Let me download so that i can give my comments

---

let me download the presentation to give my comments

Head of Raw Rubber Process Development and Chemical Engineering Department of Rubber Research Institute of Sri Lanka (RRISL).

Natural rubber (NR) latex, a polydispersed colloidal dispersion of rubber particles in aqueous medium, commonly extracted from Hevea brasiliensis tree, is converted into soft viscoelastic material, in most cases, with acid coagulation. Natural rubber contains, in addition to rubber hydrocarbon, non rubber substances such as proteins, fatty acids, carbohydrates and mineral salts in small quantities which influence the processability and physical properties of the natural rubber.
Although the characteristic elasticity and resilient behaviour of natural rubber was known for long, actual commercial potential of this material was realized with the invention of sulphur vulcanization by Charles Goodyear in 1839. Since then natural rubber is used as an engineering material for many industrial applications.
However, pure form of natural rubber has little commercial value for most of the practical applications because of its softness, low strength, poor wear properties and poor resistance to environmental degradation. In general, natural rubber is compounded with fillers to either achieve the correct reinforcement or to balance the cost- performance ratio.
Sri Lankan rubber industry
From the introduction of rubber tree to Sri Lankan soil in 1876 by Sir Henry Wickem, rubber industry has begun and since then natural rubber has been one of a major plantation crops in the country. Until the rubber products manufacturing industry expanded in late 1970’s in the country, almost all natural rubber produced by the country was exported in the raw form.. However, with the establishment of rubber products manufacturing industry, the situation has gradually changed and as a result local rubber industry started consuming raw NR produced in the country.
Recently, NR exports decreased gradually whilst local consumption continued to increase indicating a steady growth rate of rubber product manufacturing industry, although natural rubber production shows a setback currently. At present, out of total natural rubber production, about 70 – 75 % of raw rubber is consumed by local rubber industries to convert raw natural rubber into value added rubber products. This is mainly accounted by solid and pneumatic tyres, medical and industrial latex gloves and various engineering moulded components.
Sri Lanka is the leading manufacturer of solid rubber tyre to the world and enjoys 4th position in latex glove manufacturing industry. Despite the current position achieved globally, production of high end value-added rubber products like pharmaceutical and medical products is still in the primary stage, indicating that value addition, as measured in terms of value per tonne of rubber used, is well below the global norms.
At present, Sri Lankan rubber industry requires more technological innovations and heavy investments in Research and Development activities to further enhance the value addition to natural rubber in the country.
Nanomaterials
In the recent past, the term “nanotechnology” has become a hot topic among scientists, engineers and technologists and it is widely considered as an enabling technology to produce new materials and products with promising/unique properties in all disciplines of science and technology. Nanomaterials are the core of the nanotechnology and unique/unusual chemical and physical properties of the nanomaterial compared to that of their bulk materials have created a new pathway of developing new products and systems with unique and functional properties. By definition, at least one dimension of the nano material should be in the nanometer range, 1 – 100 nm. However, even before the emergence of this novel technology, rubber industry had recognized the advantage of nanomaterials in reinforcement as primary particles of carbon black and silica falls in this category
Nanomaterials applications in rubber
In recent past, synthesis of different nanomaterials with unique properties compared to that of their bulk counterpart and their applications with polymers have become promising Research and Development activities in the field of material science and technology. With the understanding of unique properties and functionality associated with the nanomaterials, rubber scientists and technologists have realized their potential as an alternative to conventional materials commonly used in the rubber industry.
Rubber nanocomposites based on different nanomaterials have attracted great interest in academia and industry because they exhibit improved mechanical and functional properties with a lower volume fraction of nanomaterials. Rubber nanocomposite is a new class of composite material in which at least one dimension of the dispersed materials/particles, known as the effective particle, is in the nanometer range (1-100 nm).
Extraordinary higher surface area to volume ratio of nanomaterials and strong interaction between nanomaterials and the rubber matrix would result in superior/unique properties, especially reinforcement and different functionality such as thermal, electrical, barrier resistance with a lower volume fraction of nanomaterials etc. In general, rubber nanocomposites have following major advantageous over conventional highly filled rubber composites.
Lower density and as a result lighter weight products
Improved reinforcement whilst maintaining inherent elastic properties
New functional properties without sacrificing strength and elastic characteristics.
Improved flow properties; viscous and elastic properties and as a result easy processing.
Over the past few years, widely researched nanomaterial with rubber is layered silicates which belong to the structural family of 2: 1 layered silicates (smectite group). Rubber nanocomposites based on layered silicates, especially montmorillonite clay, have been developed to accomplish a higher reinforcement, to improve barrier resistance, to impart flame retardancy etc.
However, in addition to layered silicates, other potential nanomaterials such as carbon based nanomaterials like graphene and graphite derivative, carbon nanotubes and carbon fibres have been investigated to make a value addition to rubber, especially to make functional elastomeric material whilst maintaining inherited elasticity and strength characteristics of the rubber.
Commercialization of nanomaterial enabled rubber products shows a slow progress due to many reasons such as inability to achieve uniform dispersion of nanomaterials within the rubber matrix and weaker interface created between nanomaterial and rubber molecules. Most of the nanomaterials are not compatible with rubber, hence aggregation and phase separation is inevitable, resulting in imperfect property enhancement.
Novel and efficient methodologies are required to improve the efficiency of nanomaterial dispersion in the rubber matrix and to create a stronger interface between rubber and nanomaterials. Relatively little understanding of the behaviour of the interface and nano-reinforcement are the other barriers to develop rubber products with nano enhancement.
Novel research and innovations
Recently, rubber nanocomposites reinforced with a lower volume fraction of layered silicates have shown a tremendous potential as an alternative to conventional NR composites. However, present layered silicates filled nanocomposites have exhibited limited reinforcement, especially tear strength and abrasion, due to incomplete dispersion/exfoliation of layered silicates and limited interaction between silicate layers and rubber which are prerequisite to achieve desired enhancement in reinforcement.
Nanocomposite group at RRISL has developed a novel methodology to prepare natural rubber nanocomposite based on montmorillonite clay in which rubber molecules and layered silicates are modified simultaneously during processing. The layered silicate filled natural rubber nanocomposite synthesized with the novel technique has shown extraordinary exfoliation of layered silicates and much stronger interface as a result of good adhesion/interaction between NR molecules and nanostructures of layered silicates. The reinforcement achieved with nanostructures of layered silicates created by the novel methodology is superior to the conventional NR nanocomposites reinforced with layered silicates.
For example, all reinforcement parameters such as tensile strength, modulus, tear strength and abrasion resistance are significantly improved with a lower volume fraction of layered silicates. The nanocomposite developed is targeted to replace conventional highly filled rubber compounds, especially for making environment-friendly greener tyres.
Sri Lanka is the major supplier of NR latex crepe, the purest form of natural rubber, and sole crepe, which is considered as a semi finished product, to the word market. Nevertheless, presently, most of the NR latex crepe rubber produced by Sri Lanka is exported in its original form without making any value addition. RRISL has taken an initiative and research is progressing to develop a nanomaterial enabled raw natural rubber.
Nanotechnology enabled raw natural rubber, similar to NR latex crepe rubber, has shown an excellent green strength and improved thermo oxidative stability in comparison to the conventional crepe rubber. The project anticipates developing tailor-made raw natural rubber for different applications with desired visco-elastic properties and improved green strength by manipulating the nanostructures within the raw rubber.
NR sole crepe, a value added form of crepe rubber, used in un-vulcanized form for shoe soles, can further enhance its value addition with nanomaterial applications. Studies are in progress to develop NR sole crepe with improved abrasion resistance, better hardness and improved resistance to thermal oxidation which are important quality control parameters of a shoe sole.

In addition, yellow fraction (off grade), a by-product generated during the production of fractionated bleached crepe rubber, is a significant percentage in crepe rubber industry. Nanomaterial is being researched to accelerate the fractionation process and also to improve the raw rubber properties. Nanomaterial applications to yellow fraction would help to add value to this low grade of raw rubber and thereby introduce new applications for the off grade rubber.