In a second, apparently unrelated study at UiTM's Shah Alam campus, Mohd Iqbal Misnon and his collaborators in the departments of textile technology and biocomposite technology tested hybrid composites made of rubberwood, coconut shell, and woven cotton or polyester textile fabrics. Their intent was to find out how reinforcement provided by textile fabrics affects biocomposites.
Several different hybrid composites were created, with two, three, or four layers of cotton or polyester fabric. The control samples were unreinforced hybrid composites. The team conducted flexural strength, impact strength, water absorption, and thickness swelling tests.
The flexural strength and flexural modulus of fabric-reinforced hybrid composites improved compared to the control sample. The flexural modulus of composites reinforced with four layers of fabric tended to decrease slightly. Fabric also delivered better impact damage tolerance, which increased with layer count.
Since the polyester fabric did not adhere well to the rubberwood and coconut shell mixture, it was not as strong as the cotton fabric-reinforced versions. The researchers said that, if its adherence was improved, the polyester hybrid composite's flexural strength and impact properties would likely improve.
The hybrid composites reinforced with cotton had better flexural but lower-impact strength than the polyester-reinforced composites. Composites reinforced with both fabric types had lower water absorption and higher values of thickness swelling than the control sample.
Thanks Ann for this intersting article highlighting these two studies.
Before the wonder fabric known as nylon came on the scene, there was a lot of development of fabrics made from natural sources such as milk fiber, hemp and even coconut. We're dusting off some of the old research. With more modern technology and processes, I think we'll see some very intersting results.
Nadine, thanks for the history--I didn't realize that this type of modern research, i.e., materials made from natural sources, had a previous phase. Maybe it's my studies in anthropology way back when, but I've always been interested in how people experiment with the natural materials in their immediate environment for an astounding range of uses.
Dr. Pradeep Rohatgi, who is best known for his work on metal-matrix composites, also did significant work on natural fiber composites, including coconut, banana, and sisal. This kind of technology could play an important role in reducing poverty in developing countries. Instead of relying on expensive materials imported from industrialized countries, indigenous materials could be used.
Besides, many biological materials have properties which rival those of the best synthetic materials, often at a significantly lower cost. A lot of money is being spent on research to develop multifunctional, nano-structured materials, but nature has a big head start on us (about four billion years).
I had heard about this use of coconut fibers recently, but not any details. Thanks for the article. Once again nature provides. I'd like to think that we're heading into an era where nature is viewed as a cooperative ally rather than something to be overcome. Efforts like this move us in the right direction.
@Scott Orlosky: You raise a good point -- our attitudes about natural products speak to our overall relationship with nature.
In the developed world, there is often a bias against the use of natural products in industry. For example, we often use wool grease (which, as the name indicates, is a mixture of long chain fatty acid esters extracted from the wool of sheep) as a lubricant for fasteners.
When I describe this product to people, they often react in disgust or derision -- even though some of them may regularly use skin care products containing lanolin, which is actually just highly-refined wool grease. But when it comes to industrial wool grease, they see it as a "gross" product, and have a hard time believing that it is still being used in the 21st century.
The same people tend not to have the same reaction to solid film lubricants or petroleum-based lubricants. (This is especially interesting when you consider how most urban people react when they drive past a sheep pasture, compared to an oil refinery).
On the other hand, in developing countries, indigenous materials are often considered to be inferior to synthetic materials imported from abroad. There is a common prejudice, especially among the educated classes, that imported products are always better than national products, and that traditional national products are little better than garbage (even though foreign tourists may pay large sums of money for traditional products, or at least facimilies thereof).
These attitudes are largely unconscious and mostly irrational, but I would argue that they play a significant role in material selection.
Excellent points. I hadn't considered the "general attitude" aspect of material selection. Sounds like it would take a significant re-education effort to undo those biases. The more we understand the natural origins of materials the more likely we are to respect and protect them.
Scott, your earlier comment "I'd like to think that we're heading into an era where nature is viewed as a cooperative ally rather than something to be overcome." is intriguing. I also hope we are recapturing an understanding that most humans once had for many thousands of years until recently in our history: seeing ourselves as an integral part of the natural world, one that we can look to for inspiration and resources.
Dave, thanks for that background on research into natural fiber composites. I agree on the local use of local materials to reduce costs. After all, that's what people did before the industrial revolution: use what's at hand.
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