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ASTM Selected Technical Papers
Rubber and Related Products: New Methods for Testing and Analyzing
By
WH King
WH King
1
Acushnet Company
?
symposium chairman
Search for other works by this author on:
TH Rogers
TH Rogers
2
Goodyear Tire & Rubber Company
?
symposium moderator
Search for other works by this author on:
ISBN-10:
0-8031-0560-6
ISBN:
978-0-8031-0560-7
No. of Pages:
200
Publisher:
ASTM International
Publication date:
1974

Plasticity Retention Index (PRI) of raw natural rubber is expressed as a percentage ratio of aged plasticity over unaged plasticity of raw natural rubber, the plasticities being measured on standard samples before and after the samples have been subjected to standard conditions (140°C, 30 min) of oven aging. A parallel-plate plastimeter is used in the measurement of plasticities.

This paper describes the measurement of PRI and discusses the various experimental conditions which are important to the accuracy and reproducibility of testing.

The various factors which are known to have an adverse effect on PRI are surveyed as this property of raw natural rubber is somewhat subject to change with time.

A brief outline is then given on the technological importance of PRI of raw natural rubber to the consumer.

1.
Raw Rubber—Sample Preparation
,” ISO 1796,
International Organization of Standardization
.
2.
Raw Rubber and Vulcanized Rubber—Rapid Plasticity Test
,” ISO/R 2007,
International Organization of Standardization
.
3.
Raw Rubber—Plasticity Retention Index
,” ISO/DIS 2930,
International Organization of Standardization
.
4.
Test Methods for Standard Malaysian Rubbers
,” SMR Bulletin No. 7,
Rubber Research Institute of Malaysia
,
1970
.
5.
Lee
Soh Hoong
, Chemistry Division Report No. 14,
Rubber Research Institute of Malaysia
,
1968
.
6.
Significance of PRI in Raw and Vulcanized Natural Rubber
,” SMR Bulletin No. 4,
Rubber Research Institute of Malaysia
,
1966
.
7.
Hon
Kok Kee
and
Amlir
Aziz
, “
Plasticity Retention Index—A Measure of the Quality of Raw Natural Rubber
,”
Rubber Research Institute of Malaysia
,
1971
.
8.
Chin
Peng Sung
and
Soh
York Beng
, “
Factors Influencing Consistency of SMR Production
,” Rubber Research Institute of Malaysia Planter's Conference,
1971
.
9.
Greensmith
,
H. W.
 et al
,
Transactions, Proceedings, Institution of the Rubber Industry
, Vol.
42
, No.
5
,
1966
.
10.
Nair
,
S.
, “
Dependence of Bulk Viscosities of Molecular Parameter of Natural Rubber
,”
Journal of the Rubber Research Institute of Malaysia
 0035-953X, Vol.
23
, No.
1
,
1970
.
11.
PRI in Standard Malaysian Rubber
,” SMR Bulletin No. 3,
Rubber Research Institute of Malaysia
,
1966
.
12.
Watson
,
A. A.
,
Journal of the Rubber Research Institute of Malaysia
 0035-953X, Vol.
11
, No.
1
,
1969
, p. 104.
13.
Plasticity Retention Index
,” Natural Rubber Technical Bulletin,
Natural Rubber Producer's Research Association
.
14.
Po and PRI as a Replacement for Cu and Mn Specifications
,” ISO/TC 45 2283,
International Organization for Standardization
.
15.
Raw Natural Rubber Specifications
,” ISO/TC 45, Annexes I and II, DIS 2000(2),
International Organization for Standardization
.
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