Natural Rubber – R1 Delta CIS

Natural rubber, in its milky sap, is tapped from the Hevea Brasiliensis tree. Most of the latex is either processed into sheets or solid crumb rubber. It can also be kept in its liquid form through use of chemicals to prevent the latex from coagulation. In the solid form, the rubber sheets or crumbs are used in the manufacture of solid rubber based products, eg. tyres etc, while the liquid form is used for dipping products such as gloves, balloons and condoms.

Technically Specified Rubber (TSR)

Rubber grading under TSR was established in the early 1970s. The rubber is graded by its dirt, ash, nitrogen content, volatile matter content and plasticity retention index.

They have good processing characteristics and physical properties. Usually, such grades of rubber are high in green strength, tack, easy to mix and has low viscosity.

Common sources of TSR include Thailand, Indonesia, Malaysia, Vietnam, India etc. However quite recently the African and South American rubbers are gaining popularity. Most Asian countries have a nomenclature of labelling their standard rubbers with the country of their origin viz. Standard Malaysia Rubber as SMR, Standard Indonesia Rubber as SIR, Standard Thailand Rubber as STR and Standard Vietnam Rubber as SVR.

These are used in high performance passenger tyres, motorcycle and bicycle tyres, heavy load truck tyres, conveyor belt, inner tubes and hose.

The typical standard specifications of most common TSR grades are:

		TSR 5				TSR 10				TSR 20
Parameter	Unit	SIR 5	SMR 5	STR 5	SVR 5	SIR 10	SMR 10	STR 10	SVR 10	SIR 20	SMR 20	STR 20	SVR 20
Dirt (max)	%wt	0.05	0.05	0.04	0.05	0.1	0.08	0.08	0.08	0.2	0.16	0.16	0.16
Ash (max)	% wt	0.5	0.6	0.6	0.5	0.75	0.75	0.6	0.6	1	1	0.8	1
Nitrogen (max)	% wt	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.6
Volatile Matter (max)	% wt	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8
Po (min)		30	30	NA	30	30	30	30	30	30	30	30	30
PRI index (min)		70	60	60	60	60	50	50	50	50	40	40	40

Ribbed Smoked Sheets (RSS)

Ribbed Smoked Sheets, or air dried sheets are commonly known as RSS. It can be graded into RSS1 to RSS5, with RSS1 as top grade. It is usually packed in large bales of 111.11kg/bale or 19 metric tons per 20 foot FCL.

The different grades are determined by the percentage of particles in the rubber sheet.

Grade	Unacceptable Conditions	Acceptable Conditions
RSS1	Oxidized spots, weak heated, under-cured, over-smoked, opaque and burnt sheet are not acceptable.	Slight traces of dry mould on the packaging are acceptable but mould should not penetrate inside the bale. Small scattered pinhead bubbles are permissible.
RSS2	Oxidized spots, weak heated, under-cured, over-smoked, opaque and burnt sheet are not acceptable	Slight traces of rust and dry mould on the packaging and interior sheets are acceptable but it should not be >5% of the bales sampled. Small bubbles and slight specks of bark are permissible.
RSS3	Oxidized spots, weak heated, under-cured, over-smoked, opaque and burnt sheet are not acceptable	Slight traces of rust and dry mould on the packaging and interior sheets are acceptable but it should not be >10% of the bales sampled. Small bubbles, slight specks of bark, slight blemishes in colour are permissible.
RSS4	Oxidized spots, weak heated, under-cured, over-smoked (exceeding the degree shown in samples), opaque and burnt sheet are not acceptable	Slight traces of rust and dry mould on the packaging and interior sheets are acceptable but it should not be >20% of the bales sampled. Medium sized black particles, bubbles, translucent stains, slightly sticky or over-smoked rubber are permissible.
RSS5	Oxidized spots, weak heated and burnt sheet are not acceptable	Slight traces of rust and dry mould on the packaging and interior sheets are acceptable but it should not be >30% of the bales sampled. Large particles, bubbles or barks, small stains or blisters, slightly sticky, slightly under-cured or over-smoked rubber, blemishes are permissible.