Polyvinyl Chloride is available in two broad categories:
Plasticized or Flexible PVC or PVC-U (Density: 1.1-1.35 g/cm3): Addition of compatible plasticizers to PVC lowers the crystallinity and by acting like lubricants, yields a much clearer and flexible plastic.
Unplasticized or Rigid PVC or PVC-P (Density: 1.3-1.45 g/cm3): It is a stiff and cost effective plastic material with high resistance to impact, water, weather, chemicals and corrosive environments.
Here are their specific differences:
Strengths | Limitations |
Rigid PVC |
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· Low cost & high stiffness · Intrinsic flame retardant · FDA compliant & also suitable for transparent applications · Better chemical resistance than plasticized PVC · Good electrical insulation & vapor barrier properties · Good dimensional stability at room temperature | · Difficult to melt process · Limited solvent stress cracking resistance · Becomes brittle at 5°C (when not modified with impact modifiers and/or processing aids) · Low continuous service temperature of 50°C |
Flexible PVC |
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· Low cost, flexible & high impact strength · Good resistance to UV, acids, alkalis, oils and many corrosive inorganic chemicals · Good electrical insulation properties · Non-flammable & versatile performance profile · Easier to process than rigid PVC | · Properties can change with time, due to plasticizer migration · Attacked by ketones; some grades swollen or attacked by chlorinated and aromatic hydrocarbons, esters, some aromatic ethers and amines, and nitro- compounds · Tends to degrade at high temperatures · Non suitable for food contact with some plasticizers · Lower chemical resistance than rigid PVC |
In addition, their uses are different. The main applications of these two PVs (rigid and flexible) include:
Application | Rigid PVC | Flexible PVC |
Construction | Window Frames, Pipes, House Siding, Ports, Roofing | Waterproof Membranes, Cable Insulations, Roof Lining, Greenhouses |
Domestic | Curtain Rails, Drawer Sides, Laminates, Audio and Videotape Cases, Records | Flooring, Wall Coverings, Shower Curtains, Leather Cloth, Hosepipes |
Packaging | Bottles, Blister Packs, Transparent Packs and Punnets | Cling Film |
Transport | Car Seat Backs | Under Seal, Roof Linings, Leather Cloth Upholstery, Wiring Insulation, Window Seals, Decorative Trim |
Medical | - | Oxygen Tents, Bags And Tubing For Blood Transfusions, Drips and Dialysis Liquids |
Clothing | Safety Equipment | Waterproofs for Fishermen and Emergency Services, Life-Jackets, Shoes, Wellington Boots, Aprons and Baby Pants |
Electrical | Insulation pipes, Jacketing, Electricity Distribution Boxes, Switches, Transparent Distributor Box Housings, Plug Housings & Battery Terminals | Cable & Wire insulation, plugs, cable jackets, sockets, Sable Heads and Distributors |
Others | Floppy-Disk Covers, Credit Cards, Traffic Signs | Conveyor Belts, Inflatables, Sports Goods, Toys, Garden Hoses |
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