Effect of Hydrothermic Ageing on Dielectric and Mechanical Properties of Rigid Poly(vinyl chloride)

An accelerated hydrothermic ageing (according to N.F.T. 54043 method) was performed on samples of rigid poly(vinyl chloride). The test consisted of sample immersion in boiling water at 100°C for different exposure periods up to 480 h. The samples were removed from the boiling water every two hours for mechanical and dielectric characterization and color test. The dielectric measurements carried out on aged samples, up to 40 h, showed that the permittivity remained almost constant and its value was found to be 2.3 in the range –100 to +62.8°C. However, as the temperature approaches the glass transition (T_g = 88.3°C), the permittivity was observed to increase rapidly. It was also found that the permittivity of aged samples was lower than that of the non‐aged samples. The dielectric loss factor (tan δ) measurements with respect to temperature have confirmed the presence of two relaxations: β at low temperature (around –35°C) and α near the T_g. The combined action of water and temperature reduced the intensity of the corresponding relaxation peaks. The sample color index was evaluated up to 480 h using the SYNMERO scale in order to estimate the degradation extent. Unexpectedly, elongation at break under uniaxial traction remained unaffected by the hydrothermic ageing, meaning that two competing processes were involved simultaneously (sample degradation via chain scission and sample plastification via water absorption).     

THE PRODUCTION OF SOME WHITE ENAMELS FOR COPPER1

The investigation deals with the development of some white enamels for copper watch dials, thermometer scale plates, and signs. The effect of varying Na₂O, PbO, cryolite, SiO₂ and B₂O₃ on the properties of the enamels was studied in twenty enamel compositions. The following conclusions were reached: (1) Correct melting is extremely important in the preparation of copper enamels; (a) Slow air cooling of the frit is preferable to quenching in water. (b) Repeated melting tends to promote opacity and to eliminate dissolved gases. (2) A somewhat reducing atmosphere during firing avoids oxidation of the copper. (3) Slight changes in enamel composition have a decided effect on the resultant properties. (4) Sodium oxide promotes gloss but reduces opacity very decidedly. (5) Lead oxide promotes fusibility without materially reducing opacity, except by dilution. (6) Cryolite is not a desirable flux or opacifier as it tends to develop a matt finish. (7) It is desirable to keep the boric oxide content low and good enamels may be produced without it. (8) By using “white arsenic” as an opacifier tin oxide is unnecessary. (9) The following were the best enamels obtained and these appear to be equal to a number of watch dial enamels examined: C-19 and C-20. 20. (10) A second group of compositions which appear to promote results equal to those in use for thermometer scales, advertising letters, etc., are C-10. 10. C-21, C-22, and C-24. In selecting these compositions, all factors such as opacity, gloss, texture, fit and resistance to attack of copper have been considered.     

TESTING RESISTANCE OF ENAMELED SURFACES TO SCRATCHING GOUGING,AND ABRASION*

Seven types of cover-coat enamels were tested for resistance to scratching, gouging, and abrasion by various methods. These methods were (a) P.E.I. abrasion test, (b) P.E.I. gouge test, (c) variations of the gouge test, (d) Taber Abraser, and (e) a scratch test. Chemical durability and reflectance were found to have little or no correlation with the resistance of the enamels to abrasion. The bubble structure of the enamel layer seemed to have the greatest effect on abrasion and scratch resistance of the enamel layer.     

POROSITY: III. WATER AS AN ABSORPTION LIQUID

Classes of absorption method .—The ordinary immersion method has been shown by previous investigators to be unreliable. Simple immersion in low vacuo without boiling is also shown theoretically to be unreliable. An analysis of the results of previous investigators indicates the presence of unsuspected sources of error. Effect of adsorbed gases upon dry weights of test pieces .—Dry air is shown to be without appreciable influence. Depending upon the humidity of the atmosphere, adsorbed water vapor may cause errors up to 2 per cent in the porosity value. Perfectly dry fired clay will remove water from conc. H₂SO₄, and from fused CaCl₂. Saturation by boiling at atmospheric pressure .—A one hour's (and in one instance a 5 hours') boiling failed to saturate completely. On continued boiling the saturated weight increases linearly with the time and this in spite of the fact that appreciable quantities of dissolved materials are removed from the test piece by the hot water. This result is shown to be due to a gradual and continuous rehydration of the clay by the hot water. The error from this factor may amount to as much as 3% and the error from dissolved materials to as much as 2%, during a 3 hours' boiling. The nature of the dissolved material was determined. Method of cooling the test piece .—It is recommended that the test piece be kept in a closed vessel over 95% sulphuric acid for several hours before its dry weight is taken. Saturation procedure .—A vacuum method is described in which water may be employed as the saturation liquid under conditions where the above sources of error are reduced to a minimum. The method is not however recommended as a primary standard. Necessity of a soaking period .—It is shown from theoretical considerations that a soaking period is necessary and methods are given for calculating and for measuring the minimum soaking period required for a given test piece and a given liquid of known penetrativity.     

Flow properties at elevated temperatures and clarity of HSPAN gel–water dispersions

Dispersions of hydrolyzed-starch–polyacrylonitrile (HSPAN) gel and distilled water underwent permanent diminuntion of room-temperature viscosity after maintenance above a threshold temperature of 75°C for periods of several weeks. Below the threshold temperature, viscosity measured at room temperature was unaffected. Above the threshold temperature, the final room-temperature viscosity exponentially varied as the inverse absolute temperature, and the viscosity decreased with increasing temperature. The HSPAN gel–distilled water dispersions exhibited both yield stress and velocity slip at a solid boundary, but the latter was not present at low shearing stresses. The former inhibited natural convection in a vertical slot with an imposed horizontal temperature difference. Clarity of the dispersions was demonstrated by a character-visibility test. Deaerating the distilled water by boiling before mixing with HSPAN gel improved the clarity of the resulting dispersion by eliminating the formation of bubbles at elevated temperature. © 1995 John Wiley & Sons, Inc.     

DISINTEGRATION OF SODA LIME GLASSES IN WATER1

Soda lime glasses have been treated in water at temperatures helow boiling point, at boiling point, and up to 25 lb. pressure in an autoclave. Effects produced are illustrated with photographs and show that glass disintegrates, i. e., cracks, spalls, and loses weight when treated at any temperature used. The rate of disintegration depends upon time, temperature, composition, and heat treatment of glass surface during forming, the latter factor apparently affecting considerably the tendency to spall or chip. Treatment given glasses conforms in many ways to treatment glass receives in service, either when sterilized when used for food packing or continued washing and sterilizing as when used for delivering or serving food daily. The relative endurance of glasses may be studied by the methods used, and standard methods of testing based upon them can be worked out. An article must stand at least six hours in boiling water without apparent disintegration or chipping to be of good quality. Spalling always appeared on the exterior only of pressed or blown ware. Disintegration of the glass is cumulative with time of treatment whether it be periodic or continuous treatment. Treating glass in hot water with increasing pressures does not seem to give greatly increased disintegration as the temperature and pressure rises. Surfaces of blown or pressed articles are shown to be laminated rather than smooth and impervious.     

Boiling water aging of polycarbonate and polycarbonate/acrylonitrile–butadiene–styrene resin and polycarbonate/low‐density polyester blends

The effects of boiling water on the mechanical and thermal properties and morphologies of polycarbonate (PC), PC/acrylonitrile–butadiene–styrene resin (PC/ABS), and PC/low‐density polyester (PC/LDPE) blends (compositions of PC/ABS and PC/LDPE blends were 80/20) were studied. PC and the PC/ABS blend had a transition from ductile to brittle materials after boiling water aging. The PC/LDPE blend was more resistant to boiling water aging than PC and the PC/ABS blend. The thermal properties of glass‐transition temperature (T_g) and melting temperature (T_m) in PC and the blends were measured by DSC. The T_g of PC and PC in the PC/ABS and PC/LDPE blends decreased after aging. The T_g of the ABS component in the PC/ABS blend did not change after aging. The supersaturated water in PC clustered around impurities or air bubbles leading to the formation of microcracks, which was the primary reason for the ductile–brittle transition in PC, and the microcracks could not recover after PC was treated at 160°C for 6 h. The PC/ABS blend showed slightly higher resistance to boiling water than did PC. The highest resistance to boiling water of the PC/LDPE blend may be attributed to its special structural morphology. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 589–595, 2003     

CHEMICAL DURABILITY OF PORCELAIN ENAMELS *

The resistance of representative porcelain enamel surfaces to the chemical attack of different concentrations of various solutions was investigated in considerable detail. Cylindrical cup-shaped samples were coated with (1) a ground coat, (2) a white fluoride cover enamel, (3) a white antimony cover enamel, (4) a white zirconium cover enamel, (5) an acid-resistant white cover enamel, (6) a sign blue cover enamel, (7) a blue zirconium enamel, and (8) a chemical acidproof blue cover enamel. The loss in weight of these enamel surfaces, after exposure to chemical attack, was determined at definite time intervals. The solutions studied consisted of different concentrations of the inorganic acids, alkalis, several organic acids, as well as selected salt solutions at both room and boiling temperatures. Numerous curves are presented showing the comparative chemical durability of the various porcelain enamel surfaces in which the cumulative loss in weight is plotted against time. Several photomicrographs show the nature and type of chemical attack on the different surfaces. The porcelain enamel surfaces showed considerable variation in their resistance to the chemical attack of the various solutions. All of the porcelain enamels were, in general, resistant to attack at room temperature by the alkali and salt solutions. The acid-resistant and acidproof enamels were resistant to the action of both inorganic and organic acids at room and at boiling temperatures; a wide variance, however, was shown in the comparative acid resistance of the non-acid-resisting enamel to the attack of either organic acids or inorganic acids at room temperature. AU porcelain enamels showed equally low resistance to boiling alkali solutions, but some of the enamel surfaces were attacked markedly by the boiling salt solutions.     

Predicting water diffusivity in elastomers

By the use of water absorption data (rate and equilibrium), the diffusivity of distilled and salt water through Neoprene, styrene-butadiene, and ethylene-propylene-diene elastomers was predicted. Activation parameters were calculated from the Arrhenius plots and were used to calculate heats of solution (all negative). Solubility coefficients (S) were calculated from permeability (P) and diffusion (D) coefficients. For all materials salt water showed a lower D than distilled water but a higher S and P.     

Synthesis and properties of the copolymer of acrylamide with 2‐acrylamido‐2‐methylpropanesulfonic acid

A cross‐linked copolymer of acrylamide (AM) with 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) was prepared by solution polymerization. In this reaction, potassium persulfate (PPS) and N,N′‐methylenebisacrylamide (NMBA) were used as initiator and cross‐linker, respectively. This copolymer, poly(acrylamide‐co‐2‐acrylamido‐2‐methylpropanesulfonic acid) (PAMA), can absorb up to 1749 g/g of dry polymer in distilled water and 87 g/g of dry polymer in 0.9 wt % NaCl aqueous solution at room temperature. The PAMA also has excellent performance in absorbing pure alcohols. Its absorbencies in methanol and glycol are about 310 g/g and 660 g/g, respectively. The effects of various salt solutions on the swelling properties were studied systematically, and the relationship between the absorbency and the concentrations of the different salt solutions can be expressed as Q = kcⁿ. Experimental results indicate that the absorbencies were stable at different water temperatures. The swelling rates of the copolymer in distilled water and a water/ethanol mixture (V_water:V_alcohol = 1:1) were also investigated, and the results showed that PAMA could absorb 992 g of distilled water per gram of dry polymer and 739 g of water/ethanol mixture per gram of dry polymer in five minutes. The PAMA has such good water retention at higher temperatures that the swollen gel can retain 71.6 and 49.5% of the maximum absorbency after being heated for 9 hours at 60 and 80 °C, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3481–3487, 2003     

Properties of rigid polyurethane foams blown by HCFC 141B and distilled water

Rigid polyurethane foams (PUFs) were prepared from polymeric 4,4′‐diphenylmethane diisocyanate, polyester polyol, 1,4‐butane diol, silicone surfactant, hydrochlorofluorocarbon (HCFC) 141B, and distilled water. The properties and structure of the PUFs were investigated with differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and a universal testing machine. The density of the PUF blown by distilled water and/or HCFC 141B decreased from 175.7 to 28.2 kg/m³ with an increase of blowing agents. From the SEM results, the average cell size of the PUF blown by distilled water increased from 150 to 290 μm with the distilled water content. From the DSC results, the glass‐transition temperature (T_g) of the PUF blown by distilled water increased from 85.7 to 101.7°C with increasing distilled water content, whereas the T_g of the PUF blown by HCFC 141B remained unchanged with HCFC 141B content. The compressive strength and modulus of the PUF blown by a mixture of distilled water and HCFC 141B was increased from 0.13 to 0.25 MPa and from 3.00 to 7.23 MPa, respectively, with the distilled water content at the sample density of about 44.0 kg/m³. The increase of the compressive strength and modulus of the PUF at the same density was related to the increase of the T_g from 86.0 to 100.9°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 486–493, 2001     

Surface Preparation of Tantalum for Encapsulation and Adhesive Bonding

A number of methods of surface preparation of tantalum for encapsulation in silicone rubber and for structural adhesive bonding were explored. The only ones which could be generally useful were boiling for 24 hours in distilled water (28% improvement) or boiling for 4 hours in 20% sodium hydroxide solution followed by boiling for 2 hours in dilute hydrochloric acid (34% improvement). An alternative, which could sometimes be used, was heating in air for at least 2 hours at 100°C.     

Effect of boiling water aging on strength and fracture properties of chopped strand mat–polyester laminates

Four types of unsaturated polyesters and chopped strand mat laminates prepared from these resins were examined for their durability after immersion in boiling water. The boiling water aging of fiber-reinforced plastics (FRP) by use of a pressure cooker was found to be 3–4 times faster than boiling water immersion at atmospheric pressure. The weight gain of neat resins increased, and their tensile strength decreased with an increase in immersion time. No variation in the plane strain fracture toughness, K_Ic of the neat resins was observed after boiling water immersion. The elastic–plastic fracture toughness J_Ic of the immersed FRP was measured by a partial unloading procedure. Although J_Ic showed considerable scatter, on the whole, J_Ic of FRP was found to be independent of the four types of matrix resins and also was not effected by immersion in boiling water at 116°C for 24 h.     

EFFECT OF COMPOSITION ON PROPERTIES OF TITANIUM ENAMELS*

The development of a superopaque, acid-resistant titanium enamel is described. Different components of the batch were varied systematically and the properties, such as reflectance, color, flow, gloss, and acid resistance, were determined. Variations in composition, reflectance curves, and spectrophotometer curves are given for all of the enamels investigated. The stability of this type of enamel during firing and smelting was also studied. Spectrophotometric analyses of this type of enamel show a characteristic low reflectance in the short-wave length region of the visible spectrum, differing in this respect from superopaque antimony and zirconia enamels. Additions of as much as 0.5% Fe₂O₃ and 0.2% V₂O₅ to the titanium enamel did not cause any appreciable variations in color. Although some differences in the spectrophotometer curves were noted over the field of enamels investigated, the only major change in color occurred when minute amounts of Cr₂O₃ were present. X-ray diffraction patterns of enamels show that rutile crystals in most cases, or sometimes anatase, are the crystals causing opacity.     

UVERITE—A MILL ADDITION OPACIFIER FOR PORCELAIN ENAMEL*

Uverite is the trade name for an antimony-titanium opacifier, having an approximate formula of 7CaO·CaF₂·6TiO₂·2Sb₂O₅. When compared with tin oxide in a range of commercial enamels, it has proved to be equivalent in its effect on opacity, color, gloss, firing range, general workability, and durability.     

Fatigue durability assessment of automotive adhesive joints by an in situ corrosion fatigue test

Fatigue and corrosion damage are the major concerns of automotive adhesive joints, yet literature reports few works about the in situ fatigue durability of adhesive joints in corrosive environment. This study presents an investigation on the fatigue durability of automotive adhesive single lap joints by an in situ corrosion fatigue test. The joints were manufactured with commercial coated AA5754-O aluminum sheets bonded by a toughened epoxy structural adhesive. An in situ corrosion chamber was designed and employed to simulate a humid and corrosive environment by spraying 5% saline solution or distilled water mist around the joints’ overlap area during fatigue testing. The test results show that in the 5% saline solution mist environment, the joints’ fatigue lives encountered a great loss for about an order in magnitude compared to the joints tested in laboratory environment. The difference of fatigue lives between 5% saline solution mist test and distilled water mist test is insignificant. The fracture surface analysis by scanning electron microscope and EDX techniques indicates that the adhesive joints failed interfacially in the corrosive environment, which differs from the cohesive failure mode in the laboratory environment.     

Accelerated weathering performance of Scots pine preimpregnated with copper‐based chemicals before varnish coating Part:1 coated with cellulosic and polyurethane varnishes

This study aimed to determine the effect of accelerated weathering on gloss, surface hardness and colour changes of Scots pine (Pinus sylvestris L.). Test samples were impregnated with Adolit KD‐5, Wolmanit CX‐8 and Celcure AC‐500 covered with cellulosic and polyurethane varnishes. The results showed that the values of surface hardness and gloss increased after accelerated weathering. While the surface hardness of Scots pine was increased for impregnated and polyurethane‐coated varnish, it decreased for impregnated and cellulosic varnish‐coated Scots pine after 1000 hours of accelerated weathering exposure. Copper‐based chemical impregnation and varnish coating developed the gloss of Scots pine specimens relative to the surface characteristics observed in single‐coated Scots pine specimens. While the most appropriate chemical was Celcure AC‐500 for surface hardness, it was Adolit KD‐5 for the gloss of Scots pine after 1000 hours of accelerated weathering exposure. Wood specimens impregnated prior to the application of varnish were more effective in stabilising the colour of Scots pine than Scots pine only coated with varnish. Polyurethane varnish‐treated Scots pine showed better colour stability for each partial and total accelerated weathering exposure period. The total colour changes were lowest for polyurethane varnish‐coated Scots pine impregnated with Celcure AC‐500 after 1000 hours of accelerated weathering exposure.     

Combustion products from polydiallylamine

Crosslinked polydiallylamine (Sirorez Au¹) was prepared by the redox-initiated (K₂S₂O₈/TiCl₃) polymerization of freshly distilled diallylamine [containing 2% 1,6-bis(N,N-diallylamino)hexane] as a 30% solution in 80% phosphoric acid at 0°C. The resulting crosslinked resin is thoroughly washed with water and then sodium hydroxide solution (10%) before a final distilled water washing and air drying. Polydiallylamine resin containing ? 50% by weight gold was prepared by soaking the above resin in a three fold molar excess of gold cyanide solution (2 g/L at pH 8.5) overnight and then filtering the resin, washing with distilled water, and air drying. The samples were dried for 24 h over P₂O₅ before combustion.     

The Effect of CNT‐modified matrix of cyanate ester CFRPs on the hydrothermal behavior of the material. Evaluation of the water uptake using electrical resistance measurements

In this work, reference and nanomodified unidirectional cyanate matrix, carbon fiber‐reinforced polymers (CFRPs), were exposed to distilled water at 80°C. Water uptake was investigated as a function of the carbon nanotube CNT wt% content up to saturation level. In parallel the variation of glass transition temperature (T_g) was also monitored using dynamic mechanical analysis tests. The distilled water absorption process was modeled following the Fick's law, and the experimental results were found to be in very good agreement with the theoretical predictions up to saturation. Finally, during the tests and, at defined time intervals the variation of the electrical conductivity of the materials under investigation was studied and a correlation between the water absorption and the variation of the electrical conductivity was established. It was shown that the presence of CNTs into the cyanate matrix affects the water absorption mechanism, since an important amount of additional interfaces has been introduced. POLYM. COMPOS. 37:1072–1077, 2016. © 2014 Society of Plastics Engineers     

一种新型玻璃鳞片涂料的研制

舰艇蒸馏水舱内壁主要使用环氧聚酰胺类涂料作为防护涂料,防止舱壁腐蚀,防护期限一般为5年左右。这类涂料不仅防护期效短,而且在使用过程中涂膜易产生起泡、脱落等现象。本文中以硅氧烷包覆过的片状玻璃鳞片为主要防锈颜料,以低粘度环氧树脂为基料,制备了一种新型高固体份环氧玻璃鳞片涂料。实验表明,该涂料耐中性盐雾试验可达3000小时以上;常温条件下,在蒸馏水浸泡环境中,涂膜的有效防护期可达15年以上,并且经长期的蒸馏水浸泡,侵蚀,漆膜不会有可溶物质溶出,不会影响存储的蒸馏水水质,非常适合于长时间存储高纯度蒸馏水的水柜、水罐等设备的内壁防护需要,可有效满足舰艇、电厂等部门对蒸馏水存储设施的防腐要求。