Rigid PVC Pipe: Start-Up

Although this procedure describes CM-80 twin screw pipe extrusion start-up using pressure sizing, many of the same steps are also necessary for any extrusion process, regardless of end product or extruder type.

A THUMBNAIL TUTORIAL FOR HIGH SCHOOL OR EARLY COLLEGE STUDENTS)

By Skip Thacker

What is a Polymer?----- Repeating units, as LONG CHAINS, (straight chained or branched chained) of one or more types of MONOMER molecules.

Poly (many) mers (units),<--------Mono (one) mer (unit)

                                           FOREWORD

PVC processing dates back to the industrys beginning in the late 1930s and early 1940s, when oiled litharge, white lead, and the first metal-containing liquid stabilizers ( cadmium, tin) were some early additives used in the germinating vinyl industry. Over the next  twenty years PVC grew to become one of the big three of the United States plastics industry at the billion pound per year level of consumption---yet without rigid PVC extrusion applications, which remained essentially undeveloped up to the early 1960s. Beginning in the mid 1960s, the uses of rigid PVC extruded products grew at an increasing rate which even outpaced the total PVC industry growth rate, to the point that rigid vinyl extrusion now consumes a greater amount of PVC resin (almost 70%) than any other process. Primary extrusion products include pipe, conduit, siding, window profile, foam-core pipe, solid and foamed profile, and sheet, with fencing and docking among emerging newer applications.

Understanding the salient differences between single and twin screw extrusion of rigid PVC powder blends is an important part of  a full, overall understanding of  rigid PVC processing technology