Seasonal and clonal variations in technological and thermal properties of raw <i>Hevea</i> natural rubber

Galiani, Patrini D.; Martins, Maria Alice; Gonçalves, Paulo de Souza; McMahan, Colleen; Mattoso, Luiz H. C.

doi:10.1002/app.34040

Cited by 14 publications

(8 citation statements)

References 25 publications

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“…The trait Po provides an estimate of the length of the polymeric chain and the state of degradation of the raw material 17 . The studied genotypes exhibited an average P O value of 57.69 ± 9.9%.…”

Section: Discussionmentioning

confidence: 99%

“…All of the genotypes studied exhibited an average Po value higher than the minimum established by the standard (Po = 30) 39 , indicating that they produce rubber with long polymer chains. Mooney viscosity (V R ) indicates the resistance of natural rubber to a rotor operating at a constant speed at ML (1 + 4) 100°C 17 . The average value of this trait across the genotypes was approximately V R = 99.46, with the highest value found for RRIM 713 (V R = 118) and the lowest for PB 326 (V R = 65).…”

Section: Discussionmentioning

confidence: 99%

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Genetic diversity associated with natural rubber quality in elite genotypes of the rubber tree

Sant’Anna

Gouvêa

Martins

et al. 2021

Sci Rep

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The objective of this study was to evaluate the genetic variability of natural rubber latex traits among 44 elite genotypes of the rubber tree [Hevea brasiliensis (Willd. ex Adr. de Juss.) Müell. Arg.]. Multivariate analysis and machine learning techniques were used, targeting the selection of parents that demonstrate superior characters. We analyzed traits related to technological or physicochemical properties of natural rubber latex, such as Wallace plasticity (P0), the plasticity retention index [PRI (%)], Mooney viscosity (VR), ash percentage (Ash), acetone extract percentage (AE), and nitrogen percentage (N), to study genetic diversity. Multivariate [unweighted pair group method with arithmetic means (UPGMA) and Tocher)] and machine learning techniques [K-means and Kohonen’s self-organizing maps (SOMs)] were employed. The genotypes showed high genetic variability for some of the evaluated traits. The traits PRI, Ash, and PO contributed the most to genetic diversity. The genotypes were classified into six clusters by the UPGMA method, and the results were consistent with the Tocher, K-means and SOM results. PRI can be used to improve the industrial potential of clones. The clones IAC 418 and PB 326 were the most divergent, followed by IAC 404 and IAC 56. These genotypes and others from the IAC 500 and 400 series could be used to start a breeding program. These combinations offer greater heterotic potential than the others, which can be used to improve components of rubber latex quality. Thus, it is important to consider the quality of rubber latex in the early stage of breeding programs.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Genetic diversity associated with natural rubber quality in elite genotypes of the rubber tree

Sant’Anna

Gouvêa

Martins

et al. 2021

Sci Rep

Self Cite

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“…The stretching vibration peak of the C═O bond occurs at a wavenumber of 1745 cm À1. 23,24 It should be indicated that PO is an unsaturated fatty acid salt, which contains many C═O double bonds. However, the two rubber groups have the same peaks, demonstrating that C═O in PO is consumed for reaction with amino groups in protein.…”

Section: Fourier-transform Infrared Spectroscopymentioning

confidence: 99%

Mechanism of the foaming agent‐assisted microwave drying process on the construction of natural raw rubber network and cross‐linking network

Xiao

Yan

Hao

et al. 2022

J of Applied Polymer Sci

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The drying process of natural rubber latex significantly affects the structure of the raw rubber network and vulcanizate crosslinking network, resulting in various anti-aging performances. In the present study, a microwave generator was used as an efficient source of clean energy; potassium oleate was introduced as a foaming agent to increase the porosity and water loss channel of the latex system. Aiming at dehydrating and drying natural rubber latex efficiently, an aging resistant rubber composite was prepared. Meanwhile, the mechanism of the foaming agent-assisted microwave drying process on the raw rubber network and the cross-linking network was studied. The experimental results show that the prepared rubber using by this process has higher plastic retention and fluidity. Moreover, it contains more non-rubber components (e.g. protein and acetone extract) and better network structure of raw rubber and vulcanized rubber. It is found that applying this process increases the tensile product by 13.5% and the retention rate of the tensile product after aging by 15.3 times. This process is important for the development of the rubber industry in the direction of green environmental protection, energy conservation, and high efficiency.

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“…Briefly, the manufacture of NR involves bioproduction, collection, coagulation, maturation and drying of natural rubber latex, where biocomponents as well as natural occurring network change significantly [ 17 ]. As a bioproduct of Hevea brasiliensis tress, the mesostructured and nonisoprene content of NR can be tuned by collecting NRL from different clones [ 16 , 18 ]. The macromolecular structure also changed after tree opening, while the weight-average molecular weight increased and stabilized after 7.5 months of tapping, the bimodal molar mass distribution primarily involved short chains at the opening of the trees [ 19 ].…”

Section: Introductionmentioning

confidence: 99%

Effect of Nonisoprene Degradation and Naturally Occurring Network during Maturation on the Properties of Natural Rubber

et al. 2022

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It well-known that the superior performance of natural rubber (NR) compared to its synthetic counterpart mainly derives from nonisoprene components and naturally occurring network, which varies during the progress of the maturation and thereby results in technically graded rubber with different properties. However, identifying the roles of these two factors in the forming of excellent performance of NR is still a challenge as they change simultaneously during the maturation process. Here, influences of naturally occurring networking and nonisoprene degradation on the components, structures and properties of NR were systematically investigated by tailored treatments of maturation. It was found that the maturation-induced formation of natural network structure contributes to the increase in initial plastic value, Mooney viscosity and gel content for un-crosslinked NR, while the decomposition of nonisoprene components plays a dominant role in improving the mechanical properties of vulcanized NR. Stress-strain curve and Mooney-Rivlin analysis demonstrate that the biodegradation of the nonisoprene components significantly boost the vulcanization process, which significantly increases the number of chemical cross-link networks and effective cross-link density of the material, greatly improving the mechanical properties of NR vulcanizates. This resulted in the tensile strength of TSR 10CV being able to reach 22.6 MPa, which is significantly improved compared to 15.8 MPa of TSR 3CV. Evidenced by tubular model fitting, the increase in chemical cross-linking points effectively reduces the movable radius of the molecular chain under dynamic loading, making the molecular chain more difficult to move, which suppresses the entropy change under dynamic loading and consequently endows NR excellent dynamic mechanical properties. This resulted in a significant decrease in the temperature rising of TSR 10CV to 3.3 °C, while the temperature rising of TSR 3CV was still as high as 14.5 °C. As a minor factor, the naturally occurring network improves the mechanical properties of vulcanizates in the form of sacrificial bonds.

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Seasonal and clonal variations in technological and thermal properties of raw Hevea natural rubber

Cited by 14 publications

References 25 publications

Genetic diversity associated with natural rubber quality in elite genotypes of the rubber tree

Genetic diversity associated with natural rubber quality in elite genotypes of the rubber tree

Mechanism of the foaming agent‐assisted microwave drying process on the construction of natural raw rubber network and cross‐linking network

Effect of Nonisoprene Degradation and Naturally Occurring Network during Maturation on the Properties of Natural Rubber

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