Pale Crepe

Pa.le Crepes. Sri Lanka is the largest producer of crepe mbber, as either thin pale crepe or thick pale crepe, which accounts for 35% of mbber production. Pale crepes are divided into one of three classes, depending on the manufacturing process (11,12) fractionated and bleached mbber (FB) unfractionated, but bleached mbber (UFB) or yellow fraction mbber (YF). 

In solid form, the natural rubber is graded according to the content of dirt remaining from the precipitation of latex at the plantation. Eight basic NR types have been traditionally recognized internationally. Only the so-called ribbed smoked sheets and the pale crepes are normally used for adhesives. The predominant grade system, the Standard Malaysian Rubber system, has been used since 1965. 

Oxidation of Natural Rubber (NR) Pale Crepe at 46°C, Accelerated by Ultraviolet (UV) Light... 

A substance added to latex in the preparation of pale crepe rubber sodium bisulphate prevents darkening of the crepe due to the presence of oxidising enzymes, xylyl mercaptan is an effective bleaching agent proper. 

Crepe rubber of lower quality than pale crepe it is made from the pre-coagulated lumps which form in the latex before the coagulation process is carried out. 

Any form of natural rubber which is marketed with the rough surface produced by passing the rubber through a series of mills with grooved rolls travelling at differential speeds. The main types are pale crepe, sole crepe, brown crepe and flat bark crepe. 

NaHS03, is added to latex from which pale crepe rubber is to be made. It prevents discoloration of the crepe and destroys microorganisms which may cause later deterioration of the rubber. Sodium Dibutyl Dithiocarbamate SDBC, accelerator. 

An efficient peptising agent for natural rubber it is also used as a bleaching agent in the preparation of pale crepe rubber. 

Ribbed smoke sheets White and pale crepes Estate brown crepes Compo crepes Thin brown crepes Thick blanket crepes Flat bark crepes Pure smoked crepe... 

Pale crepe, 3 dicumyl peroxide 50 min at 140° C Methyl methacrylate 87 93 97 94... 

Acetone-extracted pale crepe, 5 zinc oxide, 1 stearic acid, 1 phenyl-/3-naphthylamine, 0.7 Santocure, 2.5 sulfur 30 min at 140° C Methyl methacrylate 5 20 23 ... 

Pale crepe, 50 phenol-formaldehyde resin, 5 zinc oxide, 1 stearic Methyl methacrylate 68 85 95 —... 

Pale crepe, 20 phenol-formaldehyde resin, 3 dicumyl peroxide Methyl methacrylate 94 95 94 95... 

Pale crepe, 20 cresol-formaldehyde resin, 2 hexamethylene tetramine, 3 dicumyl peroxide 50min at 140° C Methyl methacrylate 91 95 12 -—... 

Pale crepe and N330 carbon black 50 160 15.8 (2,291) Irradiated in air... 

Smoked Sheets and N330 Carbon black plus octyl acrylate Smoked Sheets and N330 Carbon black plus tetramethylene diacrylate Smoked Sheets and N330 Carbon black plus glyceryl triacrylate Pale Crepe and N330 Carbon black Pale Crepe and N330 Carbon black plus octyl acrylate... 

Raw rubber can be either natural or synthetic. The standard grades of natural rubber are smoked sheets and pale crepe. For high grade products, first grade smoked sheets, namely RMAIX or Pale Crepe, is used. Pale Crepe is practically colourless and is preferred in products where delicate colour, extreme whiteness or transparency... 

Crepe. Another popular type of commercial rubber, known as crepe, consists of two major classes—pale crepe and thick blanket crepe. Pale... 

Natural Rubbers (NR). The chemical name for NR is polyisoprene, which is a homopolymer of isoprene. It has the cis-1,4 configuration. In addition, the polymer contains small amounts of non-rubber substances, notably fatty acids, proteins, and resinous materials that function as mild accelerators and activators for vulcanization. Raw materials for the production of NR must be derived from trees of the Hevea Brasiliensis species. NR is available in a variety of types and grades, including smoked sheets, air-dried sheets, and pale crepes. 

A sample of milled pale crepe hevea was reported to have 0.18% head-to-head and 1.7% tail-to-tail while Coral Rubber contains approximately 0.3 to 0.5% head-to-head and as much as 4.8 to 6.8% tail-to-tail. Coral Rubber thus contains a quite appreciable amount of tail-to-tail structure. 

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