Aliphatic Polyester Foamed Sheet Fine Cell Structure
Solution Overview
Problem
Existing foamed sheets made from polylactic acid suffer from poor strength and flexibility due to large and uneven foam diameters, making them unsuitable for industrial-scale production and replacement of non-degradable plastics.
Innovation Solution
A foamed sheet composed of an aliphatic polyester resin and a filler, with an average foam diameter of 15 micrometers or less and a thickness of 3,000 micrometers or less, where the filler is highly dispersed to achieve fine and uniform foams, enabling mass production and improved physical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If large foam diameters are used to reduce the amount of polylactic acid, then productivity is improved, but strength and flexibility degrade, causing cracking
Solution Approach 1:
The foam structure is segmented into fine, uniform cells with diameters of 15 micrometers or less, creating a dense network of small cells rather than large cells. This segmentation maintains material efficiency while preserving structural integrity and preventing cracking, as the fine cell structure distributes stress more evenly throughout the material.
Solution Approach 2:
The foam diameter parameter is changed from conventional large sizes to 15 micrometers or less, fundamentally altering the foam architecture. This parameter change enables the material to achieve both reduced polylactic acid content and maintained strength, as the fine cell structure provides better mechanical properties while using less material.
2Strength
If foam diameter is reduced to improve strength, then strength is improved, but manufacturing complexity increases due to difficulty in achieving fine and uniform foams
Solution Approach 1:
A specific blowing agent is introduced as an intermediary substance to control foam formation. This blowing agent enables the generation of fine, uniform foam cells with diameters of 15 micrometers or less by controlling nucleation and growth processes, thereby achieving the desired fine cell structure without requiring excessively complex manufacturing equipment or processes.
Solution Approach 2:
Manufacturing parameters such as temperature, pressure, and blowing agent concentration are optimized to enable fine foam formation. By changing these parameters within specific ranges, the process achieves uniform 15-micrometer or smaller foam cells through controlled chemical reactions, simplifying the manufacturing approach while maintaining strength.
3Object-affected harmful factors
If polylactic acid is used to replace non-degradable plastics, then environmental compatibility is improved, but physical properties similar to polystyrene are not easily achieved
Solution Approach 1:
The polylactic acid is transformed into a foamed sheet with a controlled porous structure consisting of fine, uniform cells. This porous structure reduces the density and amount of polylactic acid required while maintaining adequate mechanical properties through the cellular architecture, thereby achieving both biodegradability and acceptable physical properties for replacing non-degradable plastics.
Solution Approach 2:
The foamed sheet creates a composite structure within the polylactic acid matrix, combining solid polymer regions with air-filled cellular spaces. This composite architecture reduces material usage while maintaining strength-to-weight ratio, enabling biodegradable polylactic acid to achieve physical properties comparable to conventional non-degradable plastics like polystyrene.
Data Source
Figure 1~2
Figure 3~4
AI summary
A foamed sheet includes an aliphatic polyester resin and a filler. An average foam diameter of the foamed sheet is 15 micrometers or less. An average thickness of the foamed sheet is 3,000 micrometers or less. A ratio of a length of a side of the foamed sheet in a longer direction or a side of the foamed sheet in a direction perpendicular to the longer direction to the average thickness is 250 or more.