The Effect of Sterilization on Plastics and Elastomers

Laurence W. McKeen

• Publisher: William Andrew
• Year: 2018
• eBook ISBN: 9780128145128
• Edition: 4
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

The Effect of Sterilization Methods on Plastics and Elastomers, Fourth Edition brings together a wide range of essential data on the sterilization of plastics and elastomers, thus enabling engineers to make optimal material choices and design decisions. The data tables in this book enable engineers and scientists to select the right materials and sterilization method for a given product or application. The book is a unique and essential reference for anybody working with plastic materials that are likely to be exposed to sterilization methods, be it in medical device or packaging development, food packaging or other applications.- Presents essential data and practical guidance for engineers and scientists working with plastics in applications that require sterile packaging and equipment- Updated edition removes obsolete data, updates manufacturers, verifies data accuracy, and adds new plastics materials for comparison- Provides essential information and guidance for FDA submissions required for new medical devices

1

Introduction to Food Irradiation and Medical Sterilization

Abstract

This chapter is comprehensive overview of sterilization and disinfectant processes used for foodborne disease control and medical sterilization. Pathogens such as bacteria, viruses, and endospores are described along with other infectious agents.

The processes for controlling these infectious agents in food are summarized. These processes include not only irradiation by the two most important processes, electron beam and gamma ray, but by other processes such as ultraviolet, microwave, and infrared radiation.

Medical sterilization and disinfectant processes are reviewed. Besides irradiative processes, thermal processes such as steam autoclave and dry heat are reviewed. Many liquid and gaseous chemical disinfectants are covered. The commercially important ethylene oxide sterilization process is discussed.

Dealing with bioterrorism agents is briefly discussed.

Throughout this chapter the mechanisms the irradiation, sterilization, and chemical disinfectant processes use to destroy the pathogens are discussed often in chemical detail.

Keywords

Bacteria; viruses; endospores; prions; helminthes; fungi; molds; yeasts; protozoans; biofilm; electron beam irradiator; gamma irradiator; X-ray irradiator; ultraviolet; UVGI; microwave; infrared; steam sterilization; autoclave; flash sterilization; dry heat sterilization; glass bead sterilizer; chemical disinfectants; alcohol; chlorine; hypochlorites; chlorine dioxide; sodium dichloroisocyanurate; Chloramine-T; superoxidized water; formaldehyde; glutaraldehyde; hydrogen peroxide; iodophors; ortho-phthalaldehyde; OPA; peracetic acid; phenolics; quaternary ammonium compounds; surfacine; ethylene oxide; EtO; ozone; gas plasma; bioterrorism

This first chapter primarily focuses on the processes used to destroy microbiological life. Microbiological life, microbes, or pathogens in food contribute to food spoilage, disease, illness, and even death. Similarly, microbes in a health-care environment may cause disease, infections, sickness, illness, and death. The elimination, killing, or control of microbes is therefore critically important. The processes used for microbe control can affect the properties of materials, especially plastics. That effect is the subject of the bulk of this book. This introductory chapter will be split up into three parts. First will be background on the biology and types of microbes. Then the processes used to control microbial life in the food supply are discussed. That is followed by the control of microbes in the health-care environment.

1.1 Pathogens

Sterilization processes are intended to deal with contamination of food, surfaces, or equipment by potentially harmful life forms. These life forms are primarily bacteria, viruses, and endospores, but could also include parasites, prions, molds, fungi, yeasts, protozoa, etc. Organisms that cause disease are called pathogens. This section briefly summarizes what these life forms are, which leads to a better understanding of how sterilization processes kill or control them.

1.1.1 Bacteria

Bacteria consist of only a single cell. Bacteria fall into a category of life called the prokaryotes. Prokaryotes’ genetic material, or DNA, is not enclosed in a cellular compartment called a nucleus as it is in eukaryotes. Not all bacteria are harmful. However the subject of this book implies the killing of harmful bacteria. Most people know harmful bacteria best because of the diseases they cause. Some of these diseases are produced when bacteria attack directly the tissues of a plant or animal. For example, fruits and vegetables that become discolored as they are growing may be under attack by bacteria, though discoloration may also be the result of oxidation.

Bacteria also attack cells by releasing chemicals that are poisonous to plants and animals. Such poisons are known as toxins. As an example, Clostridium botulinum releases a toxin that causes the most severe form of food poisoning, botulism.

Some forms of dangerous bacteria live on the human skin, but cause no harm unless they are able to enter the body. Among these bacteria is Staphylococcus, responsible for the potentially fatal toxic shock syndrome and gastroenteritis. The bacteria may enter the bloodstream through a break in the skin or the digestive tract through contaminated food. And although Escherichia coli is helpful within the digestive system, if it is ingested it may cause cramping and diarrhea. If it enters the bloodstream it causes fever, hypotension, altered mental status and possibly death.

A diagram of a typical bacterium is shown in Fig. 1.1 and a micrograph of cholera bacteria is shown in Fig. 1.2. Bacteria can be many other shapes however some of which are shown in Fig. 1.3.

Figure 1.1 Diagram of a typical bacterium.¹

Figure 1.2 Scanning electron micrograph of cholera bacteria.¹

Figure 1.3 Common bacterial morphologies.

Bacteria are often classified as Gram positive and Gram negative. The main difference between the two forms of bacteria is between the composition and structure of the cell walls of the two as shown in Fig. 1.4. Referring to the figure:

• • Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of bacteria forming the cell wall.
• • The periplasm is a space bordered by the two selective permeable biological membranes, which are the inner plasma membrane and the outer membrane in Gram-negative bacteria.
• • There is no periplasmic space in Gram-positive bacteria because there is only...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Preface
• 1. Introduction to Food Irradiation and Medical Sterilization
• 2. Introduction to Plastics and Polymers
• 3. Introduction to the Physical, Mechanical, and Thermal Properties of Plastics and Elastomers
• 4. Styrenic Plastics
• 5. Polyesters
• 6. Polyimides
• 7. Polyamides (Nylons)
• 8. Polyolefins
• 9. Polyvinyls and Acrylics
• 10. Elastomers
• 11. Fluoropolymers
• 12. High-Temperature/High-Performance Polymers
• 13. Renewable Resource and Biodegradable Polymers
• Appendix A. Guidelines for Component Sterilization Based on Material and Process
• Index