The Production of PVC and Environmental Concerns

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PVC PPRODUCTION GREEN PROCESS


CONTENTS

  1. Introduction
  2. History
  3. PVC’s proprieties

  1. PVC process
  • Row material
  • Chemical process
  • PVC production

  1. Application
  2. Green process
  3. Eco-profiles and LCA
  4. Benefits of useing PVC
  5. References

1. INTRODUCTION

Poly Vinyl Chloride (abbreviated PVC), is the third-most widely produced , after  and .

PVC comes in two basic forms: rigid (sometimes abbreviated as RPVC) and flexible. The rigid form of PVC is used in  for pipe, and in profile applications such as doors and windows. It is also used for bottles and other non-food packaging, and cards (such as bank or membership cards). It can be made softer and more flexible by the addition of  the most widely used being  In this form, it is also used in plumbing, electrical cable insulation, imitation leather, signage, inflatable products and many applications where it replaces rubber.

2. HISTORY

PVC was discovered accidentally on at least two occasions in the 19th century. The first, in 1838, was by the French physicist and chemist Henri Victor Regnault and the second in 1872 by the German Eugen Baumann. On both occasions, the polymer appeared as a white solid inside flasks of the newly discovered vinyl chloride gas that had been left exposed to sunlight. The material was difficult to work with and no one mastered the challenge of commercial applications.

In 1913, German inventor Friedrich Heinrich August Klatte took out a patent on PVC. His method used polymerization of vinyl chloride with sunlight.


3. PVC's PROPRIETIES

PVC, PE, PP and PS are general purpose plastics. The features of the particular plastic are determined by its chemical composition and type of molecular structure (molecular formation: crystalline/amorphous structure)

Fire retarding properties

PVC has inherently superior fire retarding properties due to its chlorine content, even in the absence of fire retardants. For example, the ignition temperature of PVC is as high as 455°C, and is a material with less risk for fire incidents since it is not ignited easily.

Furthermore, the heat released in burning is considerably lower with PVC, when compared with those for PE and PP. PVC therefore contributes much less to spreading fire to nearby materials even while burning.

Durability

Under normal conditions of use, the factor most strongly influencing the durability of a material is resistance to oxidation by atmospheric oxygen. PVC, having the molecular structure where the chlorine atom is bound to every other carbon chain, is highly resistant to oxidative reactions, and maintains its performance for a long time. Other general purpose plastics with structures made up only of carbon and hydrogen are more susceptible to deterioration by oxidation in extended use conditions (such as, for example, through repeated recycling).

Oil/Chemical resistance

PVC is resistant to acid, alkali and almost all inorganic chemicals. Although PVC swells or dissolves in aromatic hydrocarbons, ketones, and cyclic ethers, PVC is hard to dissolve in other organic solvents. Taking advantage of this characteristic, PVC is used in exhaust gas ducts, sheets used in construction, bottles, tubes and hoses.


Mechanical stability

PVC is a chemically stable material, which shows little change in molecular structure, and also exhibits little change in its mechanical strength. However, long chain polymers are viscoelastic materials and can be deformed by continuous application of exterior force, even if the applied force is well below their yield point. This is called creep deformation. Although PVC is a viscoelastic material, its creep deformation is very low compared with other plastics due to limited molecular motion at ordinary temperature, in contrast to PE and PP, which have greater molecular motion in their amorphous sections.

Processability and mouldability

The processability of a thermoplastic material depends largely on its melt viscosity. PVC is not suitable for injection moulding of large sized products, since its melt viscosity is comparatively high. On the other hand, the viscoelastic behaviour of molten PVC is less dependent on temperature and is stable. Therefore PVC is suitable for complex shaped extrusion profiling (e.g., housing materials), as well as calendaring of wide films and sheets (e.g., agricultural films and PVC leather).

Other properties that make PVC versatile

PVC has polar groups (chlorine), and is amorphous, therefore mixes well with various other substances. The required physical properties of end products (e.g., flexibility, elasticity, impact resistance, anti-fouling, prevention of microbial growth, anti-mist, fire retarding) can be freely designed through formulation with plasticisers and various additives, modifiers, and

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colouring agents. PVC is the only general purpose plastic that allows free, wide and seamless adjustment of the required physical properties of products such as flexibility, elasticity, and impact resistance, by adding plasticisers, additives and  modifiers. Since the physical properties of end products are adjustable through compounding with additives, only a few types of resin are required to cover all applications (fibre, rigid and flexible plastic, rubber, paint, and adhesive). This controllability is also extremely beneficial for recycling.


4. PVC PROCESS

PVC manufacturing process

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