scholarly journals Preparation and Characterization of Low-Molecular-Weight Natural Rubber Latex via Photodegradation Catalyzed by Nano TiO2

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1216 ◽  
Author(s):  
Suhawati Ibrahim ◽  
Nadras Othman ◽  
Srimala Sreekantan ◽  
Kim Tan ◽  
Zairossani Mohd Nor ◽  
...  

Natural rubber is one of the most important renewable biopolymers used in many applications due to its special properties that cannot be easily mimicked by synthetic polymers. To sustain the existence of natural rubber in industries, modifications have been made to its chemical structure from time to time in order to obtain new properties and to enable it to be employed in new applications. The chemical structure of natural rubber can be modified by exposure to ultraviolet light to reduce its molecular weight. Under controlled conditions, the natural rubber chains will be broken by photodegradation to yield low-molecular-weight natural rubber. The aim of this work was to obtain what is known as liquid natural rubber via photodegradation, with titanium dioxide nanocrystals as the catalyst. Titanium dioxide, which was firstly synthesized using the sol–gel method, was confirmed to be in the form of an anatase, with a size of about 10 nm. In this work, the photodegradation was carried out in latex state and yielded low-molecular-weight natural rubber latex of less than 10,000 g/mol. The presence of hydroxyl and carbonyl groups on the liquid natural rubber (LNR) chains was observed, resulting from the breaking of the chains. Scanning electron microscopy of the NR latex particles showed that titanium dioxide nanocrystals were embedded on the latex surface, but then detached during the degradation reaction.

2014 ◽  
Vol 1024 ◽  
pp. 193-196
Author(s):  
Ibrahim Suhawati ◽  
Asrul Mustafa

The molecular weight of natural rubber (NR) can be reduced via depolymerization reaction to produce liquid natural rubber (LNR) with a molecular weight less than 50 000 g/mol. In the reaction, hydrogen peroxide and sodium nitrite were added to natural rubber latex to initiate a redox type reaction which then breaks the NR chain. Low permeation of reagents into latex particles allows the degradation to occur greater at the latex particle surface relative to the inner core contributes to high molecular weight distribution (MWD) or polydispersity of the LNR obtained. In this recent works, the reaction was carried out in a biphasic medium consisting of water and toluene phases. Toluene swells latex particles as indicated by the SEM micrographs showing changes in the size of latex particles. This occurrence is suggested to increase the influx of reagents into the latex particles. Consequently, with higher permeation of reagents into the latex particles resulted in the decrease of molecular weight and lower polydispersity of the LNR obtained. Chemical structure analysize showed that the LNRs obtained were attached with hydroxyl and carbonyl groups.


1998 ◽  
Vol 71 (4) ◽  
pp. 795-802 ◽  
Author(s):  
Jitladda Tangpakdee ◽  
Megumi Mizokoshi ◽  
Akiko Endo ◽  
Yasuyuki Tanaka

Abstract Low molecular-weight natural rubber (LNR) and LNR latex was prepared by oxidative degradation of de-proteinized natural rubber (DPNR) latex in the presence of 1 phr of K2S2O8 and 15 phr of propanal, by shaking at 60 °C. The intrinsic viscosity [η] of DPNR with only K2S2O8 decreased from 7.2 to 5.5 after 2 h and then increased to 6.5 after 3 h. By the addition of propanal, DPNR showed a significant decrease in the [η] value of LNR with [η] of about 0.5 after 5 h of the reaction, while rubber from high-ammonia natural rubber (HANR) latex showed a slight decrease in [η]. The concentration of latex and the kind of surfactant used for stabilizing the latex had little effect on the degradation rate of DPNR latex. The LNR latex is stable as the latex form and the dried rubber coagulated from latex is transparent and colorless. The LNR was a telechelic polymer containing aldehyde and ketone groups at both terminals as determined by NMR and molecular weight analyses.


2014 ◽  
Vol 1024 ◽  
pp. 108-111 ◽  
Author(s):  
Kim Song Tan

The feasibility of synthesizing TiO2 nanoparticles using tetramethylammonium hydroxide (TMAOH) stabilized titanium tetraisopropoxide (TTIP) in natural rubber latex medium was investigated. The TiO2 nanoparticles were separated using centrifugation and were characterized using SEM, TEM and XRD. It was found that the weight fraction of latex loaded in the reaction vessel affects the shape and size of the TiO2 particles


2016 ◽  
Vol 83 (1) ◽  
Author(s):  
. Siswanto

AbstrakLateks alam maupun produk jadi yang berasal dari karet alam diketahui mengandung protein alergen. Namun demikian identifikasi jenis protein allergen belum banyak dilaporkan. Penelitian ini bertujuan untuk mendeteksi protein alergen dari sarung tangan dan lateks karet alam menggunakan metode immuno-chemiluminescense. Protein di-ekstrak dari tiga fraksi sentrifugasi lateks (serum B, serum C dan partikel karet) serta tujuh jenis sarung tangan komersial, kemudian dipisahkan berdasarkan berat molekulnya melalui Gel elektroforesis 1-D (SDS PAGE) dan 2-D. Selanjutnya untuk deteksi protein allergen secara immuno-chemiluminescense dilaku-kan imunobloting menggunakan serum Ig_E tiga pasien yang terbukti positif alergi terhadap protein asal sarung tangan lateks, kemudian diwarnai dengan Sypro Ruby protein blot fluorescence. Hasil penelitian menunjukkan bahwa  berdasarkan hasil analisis Western blot one-DE sampel protein lateks menggunakan serum tiga orang tenaga medis yang terbukti positif alergi terhadap protein lateks, maka dapat diidentifikasi 14 jenis protein alergen pada sarung tangan lateks, empat diantaranya merupakan pita major yaitu Berat Molekul (BM) 35, 38, 46 dan 56 kDa. Protein allergen pada sarung tangan tersebut kemungkinan berasal dari bagian C-serum terutama protein  BM 46 dan 56 kDa ataupun campuran antara C-serum dan B-serum dari lateks karet alam. Hal ini dibuktikan bahwa dari sampel C-serum lateks dapat teridentifikasi 12 protein alergen,  empat diantaranya merupakan pita major yaitu BM 42, 46, 51 dan        56 kDa. Sedangkan dari sampel B-serum teridenti-fikasi tiga pita major dengan BM 14, 16 and 51 kDa. Hasil analisis Western blot 2-DE ekstrak protein sarung tangan menggunakan serum tiga orang tenaga medis yang terbukti positif alergi terhadap protein lateks, maka dapat diidentifikasi 12 - 13 spot protein alergen dengan pI at 4.0 to 7.0 dan yang paling dominan adalah dengan BM 23, 35, 38, 42, 45, 46 kDa.Abstract  Natural rubber latex and finished products derived from natural rubber is known to contain allergenic proteins. Nevertheless identification of allergenic protein has not been widely reported. This study aims to detect the protein allergens from the glove of hands and natural rubber latex using immuno-chemiluminescense. Proteins extracted from the latex centrifugation three fractions (serum B, serum C and rubber particles) as well as seven types of commercial gloves, then separated by molecular weight through 1-D gel electrophoresis (SDS PAGE) and 2-D. Furthermore, for the detection of allergen proteins in immuno-chemiluminescense performed immunoblotting using the serum IgE three patients who tested positive for allergy to latex gloves native protein, and then stained with fluorescence Sypro Ruby protein blot. The results showed that based on the results of Western blot analysis of one-DE latex proteins using serum samples three medical personnels who tested positive for allergy to latex proteins, we can identify 14 types of protein allergens in latex gloves, four of which are major bands that having Molecular Weight (MW) 35, 38, 46 and 56 kDa. Protein allergen on the gloves are likely to come from the C-serum protein mainly MW 46 and 56 kDa, or a mixture of C-serum and B-serum of natural rubber latex. It was proved that from C-serum samples could be identified as many as 12 protein latex allergens, four of which were major bands that MW 42, 46, 51 and 56 kDa. While the B-serum samples identified three major bands with MW 14, 16 and 51 kDa. Results of Western blot analysis of 2-DE protein extracts glove using the serum three medical personnel who tested positive for allergy to latex proteins, it could be identified 12-13 allergen protein spot with pI at 4.0 to 7.0 and most dominant is the MW 23, 35, 38, 42, 45, 46kDa.


2016 ◽  
Vol 54 (3) ◽  
pp. 340 ◽  
Author(s):  
Le Duc Giang ◽  
Dinh Long Mong Thao ◽  
Hoang Thi Huong ◽  
Le Thi Thu Hiep

Hydroxyl terminated liquid natural rubber (HTLNR) was prepared by the depolymerization of deproteinized natural rubber (DPNR) in mixture of toluene and water at 60oC for 24 hours in the presence of ammonium persulfate as an initiator and tetrahydrofuran (THF) as a homogenizing agent. GPC analysis revealed that the number-average molecular weight (Mn) and weight-average molecular weight (Mw) of HTLNR were found to be 4.334×103 g/mol and 11.702×103 g/mol, respectively, with polydispersity index (PDI) of  2.7. The chemical structure of HTLNR was determined by FTIR and 1H-NMR and 13C-NMR spectroscopic analysis. The mechanism of depolymerization and hydroxylation of NR to form HTNR based on the analytical data is also suggested in this study.


2021 ◽  
Vol 59 (5) ◽  
Author(s):  
Lai Thi Kim Dung ◽  
Le Nghiem Anh Tuan ◽  
Bui Duy Du

Natural rubber latex (NRL) with “low protein content” is regarded as less allergenic latex for medical gloves, medical products, condoms, etc. Therefore, this study was conducted to strengthen the fundamental approach of making “low protein NRL” via oligosaccharide hydroxyl ethyl cellulose (oligoHEC) treatment. OligoHEC (Mw ~10,000 g/mol) is degradation product of HEC (Mw ~90,000 g/mol) by 1.5% H2O2 treatment combined with hydrothermal at temperature for 30 minutes at 121°C, pressurized rate of 0.38 mPa by autoclave equipment. OligoHECs were employed to form electrical bonds with the proteins. The target of this study is protein content of NRL ≤ 50 µg/g of rubber, we surveyed the effect of oligoHEC treatment towards the solution proteins content of NRL. Results show that oligoHEC at low concentration (0.25%) effectively extracted the proteins molecules. Interestingly, allergenic proteins content of NRL serum was decreased proportionally (< 50 µg/g of rubber) with the upsurge of oligoHEC concentration, suggesting deactivation of allergenic. These preliminary results indicate a potential approach to produce low allergenic risk NRL products with adding of oligoHEC


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