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Rosemarie S. Salazar* and Sonora L. Buñag**

*DOST IX RSTL Head, **Technical Manager, Chemistry Laboratory

Laboratory testing provides objective evidences on the state and quality of rubber and rubber products. It is a scientific approach to ensure compliance to industry regulations and market requirements.

Analytical data of rubber crumb are obtained from chemical and mechanical testing using fit-for-purpose methodology, instrumentation, appropriate management system, and employing competent and skilled manpower.

The Philippine Rubber Industry Association (PRIA) identified the need for rubber testing facilities in the country. In its National Rubber R&D Agenda, the Department of Science and Technology (DOST) also acknowledged that quality of natural rubber is one of the top issues affecting the competitiveness of the industry.


To support the rubber industry, the DOST, through its Grants-in-Aid program, provided funds to set-up a laboratory testing facility capable of analyzing the quality of natural rubber crumbs.

Considering that Zamboanga Peninsula has the highest production of natural rubber in the Philippines (171,126MT in 2010; 188,934MT in 2011), the Regional Standards and Testing Laboratories (RSTL) of DOST IX expanded its scope of services to include testing for natural rubber crumbs.

The Rubber Testing Laboratory is located at DOST IX Compound at Pettit Barracks, Zamboanga City. The laboratory has the capability to test for seven (7) parameters, namely: Dirt content, Nitrogen content, Ash, Volatile Matter, Plasticity Retention Index, Mooney Viscosity and Color.

These parameters are important measures not only in establishing the quality of the natural rubber crumbs but also provide an indication on the handling and processing practices of a company.

Presence of dirt helps detect adulteration in the product. It affects the processing of rubber and quality of finished goods which will result in poor fatigue resistance, tensile strength and elongation.

High nitrogen content (>0.6%) indicates possible adulteration with skim latex.

Ash content helps detect adulteration with clay, talc, sludge and silicates and coagulants such as sulfuric acid and phosphoric acid.

Volatile matter, which indicates dryness of the rubber, should not exceed 0.8%. Wet rubber may develop molds and putrefactive odor.

Plasticity Retention Index measures the resistance of rubber to oxidative degradation or aging. High PRI value indicates good quality of rubber.

Mooney viscosity characterizes the processibility of the rubber especially in terms of calendering, extruding or injection molding.

Color determines the grade of rubber crumbs.

The Rubber Testing Laboratory is manned by two competent analysts who underwent a customized 5-day hands-on training at the Malayan Testing Laboratory, a Malaysian Rubber Board accredited laboratory, in Malaysia.

The facility is equipped with the following major equipment: Plastimeter, Mooney Viscometer, Kjeldahl Block Digestion and Distillation System, Furnace, Laboratory Mill, Aging Chamber, Analytical Balance, Ultrasonic Bath, Hydraulic Press.

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Department of Science and Technology
Regional Office No. IX
2nd Flr. Limbo Bldg., Sanson St. cor. Roxas St., Barangay San Francisco, Pagadian City
Tel.: (062) 947-3894