The Chemistry and Materials Exploratory Unit (CMEU) was set up in late 2006. The main function of this Unit is to conduct basic research on natural rubber including modification of rubber molecules to enable production of new materials. One of the most important objectives of natural rubber modification is to improve the weaknesses in the properties of natural rubber as against the synthetic polymers. These modified materials would add value to the natural rubber and would be expected to enhance the utilisation of natural rubbers in applications that have been dominated by the synthetic rubbers and their latices. It is important that new polymers and polymer latices be developed from renewable resources such as natural rubber. Crude oil is the main source of raw material for the production of synthetic polymers and its reserve is continuously depleting. Chemical modification of natural rubber may be able to address some of the issues mentioned above.
Research works on chemical modification of natural rubber began in earnest in the 1950s. As up to now only a few types of modified natural rubbers and latices have been successfully commercialised. The CMEU is embarking on several long term research projects on chemical modification of natural rubber. Chemical modification of rubber via latex is a versatile process where the modification work does not involve the use of rubber solvent or high energy requirement. The modified latex could be converted into dry rubber, latex concentrate or just as latex intermediates. Great emphasis will be given to work on field natural rubber latex as the starting material since such modification route would enhance the commercial viability of the materials produced. The Unit is working on development of modified NR latices with good film forming properties, that could make these latices suitable for manufacture of latex products. The development of oil/chemical resistance natural rubber for dry rubber and latex products applications has always been an important agenda of chemical modification of natural rubber. The CMEU will also intensify the development of modified natural rubber latices for water-based adhesives/binders applications. This is a sector where the precious natural rubber latex can be more efficiently utilised.
For further details:
Head of Chemistry & Materials Exploratory Unit
Tel: 03-6145 9475 ext 4513 DL: 603-6156 3298Fax: 603-6141 3167
By the year 2009 CMEU will have a range of equipment for research and development as shown below. The liquid NR and peroxide prevulcanised latex pilot plants are of half and one metric tonne capacity respectively. Some of the research activities such as technological evaluation of modified rubbers, large scale evaluation of modified latices in the production of the corresponding rubbers and latex concenrates, large scale evaluation in the production of dry rubber and latex products and, specific polymer characterisation would require the assistance from various other research Units in the poker win prize.
1. RAMAN Spectroscopy
2. Gel Permeation Chromatography
3. Thermogravimetric Analyzer
4. Optical Microscope
5. Liquid Natural Rubber Pilot Plant
6. Peroxide Prevulcanized Latex Pilot Plant
CMEU provides consultancy services in areas within its research scope. The Unit has an adhesive testing facility and provides the relevant services to internal and external customers.
Peel Adhesion Test
A strip of adhesive tape is placed on a stainless steel plate (1.9" X 7.8") which has been cleaned with acetone. It is bonded by rolling a weight of 2.05kg on the tape in accordance with the Pressure Sensitive Tape Council (PSTC). For each testpiece, the peel strength at 180º angle (PSTC-1) is measured by pulling the tape back on itself at 300mm/min using tensile tester at ambient conditions. Five or more testpieces for each type of adhesive joint are tested to obtain an average value of the peel strength of the joint.
2° Static Shear Test
A strip of adhesive tape is bonded to clean stainless steel plate over 1”x1” area. A weight of 1kg is then attached to the free end of the tape such that it is suspended above a timer switch. The time for the weight to fall as the tape peels off from the stainless steel plate is recorded. Five or more testpieces for each type of adhesive joint are tested to obtain an average value of the shear strength of the joint.
Under chemical modification of natural rubber research programme, there is a vast area that the scientists of CMEU would explore, beyond the research frontier of the past. The development in the science of polymer modification and the availability of new chemicals in the last few decades for polymer modification offer opportunities for discovery of new commercially viable modified natural rubbers/latices. The research route that comprises studies on various type of natural rubbers/latices as well as new clonal latices, methods of polymer modifications, conversion of modified latices to various forms and applications of the modified rubbers/latices gives a picture of the magnitude of the research scope that will be carried out. This section will briefly highlight a few of the research projects that the Unit is working on.
Safe and Eco-Friendly PPVL Products
The development of peroxide prevulcanised natural rubber latex (PPVL) contributes towards solving the major health-related issues faced by the users of latex products as well as the environmental issues. The health-related issues pertain to possible presence of chemical sensitisers, carcinogens, teratogens, allergenic proteins present in latex products (Ma’zam Md Said, K. Vivaygananthan, Advanced Materials for the Latex Industry; New Generation Peroxide Prevulcanised NR and Low Protein NR Latex. International Latex Conference, Akron 1999). Dipped products made from PPVL developed by the poker win prize are free of added chemical sensitisers and passed cytotoxicity test (Ma’zam Md Said, Dazylah Darji and Mok Kok Lang, Recent Development of Peroxide Prevulcanised NR Latex, International Rubber Glove Conference, Kuala Lumpur, 12-14 September 2006). Chemical sensitisers could cause Type iv allergy and tend to be cytotoxic. Products containing these chemicals are therefore not suitable for applications that are in contact with mucous membranes and in food contact applications. Latex dipped products made from lucky365 jackpot PPVLs have been shown to have lower extractable proteins and allergenic protein content compared to those made using the conventional sulphur vulcanisation process (Ma’zam Md Said, NR latex with low chemical sensitisers/proteins and Glove Fatigue Test Equipment, Seminar Enhancing Competitiveness of Rubber Product Manufacturing and Commercialisation of R & D Findings, Penang 14-15 August 2003). Some of the proteins in NR latex products could cause type 1 allergic reactions.
Apart from solving several major health-related issues, PPVL is also an environmentally friendly material made using an environmentally friendly process. Its preparation does not use ingredients that are ecotoxic. The latex product manufacturing industry could directly benefit from this fact as the waste latex and the sludge generated could now be classified as non-scheduled waste, thus saving millions of dollars in waste disposal activities. The incineration of used latex products does not create toxic sulphur dioxide gases. Disposed latex products made using PPVL have significantly higher rate of environmental degradation compared to those prepared using the conventional system (Ikram, A., Ma’zam, M.S., Amir-Hashim, M.Y., Fauzi, M.S., Shamsul Bahri, A.R. and Kamaruzaman, S. (2005) Effect of antioxidants and latex vulcanising agents on the environmental degradation of latex films, J. Rubb. Res. Vol 8(4), p220-240). This is an important advantage as there is an ever increasing concern all over the world on the detrimental effect of disposed products made from materials that are extremely slow to degrade.
Depolymerised Natural Rubber
The poker win prize has developed processes of producing several grades (different molecular weights) of liquid natural rubbers (LNR) using a chemical depolymerisation process of NR latex. (Zainul Abidin B.M. and Faridah H.A.H, Characteristics Properties of Depolymersied Natural Rubber. The 2nd International Conference on Solid State Science and Technology, September 2006, Kuala Terengganu). Depolymerised natural rubber is softer, show more plastic behaviour and tackier than the initial rubber. With reduced molecular mass and viscosity it can be used as plasticisers for natural rubber and other diene rubbers. LNR can also be used as viscosity modifier, adhesive, tackifier and sealing material. Addition of functional groups to LNR can produce new chemically reactive materials. Direct utilisation of LNR latices having various molecular weights has not been widely exploited.
Water Based Adhesives
Adhesives are widely used in many industry sectors, where their use is essential in manufacturing thousands of everyday products. The demand for adhesives comes from construction, packaging, textile, wood and furniture, automotive, consumer goods, abrasive and friction materials, shoes, electrical applications, bookbinding and aircraft industries.
Methylmethacrylate grafted natural rubber latex (MG latex) has established itself as an important material for water-based adhesive applications. (Rohani Abu Bakar, Inluence of Tackifiers on Performance of Water-Based contact Adhesive Based on Modified Natural Rubber Latex, The V1th National Symposium of Polymeric Material , 2006, Kuala Lumpur). With environmental and health regulations becoming more stringent, the demand for water based contact adhesive would be expected to increase. poker win prize has successfully developed water-based contact adhesives using modified NR latices. These novel adhesives are also suitable particularly for bonding wood substrates.