Common Milkweed as an Alternative Cellulose Fiber Source for Making Paper with Strength and Moisture Resistance

Hans Kellogg, Heather Hendrixson,and Renmei Xu, Ball State University;
Maruthi Srivatsan Mogundan and Paul D. Fleming, III, Western Michigan University

With increased interest in sustainability, researchers look to alternative fiber sources such as the common milkweed as an alternative material for making paper1, 2. Extremely prolific, milkweed grows in varied climates from far south to the northern plains, flourishing in both wet and dry climates3.  Currently the plant is considered a noxious weed, and farmers work to eliminate it from their fields as it competes with plants grown for commercial value. However, there is interest to the use of the common milkweed because of the concern for the dwindling population of Monarch butterflies. The Monarch larva use only milkweed as their source of sustenance4. While this study did not deal directly with the declining Monarch populations, interest in planting milkweed would increase the viability of using this plant for making paper. Research has shown that milkweed is easily cultivated and can be commercially grown with the intent to maximize the output of cellulose fiber2.

This study explores two specific portions of the plant containing cellulose. One is the plant’s stem5, with its long fibers lend itself to an increase strength. The other is the floss6, where buoyant white fibers are attached to the seeds and utilize their light weight and hollow structure to catch the wind, transporting the seeds away from the plant to begin germination. During WWII, the floss was used for life preservers as the Japanese cut off shipping of traditional materials used for life vests. Naturally resistance to moisture, the paper produced with these fibers would be proven beneficial to specific areas of packaging, where moisture protection is crucial. When combined together, fibers from the floss and stems could produce a paper that is both strong and moisture resistant, lending itself for use in packaging where these attributes are advantageous.

Waiting until the plants had died back, common milkweed was collected for processing. Separating the two portions of the plants, the material was then broken into manageable sized portions and bagged, ready to process. Using traditional papermaking techniques, the fibrous plant material was processed through a Holland Beater with water added to produce a slurry of approximately 97% water and 3% consistency cellulose plant fiber. At that point, numerous hand sheets were produced to create a suitable number of samples for testing. During the creation of hand sheets, sizing was added to produce paper that would be defined as slack-sized, and hard-sized. Once dried, each of the hand sheets was tested for moisture resistance using the contact angle method.  Surface energy of the paper was determined from the contact angle measurements. For evaluation of the strength of the hand sheets, the samples were tested for wet tensile breaking strength and tensile energy absorption (TEA).

Cobb, Emco DPM and and MVTR (Moisture Vapor Transmission Rate) tests were also performed. The Kappa number was determined to measure lignin content. Fibers were also analyzed with a Fiber Quality Analyzer and Microscopy.

While further testing is necessary, test results indicated an increase in moisture resistance and strength (both wet and dry) resulted in a paper material that would be suitable for use in packaging where both strength and moisture resistance are critical.

Printability tests were performed with various processes used for packaging.

References

  1. Michael Alan Hermans, Robert Dale Sauer, Shafi Ul Hossain and John Dennis Litvay, “Tissue products made from low-coarseness fibers” US004001672B2
  2. Narendra Reddy and Yiqi Yang, “Extraction and characterization of natural cellulose fibers from common milkweed stems”, Polymer Engineering and Science, 49:11 (2009), pp. 2212–2217.
  3. David Taylor “Common Milkweed (Asclepias syriaca L.)”, downloaded Oct. 5, 2018 from https://www.fs.fed.us/wildflowers/plant-of-the-week/asclepias_syriaca.shtml.
  4. Marjie Ducey, “Monarch food shortage has butterfly advocates planting milkweed ‘from Nebraska to Pennsylvania’”, downloaded Oct. 5, 2018 from https://www.omaha.com/living/monarch-food-shortage-has-butterfly-advocates-planting-milkweed-from-nebraska/article_e74bafe3-0ef9-56eb-9d60-dbc4b86695de.html
  5. Michelle Stevens, “COMMON MILKWEED”, downloaded Oct. 5, 2018 from https://plants.usda.gov/plantguide/pdf/cs_assy.pdf.
  6. Patricia Cox Crews, Shiela A. Sievert, and Lisa T. Woeppel, Elizabeth A. McCullough “Evaluation of Milkweed Flossasan Insulative Fill Material”, Textile Research Journal 61, no.4 (April 1991), pp. 203–210.