i 1. 1915.] 



THE INDIA RUBBER WORLD 



' 



PLANTATION RUBBER'S VULCANIZING CAPACITY. 

 By Our I dent. 



AS a result of experimental work carried out in the vul 

 and testing laboratorj established nol long ago in M 

 by the Agricultural Department of the Malay Si 



'.I ! aton and J. Grantham have arri ■■tain impi 



is on the subjeel riability of plantation ru 



which have been embodii d in apei • 

 ■ ii ultural Bulletin." 



-it ..ut that during the last two or three years much 

 has been written and man ents made concerninf 



in plantation Para rubber. The opinii ns essed general! 



manufacturers are to the effect that variation 

 in the cum- of "first latex" rubbers when compared with fine hard 

 Para as the highest grade of wild'Para rubber. On the other 

 hand, leading rubber technologists and chemists have maint; 

 that the hest grades of plantation Para rubl i allj sheet, 



tiperior tn fine hard Para. According to I al n and ' irantham 

 both opinions may be taken as correct and are not necessarily con- 

 tradictory. Unfortunately, neither the statements made by manu- 

 facturers nor the published results of experiments carried out by 

 ■- have indicated the nature of this variation; 

 -till less have any published results enabled us to attribute this 

 variation to any definite cause. 



It is particularly noteworthy that Eaton and Grantham combat 

 the familiar notion that variability refers only to thos< propi 

 of rubber which may be tested by physical mean.-. The general 

 assumption, they state, that variation refer- to differences in the 

 mechanical properties of the raw or vulcanized rubber, i. e., 

 strength, elasticity, etc.. is only true to a limited extent among 

 "first latex" rubbers and represents only a part of such variation. 

 It is claimed by the author- of the paper that these experimental 

 results are the first, so far as the writers are aware, which have 

 indicated the most important variation in plantation Para rubber. 

 namely, its variable vulcanizing capacity. 



Importance is also attached to the fad that the author- were 

 acquainted with the entire history of their samples — a condition 

 impossible of realization to chemists and scientists resident in 



I uri 



l MARY OF RESULTS. 



According to the summarized re-ults given at the conclusion of 

 the paper, it i- found that considerable variation occur- in planta- 

 tion Para rubbers, both from the same estates and from different 

 This variation is connected principally with the behavior 

 of the rubber on vulcanization, i. e.. its rate of cure, and not in 

 respect to its strength, elasticity and general mechanical prop- 

 lly in the case of properly prepared "fir- 1 latex" 

 samples. If the rate of cure be known or ascertained under 

 specific conditions, vulcanized rubber, having similar mechanical 



properties, can be made from all g 1 samples of "first latex" 



rubbers. The differences in mechanical properties are ni t so im- 

 portant to the manufacturer as the differences in rate of cure 

 and are not of the same order. The rate of cure i- due to the 

 presence of some non-caoutchouc substance in tin latex, po 

 the proteins or some other constituent. This substance m. 

 already present in the latex, and its amount in the raw r 

 determined by the mode of preparation and coagulation, or it 

 may be subsequently formed in the latex by decomposition, or it 

 may be formed in the coagulum. The alternative theories await 

 investigation. 



Another of the conclusions arrived at appears to be worth 

 special note: "The rate of cure of a rubber under specified condi- 

 tions is not indicated in any way by the apparent mechani 

 any o ther apparent properties of the raw material: hence the ab- 

 surdity of the present methods of valuation of rubber. A manu- 

 facturer probably prefers a rapidly curing rubber, as it repp 

 economy in heat, labor and time costs ; and secondly, a rubber 

 which cures rapidly is said to have better keeping qualities under 



btain 

 a premium in thi would if valuation 



carried out on i-. provided uniformity in r: ' 



cure be maintain- 



It i I hal uniioi mity betvt i from 



cliff er> will be very difficult ol nt with present 



cure and 

 it this cun- ; anil I ■uinieiit of 



more uniformity bj a method m which ru 



during I which 



may be described as the method ol avera 



STRAITS SETTLEMENTS RUBBER EXPORTS. 

 An official cablegram fl - announces that the ex- 



la illation rubber from the Strait- Settlements port- dur- 

 in the month of June amounti d to I I with 



3,588 tons in May and 1,480 tons in the corri 

 ear. 

 The following is a comparative table showing the export for 



three years : 



1913. 1914. 1915. 



January Ions 1,181 



743 J. 741 



March 898 2.477 



April 



May 814 1,309 3,588 



Tunc 812 2.249 



■1 4.K13 8.506 



These figures include transhipments of rubber from various 



places in the neighbor! d of the Straits Settlement-, such as 



Borneo, .lava. Sumatra and the non-Federated Malay States, as 

 well as rubber actually exported from the I olony, but do not 



include rubber exports from the Federated Malay Stati 



FEDERATED MALAY STATES RUBBER EXPORT. 



An official cablegram rei Kuala Lumpur announces 



that the export of plantation rubber from the Federated Malay 

 - during the month of June amounted to 3,403 tons as 

 compared with 2,708 tons in May last and _'.. ; 

 nding month last year. 

 The following i- a comparative table showing the export for 

 three j i ars 



1913. 1914. 



II .131 3.473 



nuary 1,757 3,4] 1 



March 1,737 



il 1,6 



May I, . 2,7 



June 2,005 



II 13,850 



EXPORTS OF RUBBER AND COTTON FROM FRENCH INDOCHINA. 



During 1914 1 I crude rubber from French Indo-China 



amounted to 397.522 pounds as compared with 338.589 pounds 

 exported during the previous year; showing an increase of 58,933 

 pound-, 'if these total exports of crude rubber 297.161 pounds of 

 plantation rubber and 792 pounds of wild rubber were -hipped 

 to France, and 100.283 pounds of plantation rubber were shi 

 to Singapore. 



The total exports of cotton amounted to 10.024.97s pounds in 

 1914. as compared with 18.482,471 pounds in 1913; showing a 

 decrease of 8,457,493 pounds. 



Fxports of rubber from French West Africa have fallen 

 off during the past few years, amounting in 1913 to only 

 as against $5,064,000 in 1912 and $5352,000 in 1911. 

 Rubber is prohibited export from this district in any other 

 form than thin slabs, and in order to encourage commerce 

 in this product the government has recently lowered the 

 export duty. 



