The word fibre immediately conjures up an image of something one should ingest in sufficient quantities to keep the digestive system healthy — and perhaps it brings to mind advertising messages with shrinking images showing the positive effects of getting it right.
But fibre — or fibrous materials — are present in every step of a person’s day. From the pillow and bedding on the bed, to curtains and the carpet fibres underfoot.
In cars nylon fibres are used extensively. And in clothing, too. Nylon fibres, cotton fibres, jute for sacking used in the agricultural industry and, of course, there is a wide variety of applications of fiberglass, from shower panels to power boats.
Perhaps one of the oldest uses of fibre is in making paper — without which we would not have had the opportunity to read the millions upon millions of words we consume as readers of newspapers, magazines and books each year, or the school books our children use to hone their newly acquired reading and writing skills.
The pulp and paper industry is the main driver for the South African forestry industry, using more than 60% of the annual production. Pulp from sugar cane fibre represents 6% of chemical pulping capacity.
Seeking an alternative to trees
In 1939 an enterprising Italian led the way to produce paper and paper board from straw at the Enstra mill in Springs, Gauteng.
Its quality was not good enough to make it a permanent alternative to wood pulp. Besides, there was no incentive to develop alternatives at that time.
However, the bleaching and chemical processes used in the paper and pulping industry today remain cause for concern and alternative products have become sought after. The global demand for natural fibres is growing by 25% a year.
Stepping into this scenario is kenaf (hibiscus cannabinus), a fibre alternative that has made its mark already in the United States, where several newspapers are printed on kenaf paper. In fact, large corporations like Sony print their catalogues on this paper.
But kenaf fibre is far more than a source of paper. In South Africa the first applications of kenaf fibres have been in the motor industry.
Professor Maryke Labuschagne heads a research team at the University of the Free State, which, in collaboration with 10 farmers and an industry partner, is building a pulping factory in Winterton, KwaZuluNatal. The project has been running for three years and the farmers are involved in the commercial farming of kenaf. In the 2006/07 season 2 300ha were planted.
Labuschagne says: ‘Kenaf is a warm season annual that is closely related to cotton and okra. It is a rapidly growing crop that is a viable source of low-cost natural fibre. These fibres can be used successfully to make a wide range of paper, pulp and paperboard and can be used as a substitute for fibreglass and a variety of other synthetic fibres.
Friendlier pulping process
Kenaf fibres, both the bast and core, can be pulped as a whole stalk and are an alternative fibre crop for paper pulp production. The grown plant’s stem height usually varies between 1,5m and 4m. The stem has a central core, rich in short fibres, and an external bark consisting of long fibres. Kenaf is receiving increasing interest in the paper industry as a source of good quality cellulose fibres.
‘A very important aspect of commercial production of kenaf is the selection of the variety. This is why we are testing nine different varieties. Stalk yield and stalk biomass is crucial. Stalk biomass percentage is the stalk by weight on a whole plant basis. Our farmers have attained yields of up to 30 tons per hectare stem dry mass,” says Labuschagne.
Its rapid growth counts in its favour too — planting pine trees, for example, requires between 14 and 17 years of input before any output can be expected. Kenaf, as a hardy annual, reaches full growth in about 150 days.
In pulping terms, fewer chemicals, heat and time are required to pulp the fibres as they are not as tough as wood fibres, containing less lignin. On average kenaf contains about 9% lignin compared with the 29% of pine.
Pulping kenaf is done with hydrogen peroxide, which breaks down into water in the process. This water can be re-used in many different ways. Conventional pulping plants use chlorine, which is toxic to both man and environment. The environmental cost of kenaf is considerably less — in chemicals, electricity and of course, use of the land.
The Kenaf project in South Africa aims to supply non-woven fibre for use in car seats, door panels and other automotive components. These natural fibre products can be recycled, yet another of its advantages. It reduces the need for plastic and fiberglass.
Labuschagne says kenaf research focuses on the seed and its components, production guidelines in terms of seedling density, row width, use of herbicides and insecticides and harvesting.
Defoliation practices are under the spotlight to determine recovery indices and economic thresholds of various processes. The pulping factory being built in Winterton will bring 55 new jobs to the area, not to mention increased job opportunities in future farming ventures. The pulp produced in this plant, which should be operational in the next year, will be sent to the Brits textile production line in Pinetown.
Kenaf clearly could be the true fibre alternative, being eco-friendly, recyclable and biodegradable.