Multiphased polyhydroxyalkanoate-based compositions and articles made therefrom
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Solution Overview
Problem
Polyhydroxyalkanoates (PHAs) face challenges in achieving improved durability, toughness, and impact strength without compromising their inherent stiffness, strength, biodegradability, and nutritional value.
Innovation Solution
A novel composition comprising a blend of poly (3-hydroxybutyrate) homopolymer (PHB) as the continuous phase and amorphous polyhydroxyalkanoate (aPHA) as the discrete phase, with a glass transition temperature below 20°C and a melting temperature between 80°C to 180°C, is developed. This blend is processed with a peroxide and a co-agent to enhance toughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If copolymers with low levels of valerate are used to overcome brittleness, then toughness is improved, but melting point decreases narrowing the utilization temperature range
Solution Approach 1:
The invention divides the polymer system into two distinct phases: a continuous crystalline PHB phase and a discrete amorphous aPHA phase. This segmentation allows each phase to contribute its advantageous properties independently, resolving the contradiction between toughness and melting point by spatial separation of functions
Solution Approach 2:
The invention creates a composite material system combining PHB and aPHA in a multiphased blend. The composite structure enables the crystalline PHB to maintain high melting point and stiffness while the amorphous aPHA phase provides toughness, achieving both properties simultaneously through material composition
2Strength
If high modulus fillers like clay are incorporated to regain strength and stiffness, then strength is improved, but biodegradability and nutritional value are compromised
Solution Approach 1:
The invention changes the compositional parameters by using purely biodegradable PHA polymers with controlled molecular weights and structures. The crystalline PHB and amorphous aPHA phases are both biodegradable, eliminating the need for non-biodegradable fillers while maintaining strength through the multiphased blend structure
Solution Approach 2:
The invention creates a composite of two biodegradable PHA phases that work synergistically: the crystalline PHB provides strength and stiffness, while the amorphous aPHA provides toughness. Both components are biodegradable, so the composite maintains biodegradability while achieving enhanced mechanical properties
Data Source
AI summary
The present specification generally relates to a composition for the manufacture of bio-degradable, bio-compostable, ocean degradable, biocompatible articles that contain a bio-based thermoplastic component. In particular, it has been found, in accordance with the practice of this invention, that marked improvement in tensile strength, toughness and elongation of polyhydroxyalkanoate (PHA) can be achieved by dispersing in the PHA an amorphous PHA and then optionally coupling the dispersed amorphous PHA. The polyhydroxyalkanoate/amorphous polyhydroxyalkanoate blends of the present invention comprise from 70-97.5 percent by weight of the PHA, from 2.5-30 percent by weight of the amorphous PHA can be used to produce a wide array of articles.