Aqueous PHA Suspension Stabilization via Hydrogen Peroxide
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Solution Overview
Problem
Existing methods for producing aqueous polyhydroxyalkanoate (PHA) suspensions face challenges with odor and mold growth over time, especially at high temperatures, and undergo significant molecular weight decrease during heating and drying processes.
Innovation Solution
Adding hydrogen peroxide to an aqueous PHA suspension with a pH of 5 or less effectively reduces odor and mold growth and minimizes the decrease in molecular weight of PHA during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the aqueous PHA suspension is stored for a long time or at high temperature, then the PHA can be used for coating applications, but odor and mold growth occur due to bacterial proliferation
Solution Approach 1:
The patent applies preliminary action by adjusting the pH to 5 or less and adding hydrogen peroxide before storage to prevent bacterial proliferation. This preventive measure is taken in advance to eliminate the cause of odor and mold growth, allowing the suspension to be stored for extended periods without degradation.
Solution Approach 2:
The patent changes the pH parameter to 5 or less and introduces hydrogen peroxide concentration as a new parameter (0.01-1 wt%) to control bacterial growth. These parameter changes transform the suspension from being susceptible to bacterial proliferation to being stable during storage.
2Loss of time
If heating and drying treatment is applied to the aqueous PHA suspension, then the coating can be dried on the substrate, but the molecular weight of the PHA decreases
Solution Approach 1:
The patent applies preliminary action by adjusting the pH to 5 or less before heating and drying treatment. This pre-adjustment prevents excessive molecular weight degradation during the subsequent thermal processing, allowing the coating to be dried while maintaining PHA molecular weight.
3Reliability
If conventional purification methods (ozone or hydrogen peroxide treatment at high pH) are applied to the PHA, then the PHA can be deodorized and decolorized, but the resulting aqueous suspension still develops odor and mold over time
Solution Approach 1:
The patent changes the pH parameter from conventional high pH (7-13) to acidic pH (5 or less) and introduces hydrogen peroxide concentration control (0.01-1 wt%). This parameter change creates a stable environment that prevents bacterial growth while maintaining purification effects, solving the storage stability problem.
Solution Approach 2:
The patent uses hydrogen peroxide as an intermediary substance that serves dual functions: maintaining purification effects and preventing bacterial proliferation through its antimicrobial properties at low concentrations. This intermediary approach allows the suspension to remain stable during storage.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method results in an aqueous PHA suspension with improved storage stability, reduced bacterial count, minimal odor, and minimal molecular weight loss when heated, enabling the production of high-quality PHA-based laminates.
Implementation Method 1
adding hydrogen peroxide to an aqueous suspension containing a polyhydroxyalkanoate and having a pH of 5 or less
Implementation Method 2
the aqueous polyhydroxyalkanoate suspension contains 0.05 to 1.5 wt % hydrogen peroxide based on a weight of solids including the polyhydroxyalkanoate
Data Source
AI summary
Provided is a method for producing an aqueous polyhydroxyalkanoate suspension, the method including the step of adding hydrogen peroxide to an aqueous suspension containing a polyhydroxyalkanoate and having a pH of 5 or less. Preferably, the amount of the hydrogen peroxide added is from 0.1 to 1 wt % based on the weight of solids including the polyhydroxyalkanoate. Preferably, the bacterial count in the aqueous suspension containing the hydrogen peroxide added is 4×102/ml or less. Preferably, the concentration of solids including the polyhydroxyalkanoate in the aqueous suspension is from 20 to 60 wt %.