Polyvinyl biodegradation

Lactic acid and levulinic acid are two key intermediates prepared from carbohydrates [7]. Lipinsky [7] compared the properties of the lactide copolymers [130] obtained from lactic acid with those of polystyrene and polyvinyl chloride (see Scheme 4 and Table 5) and showed that the lactide polymer can effectively replace the synthetics if the cost of production of lactic acid is made viable. Poly(lactic acid) and poly(l-lactide) have been shown to be good candidates for biodegradeable biomaterials. Tsuji [131] and Kaspercejk [132] have recently reported studies concerning their microstructure and morphology. 

Compared with tar, which has a relatively short lifetime in the marine environment, the residence times of plastic, glass and non-corrodible metallic debris are indefinite. Most plastic articles are fabricated from polyethylene, polystyrene or polyvinyl chloride. With molecular weights ranging to over 500,000, the only chemical reactivity of these polymers is derived from any residual unsaturation and, therefore, they are essentially inert chemically and photochemically. Further, since indigenous microflora lack the enzyme systems necessary to degrade most of these polymers, articles manufactured from them are highly resistant or virtually immune to biodegradation. That is, the properties that render plastics so durable... 

L Chen, SH Imam, SH Gordon, RV Greene. Starch polyvinyl alcohol crosslinked film—Performance and biodegradation. J Environ Polym Degradation 5 111-117, 1997. 

Polyvinyl alcohol is unique in being the only biodegradable carbon-carbon backbone polymer.(35,36) The degradation is oxidative, followed by hydrolytic cleavage, Suzuki claims acids and ketones as metabolites, and Watanabe acids and alcohols. This difference is shown below, schematically. 

Biodegradation of Polyvinyl-Type Poly(sodium carboxylate). PVA is the only substance which is known to be biodegradable in the class of polyvinyl-type synthetic polymer. It may be biodegraded by oxidizing hydroxyl group of PVA to the corresponding carbonyl group and subsequent hydrolysis as shown below (17, 18). 

As a design to develop a polyvinyl-type poly(sodium carboxylate), acrylate copolymers containing hydroxyl or carbonyl groups which are susceptible to the enzymatic reaction, were prepared. It is presumed that the copolymer is first cleaved at a hydroxyl or carbonyl group as in the case of PVA, then the resultant acrylate oligomer is further assimilated by the microbes. The biodegradation of oligomeric acrylic acid (11), in fact, occurs as shown in Table I. 

From dimeric to oligomeric sodium acrylate having a molecular weight of 500 was easily biodegraded. However, it seems that the specific microbes utilizing this polyvinyl-type copolymers as a sole carbon source are relatively scarce in the environment, and the biodegradability of these types of copolymers differ according to... 

Chiellini E, Corti A, Politi B, Solaro R (2000) Adsorption/desorption of polyvinyl alcohol on solid substrates and relevant biodegradation. J Polym Environ 8 67-79... 

Russo M, O Sullivan C et al (2009) The anaerobic degradability of thermoplastic starch Polyvinyl alcohol blends Potential biodegradable food packaging materials. Bioresour Technol 100 1705-1710... 

Chen J, Zhang Y et al (2007) Biodegradation of polyvinyl alcohol by a mixed microbial culture. Enzyme Microb Technol 40 1686-1691... 

Huang MH, Shih YP, Liu SM (2002) Biodegradation of polyvinyl alcohol by Phanerochaete chrysosporium after pretreatment with Eenton s reagent. J Environ Sci Health A Tox Hazard Subst Environ Eng 37 29 1... 

E Matsumura S, Kurita H, Shimokobe H (1993) Anaerobic biodegradability of polyvinyl alcohol. Biotechnoi Lett 15 749-754... 

Vinyl chloride (VC) is the monomer from which the common polymer, polyvinyl chloride, is produced. Hence, VC is produced on a very large scale. Not surprisingly, occasional releases of the rather toxic VC to the environment occur. What initial biodegradation product would you expect from VC if it were released into an oxic environment ... 

There is also US research interest in using pectin in polymer applications. Pectin is a complex plant cell wall heteropolysaccharide (based on galactose, rhamnose, arabinose and xylose) that can be blended with synthetic polyvinyl alcohol (PVA) to produce biodegradable polymers with a wider range of properties than those of starch-based polymers alone. The new pectin/PVA biodegradable polymer should be capable of replacing conventional PVA applications in blow-moulded, extruded, film and injection-moulded applications. 

The effect of NaOH on drug release was examined with microspheres prepared with thioridazine and two biodegradable polymers. The wall-forming polymers were poly(DL-lactide) and poly(L-lactide). Sodium oleate was used as the emulsifier, with the exception of one set of experiments where the emulsions were stabilized with polyvinyl alcohol. 

INFLUENCE OF BIODEGRADATION ON THE LOSS OF A PLASTICISER FROM POLYVINYL CHLORIDE... 

Polyvinyl alcohol is a vinyl polymer with a carbon-carbon backbone similar to other polymers such as polyethylene and polystyrene and is widely used as a water-soluble biodegradable polymer in the manufacture of delivery systems for fertilizers, pesticides and herbicides and is also used to manufacture containers and films. To date, only bacteria have been described as causing biodegradation of polyvinyl alcohols with some causing complete degradation of the polymer (see Shimao, 2001 for review). 

Sabev, H. A. (2004). Fungal biodeterioration and biodegradation of plasticised polyvinyl chloride in soil. Unpublished Ph.D. thesis. University of Manchester. 

United States alone, 5 x 109 kg of plastic resins (typically used in packaging and transportation) are produced every year. Disposable goods and packing material represent about one-third of the total plastic production and have the largest environmental impact. More than 90% of the plastic material in municipal waste consists of polyethylene, polyvinyl chloride, and polystyrene, which are all resistant to biodegradation (see Table 9.1). 

SULFANOLE 334 surfactant is a nonionic biodegradable penetrant and detergent which does not rewet after drying. It may be used in acid or alkaline mediums with minimal effect on its wetting or detergent properties. It is very effective in the removal and suspension of waxes and polyvinyl alcohols during preparation. 

Several other biodegradable, biocompatible, injectable polymers are being investigated for drug delivery systems. They include polyvinyl alcohol, block copolymer of PLA-PEG, polycyanoacrylate, polyanhydrides, cellulose, alginate, collagen, gelatin, albumin, starches, dextrans, hyaluronic acid and its derivatives, and hydroxyapatite. ... 

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