymeric nature of AcCuH2O, the powder mixtures were compacted without pressing additives. Pellets with ZnO+x mol % Cu (x=0.05, 0.5, and 5.0) compositions were sintered in air from 750 to 1150 °C for 1 h. After sintering, the density, shrinkage and mass loss increased as the concentration of AcCuH2O increased. A microstructural analysis of samples sintered at 950 °C for 1 h revealed Cu-doped ZnO grains with Cu-clusters of x=5.0 mol % Cu; the J–E curves showed that both the breakdown electric field, Ebr, and the nonlinearity coefficient, α, increased as x increased from 0.05 to 0.5. Complex acceptor defects involving Cu+Zn in the grain boundary are believed to have compensated for the n-type conductivity of the ZnO grains, giving rise to high Ebr values.

Effect of carbonizing speed on the property changes of woodceramics impregnated with liquefacient wood

Properties of the woodceramics impregnated with liquefacient wood and carbonized at different heating rate were performed by dimension shrinkage and weight loss, density, compressive, tensile strength and specific surface area. The results showed that the heating rate played an important role upon the properties of the woodceramics; the dimension shrinkage and the weight loss increased with the increase of heating rate, while the compressive and tensile strength decreased. The results also indicated that high heating rate promoted high surface area.

Drying study of siloxane-PPG nanocomposites

This is a study of the structural transformations occurring in hybrid siloxane-polypropyleneglycol (PPG) nanocomposites, with different PPG molecular weight, along the drying process. The starting materials are wet gels obtained by the sol-gel procedure using as precursor the 3-(trietoxysilyl)propylisocyanate (IsoTrEOS) and polypropylenglycol bis(2-amino-propyl-ether) (NH2-PPG-NH2). The shrinkage and mass loss measurements were performed using a temperature-controlled chamber at 50°C. The nanostructural evolution of samples during drying was studied in situ by small angle x-ray scattering (SAXS). The experimental results demonstrate that the drying process is highly dependent on the molecular weight of polymer. After the initial drying stage, the progressive emptying of pores leads to the formation of a irregular drying front in gels prepared from PPG of high molecular weight, like 4000 g/mol. As a consequence, an increase of the SAXS intensity due to the increase of electronic density contrast between siloxane clusters and polymeric matrix is observed. For hybrids containing PPG of low molecular weight, the pore emptying process is fast, leading to a regular drying front, without isolated nanopockets of solvents. SAXS intensity curves exhibit a maximum, which was associated to the existence of spatial correlation of the silica clusters embedded in the polymeric matrix. The spatial correlation is preserved during drying. These results also reveal that the structural transformation during drying is governed by capillary forces and depends on the entanglement of polymer chains.

Bulk Characteristics of Jute / Polypropylene Yarns Texturized by Sodium Hydroxide Solution

Depending on the blend proportions of jute and polypropylene, the combined effect of axial shrinkage (14.5-27.0%) and weight loss (7.0-15.7%) of yarns was an increase in yam specific volume due to texturization by sodium hydroxide solution (18% w / v). The higher the proportion of polypropylene in the blend, the higher the specific volume of the yam. The specific volume of the texturized yarns falls with the increase in twist factor, and this effect is more pronounced when the proportion of jute in the blend is high.

Durability of Firefighters' Protective Clothing to Heat and Light

Fabrics used in firefighters' protective clothing were exposed to simulated sunlight from a xenon are Weather-Ometer and heat in a forced air circulating oven, and the resulting changes in properties were measured (color, tearing strength, flame resistance and thermal protective performance). The thermal shrinkage and weight loss associated with heat exposure were also noted. Outer shell fabrics of Nomex III, Zirpro flame resistant wool, and PBI/Kevlar were all susceptible to light and underwent marked reductions in tensile tearing strength as a result of light exposure. Heat exposure resulted in a significant reduction in the tearing strength of all outer shell fabrics while increasing the tearing strength of moisture barrier fabrics. A polyamid/flame resistant viscose blend was extremely sensitive to heat exposure, undergoing a substantial loss in tearing strength and appreciable thermal shrinkage. Zirpro flame resistant wool was particularly sensitive to temperatures greater than 230°C. Although both light and heat caused losses in physical strength, there was no noticeable reduction in the flame resistance or thermal protective performance of the individual fabrics and garment assemblies studied.

Microstructure Development of Aluminum Oxide: Graphite Mixture During Carbothermic Reduction

Reactions in the system Al-0-C are discussed. Reaction conditions which produce an α-alumina body having a <70%-dense bulk region coated with an impervious, ∼100-μm thick surface layer are described. The development of the unique composite microstructure is attributed to reactions which serve to coarsen internal grains by vapor-phase transport of volatile aluminum suboxides and, thereby, reduce firing shrinkage. Proper control of the furnace atmosphere is necessary to produce the thin, dense surface layer. The effect of varying the carbodalumina molar ratio on linear firing shrinkage, tired density, and weight loss was examined. In addition, the effect of oxygen partial pressure on the oxidation of carbon and the formation of an intermediate reaction product, Al4O4C, was examined.

Acceptability of Smoked Turkey Drumsticks with and without Nitrite Addition

Two methods of preparing smoked turkey drumsticks were compared as to consumer acceptance. Smoking and cooking methods were the same; however, one brine solution contained nitrite (Product A) and the other did not (Product B). Consumers were asked to rate both products for color, appearance, flavor, and tenderness as follows; 1–very good; 2–good; 3–fair; 4–poor. They were also asked: 1) Which product do you like best?, 2) Which product would you buy?, and 3) What is your opinion on the nitrite-nitrate controversy? Results indicated 65% preferred Product A, 31% Product B, and 4% both products. Results on buying indicated 58% would buy Product A, 28% Product B, 7% both, and 7% neither. Ratings for color were: Product A 1.6, Product B 2.3 (P<.01); appearance: Product A 1.8, Product B 2.3 (P<.01); flavor: Product A 1.8, Product B 2.1 (non-significant); tenderness: Product A 1.8, Product B 2.0 (non-significant). Responses to the nitrite-nitrate question varied greatly from “needed to prevent food poisoning” to “against the use of nitrite”. The drumsticks had a 20% shrinkage loss which occurred during smoking and cooking. Drumsticks were priced at $25.00/cwt, brine cost was $4.12/cwt, and total cost was $29.12/cwt for meat and brine. This resulted in an investment of 36.4¢/lb of cured-cooked product.

EVALUATION OF A CALCIUM ALGINATE FILM FOR USE ON BEEF CUTS

ABSTRACTEffects of a calcium alginate coating on retail beef pieces and steaks were studied. Microbiological analyses were performed on beef pieces following treatments with: (1) a calcium alginate coating; (2) a 200 ppm HOCl solution; (3) a combination of 1 and 2; (4) a coliform inoculation and/or (5) no treatment (control). Each sample was wrapped in a polyvinyl chloride (PVC) film and stored at 5°C for up to 7 days. The rate of microbial growth for total and coliform counts on the meat was not significantly different with coated and uncoated meat samples. The HOCl treated meat had significantly lower total microbial counts and coliform populations when compared to either the calcium alginate or the HOCl‐calcium alginate treated meat. Acceptance of the calcium alginate film involved retail display and organoleptic evaluations of 40 2.54 cm thick beef steaks. Steaks that received the calcium alginate coating were significantly lower in shrinkage loss, drip and degree of off‐odor detected through 96 hr storage when compared to the uncoated steaks. The coating significantly prolonged muscle color through 96 hr storage. No significant differences were observed between treatments for appearance, surface discoloration, flavor, juiciness, tenderness, overall acceptability or cooking loss.

EVALUATION OF A CALCIUM ALGINATE COATING AND A PROTECTIVE PLASTIC WRAPPING FOR THE CONTROL OF LAMB CARCASS SHRINKAGE

ABSTRACTNinety lamb carcasses were evaluated for shrink loss, microbial growth and temperature reduction following treatment with: (1) an edible calcium alginate coating, Flavor‐Tex®; (2) plastic wrap; or, (3) no treatment (control). Lambs (n = 30) were slaughtered on three consecutive days with 10 carcasses/day being randomly assigned to each treatment. Carcasses receiving the edible coating were significantly (P &lt; 0.05) lower in 24‐hr shrinkage loss (1.55%) than the controls (2.77%); however, those in plastic wrap had the least amount of shrinkage (1.20%), and maintained this advantage through 7 days postmortem. Total surface microbial counts from the sirloin area indicated a significant (P &lt; 0.05) reduction at day 5 and 7 for the alginate coated carcasses, with the plastic wrap carcasses having the highest counts on all days. Internal leg temperature reduction (chilling) was essentially uniform at the end of a 24‐hr chill at 2°C regardless of treatment. No significant differences were observed between treatments for cooking loss, flavor, juiciness, off‐odor or overall acceptability.

Humidification of potatoes ventilated by outside air cooling and by artificial cooling

Abstract Humidification of potatoes cool-stored at about 4°C using low-cost equipment to inject a fine mist of water into the ventilating airstream at 4 bar (60 lb/in 2 ), was carrid out in 35–40 tonne bins during 1969, 1970 and 1971, all at an airflow rate of 100 m 3 /hr/tonne (60 ft 3 /min/ton). Intermittent humidification given on each occasion of outside air cooling had negligible effect on the relative humidity of the store air, or on shrinkage losses compared to outside air cooling without humidification. Continuous humidification during continuous recirculation of artificially cooled air was superior to continuous artificial cooling without humidification, and gave the highest mean relative humidity (95% r.h.) and lowest mean shrinkage loss (3·7%) of all 4 treatments, over the 5–6 months storage period. It is tentatively concluded that any worthwhile benefit to be derived from humidification would be obtainable only in stores designed to allow the maintenance of a continuously high relative humidity of the store atmosphere.

Prestress Loss as Affected by Type of Curing

This report describes a three-year investigation of the effect of accelerated curing conditions on the creep and shrinkage properties of the type of concrete frequently used in precasting plants. These concretes were proportioned to achieve a nominal compressive strength of at least 4,000 psi after five or six days of moist curing or in one day of atmospheric steam or autoclave curing. The study included Types I and III cements and three types of aggregate: an expanded slag, an expanded shale, and a normal weight sand and gravel. A major portion of the study involved the direct measurement of prestress loss in terms of force rather than of strain measurement. For this purpose two sizes of post-tensioned concrete prisms were tested in special equipment designed to limit the observed losses to those due to creep and shrinkage. The prism sizes were 4 x 6 x 36 in. and 8 x 12 x 36 in. Thus, the effect of size of member on the prestress loss might also be investigated. Standard 6 x 12 in. concrete cylinders also were utilized for creep and shrinkage tests. The results have demonstrated the beneficial reduction of prestress loss due to creep and shrinkage by the accelerated curing methods. Atmospheric steam curing reduced the creep, shrinkage, and prestress loss of the concretes by as much as 40 per cent of the losses observed for normally cured concretes. Even greater benefit to these properties was achieved by autoclave curing. The creep and shrinkage under that type curing was almost negligible. The study has indicated that structural lightweight concrete of high quality may be used in prestressed structures with confidence that the prestress losses due to creep and shrinkage will not be materially larger than those obtained with normal weight concrete. Little difference in observed prestress loss was found between one of the lightweight aggregate concretes and the sand-and-gravel concrete, while the losses in concrete containing the other lightweight aggregate were somewhat greater than those of the normal weight concrete.