Bio-based polyesters

Thtiner, S., Brenner, G., Diehl, C., 2011. Bio-based polyester polyols for reactive PUR hot melts. Adhes. Adhes. Sealants 4,18-21. 

In addition to bio-based polyesters such as poly(lactic acid) (PLA), polyhydroxyalkanoates (PHAs), and poly(ethylene furanoate) (PEE), all based upon biomass-derived building blocks that have a structure different from today s commercial petrochemical-based polyesters, biobased polyesters can be developed having an identical structure to well-known petrochemical based polyesters. A very important class of such drop-in type bio-based polyesters are represented by polyesters based upon either isophthalic acid or terephthalic acid, such as PET,... 

Bio-based polyesters composed of 1,3-propanediol, sebacic acid, and itaconic acid in various ratios showed excellent SM properties after cross-linking with peroxide. could be tuned by the composition between 12 and 54"C [46]. 

A fully bio-based polyester beverage bottle was subsequently developed (lab scale) by PepsiCo. Coca-Cola is also pursuing a 1(X)% bio-based bottle. TPA can also be derived from bio-derived intermediates such as bio-xylene or from bio-derived 5-hydroxymethylfurfural or furandicarboxylic acid [EDCA] from fructose via alk-oxymethyl fufural. Efforts to synthesize bio-TPA via the muconic acid route without going via p-xylene are also under development. ... 

The bio-based polyester polyol used in this study was kindly supplied by Croda (Yoikshire, UK) and it is based on dimmer fatty acids from rape-seed oil, with purity higher than 98% and weight average molar mass (M ) around 3000 g mol. Hydroxyl and acid values are 40 mg KOH g and 0.253 mg KOH g respectively, as given by the supplier. 4,4 -di-phenylmethane di-isocyanate (MDI) was supplied by Brenntag (Rosheim, France). 1,4-butanediol (BDO), dibutylamine, toluene and hydrochloric acid were purchased from Sigma Aldrich (Lyon, France). All reagents were used without any further purification step. 

The attractive price and commercial availability of lactic acid were important reasons why PLA became the first mass-produced bio-based polyester. The critical success factor for a final breakthrough of all green chemicals and plastics based on annually renewable materials is economic sustainability. Thus, the very basis of cost-competitive PLA is an industrial fermentative production process for lactic acid with efficient use of carbohydrates followed by excellent purification technology with minimum generation of by-products. 

A number of partially bio-based polyesters are also commercially available. Among the first introduced to the market in 2001 is poly(trimethylene terephatalate) (PTT) synthesized by DuPont under the trad aik Sorona . This polymer contains 37% renewable 1,3-propanediol made from glycerol produced from com sugar via fermentation. The propanediol is polycondensed with fossil-derived terephthaUc acid (TPA). Although PTT has a 7 of 45 C-55°C and a of 230 C, values that are... 

In contrast to specifying to suppliers what chemicals or materials are restricted, it is useful to specify exactly what chemicals and materials are desired. Once a material or chemical is well characterized, and it is considered benign with respect to human and environmental health, it can be added to a preferred or positive list (i.e., P-list). For example, a textile manufacturer may source certified organic cotton, or polyester made with antimony-free catalysts, to develop a product line based on these fibres. Or a cleaning product formulator may seek bio-based solvents or rapidly biodegradable surfactants consistent with their product development objectives. 

Different routes for converting biomass into chemicals are possible. Fermentation of starches or sugars yields ethanol, which can be converted into ethylene. Other chemicals that can be produced from ethanol are acetaldehyde and butadiene. Other fermentation routes yield acetone/butanol (e.g., in South Africa). Submerged aerobic fermentation leads to citric acid, gluconic acid and special polysaccharides, giving access to new biopolymers such as polyester from poly-lactic acid, or polyester with a bio-based polyol and fossil acid, e.g., biopolymers . 

Biodegradable plastics have been used on an industrial scale since the end of the 1990s when BASF launched Ecoflex . This is a fossil-based, man-made polyester but yet is completely biodegradable due to its chemical structure. This structure is also the reason why Ecoflex combines excellent mechanical properties with the good processability of synthetic thermoplastics. Ecoflex is the preferred blend partner for bio-based and biodegradable polymers, which typically do not exhibit good mechanics and processability for film applications by themselves. Ecoflex therefore is a synthetic polymer that enables the extensive use of renewable raw materials (e.g., starch). 

The condition that the biodegradable enabling polyester forms the coherent phase [12] limits the amount of starch and, with this, the amount of renewable resources of pure Ecoflex /starch blends that can be used for the finished film products (typically <50%). An increase in the content of renewable resources can only be achieved by applying (partly) bio-based enabling polyesters (see Sect. 4.1.2 for details of a special grade of Ecoflex - Ecoflex FS). 

At the same time, prices for the three major types of bio-based resins, starch-based biopolymers, polylactic acid (PLA) and aliphatic aromatic co-polyester, have dropped considerably over the last... 

Figure 1. Production and chemical recycling of potentially bio-based aliphatic polyesters via cyclic oligomers using lipase.

Various systems are available depending on the end use. Typical systems are based on saturated polyesters, a.tw-acid-terminated cured with an epoxy (triglycidyl isocyanurate TGIC), or a.ty-OH-terminated cured with an isocyanate (or a blocked isocyanate). Recently, bio-based formulations with aliphatic nonyellowing monomers have been proposed [15]. 

We can classify the different biodegradable and bio-based polymers into two major families agropolymers (categoiy a) and biodegradable polyesters (categories b and c). To illustrate the latter, the next section focuses on the description of biodegradable polyesters, from synthesis to application. 

Figure 9.4 illustrates the chemical stmctures of the different biodegradable polyesters. They can be classified into bio-based or non-renewable-resouree-based polymers. Table 9.1 hsts the main physico-chemical and mechanical properties of commercially used polyesters. 

Showa Highpolymer (Japan) developed a wide range of polybutylene succinate (PBS) by polycondensation of 1,4-butanediol and succinic acid. Polybutylene succinate-co-adipate (PBSA), shown in Figure 9.4, is obtained by the addition of adipic acid. These copolymers are commercialized under the brand name Bionolle (Showa Denko K.K.). Industrial production of these polyesters from bio-based succinic acid was launched in 2012 by Showa Denko. Mitsubishi Chemical (Japan) produces and also commercializes partially bio-based PBS. 

Aromatio and biodegradable eopolyesters are, for the most part, based on terephthalie aeid [AVE 12]. As with ahphatic copolyesters, aromatie polyesters are increasingly bio-based, notably with the future development of bio-based terephthalie acid production, alongside 100% bio-based PET projeets. 

The book addresses the most important biopolymer classes like polysaccharides, lignin, proteins and polyhydroxyalkanoates as raw materials for bio-based plastics, as well as materials derived from bio-based monomers like lipids, poly(lactic acid), polyesters, polyamides and polyolefines. Additional chapters on general topics - the market and availability of renewable raw materials, the importance of bio-based content and the issue of biodegradability - will provide important information related to all bio-based polymer classes. 

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