Effects of Type and Concentration of Initiator on Grafting of Acrylic Monomer onto Depolymerized Natural Rubber

Highly crosslinked epoxy resin for engineering applications is normally stiff but brittle. Therefore, many attempts have been made to improve its toughness. Nowadays, several studies have been done on toughening epoxy resin using natural rubber (NR) because it is abundant and comes from renewable resource. In the present work, NR was subjected to depolymerize in order to achieve molecular dispersion of NR in epoxy matrix. Depolymerized natural rubber (DNR) was prepared by adding a carbonyl compound to natural rubber latex solution and subjecting the mixture to air oxidation in the presence of a radical forming agent at 70°C. In addition, the interfacial adhesion between rubber and matrix must be present to achieve a significant increase in toughness. Hence, DNR was further functionalized by grafting with monomer mixture of methyl methacrylate (MMA)/glycidyl methacrylate (GMA) (90/10 wt/wt%) in an amount of 50% based on rubber content. Solution polymerization was used to graft such monomers using 2 hours reaction times at a reaction temperature of 80oC. Two types of initiator used were benzoyl peroxide (BPO) and azo-bisisobutyronitrile (AIBN). The amounts of initiator in the grafting process were 1, 2, and 3 parts per hundred of DNR. Effects of type and concentration of initiator on grafting efficiency of MMA/GMA monomer mixture onto depolymerized natural rubber were studied by proton nuclear magnetic resonance (1H-NMR) analysis. The molecular weight of DNR was characterized by gel permeation chromatography (GPC). The results indicated good evidence for the formation of graft co-polymers in the presence of both initiators, AIBN or BPO. However, the amounts of grafted MMA/GMA on DNR backbone using BPO was higher than those on DNR backbone using AIBN.

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Effects of Frequency and Sonication Time on Ultrasonic Degradation of Natural Rubber Latex

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.747.721 ◽

2013 ◽

Vol 747 ◽

pp. 721-724 ◽

Cited By ~ 4

Author(s):

S. Utara ◽

U. Moonart

Keyword(s):

Molecular Weight ◽

Natural Rubber ◽

Average Molecular Weight ◽

Natural Rubber Latex ◽

Gel Permeation Chromatography ◽

Chain Scission ◽

Polymer Chains ◽

Rubber Latex ◽

Ultrasonic Degradation ◽

The Fourier Transform

Ultrasonic degradation of fresh latex was investigated at frequencies of 20 and 25 kHz, at a constant temperature of 25o C (±1o C) to avoid temperature-related effects. The time-dependent evolution of the molecular weight of the natural rubber latex was determined using gel permeation chromatography, and its structure by means of the fourier transform infrared (FTIR) technique. A 10 minute period of sonication resulted in reduction in the molecular weight of both the 20 and 25 kHz treated samples, the lowest average molecular weight () being obtained in the case of the 25 kHz sample. The of the 25 kHz sample also decreased with increasing latex concentration. However, after 30 minutes, fluctuations had occurred in both samples with respect to the and and also the molecular weight distributions, an effect possibly explained by the competing processes of chain scission and radically-induced cross-linking of the polymer chains. The FTIR results also suggest that the structure of polyisoprene is unaltered by ultrasonic wave treatment at these frequencies.

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Composite Materials Based on Natural Rubber Modified Epoxy Resin and Sisal Fiber

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.410.43 ◽

2011 ◽

Vol 410 ◽

pp. 43-46

Author(s):

Sawitri Srisuwan ◽

N. Prasoetsopha ◽

Nitinat Suppakarn ◽

Pranee Chumsamrong

Keyword(s):

Impact Strength ◽

Natural Rubber ◽

Epoxy Resin ◽

Flexural Modulus ◽

Neat Epoxy ◽

Proton Nuclear Magnetic Resonance ◽

Sisal Fiber ◽

Resonance Spectroscopy ◽

H Nmr ◽

The Impact

In the present work, bisphenol-A based epoxy resin was blended with methyl methacrylate (MMA)/glycidyl methacrylate (GMA) grafted depolymerized natural rubber (GDNR). GDNR/epoxy resin blend was composite with woven sisal fiber. GDNR was prepared by solution grafting MMA/GMA (90/10 w/w%) onto depolymerized natural rubber (DNR). The occurrence of GDNR was confirmed by proton nuclear magnetic resonance spectroscopy (1H-NMR). Amount of GDNR in the blend was 1 part per hundred resins. Impact strength of epoxy resin was increased by 62% when GDNR was added. Composites of GDNR/epoxy resin and woven sisal fiber were prepared by hand-lay up process. Amounts of woven sisal fiber in the composite were 3, 5 and 7% by weight (wt%). The flexural modulus of the composites was higher than that of neat epoxy resin and increased with increasing amount of woven sisal fiber. Nevertheless, flexural strength of all composites was lower than those of neat epoxy resin and the blend. Compared to neat epoxy resin, the impact strength of the composite containing 7 wt% woven sisal fiber was further increased to 114%.

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EXTRACTION OF LIGNIN FROM SUGARCANE BAGASSE BY DEEP EUTECTIC SOLVENTS (DESs)

Vietnam Journal of Science and Technology ◽

10.15625/2525-2518/57/3a/13951 ◽

2019 ◽

Vol 57 (3A) ◽

pp. 134

Author(s):

Bui Thi Thao Nguyen ◽

Nguyen Nhi Tru ◽

Thai Ngoc Minh Hoang ◽

Nguyen Hoang Duong ◽

Tran Manh Cuong

Keyword(s):

Sugarcane Bagasse ◽

Choline Chloride ◽

Gel Permeation Chromatography ◽

Renewable Resource ◽

Deep Eutectic Solvents ◽

Raw Material ◽

Proton Nuclear Magnetic Resonance ◽

Plant Cell Walls ◽

Average Molecular Mass ◽

Ft Ir

Lignin plays a crucial role as a structural material of plant cell walls and is also known as a significant renewable resource that has the potential to be a raw material for producing high value chemicals. The article aimed to research on the extraction of lignin from sugarcane bagasse by environmental method using deep eutectic solvents (DESs) containing choline chloride and formic acid. In the process, lignins dissolved in DESs were isolated from the solution by dilution with water and ethanol. The obtained lignin samples were characterized with UV - Vis (Ultraviolet – visible spectroscopy), FT-IR (Fourier-transform infrared spectroscopy), GPC (Gel permeation chromatography), and 1H-NMR (Proton nuclear magnetic resonance). The initial results showed that the extracted lignin obtained adequately distinct functional groups and the weight average molecular mass of the lignin was about 28265 g/mol.

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Preparation of Cyclized Deproteinized Natural Rubber in Latex State via a Combination of Benzotrichloride and Sulfuric Acid System, and Its Properties

Rubber Chemistry and Technology ◽

10.5254/1.3539412 ◽

2007 ◽

Vol 80 (2) ◽

pp. 365-377 ◽

Cited By ~ 8

Author(s):

Sa-ad Riyajan ◽

Yasuyuki Tanaka ◽

Jitladda T. Sakdapipanich

Keyword(s):

Sulfuric Acid ◽

Natural Rubber ◽

Reaction Times ◽

Catalyst System ◽

Proton Nuclear Magnetic Resonance ◽

Ionic Surfactant ◽

Gravimetric Analysis ◽

Infrared Spectrometer ◽

Deproteinized Natural Rubber ◽

Better Than

Abstract Partially cyclized deproteinized natural rubber (DPNR) in latex form was successfully prepared by using a combination of sulfuric acid (H2SO4) and benzotrichloride (PhCCl3) in the presence of Terric 320 as a non-ionic surfactant. The main parameters of the cyclization process such as various reaction times, dry rubber contents, concentrations of catalyst and temperatures were investigated. The resulting rubber was subjected to characterization by proton Nuclear Magnetic Resonance (1H-NMR), Fourier-Transform Infrared spectrometer (FTIR), Thermal Gravimetric Analysis (TGA), and Differential Scan Calorimeter (DSC). In addition, the topology of partially cyclized rubber was also analyzed by Transmittance Electron Microscopy (TEM). The mechanism will be also discussed. It was interesting to note that the obtained partially cyclized rubber using this catalyst system contained no gel, which was easily soluble in rubber solvents. This is different from the partially cyclized rubber obtained from the other methods. Through, using structural characterization, it was found that the PhCCl3 linked onto the rubber chain. It was also found that the thermal stability of this cyclized rubber was better than that of normal rubber. The efficiency of cyclization in this system could be increased by an increase of PhCCl3 concentration.

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