High-Amylopectin Starch Superabsorbents via Extrusion
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Solution Overview
Problem
Current superabsorbent materials, such as polyacrylates and polyaspartates, are not biodegradable, hypoallergenic, or cost-effective, and polysaccharide-based materials face challenges in absorption performance and production costs due to the use of non-renewable sources and organic solvents.
Innovation Solution
A starch-based absorbent or superabsorbent material with at least 90% amylopectin content, either self-entangled or cross-linked, is produced through an extrusion process, utilizing high amylopectin content starches and specific cross-linking agents like sodium trimetaphosphate, and processed to achieve high centrifuge retention capacity and free swell capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyacrylates are used as superabsorbent materials, then absorption performance is improved, but biodegradability and hypoallergenic properties deteriorate
Solution Approach 1:
The invention changes the chemical composition parameters by using starch-based materials with controlled cross-linking degrees and molecular weights to achieve both high absorption performance and biodegradability. Specifically, cross-linking degrees of 5-50% and molecular weights of 10^5-10^8 are optimized to balance absorption capacity with environmental compatibility
Solution Approach 2:
The invention creates composite starch-based materials by combining native or modified starch with cross-linking agents such as borax, epichlorohydrin, or citric acid. This composite approach maintains the biodegradable nature of starch while introducing functional groups that enhance absorption performance to levels comparable with synthetic polyacrylates
2Object-affected harmful factors
If polysaccharide-based materials are used, then biodegradability is improved, but absorption performance and production cost deteriorate
Solution Approach 1:
The invention optimizes physical parameters including cross-linking degree (5-50%), molecular weight (10^5-10^8), and particle size (0.1-5 mm) to maximize absorption performance. These parameter adjustments enable starch-based materials to achieve CRC ≥ 10 g/g and FSC ≥ 15 g/g, matching or exceeding traditional polysaccharide materials
Solution Approach 2:
The invention applies local modification to starch molecules through selective cross-linking at specific regions and controlled gelatinization to create heterogeneous structures with enhanced absorption zones. This local quality enhancement allows biodegradable materials to achieve high absorption performance without requiring complete structural transformation
3Productivity
If traditional extrusion process is used, then production efficiency is improved, but material performance deteriorates
Solution Approach 1:
The invention performs preliminary starch modification and cross-linking before extrusion to ensure optimal material performance. By pre-establishing the molecular network structure and selecting appropriate cross-linking agents, the subsequent extrusion process maintains both high production efficiency and superior absorption performance without requiring complex post-processing
Solution Approach 2:
The invention optimizes extrusion parameters including temperature profile, screw speed, and moisture content to achieve the desired molecular network structure. These parameter adjustments enable the continuous extrusion process to produce materials with CRC ≥ 10 g/g and FSC ≥ 15 g/g while maintaining high productivity
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 resulting starch-based material exhibits improved absorption performance with CRC of at least 10 g/g and FSC of at least 13 g/g, is biodegradable, and cost-efficient, suitable for various applications including disposable products and agricultural uses.
Implementation Method 1
The use of extruders as continuous reactors for processes such as polymerization, polymer modification or compatibilization of polymer blends
Implementation Method 2
The molecular network of starch molecules can be composed of either self-entangled starch molecules, or cross-linked starch molecules
Implementation Method 3
The resulting starch-based material exhibits improved absorption performance with CRC of at least 10 g/g and FSC of at least 13 g/g
Implementation Method 4
Superabsorbent polymers are primarily used as absorbents for biological fluids, water and aqueous solutions
Data Source
AI summary
The present invention relates an absorbent material consisting of a molecular network of starch molecules, the starch molecules comprising an amylopectin content of at least 90% (w/w). The molecular network can either be comprised of self-entangled starches or cross-linked starches.