Long-chain branching and mechanism controlling molecular weight in Hevea rubber

Jitladda Tangpakdee Sakdapipanich; Tippawan Kowitteerawut; Krisda Suchiva; Yasuyuki Tanaka

doi:10.5254/1.3538828

Long-chain branching and mechanism controlling molecular weight in Hevea rubber

Jitladda Tangpakdee Sakdapipanich
, Tippawan Kowitteerawut
, Krisda Suchiva
, Yasuyuki Tanaka

Mahidol University
Tokyo University of Agriculture and Technology

Research output: Contribution to journal › Article › peer-review

19 Citations (Scopus)

Abstract

The linear character of transesterified deproteinized natural rubber (DPNR-TE) was confirmed by the analysis of terminal groups with NMR and viscometric analyses. The branch content of DPNR rubber from fresh latex was found to range from 0.3 to 1.3 and 0.7 to 3.2, based on tri-and tetra-functionalities, respectively. The plot between the number of branch-points and molecular weight (MW) can be divided into three fractions: (A) the rubber fractions in MW ranging from 2.4 × 10⁵ to 1.9 × 10⁶; (B) between 1.9 × 10⁵ and 2.4 × 10⁵; and (C) those of MW less than 1.9 × 10⁵. The fraction (A) showed the number of branch-points per a branched molecule (m) higher than that of tractions (B) and (C). This plot is superimposable with the bimodal molecular-weight distribution (MWD) of Hevea rubber, showing a good coinciding of peak-tops at the high and low MW fractions. It seems likely that there is a close relationship between the number of branch-point and bimodal MWD of natural rubber.

Original language	English
Pages (from-to)	712-720
Number of pages	9
Journal	Rubber Chemistry and Technology
Volume	72
Issue number	4
DOIs	https://doi.org/10.5254/1.3538828
Publication status	Published - 1999
Externally published	Yes

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title = "Long-chain branching and mechanism controlling molecular weight in Hevea rubber",

abstract = "The linear character of transesterified deproteinized natural rubber (DPNR-TE) was confirmed by the analysis of terminal groups with NMR and viscometric analyses. The branch content of DPNR rubber from fresh latex was found to range from 0.3 to 1.3 and 0.7 to 3.2, based on tri-and tetra-functionalities, respectively. The plot between the number of branch-points and molecular weight (MW) can be divided into three fractions: (A) the rubber fractions in MW ranging from 2.4 × 105 to 1.9 × 106; (B) between 1.9 × 105 and 2.4 × 105; and (C) those of MW less than 1.9 × 105. The fraction (A) showed the number of branch-points per a branched molecule (m) higher than that of tractions (B) and (C). This plot is superimposable with the bimodal molecular-weight distribution (MWD) of Hevea rubber, showing a good coinciding of peak-tops at the high and low MW fractions. It seems likely that there is a close relationship between the number of branch-point and bimodal MWD of natural rubber.",

author = "Sakdapipanich, \{Jitladda Tangpakdee\} and Tippawan Kowitteerawut and Krisda Suchiva and Yasuyuki Tanaka",

year = "1999",

doi = "10.5254/1.3538828",

language = "English",

volume = "72",

pages = "712--720",

journal = "Rubber Chemistry and Technology",

issn = "0035-9475",

publisher = "Rubber Division of the American Chemical Society",

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TY - JOUR

T1 - Long-chain branching and mechanism controlling molecular weight in Hevea rubber

AU - Sakdapipanich, Jitladda Tangpakdee

AU - Kowitteerawut, Tippawan

AU - Suchiva, Krisda

AU - Tanaka, Yasuyuki

PY - 1999

Y1 - 1999

N2 - The linear character of transesterified deproteinized natural rubber (DPNR-TE) was confirmed by the analysis of terminal groups with NMR and viscometric analyses. The branch content of DPNR rubber from fresh latex was found to range from 0.3 to 1.3 and 0.7 to 3.2, based on tri-and tetra-functionalities, respectively. The plot between the number of branch-points and molecular weight (MW) can be divided into three fractions: (A) the rubber fractions in MW ranging from 2.4 × 105 to 1.9 × 106; (B) between 1.9 × 105 and 2.4 × 105; and (C) those of MW less than 1.9 × 105. The fraction (A) showed the number of branch-points per a branched molecule (m) higher than that of tractions (B) and (C). This plot is superimposable with the bimodal molecular-weight distribution (MWD) of Hevea rubber, showing a good coinciding of peak-tops at the high and low MW fractions. It seems likely that there is a close relationship between the number of branch-point and bimodal MWD of natural rubber.

AB - The linear character of transesterified deproteinized natural rubber (DPNR-TE) was confirmed by the analysis of terminal groups with NMR and viscometric analyses. The branch content of DPNR rubber from fresh latex was found to range from 0.3 to 1.3 and 0.7 to 3.2, based on tri-and tetra-functionalities, respectively. The plot between the number of branch-points and molecular weight (MW) can be divided into three fractions: (A) the rubber fractions in MW ranging from 2.4 × 105 to 1.9 × 106; (B) between 1.9 × 105 and 2.4 × 105; and (C) those of MW less than 1.9 × 105. The fraction (A) showed the number of branch-points per a branched molecule (m) higher than that of tractions (B) and (C). This plot is superimposable with the bimodal molecular-weight distribution (MWD) of Hevea rubber, showing a good coinciding of peak-tops at the high and low MW fractions. It seems likely that there is a close relationship between the number of branch-point and bimodal MWD of natural rubber.

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DO - 10.5254/1.3538828

M3 - Article

AN - SCOPUS:0008625126

SN - 0035-9475

VL - 72

SP - 712

EP - 720

JO - Rubber Chemistry and Technology

JF - Rubber Chemistry and Technology

IS - 4

ER -

Long-chain branching and mechanism controlling molecular weight in Hevea rubber

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