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The biomaterial for green composites

News International-French

7 Feb 2011

Natural fibres are generally derived from plants, animals, or mineral resources. This article focuses on natural fibres from plants.

MS. LOH YUEH FENG, RESEARCH OFFICER FIBRE AND BIOCOMPOSITE DEVELOPMENT CENTRE (FIDEC) MALAYSIA TIMBER INDUSTRY BOARD (MTIB)
(Published on February-March 2010 – JEC Magazine
#55)

 

Various types of natural fibres are obtained from plants. The properties of these fibres and the applications for them may vary as a function of the part of the plant they originate from. Table 2 summarizes the types of fibres extracted from various plants and their mechanical properties as compared to glass fibre.

 

Demand for new materials in the global composite industry is stronger than ever, and supply constraints are becoming increasingly crucial. Current research findings show that the performance of natural fibres in certain composite applications is competitive with that of glass fibres. The advantages of natural fibres over synthetic fibres like glass and carbon include biodegradability, reduced greenhouse gas emissions, low energy consumption, low cost, low density and acceptable specific strength properties. Their use can also contribute to develop the non-food segment of an agriculturebased economy. Environment-friendly biocomposites have the potential to be the new materials of the 21st century, as well as a partial solution to many global environmental problems.

 

What are biocomposites

The term “biocomposite” covers: 1) petroleum-derived, nonbiodegradable polymers like polypropylene (PP), polyethylene (PE) or epoxies, reinforced with natural fibres; 2) biopolymers (e.g. PLA, PHA) reinforced with natural fibres; and 3) biopolymers reinforced with synthetic fibres such as glass or carbon. Biopolymers reinforced with natural fibres, generally considered to be more environment friendly, are sometimes called “green composites”.

 

These biocomposites are emerging as a viable alternative to glass-fibre composites, particularly in building, automotive and consumer products.

 

The current supply of timber is proving to be insufficient, and Malaysia is now trying to use other natural fibres to produce high-value-added biocomposite products.

 

Huge amounts of natural fibre materials are available in Malaysia: each year, an estimated 10 million m3 are produced from wood residues, 46 million m3 from agricultural residues such as oil palm, and 3,200 metric tons from coconut stems. Malaysia produces more than 30 million metric tons of oil palm biomass palm trunk (OPT), oil palm frond (OPF) and empty fruit bunch (EFB) fibres.

 

Table 1: Estimated raw natural fibre capacity available in Malaysia

Resources

Estimated capacity
/year

Log production

~ 20.7 million
m3/year

Forest and wood
residues

~ 10 mill. m3/year

Rubberwood

2.1 mill m3/year

Oil palm biomass
(trunk, EFB, frond)

30 million metric
tons / year

Coconut stems

3 , 2 00 metric tons
/year

Rice husk/ straw

5 00,000 metric
tons /year

Bagasse

180,000 metric
tons /year

Bamboo

10 million culms
/year

 

The estimated amount of alternative raw natural fibres available in Malaysia is provided in Table 1. All of these have excellent mechanical and physical properties, and a potential for use in the production of composite products for various end uses, especially in the building & construction and automotive sectors.

 

Source: Kozlowski, 2006

Tab. 2: Different types of natural plant fibres and their properties relative to glass fibre

 

Fibre type

Properties

E-glass

Kenaf

Flax

Hemp

Jute

Ramie

Coir

Sisal

Abaca

Cotton

Density g/cm3

2.55

1.5

1.4

1.48

1.46

1.5

1.25

1.33

1.5

1.51

Tensile strength*
10E6 N/m2

2,400

350-600

800-1,500

550-900

400-800

500

220

600-700

980

400

E-modulus (GPa)

73

40

60-80

70

10-30

44

6

38

-

12

Specific
(E/density)

29

27

26-46

47

7-21

29

5

29

-

8

Elongation
at failure (%)

3

2.5-3.5

1.2-1.6

1.6

1.8

2

15-25

2-3

-

3-10

Moisture absorption (%)

-

-

7

8

12

12-17

10

11

-

8-25

Price/kg ($),
raw (mat/fabric)

1.3
(1.7/3.8)

0.33-0.88

1.5
(2/4)

0.6-1.8
(2/4)

0.35
(1.5/0.9-2)

1.5-2.5

0.25-0.5

0.6-0.7

1.5-2.5

1.5-2.2

 

 

Technical applications

The use of natural fibres for technical composite applications has been the subject of intensive research in both Europe and the USA. Mainly automotive components are produced from natural fibres like flax, hemp or sisal bonded with PP or PE. The adoption of natural-fibre composites in this industry is driven by price, weightsaving and marketing considerations rather than by technical demands. In Malaysia, natural fibres such as EFB and kenaf are currently being utilized commercially in combination with PP in biocomposites for automotive applications.

 

Composites are used in a wide range of applications and contribute to the growth of various industries. The compositeindustry value chain spans a full range of activities, from the preparation of raw materials from natural fibres and binder production to the manufacture of end products. Biocomposite products need to be further developed in Malaysia, as a long-term strategy to develop the tremendous wealth of natural fibres that are currently under-utilized. The value chain of the composites industry is described in Figure 1.

 

 

It is well recognized that the composite industry is a significant contributor to the global economy. The declining supply and growing price of raw materials are causing concern and, in this regard, natural fibre materials can be seen as a good alternative material for the industry to produce value-added biocomposite products. The industry is therefore encouraged to explore the potential of the resources available for the production of new green composite products that will enhance the industry’s growth, competitiveness and sustainability. The commercial applications of green composites are currently limited, principally to biocomposites for some construction and automotive applications. However, ongoing research and development programmes into natural-fibre-reinforced composites and biopolymers should lead to further advances and new opportunities in this industry. In Malaysia, the Fibres and Biocomposite Development Centre (FIDEC) under the Malaysian Timber Industry Board (MTIB) will play a greater role in R&D and commercialization activities with research institutes, universities and industries, to help turn the abundance of natural fibre into wealth.