Poly unplasticised

When dipoles are directly attached to the chain their movement will obviously depend on the ability of chain segments to move. Thus the dipole polarisation effect will be much less below the glass transition temperature, than above it Figure 6.4). For this reason unplasticised PVC, poly(ethylene terephthalate) and the bis-phenol A polycarbonates are better high-frequency insulators at room temperature, which is below the glass temperature of each of these polymers, than would be expected in polymers of similar polarity but with the polar groups in the side chains. 

Figure 14.6. Relation between tensile strength and degree of hydrolysis for unplasticised poly(vinyl alcohol) film. (After Davidson and Sittig )...

Blending of ABS with an acrylic material such as poly(methyl methacrylate) can in some cases allow a matching of the refractive indices of the rubbery and glassy phases and providing that there is a low level of contaminating material such as soap and an absence of insoluble additives a reasonable transparent ABS-type polymer may be obtained. More sophisticated are the complex terpolymers and blends of the MBS type considered below. Seldom used on their own, they are primarily of use as impact modifiers for unplasticised PVC. 

Shear rate (s 1) Poly(methyl methacrylate) 230 °C Acetal copolymer 200 °C Nylon 6,6 285 °C Propylene-ethylene copolymer 230 °C Low-density polyethylene 170 °C Unplasticised PVC 150 °C... 

Flow properties of polyethylene have been widely studied. Because of the wide range of average molecular weights amongst commercial polymers the viscosities vary widely. The most commonly used materials, however, have viscosities lower than for unplasticised PVC and poly (methyl methacrylate) and higher than for the nylons. 

Poly(vinyl chloride) (PVC) is essentially a glassy (non-crystalline) polymer like PS. It is, however, tougher and when pigmented it can be used out-of-doors in exterior cladding, window frames, etc. where it is commonly designated UP VC ( unplasticised PVC ). This is a remarkably durable material in view of the known thermal- and photo-instability of PVC and this is achieved by the addition of substantial quantities of stabilisers (Chapter 3). The present trend is to incorporate fight stable impact modifiers based on saturated polyacrylates to increase toughness in the outdoor environment. 

EN 580 Unplasticised poly(vinyl chloride) (uPVC) pipes - test method for the resistance to dichloromethane at a specified temperature (DCMT). 

EN 922 Pipes and fittings of unplasticised poly(vinyl chloride) (uPVC) - specimen preparation for determination of the viscosity number and calculation of the K-value. 

ISO 2045 1988 Single sockets for unplasticised poly(vinyl chloride) (uPVC) and chlorinated poly(vinyl chloride) (CPVC) pressure pipes with elastic sealing ring type joints - Minimum depths of engagement. 

ISO 13783 1997 Plastics piping systems - Unplasticised poly(vinyl chloride) (uPVC) end-load-bearing double-socket Joints - Test method for leaktightness and strength while subjected to bending and internal pressure. 

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