Polyhydroxyvaleric acid

Structural formula
General
Surname	Polyhydroxyvaleric acid
other names	Polyhydroxyvalerate; Poly (3-hydroxyvalerate); Poly ( R ) -3-hydroxyvalerate; Poly (3HV); P (3HV); PHV; Polyhydroxy pentanoate; Poly [oxy (1-ethyl-3-oxopropane-1,3-diyl)];
CAS number	83120-66-5
Monomer	3-hydroxyvaleric acid
Molecular formula of the repeating unit	C 5 H 8 O 2
Molar mass of the repeating unit	100.116 g mol −1
Type of polymer	Biopolymer
properties
Physical state	firmly
Melting point	approx. 119 ° C
Glass temperature	−10 to −12 ° C
safety instructions
GHS labeling of hazardous substances	no classification available
	no classification available
H and P phrases	H: see above
	P: see above
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Poly (3-hydroxyvaleric acid) , abbreviation PHV, also called polyhydroxyvalerate, is a biopolymer from the group of polyhydroxyalkanoates . Besides poly (3-hydroxybutyric acid) (PHB), PHV is the best known representative of this group. PHV is a polyester that can be produced by fermentation from renewable raw materials with 3-hydroxyvaleric acid as a formal monomer . There is a stereocenter at the β carbon atom of the monomer, so the monomer is chiral . A biogenic production method produces the enantiomer with ( R ) configuration .

However, the copolymer poly (3-hydroxybutanoic acid- co -3-hydroxyvaleric acid) (PHBV, also P3HB-3HV, CAS number: 80181-31-3) is produced more frequently, as it has better thermoplastic properties.

Biogenic production

In fermentative production, the polyhydroxyalkonates are created by bacteria as intercellular energy and carbon stores inside the cell when there is a nutrient deficiency (typically limited amounts of N, P, S, O or Mg), but there is excess carbon. They can be mobilized by the bacteria as a reserve should a carbon deficiency situation arise later.

The bacterium Chromobacterium violaceum DSM 30191 accumulates 100% of the homopolymer of 3-hydroxyvaleric acid in the feed batch culture if valeric acid is fed in as the sole carbon source under nitrogen limitation. 65% of the cellular dry matter is poly (3-hydroxyvaleric acid). However, if fructose, glucanate, propionate or hexanonate are present as carbon sources, the bacterium accumulates the homopolymer of 3-hydroxybutanoic acid .

Poly (3-hydroxyvaleric acid) was also accumulated by two other different strains of Chromobacterium violaceum . Another strain of Chromobacterium violaceum together with three strains of Janthinobacterium lividum , on the other hand, accumulate the copolymer poly (3-hydroxybutanoic acid- co -3-hydroxyvaleric acid) from valeric acid.

The dynamic difference calorimetry showed a glass transition temperature between −10 and −12 ° C and a melting point between 107 and 112 ° C, with a heat of fusion = 19 kcal / kg for the pure PHV. The biosynthetic poly (3-hydroxyvaleric acid) has an approximate molar mass between 60,000 and 145,000 g / mol.

Poly (3-hydroxybutanoic acid- co -3-hydroxyvaleric acid), which consists of up to 95 mol% of 3-hydroxyvaleric acid units, was caused by the bacterium Pseudomonas sp. HJ-2 synthesized under limiting conditions when only valeric acid is added as a carbon source. The bacterium Ralstonia eutropha accumulates a copolymer with up to 90 mol% 3-hydroxyvaleric acid units if pure valeric acid is also used here.

PHB-PHV copolymer

PHB can only be used to a limited extent because it is brittle. Polyhydroxybutyrate-polyhydroxyvalerate copolymers (PHBV) have better application properties because the crystallinity is lower due to the longer side chains. A parallel arrangement of the main polymer chains is made more difficult. In the case of PHBV copolymers with up to 25% hydroxyvalerate content , the melting point decreases with increasing 3HV content from 176 to 127 ° C, so that the risk of degradation during processing decreases and the processing window is enlarged. With a higher 3HV proportion, it rises again linearly to 119 ° C.

The glass transition temperature Tg decreases with increasing 3HV content by up to 25% to −6 ° C, so that the material does not become brittle even at lower temperatures. The stiffness decreases, flexibility and toughness increase. Overall, the properties become more similar to the polyolefin polypropylene . For properties and applications of PHB-PHV copolymers with different proportions of PHV, see the main article polyhydroxybutyric acid .

Individual evidence

↑ ^a ^b ^c Gennady Efremovich Zaikov; Cornelia Vasile: Environmentally Degradable Materials Based on Multicomponent Polymeric Systems . Verlag Brill Leiden Bosten, 2009, ISBN 978-90-04-16410-9 , Chapter 6.5.2 Degradable Copolymers PHA Figure 6.2 ( google.de ).
^ ^A ^b Robert H. Marchessault1, Ga-er Yu: Crystallization and Material Properties of Polyhydroxyalkanoates
↑ ^a ^b ^c Alexander Steinbüchel; El Mehdi Debzi; Robert H Marchessault; Arnulf Timm: Synthesis and production of poly (3-hydroxyvaleric acid) homopolyester by Chromobacterium violaceum . Ed .: Applied Microbiology and Biotechnology. tape 39 , no. 4 , 1993, p. 443-449 , doi : 10.1007 / BF00205030 .
↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
↑ ^a ^b Oliver Türk: Material use of renewable raw materials, basics - materials - applications . Springer, 2014, ISBN 978-3-8348-1763-1 , chapter 5.1 polyhydroxyalkonates, doi : 10.1007 / 978-3-8348-2199-7 .
↑ Wolfgang Babel; Alexander Steinbüchel: Advances in Biochemical Engineering / Biotechnology . Springer Berlin Heidelberg New York, 2001, ISBN 3-540-41141-0 , Polyesters from Microorganisms page 57 ( google.de ).

Web links

Ralf Wilhelm Oberhoff: Modification and processing of poly (3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (PHBV) with spherical microparticles Technical University of Dresden 2005.
Srikanth Pilla: Handbook of Bioplastics and Biocomposites Engineering Applications . Wiley, 2011, ISBN 978-0-470-62607-8 , 14 Biobased and Biodegradable PHBV-Based Polymer Blends and Biocomposites: Properties and Applications, doi : 10.1002 / 9781118203699.ch14 ( google.de ).
Ray Smith: Biodegradable polymers for industrial applications . Woodhead Publishing Limited, 2005, ISBN 0-8493-3466-7 , Chapter 2 Polyhydroxyalkanoates from page 32 ( google.de ).
Kumar Sudesh: Polyhydroxyalkanoates from Palm Oil: Biodegradable Plastics . Springer Heidelberg New York Dordrecht London, 2013, ISBN 978-3-642-33538-9 , doi : 10.1007 / 978-3-642-33539-6 ( google.de ).
Volova Tatiana Grigor'evna: Polyhydroxyalkonates, Plastic Material of the 21st Century: production, properties, application . Nova Science New York, 2004, ISBN 1-59033-992-4 ( google.de ).

[Degradable-1] Gennady Efremovich Zaikov; Cornelia Vasile: Environmentally Degradable Materials Based on Multicomponent Polymeric Systems . Verlag Brill Leiden Bosten, 2009, ISBN 978-90-04-16410-9 , Chapter 6.5.2 Degradable Copolymers PHA Figure 6.2 ( google.de ).

[Crystallization-2] A ^b Robert H. Marchessault1, Ga-er Yu: Crystallization and Material Properties of Polyhydroxyalkanoates

[Steinbüchel-3] Alexander Steinbüchel; El Mehdi Debzi; Robert H Marchessault; Arnulf Timm: Synthesis and production of poly (3-hydroxyvaleric acid) homopolyester by Chromobacterium violaceum . Ed .: Applied Microbiology and Biotechnology. tape 39 , no. 4 , 1993, p. 443-449 , doi : 10.1007 / BF00205030 .

[NV-4] This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.

[Türk-5] Oliver Türk: Material use of renewable raw materials, basics - materials - applications . Springer, 2014, ISBN 978-3-8348-1763-1 , chapter 5.1 polyhydroxyalkonates, doi : 10.1007 / 978-3-8348-2199-7 .

[Biopolyesters-6] Wolfgang Babel; Alexander Steinbüchel: Advances in Biochemical Engineering / Biotechnology . Springer Berlin Heidelberg New York, 2001, ISBN 3-540-41141-0 , Polyesters from Microorganisms page 57 ( google.de ).