Biodegradable polyamides examples

Biodegradable polyamides have also been prepared from amino acids. For example, aspartic acid can be converted to polyaspartate, abbreviated as TPA (thermal polyaspartate). TRA is commonly used as an alternative to poly(acrylic acid), which is used to line the pumps and boilers of wastewater treatment facilities. 

Polyamides and polyesteramides are more recent arrivals to the commercial biodegradable polymer field. Copolymers of either glycine or serine with e-aminocaproic acid are biodegradable. For example, biodegradable polyaspartic acid was synthesized (95% yield) at low cost [Koskan, 1992]. A copolymer of butylene-adipate and e-caprolactam was recently introduced by Bayer as BAK 1095. The material has T = 125°C, density of 1070 kg/m, tensile modulus of 180 MPa, maximum strain at break of 400%, tensile stress at break of 25 MPa, and it fully degrades in 300 days under the ASTM standard conditions. 

Over 250,000 metric tons of microcrystaUine cellulose have been sold siace its commercialisation ia 1962 and demand continues to iacrease. Its utihty has led to development of other coUoidal polymer microcrystals (see Colloids). For example, polyamides and polyesters from recycled materials can be biodegraded to give microcrystals having a size of 30 nm (37). 

The ester class also comprises natural oils, such as vegetable oil [75] spent sunflower oil [940,941,992,993] and natural fats, for example, sulfonated flsh fat [161]. In water-based mud systems no harmful foams are formed from partially hydrolyzed glycerides of predominantly unsaturated Ci6 to C24 fatty acids. The partial glycerides can be used at low temperatures and are biodegradable and nontoxic [1280]. A composition for high-temperature applications is available [1818]. It is a mixture of long chain polyesters and polyamides. 

Polycondensation reactions in oriented monolayers and bilayers proceed without catalysis, and simply occur due to the high packing density of the reactive groups and their orientation in these layers. Bulk condensation of the a-amino acid esters at higher temperatures does not lead to polypeptides but to 2,5-diketopiperazines. No diketopiperazines are found in polycondensed monolayers or liposomes. Polycondensation in monolayers and liposomes leading to oriented polyamides represents a new route for stabilizing model membranes under mild conditions. In addition, polypeptide vesicles may be cleavable by enzymes in the blood vessels. In this case, they would represent the first example of stable but biodegradable polymeric liposomes. 

Bio does not necessarily have to denote low quality or inferior let alone biodegradable. As mentioned in section 10.2.1, polyamides are true high performance polymers, yet seeing that only 5% of the current biopolymer market is served by PA-types it may take a while to modify the public perception and association. In this respect, the title of this chapter has been well chosen. Furthermore, several of the main bio-based polyamide producers have opted to use the trade names originally deemed for their main petro-based polyamides to uphold the notion of high performance, for example Arkema with Rilsan or Evonik with Vestamid (see Table 10.2). 

Poly(glutamic acid), poly (u-ly sine), poly(aspartamides), and poly((W-hydroxyethyl)-L-glutamine) (PHEG) are examples of poly(amino acids) [13]. An analog polymer is poly(malic acid) that exhibits an ester linkage instead of a polyamide backbone. This is biodegradable in analogy to natural polypeptides. Other natural polymers are normally polysaccharides like dextran or chitosan. 

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