Nonreinforcing

The flexible single-ply membranes are manufactured in three forms reinforced, nonreinforced, and fleece-back sheet. 

Fleece-Back Sheet. A fleece-back sheet is a nonreinforced polymeric membrane that has had a nonwoven mat made of polyester, weighing 101.7—203.4 g/m, laminated to the back of the sheet. The prime use of the fleece-back sheet is in the fully adhered roofing systems. The fleece provides the chemical separator, which eliminates the need for an adhesive that is compatible with the specific membrane or a compatible substrate. 

EPDM is by far the most widely used material in the ballasted roofing system constmction. Because of EPDM s flexibiHty, very large sheets of up to 10,000 square feet (929 m ) can be deHvered to the job site in compact roUs that offer reduced labor on the roof in the seaming process. The typical EPDM sheet size used in ballasted systems is 12 by 30 m and 1.1 mm thick. EPDM is also widely used in both the fully adhered and mechanically fastened roofing systems. In these constmctions, both 1.1- and 1.5-mm thick material is used with widths from 2.1 to 15 m. A majority of the installations use nonreinforced sheet, although reinforced membrane can also be used in all of the system types. The majority of the reinforced sheets go into mechanically fastened systems. 

PVC. Poly(vinyl chloride) (PVC), a very versatile polymer, is manufactured by the polymerisation of vinyl chloride monomer, a gaseous substance obtained from the reaction of ethylene with oxygen and hydrochloric acid. In its most basic form, the resin is a relatively hard material that requites the addition of other compounds, commonly plasticisers and stabilisers as well as certain other ingredients, to produce the desired physical properties for roofing use. The membranes come in both reinforced and nonreinforced constmctions, but since the 1980s the direction has been toward offering only reinforced membranes. The membrane thickness typically mns from 0.8—1.5 mm and widths typically in the range of 1.5—4.6 m. 

The resins have wide appHcation. In nonreinforced form they serve as insulating coatings for electrical coils (46—47). As fiber reinforced resins, they can be made by reaction injection mol ding into laminates, castings, and coatings (48—49). Fiber-reinforced resins are used in marine appHcations (recreational boats) automotive parts (50) bathroom countertops and shower stalls and tubs and more recendy as baUistic protection for military vehicles and aircraft. 

Mineral fillers are used for light-colored compounds. Talc has a small particle size and is a semireinforcing filler. It reduces air permeabihty and has htde effect on cure systems. Calcined clay is used for halobutyl stoppers in pharmaceutical appHcations. Nonreinforcing fillers, such as calcium carbonate and titanium dioxide, have large particle sizes and are added to reduce cost and viscosity. Hydrated siUcas give dry, stiff compounds, and their acidity reduces cure rate hence, their content should be minimized. 

Dere, E., Souza-Silva, M. A., Topic, B., Spieler, R. E., Haas, H. L. and Huston, J. P. Histidine-decarboxylase knockout mice show deficient nonreinforced episodic object memory, improved negatively reinforced water-maze performance, and increased neo- and ventro-striatal dopamine turnover. Learn. Mem. 10 510-519, 2003. 

Branch Connections Branch connections may be made with manufactured tees, fabricated reinforced and nonreinforced branch connections (Fig. 10-130), or manufactured integrally reinforced branch connections. Butt-welded fittings offer the best opportunity... 

Nonreinforced. Many nonreinforced elastomeric membranes are available. These allow the roofing system to take full advantage of the elongation, which can be as much as 600%, of the elastomeric membrane. This works to its fullest advantage in handling building movement as well as thermal and other stresses. The nonreinforced membranes are most popular in ballasted roofing systems. 

Many properties of composites filled with nonreinforcing fillers, such as coefficient of expansion, heat deflection, and specific heat, may be estimated from the rule of mixtures. Thus the coefficient of expansion of the composite, ae, is related to the sum of the coefficients of expansion of the continuous phase or resin matrix m and the discontinuous phase or filler/times their fractional volumes V and (1 — V)% respectively, as follows ... 

Although glass spheres are classified as nonreinforcing fillers, the addition of 40 g of these spheres to 60 g of nylon 66 increases the flexural modulus, the compressive strength, and the melt index of the polymer. The tensile strength, the impact strength, the creep resistance, and the elongation of these composites are less than those of the unfilled nylon 66. 

Figure 9. Reinforcing and nonreinforcing filler (volume fraction = 0.5) in poly(l,2-oxypropylene)-type polyurethane rubber. I = 0.74 min. 1 T =...

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