Not only does Sunstrand supply biomaterials, but we can also provide mechanical processing services on a toll basis. Provide your own feedstock or use one of ours. The Sunstrand team will work with you to deliver a product that meets your specifications.
Sunstrand’s proprietary fiber extraction, functionalization and manufacturing processes are compatible with many natural feedstocks. We can offer custom blending with multiple natural fibers, glass or even carbon fibers. Depending on your needs, we can custom-engineer a blend to your specifications.
Bast fiber plant stems are made up of two constituents, a woody core called hurd, core, or shive, and the fiber. Both of these materials can be used in a variety of ways.
Before natural cellulose fibers from bast fiber plants can be utilized for composites, a process of cleaning and separating needs to occur to extract the fibers. For a majority of the bast fiber industry, the extraction begins in the field with a process called retting. The plants are cut down and left to ret in the field, meaning the enzymes in the air break down the compounds that hold fibers to the hurd, allowing the fiber to come off the hurd easier. What is left in the field is then baled and taken to a processing facility in order to clean the bast fibers.
First, the fibers need to be pared off the hurd that make up the main structure of the plant using a decorticator. The fiber/hurd mixture is then run through a second time to ensure the larger hurd pieces are removed. The fiber is sent through a refining machine, which generally has three stages to it, coarse, middle and fine. The refining machine increases fiber fineness and removes any excess hurd that might be still attached to the fiber. The fiber can then undergo any necessary surface treatments in order to meet customer specifications. More often than not, the fiber undergoes a chemical cottonization process in order to become suppler and can thus be a drop-in replacement for use on cotton textile equipment. The hurd that is separated from the fiber during the entire process is being captured on a series of conveyor belts underneath the processing equipment, or carried with pneumatic tubes to its final processing destination, to be used for such applications as paper applications or animal bedding.
Sunstrand has the processing capability to mill and grade fibers that would primarily be used as fillers and additives (link). Common sizes of 500 microns and 150 microns are standard, but almost any size can be produced.
Sunstrand also has the processing capability to cut fibers that would primarily be used in injection molding (link to manufacturing techniques) and various nonwovens(link). Common sizes of ¼” to 4” lengths are typical, but custom sizes can also be produced upon request.
As well as milling, Sunstrand can refine, or “beat” fibers in order to process them for further uses, such as pulping and paper-making. Refining is the process of shearing and compressing fibers to weaken them, allowing the fibers to them be treated further. For paper-making, refined fibers have more strength and are more efficiently used by machinery, in addition to improving print quality.