Glass mats

Built-Up Roofing. Built-up roofing (BUR) is a continuous-membrane covering manufactured on-site from alternate layers of bitumen, bitumen-saturated or coated felts, or asphalt-impregnated glass mats and surfacings. These membranes are generally appHed with hot bitumens or cold apphed bituminous adhesives (qv). 

The components must be anchored as protection against wind uplift, shppage, and membrane movement. Apphcation rates for BUR membranes ate given in Table 2. Membrane strength is related to felt or glass-mat strengths and the number of phes. Continuous bonding is inadvisable if the elastic... 

Property Organic felt, asphalt-saturated Fiber glass mat, asphalt-impregnated ... 

Fire and Wind Hazards. Weather resistance of roof covetings is not necessarily correlated to fire and wiad resistance. Underwriters Laboratory and the Factory Mutual System test and rate fire and wiad hazard resistance, and some durabiUty tests. Organic felt or fiber glass mat base shingles are commonly manufactured to meet minimum UL requirements, which, ia addition to minimum mass, require wiad and fire resistance properties. 

Both fiber-glass mats and polyester mats are used either individually or combined in SBS membrane sheets. Because of the elastomedc properties of the asphalt, SBS sheets have developed a reputation as being very tough and abuse-resistant. However, they do not have any better ultraviolet resistance than conventional asphalts, so most of the SBS sheets come with a factory-appHed surfacing of granules. 

Goal Tar. In roofing, coal tar is used as mopping bitumen in between 15 and 20% of the BUR roofs installed. Coal-tar pitch and asphalt are considered incompatible and should not be mixed. If mixed, an oily exudate is formed that plasticizes the bitumen, and the mixture remains soft and does not weather well. For this reason, if coal tar is used in BUR systems the felts must be coal-tar saturated. There has been some success using asphalt-coated fiber-glass mat felts with coal-tar pitch. However, this has only been done for a limited number of years so the actual compatibiHty is not fully known. 

The major process today is the hand lay-up technique in which resin is stippled and rolled into the glass mat (or cloth) by hand. Moulds are easy to fabricate and large structures my be made at little cost. 

Property Polyester/ Glass Mat Polyester/ Woven Glass Qoth Epoxy/ Woven Glass Cloth Epoxy/ Filament Wound Glass Rovings... 

Refers to materials whose properties are the same in all directions. Examples are metals and glass mats. 

The following procedure is described in U.S. Patent 3,475,407. A solution of 50 g of lincomycin hydrochloride, 120 g of triphenylphosphine, and 500 ml of acetonitrile in a 3 liter flask equipped with a stirrer was cooled in an ice bath and 500 ml of carbon tetrachloride was added in one portion. The reaction mixture was then stirred for 18 hours without addition of ice to the cooling bath. The reaction was evaporated to dryness under vacuum on a 50° to 60°C water bath, yielding a clear, pale yellow viscous oil. An equal volume of water was added and the mixture shaken until all of the oil was dissolved. The resulting suspension of white solid (03PO) was filtered through a sintered glass mat and discarded. The filtrate was adjusted to pH 11 by addition of 6N aqueous sodium hydroxide. A solid precipitated. 

The resulting slurry was extracted with four 300 ml portions of chloroform. The aqueous phase was discarded. The combined chloroform extract was washed once with 100 ml of saturated aqueous sodium chloride solution and the sodium chloride phase was discarded. The chloroform phase was evaporated to dryness under vacuum on a 50° to 60°C water bath and an equal volume of methanol was added to the residue and the resulting solution heated at reflux for 1 hour. The methanol solution was evaporated to dryness under vacuum on a 50° to 60°C water bath. The residue was a clear pale yellow viscous oil. An equal volume of water and 10 ml of 37% aqueous HCI was added and the resultant was shaken until the oil dissolved and a white solid (more 0jPO) remained in suspension. The suspension was filtered through a sintered glass mat at pH 1 to 2 and the solid discarded. 

To the crude product there was added 100 ml of ethanol with warming until a clear solution was obtained. Then 150 ml ethyl acetate was added and the resultant filtered through a glass mat and the filtrate adjusted to pH 1 by the addition of saturated ethanolic HCI. Crystallization soon occurred. The resultant was allowed to stand at 0°C for 18 hours and then filtered through a sintered glass mat. The solid was dried under vacuum at 60°C for 18 hours yielding 35 g, a 67% yield of 7(S)-chloro-7-deoxylincomycin hydrochloride as an ethanol solvate. 

In the older battery literature the term separator is frequently used very loosely, to include all nonmetallic solid components between the electrodes, such as supporting structures for active materials (tubes, gauntlets, glass mats), spacers, and separators in a narrow sense. In this section, only the last of these, the indispensable separating components in secondary cells, will be termed separators , distinguished from the others by their microscopically small pores, i.e., with a mean diameter significantly below 0.1 mm. 

Polyethylene separators Phenol- formald.- resorcinol separators PVC separators Rubber separators Micro fiber glass mat separators Total... 

Even though this version is not a distinct type of separator, this section is dedicated to it. To all leaf-type separators described, a glass mat can be applied on the side directed towards the positive electrode,... 

The development of the starter battery in Japan has taken an independent course (see Sec. 9.2.1.2), visibly expressed by the separator s thick glass mat and its lack of spacing ribs (cf. Fig. 19). The cellulosic backweb impregnated with phenolic resin, generally in use until around 1980 and largely identical to the separator of the same type already mentioned has been completely replaced by thin ( 0.3 mm) fleece materials made of organic fibers. 

Since the glass mat supplies sufficient stiffness, high backweb thickness was no longer needed These fleeces are made of organic fibers (polyester and polypropylene, as well as so-called synthetic pulp , i.e., fibrillated polypropylene) on paper machines. 

The basic materials are sufficiently stable in sulfuric acid not to require the expensive phenolic resin impregnation. Traces of adhesive are applied to hold the glass mat in order to achieve the total thickness. This separation system may be expensive to manufacture, a fact certainly largely balanced by savings in positive active mass, but it also has some indisputable advantages. 

The electrical resistance, at 60 - 90 mQ cm", is astonishingly low, because the backweb is only 0.25 - 0.30 mm thick and the glass mat with its porosity in excess of 90 percent also contributes only little. In some types of construction the low electrical resistance cannot be fully utilized, however, due to a tendency for gas to be trapped within the glass mat. 

The oxidative stability is excellent. Direct contact between the glass mat and the positive electrode effects a far lower tendency to shed active mass thus as a general rule the failure mode is positive grid coiTosion. 

The microfiber glass separators have to fill the space between the electrodes completely the backweb thickness, is thus identical to the total thickness. Due to the high compressibility of such porous glass mats, a standard measuring pressure of 2 kPa or 10 kPa (BCI method) is generally used during assembly they are compressed... 

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