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Methods for Making Degradable Materials More Economical

IP.com Disclosure Number: IPCOM000238226D
Publication Date: 2014-Aug-11
Document File: 9 page(s) / 217K

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Abstract

This document provides a brief review of current methods for producing biodegradable polymers. Biodegradable particulate materials prepared from polylactic acid (PLA) have recently been applied in a number of applications in oil field services, including providing temporary, non-damaging fluid loss control or diverting additives for well completions. Current high costs of the PLA have become a major factor that constrains the operators from broadly utilizing this material in well completions, especially in horizontal-well, multistage hydraulic fracturing treatments. This document also provides methods for lowering the cost of making PLA materials so that they can be readily available at a more affordable cost for the operators.

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Methods for Making Degradable Materials More Economical

Abstract

This document provides a brief review of current methods for producing biodegradable polymers. Biodegradable particulate materials prepared from polylactic acid (PLA) have recently been applied in a number of applications in oil field services, including providing temporary, non-damaging fluid loss control or diverting additives for well completions. Current high costs of the PLA have become a major factor that constrains the operators from broadly utilizing this material in well completions, especially in horizontal-well, multistage hydraulic fracturing treatments. This document also provides methods for lowering the cost of making PLA materials so that they can be readily available at a more affordable cost for the operators.

Introduction

Biodegradable plastics and polymers were first introduced in 1980s. They have been used in packaging, agriculture, medicine and other areas. Two classes of biodegradable polymers can be distinguished: synthetic or natural polymers. Synthetic polymers are produced from non-renewable petroleum resources, while natural polymers are derived from natural, renewable sources.

Nearly all existing polymers, including the high volume materials, polyethylene terephthalate, polystyrene, polypropylene, polyethylene, and polyvinyl chloride (PVC), are derived from petrochemical feedstocks. Polysaccharides, as starch and cellulose, represent the most characteristic family of the natural polymers. The principal polysaccharides used in materials applications are cellulose and starch.

Starch is a low cost polysaccharide, abundantly available and one of the cheapest biodegradable polymers. Starch is mainly extracted from potatoes, corn, wheat and rice. It is composed of amylose (poly-α-1,4-D-glucopyranoside), a linear and crystalline polymer and amylopectine (poly-α-1,4-D-glucopyranoside and α-1,6-D-glucopyranoside), a branched and amorphous polymer. The relative amounts and molar masses of amylose and amylopectine vary with the starch source, yielding materials of different mechanical properties and biodegradability [1,2].

Cellulose is another widely known polysaccharide produced by plants. It is a linear polymer with very long macromolecular chains of one repeating unit, cellobiose. Cellulose is crystalline, infusible and insoluble in all organic solvents [3]. Biodegradation of cellulose proceeds by enzymatic oxidation, with peroxidase secreted by fungi. Cellulose can also be degraded by bacteria [4].

Biopolymers such as PLA are made of renewable feedstocks, usually starch or sugar, although cellulose is anticipated to be used in the future. The fermentation of sugars produces monomers, which are converted to polymers [5,6]. PLA was first manufactured by Cargill Dow Polymers [7]. PLA is synthesized from lactic acid produced via starch


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fermentation from lactic bacteria. Starch is converted into sugar which is then fermented to

give...