Polybutylene adipate terephthalate

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Polybutylene adipate terephthalate
PBAT Repeat Unit.png
Identifiers
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

PBAT (short for polybutylene adipate terephthalate) is a biodegradable random copolymer, specifically a copolyester of adipic acid, 1,4-butanediol and terephthalic acid. PBAT is produced by many different manufacturers and may be known by the brand names ecoflex, Wango,Ecoworld, Eastar Bio, and Origo-Bi. It is also called poly(butylene adipate-co-terephthalate) and sometimes polybutyrate-adipate-terephthalate [1] (a misnomer) or even just "polybutyrate". [2] It is generally marketed as a fully biodegradable alternative to low-density polyethylene, having many similar properties including flexibility and resilience, allowing it to be used for many similar uses such as plastic bags and wraps. [3] The structure is a random-block polymer consisting of butanediol–adipic acid and butanediol-terephthalic acid blocks.

Contents

History

Production of plastics for use in the industrial sector around the world makes up a very large market. PET (polyethylene terephthalate) is one of the dominant plastics within this market. It is commonly used for bottles because it makes a rigid container that is very lightweight. However, because of the stability of PET, it is also highly resistant to biodegradation, posing a significant environmental problem because of the amount of PET produced, sold, used and thrown away on a daily basis. An estimated 30% of the world production of PET goes into making these plastic bottles and only from 15% to 35% is recycled; the rest usually end up in a landfill. [4] This has stimulated research into polymers that function comparably to PET, but are biodegradable. [5]

As with all developments in the realm of materials there are several requirements for the 'ideal' material. For biodegradable plastics, they would be: cheap, renewable, easy to produce and eco-friendly. In addition to these, the polymer should be resistant enough to be functional, such as handling the strain of being put under pressure, and flexible so that it is easy to mold. There are no homopolymers that perfectly provide every one of these features. Therefore, researchers have turned their attention to copolymers: combinations of polymers that have chemical and mechanical properties that complement each other. This led to identifying poly(butylene adipate-co-terephthalate) (PBAT) as a potential copolymer for blending.

PBAT is a random copolymer known for being flexible and tough. This makes it ideal for combination with other biodegradable polymers that have high elastic modulus and strength, but are very brittle. [6] This allows for the production of blended copolymers that can replace industry-standard plastics with environmentally safe and biodegradable plastics that will harmlessly disappear in a short period of time.

Properties

PBAT is classified as a random copolymer due to its random structure. This also means that it cannot crystallize to any significant degree due to the absence of any kind of structural order. This leads to several physical properties: wide melting point, low elastic modulus and stiffness, but high flexibility and toughness. The flexibility and toughness of this polymer makes it ideal for blending with another biodegradable polymer that is strong and rigid for bottle production. [5]

The drawback of this polymer is that if it has high flexibility and toughness, then it will not be strong and rigid. This makes it non-ideal for any situation in which a strong, rigid container is desired. An example of this would be transparent barriers, such as those made of plexiglass (Poly(methyl methacrylate)), a transparent glass substitute. [5]

PBAT is fully biodegradable when composted due to the presence of butylene adipate groups. The high stability and mechanical properties come from the terephthalate portions. [5]

Does not degrade in marine and fresh water. [7]

Preparation

The polyester of adipic acid is synthesized using 1,4-butanediol. The chain lengths are kept low by using an excess of diol in the reaction. PBAT Step 1.png
The polyester of adipic acid is synthesized using 1,4-butanediol. The chain lengths are kept low by using an excess of diol in the reaction.

PBAT is synthesized from the polymer of 1,4-butanediol and adipic acid and the polymer of dimethyl terephthalate (DMT) with 1,4-butanediol.

Adipic acid and 1,4-butanediol are polymerized to create their polyester (plus water). DMT and 1,4-butanediol are also reacted to form their polyester (plus methanol). This polyester is then added to the butylene adipic acid polyester by using tetrabutoxytitanium (TBOT) as a transesterification catalyst; an overabundance of 1,4-butanediol influences chain lengths. The result is a copolymer of the two previously prepared polymers.

The polyester of DMT is generated using 1,4-butanediol. This is the second polymer used with the step 1 product to create the copolymer PBAT. PBAT Step 2.png
The polyester of DMT is generated using 1,4-butanediol. This is the second polymer used with the step 1 product to create the copolymer PBAT.
TBOT is used to catalyze the transesterification of the polyesters of adipic acid and DMT to generate the random, copolymer PBAT. PBAT Step 3.png
TBOT is used to catalyze the transesterification of the polyesters of adipic acid and DMT to generate the random, copolymer PBAT.

This is a random copolymer, because there is no control on the dispersity of the polymer chain lengths or block structuring in the copolymerization reactions; repeat positions are not controlled. If A = polyester of adipic acid and B = polyester of DMT, each with 1,4-butanediol, then the chain structuring could look like any of these: AABABBABA or ABABAAAABB or ABABABBBBA; there is no selectivity for A and B reacting with themselves or each other. [8]

Commercial sources

PBAT is produced commercially by BASF under the trademark ecoflex [3] and in a blend with poly(lactic acid) called ecovio, [9] by Novamont as Origo-Bi and in a blend with starch called Mater-Bi, [10] by Zhuhai Wango Chemical Co Ltd under the name Wango, by JinHui Zhaolong as Ecoworld and in a blend with starch called Ecowill, and by Eastman Chemical as Eastar Bio. [11] Furthermore, suppliers in China and other nations now produce PBAT. These companies include Zhejiang Biodegradable Advanced Material Co. Ltd, Dongguan Xinhai Environmental Protection Material Co., Ltd., [12] Hangzhou Ruijiang Chemical Co., Ltd., [13] and Jiangsu Torise Biomaterials Co., Ltd. [14] in China as well as Green Chemical Co., Ltd. [15] and WILLEAP [16] in South Korea.

Current and future uses

PBAT is marketed commercially as a fully biodegradable plastic, with BASF's ecoflex showing 90% degradation after 80 days in testing. [17] Particular applications that are highlighted by the manufacturers include cling wrap for food packaging, compostable plastic bags for gardening and agricultural use, and as water resistant coatings for other materials, as in paper cups. [18] Due to its high flexibility and biodegradable nature, PBAT is also marketed as an additive for more rigid biodegradable plastics to impart flexibility while maintaining full biodegradability of the final blend.

PBAT is already widely marketed and used for all of the above applications, but is also being investigated as a component in antimicrobial films. In such films, PBAT serves as the bulk of the film with the antimicrobial agent being incorporated during processing. The antimicrobial films would be used in food packaging to inhibit bacterial growth, helping to preserve food products safely. [19]

Related Research Articles

<span class="mw-page-title-main">Biodegradation</span> Decomposition by living organisms

Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria and fungi. It is generally assumed to be a natural process, which differentiates it from composting. Composting is a human-driven process in which biodegradation occurs under a specific set of circumstances.

<span class="mw-page-title-main">Polyurethane</span> Polymer composed of a chain of organic units joined by carbamate (urethane) links

Polyurethane refers to a class of polymers composed of organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane is produced from a wide range of starting materials. This chemical variety produces polyurethanes with different chemical structures leading to many different applications. These include rigid and flexible foams, and coatings, adhesives, electrical potting compounds, and fibers such as spandex and polyurethane laminate (PUL). Foams are the largest application accounting for 67% of all polyurethane produced in 2016.

<span class="mw-page-title-main">Petrochemical</span> Chemical product derived from petroleum

Petrochemicals are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sources such as maize, palm fruit or sugar cane.

<span class="mw-page-title-main">Polybutylene terephthalate</span> Chemical compound

Polybutylene terephthalate (PBT) is a thermoplastic engineering polymer that is used as an insulator in the electrical and electronics industries. It is a thermoplastic (semi-)crystalline polymer, and a type of polyester. PBT resists solvents, shrinks very little during forming, is mechanically strong, is heat-resistant up to 150 °C, and can be treated with flame retardants to make it noncombustible. It was developed by Britain's Imperial Chemical Industries (ICI).

<span class="mw-page-title-main">PET bottle recycling</span> Recycling of bottles made of polyethylene terephthalate

Although PET is used in several applications, as of 2022 only bottles are collected at a substantial scale. The main motivations have been either cost reduction or recycle content of retail goods. An increasing amount is recycled back into bottles, the rest goes into fibres, film, thermoformed packaging and strapping. After sorting, cleaning and grinding, 'bottle flake' is obtained, which is then processed by either:

<span class="mw-page-title-main">Polyhydroxyalkanoates</span> Polyester family

Polyhydroxyalkanoates or PHAs are polyesters produced in nature by numerous microorganisms, including through bacterial fermentation of sugars or lipids. When produced by bacteria they serve as both a source of energy and as a carbon store. More than 150 different monomers can be combined within this family to give materials with extremely different properties. These plastics are biodegradable and are used in the production of bioplastics.

<span class="mw-page-title-main">Polylactic acid</span> Biodegradable polymer

Polylactic acid, also known as poly(lactic acid) or polylactide (PLA), is a thermoplastic polyester with backbone formula (C
3H
4O
2)
n or [–C(CH
3)HC(=O)O–]
n, formally obtained by condensation of lactic acid C(CH
3)(OH)HCOOH with loss of water. It can also be prepared by ring-opening polymerization of lactide [–C(CH
3)HC(=O)O–]
2, the cyclic dimer of the basic repeating unit.

<span class="mw-page-title-main">Bioplastic</span> Plastics derived from renewable biomass sources

Bioplastics are plastic materials produced from renewable biomass sources, such as vegetable fats and oils, corn starch, straw, woodchips, sawdust, recycled food waste, etc. Some bioplastics are obtained by processing directly from natural biopolymers including polysaccharides and proteins, while others are chemically synthesised from sugar derivatives and lipids from either plants or animals, or biologically generated by fermentation of sugars or lipids. In contrast, common plastics, such as fossil-fuel plastics are derived from petroleum or natural gas.

<span class="mw-page-title-main">Hot-melt adhesive</span> Glue applied by heating

Hot-melt adhesive (HMA), also known as hot glue, is a form of thermoplastic adhesive that is commonly sold as solid cylindrical sticks of various diameters designed to be applied using a hot glue gun. The gun uses a continuous-duty heating element to melt the plastic glue, which the user pushes through the gun either with a mechanical trigger mechanism on the gun, or with direct finger pressure. The glue squeezed out of the heated nozzle is initially hot enough to burn and even blister skin. The glue is sticky when hot, and solidifies in a few seconds to one minute. Hot-melt adhesives can also be applied by dipping or spraying, and are popular with hobbyists and crafters both for affixing and as an inexpensive alternative to resin casting.

<span class="mw-page-title-main">Polyester</span> Category of polymers, in which the monomers are joined together by ester links

Polyester is a category of polymers that contain the ester functional group in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include naturally occurring chemicals, such as in plants and insects, as well as synthetics such as polybutyrate. Natural polyesters and a few synthetic ones are biodegradable, but most synthetic polyesters are not. Synthetic polyesters are used extensively in clothing.

<span class="mw-page-title-main">Biodegradable plastic</span> Plastics that can be decomposed by the action of living organisms

Biodegradable plastics are plastics that can be decomposed by the action of living organisms, usually microbes, into water, carbon dioxide, and biomass. Biodegradable plastics are commonly produced with renewable raw materials, micro-organisms, petrochemicals, or combinations of all three.

Biodegradable polymers are a special class of polymer that breaks down after its intended purpose by bacterial decomposition process to result in natural byproducts such as gases (CO2, N2), water, biomass, and inorganic salts. These polymers are found both naturally and synthetically made, and largely consist of ester, amide, and ether functional groups. Their properties and breakdown mechanism are determined by their exact structure. These polymers are often synthesized by condensation reactions, ring opening polymerization, and metal catalysts. There are vast examples and applications of biodegradable polymers.

<span class="mw-page-title-main">Cyclohexanedimethanol</span> Chemical compound

Cyclohexanedimethanol (CHDM) is a mixture of isomeric organic compounds with formula C6H10(CH2OH)2. It is a colorless low-melting solid used in the production of polyester resins. Commercial samples consist of a mixture of cis and trans isomers. It is a di-substituted derivative of cyclohexane and is classified as a diol, meaning that it has two OH functional groups. Commercial CHDM typically has a cis/trans ratio of 30:70.

<span class="mw-page-title-main">PHBV</span> Chemical compound

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate), commonly known as PHBV, is a polyhydroxyalkanoate-type polymer. It is biodegradable, nontoxic, biocompatible plastic produced naturally by bacteria and a good alternative for many non-biodegradable synthetic polymers. It is a thermoplastic linear aliphatic polyester. It is obtained by the copolymerization of 3-hydroxybutanoic acid and 3-hydroxypentanoic acid. PHBV is used in speciality packaging, orthopedic devices and in controlled release of drugs. PHBV undergoes bacterial degradation in the environment.

Biodegradable additives are additives that enhance the biodegradation of polymers by allowing microorganisms to utilize the carbon within the polymer chain as a source of energy. Biodegradable additives attract microorganisms to the polymer through quorum sensing after biofilm creation on the plastic product. Additives are generally in masterbatch formation that use carrier resins such as polyethylene (PE), polypropylene (PP), polystyrene (PS) or polyethylene terephthalate (PET).

<span class="mw-page-title-main">Polybutylene succinate</span> Biodegradable polymer

Polybutylene succinate (PBS) is a thermoplastic polymer resin of the polyester family. PBS is a biodegradable aliphatic polyester with properties that are comparable to polypropylene.

Poly(ethylene adipate) or PEA is an aliphatic polyester. It is most commonly synthesized from a polycondensation reaction between ethylene glycol and adipic acid. PEA has been studied as it is biodegradable through a variety of mechanisms and also fairly inexpensive compared to other polymers. Its lower molecular weight compared to many polymers aids in its biodegradability.

<span class="mw-page-title-main">Biodegradable athletic footwear</span>

Biodegradable athletic footwear is athletic footwear that uses biodegradable materials with the ability to compost at the end-of-life phase. Such materials include natural biodegradable polymers, synthetic biodegradable polymers, and biodegradable blends. The use of biodegradable materials is a long-term solution to landfill pollution that can significantly help protect the natural environment by replacing the synthetic, non-biodegradable polymers found in athletic footwear.

<span class="mw-page-title-main">Edible packaging</span> Food containers which can be eaten

Edible packaging refers to packaging which is edible and biodegradable.

The methods for sequence analysis of synthetic polymers differ from the sequence analysis of biopolymers. Synthetic polymers are produced by chain-growth or step-growth polymerization and show thereby polydispersity, whereas biopolymers are synthesized by complex template-based mechanisms and are sequence-defined and monodisperse. Synthetic polymers are a mixture of macromolecules of different length and sequence and are analysed via statistical measures.

References

  1. ↑ Jacqueline Stagner (Nov 2015). "Methane generation from anaerobic digestion of biodegradable plastics – a review". International Journal of Environmental Studies. 73 (3): 462–468. doi:10.1080/00207233.2015.1108607. S2CID   101024423.
  2. ↑ Jaime Francisco Gómez-Gómez; et al. (2016). "Scrap denim-PP composites as a material for new product design". Libro de Actas - Systems & Design: Beyond Processes and Thinking (IFDP - SD2016). doi: 10.4995/IFDP.2016.3360 . ISBN   978-84-9048-440-1.{{cite book}}: |journal= ignored (help)
  3. 1 2 "Certified Compostable and Biodegradable Co-Polyester - ecoflex" . Retrieved 2017-02-09.
  4. ↑ "What is the Life Cycle of a Plastic Bottle?". Wise Geek. Retrieved February 13, 2014.
  5. 1 2 3 4 Shahlari, Mahin (November 2008). "Biodegradable Polymer/Clay Nanocomposites based on Poly(Butylene Adipate-Co-Terephthalate) and Poly(Lactic Acid)". Proceedings of the 2008 AIChE Annual Meeting. American Institute of Chemical Engineers. hdl: 10355/32635 .
  6. ↑ Jiang, Long; Wolcott, Zhang (26 October 2005). "Study of Biodegradable Polylactide/Poly(butylene adipate-co-terephthalate) Blends". Biomacromolecules. 7 (1): 199–207. doi:10.1021/bm050581q. PMID   16398516.
  7. ↑ Kliem, S.; Kreutzbruck, M.; Bonten, C. (2020). "Review on the Biological Degradation of Polymers in Various Environments". Materials (Basel, Switzerland). 13 (20): 4586. Bibcode:2020Mate...13.4586K. doi: 10.3390/ma13204586 . PMC   7602512 . PMID   33076314.
  8. ↑ Peng, Zhao; Liu, Wanqiang; Wu, Qingsheng; Ren, Jie (27 November 2009). "Preparation, Mechanical, and Thermal Properties of Biodegradable Polyesters/Poly(Lactic Acid) Blends". Nanomaterials. 2010 (2010): 8. Retrieved February 10, 2014.
  9. ↑ "Certified Compostable, Biodegradable and Biobased Polymer - ecovio" . Retrieved 2017-02-09.
  10. ↑ "Novamont launches 4th Gen bioplastic" . Retrieved 14 February 2014.
  11. ↑ "EASTAR BIO Copolyester Certified by Biodegradable Products" . Retrieved 14 February 2014.
  12. ↑ "Seen High Bioplast Limited" . Retrieved 14 March 2014.
  13. ↑ "RUIchem" . Retrieved 14 March 2014.
  14. ↑ "Torise Biomaterials Co., Ltd" . Retrieved 14 March 2014.
  15. ↑ "Green Chemical Co., Ltd" . Retrieved 14 March 2014.
  16. ↑ "WILLEAP" . Retrieved 14 March 2014.
  17. ↑ "Certified – The compostability of ecoflex" . Retrieved 2017-02-09.
  18. ↑ "Paper coatings - ecovio PS1606" . Retrieved 2017-02-09.
  19. ↑ Luis Bastarrachea; Sumeet Dhawan; Shyam S. Sablani; Jae-Hyun Mah; Dong-Hyun Kang; Jinwen Zhang; Juming Tang (2010). "Biodegradable Poly(butylene adipate-co-terephthalate) Films Incorporated with Nisin: Characterization and Effectiveness against Listeria innocua" (PDF). Journal of Food Science. 75 (4): E215–E224. doi:10.1111/j.1750-3841.2010.01591.x. PMID   20546402 . Retrieved 14 February 2014.
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