Plasticizers Derived from Post-consumer PET

Research Trends and Potential Applications

Ewa Langer, Krzysztof Bortel, Marta Lenartowicz-Klik, Sylwia Waskiewicz

• Publisher: William Andrew
• Year: 2019
• Print ISBN: 9780323462006
• eBook ISBN: 9780323461993
• Topic: Technology & Engineering
• Subtopic: Industrial & Technical Chemistry
• Index: Technology & Engineering

Plasticizers Derived from Postconsumer PET: Research Trends and Potential Applications presents a roadmap to the successful use of postconsumer PET to obtain plasticizers for later use, a proposal which presents both economic and sustainability advantages. Based on the results of the latest research into the development of chemical recycling techniques of PET waste, this book describes techniques where the plasticizer obtained can be utilized for value addition in PVC and other polymers.In addition, the book provides basic introductory information on the role of plasticizers in the modification of polymers, basic quality requirements, and the latest trends in the synthesis and use of plasticizers in industry, also presenting the available methods of PET recycling, with particular emphasis on chemical recycling, analysis of the PET market, the availability of postconsumer PET, and its value as a raw material for other products.Based on the authors' research, the book discusses the use of postconsumer PET in the synthesis of monomeric and oligomeric plasticizers. Synthesis conditions are shown in detail, and the influence of the structure of synthesized softeners on their basic quality parameters are assessed and compared with selected commercially available products. In the final sections, the book covers the economic challenges and benefits of this process and its application to newly developed products.- Presents a step-by-step introduction to the methods of recycling PET into usable plasticizers- Provides a viable, actionable alternative to landfills for postconsumer PET, enabling the recycling of more waste polymer and reducing the carbon footprint of PET- Analyzes the economic benefits and challenges of this process- Compares the quality of the output to commercially available products

1

Assessment of Traditional Plasticizers

Abstract

Plasticizers are additives introduced into the polymer matrix to make it more flexible and to improve processing of a modified polymer composition.

This chapter includes some basic information about plasticizers and plasticization process. Fundamental terms related to the subject of polymer modification by incorporation of plasticizers have been defined. The role of plasticizers in the processing of polymers was indicated.

Theories explaining the process of plasticization were presented. This chapter is an introduction to the subject of polymers softening.

Keywords

Plasticization theories; Plasticizer; Polymer modification

1.1. General Characteristic of Plasticizers

Plasticizers are an important class of compounds widely used as additives in the polymer industry to improve the properties and processing characteristics of polymers. The definition of plasticizers adopted by the International Union of Pure and Applied Chemistry (IUPAC) in 1951 is still generally accepted: a substance incorporated in a material (usually a plastic or elastomer) to increase its flexibility, workability, or distensibility. IUPAC defines a plasticizer as a substance or material incorporated in a material (usually a plastic or elastomer) to increase its flexibility, workability, or distensibility [1]. These compounds are intended to reduce the tension of deformation, hardness, density, viscosity, and electrostatic charge of a polymer, while increasing the polymer's chain flexibility by lowering the glass transition temperature (T _g ) and resistance to fracture [2].

Plasticizers are used in many polymers, but about 90% of global plasticizer production is used to produce flexible poly(vinyl chloride) (PVC) [3]. They are typically used in the range of 10–50 phr, except in PVC, where the range is about 30–100 phr. In flexible PVC, approximately 50 phr plasticizer is used. Higher quantities can change the hard rigid unplasticized PVC to a soft rubbery material [4]. The plasticizer should be compatible with PVC; be stable; have good permanence, low volatility, low odor, low toxicity and low color; be cost-effective; and not cause negative interaction with other essential ingredients comprising the formulation [5].

The plasticizers used contain polar and nonpolar groups, and their ratio determines the miscibility and compatibility of a plasticizer with the original polymer. Long-chain molecules such as aliphatic compounds play an important role in lowering the T _g . The polar groups present in plasticizer molecules, which usually consist of ester groups, interact with the polar sites of the polymer molecules, namely chlorine atoms, causing PVC chains to spread. In this case, the softener's polarity should be too high or too low, and it may exudate from the plasticizer, a process often referred to as sweating out. In other words, a plasticizer should create a stable mixture with the original PVC to form a soft product after the gelation process [6].

The use of plasticizers in the manufacture of plastic products to modify polymer characteristics began in the 1800s. It all began from the introduction of natural camphor and castor oil by manufacturers of celluloid or celluloid lacquers to plasticize the final product. This method, however, was unsatisfactory for many end uses. In 1912, triphenyl phosphate was tested to substitute camphor oil, marking the beginning of the ester plasticizer era. Phthalic acid esters were used for the first time as plasticizers in 1920 and came to represent the largest class of plasticizers. In 1930, di(2-ethylhexyl) phthalate (DEHP), also known as dioctyl phthalate, which belongs to this group of plasticizers, was introduced and has been the most widely used plasticizer in the industry ever since [5,7].

Unfortunately, one flaw of low molecular weight additives (monomeric plasticizers) is their tendency to migrate from the PVC item toward the medium it is in contact with (gas, liquid, or solid). Thus, migration limits the utilization or commercialization of plasticized PVC articles, especially in medical products, food packaging materials, and children's toys, due to their possible toxicity. Numerous phthalates are classified as toxic for reproduction, with 13 of them featuring in the REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) candidate list. Four of them (DEHP, dibutyl phthalate, benzyl butyl phthalate, and diisobutyl phthalate) also appear in the authorization list (Annex XIV of REACH) [8]. Currently, there are specific regulations in Europe, which restrict the use of reproductive toxic phthalates in toys, cosmetics, and food contact materials. In 2005, the European Union approved a ban on reproductive toxic phthalates in all toys and childcare articles [9]. Moreover, recent studies have shown that exposure to certain phthalates results in profound and irreversible changes in the development of the male reproductive system [10].

1.2. Definitions

1.2.1. Internal Plasticization

Plasticization resulting from modification of the polymer molecules. It is usually achieved by copolymerization, e.g., by the use of vinyl acetate in PVC or sometimes by chemical modification of the obtained polymer.

1.2.2. External Plasticization

Plasticization resulting from the use of a plasticizer as an additive. It is the usual method of plasticization, but it can suffer from a lack of permanence due to the loss of plasticizer through volatilization or extraction during use of a plasticized polymer.

1.2.3. Polymerisable Plasticizer

A plasticizer that may be polymerized. It enables a rigid product to be manufactured from a liquid PVC plastisol because on heating, the plasticizer can polymerize to rigisol. The most common polymerisable plasticizer is diallyl phthalate.

1.2.4. Plastisol

A stable dispersion of fine particles (about 1 μm diameter) of emulsion PVC in a plasticizer, which is a viscous fluid. Plastisols may be shear thinning or shear thickening, depending mostly not only on PVC particle size, size distribution, and shape but also on plasticizer type and other additives used. A liquid dispersion consisting of very small particles of resin in a plasticizer that can be molded, cast, or made into a continuous film by application of heat. The conventional melt processing method includes dipping, spreading, low-pressure injection molding, rotational molding, and casting. A plastisol's rheological behavior is of great importance in these processes and can be very complex.

1.2.5. Rigisol

A plastisol that contains a polymerisable plasticizer, which polymerizes during gelation, creating a rigid product after gelation, as opposed to being soft and flexible in a normal plastisol product.

1.2.6. Organosol

A plastisol to which an organic solvent has been added to lower viscosity. On gelation, the solvent is lost by evaporation.

1.2.7. Plastigel

A plastisol to which a thickening agent has been added to produce a material of putty-like consistency.

1.2.8. Dry Blend

Powder compounds resulting from the blending of prima...

Table of contents

• Cover image
• Title page
• Table of Contents
• Plastics Design Library (PDL) PDL Handbook Series
• Copyright
• Preface
• 1. Assessment of Traditional Plasticizers
• 2. Classification of Plasticizers
• 3. Essential Quality Parameters of Plasticizers
• 4. Research Trends in Plasticizer Production
• 5. Methods of PET Recycling
• 6. Synthesis of Plasticizers From Postconsumer PET
• 7. Application of New, Synthesized Plasticizers
• Index