Hydroxyl-terminated Natural Rubber Research Articles

The Preparation of Hydroxyl-Terminated Deproteinized Natural Rubber Latex by Photochemical Reaction Utilizing Nanometric TiO2 Depositing on Quartz Substrate as a Photocatalyst.

Hydroxyl-terminated natural rubber (HTNR) is a product of interest for making natural rubber (NR) easy and versatile for use in a wide range of applications. Photochemical degradation using a TiO2 film that has been deposited on a glass substrate is one of the fascinating methods of producing HTNR. Nevertheless, light energy is wasted during the photodegradation process because a glass substrate has a cutoff for ultraviolet light. To enhance the effectiveness of the process, a quartz substrate was coated with the TiO2 film for photochemical breakdown. X-ray diffraction (XRD) spectroscopy and atomic force microscopy (AFM) were applied to investigate the TiO2 deposited on glass and quartz substrates. In addition, the influence of several factors, such as rubber and surfactant concentrations, on the reaction was investigated. After the reaction, the properties of the rubber products, including intrinsic viscosity, molecular weight, and microstructure, were determined. A unique diffraction peak for the anatase (101) phase could be observed in the TiO2 film deposited on the quartz substrate, resulting in photochemical activity and photocatalytic efficiency significantly higher than those of the substrate made of glass. In the scenario of deproteinized NR (DPNR) latex containing 10% DRC, 20% w/w H2O2, and TiO2 film coated on a quartz substrate, the HTNR could be manufactured effectively.

Thermo-mechanical and antimicrobial properties of natural rubber-based polyurethane nanocomposites for biomedical applications

A polyester-type polyurethane (PU) was prepared using hydroxyl-terminated natural rubber (HTNR) as the soft polymer segments, 4,4-methylene dicyclohexyl diisocyanate (H12MDI) as the hard segments and 1,4-butane diol (BDO) as a chain extender. A simple one-shot bulk polymerization method using tetrahydrofuran (THF) as the solvent was chosen. The molar ratio of (H12MDI:HTNR:BDO) was fixed at 1.05:0.5:0.5. The pristine PU and its composite films with titanium nanoparticles (TiO2), silver nanoparticles (AgNPs) and benzoic acid (BA) were prepared with a constant 0.5 wt% loading of the antimicrobial fillers. The pristine PU and PU composite films were obtained by solution casting and drying at 60 °C in a vacuum oven. The effects of the antimicrobial fillers on the physical structure, mechanical properties, thermal properties, and antimicrobial activities were investigated. The SEM images showed that TiO2 and AgNPs aggregated. The aggregates reduced the films’ tensile strength as they obstructed the transfer of mechanical loads from PU matrix to the dispersed fillers. In contrast, BA was clearly well dispersed in the matrix giving much better mechanical properties (12 MPa tensile strength and 278% strain at break) and the PU–BA films were transparent. The PU–BA composites appear promising for biomedical applications.

Renewable Interfacial Modifier for Silica Filled Natural Rubber Compound

A main problem of using silica as reinforcing filler in natural rubber (NR) compound is a poor dispersion of silica in the rubber matrix due to incompatibility between them. As silica contains high silanol groups on its surface, these polar groups promote strong filler-filler interactions leading to high degree of aggregation and agglomeration of silica particles. To overcome this drawback, many types of modifiers have been applied into silica filled recipes. In this work, a renewable and sustainable interfacial modifier, namely low molecular weight hydroxyl terminated natural rubber (HTNR). HTNR was prepared by controlled epoxidation and cleavage of natural rubber, following by reduction reaction of the obtained carbonyl telechelic natural rubber. Influence of the prepared interfacial modifier on enhancement of rubber-filler interaction was studied by focusing on the cure characteristics and the mechanical properties of silica filled natural rubber at a fixed silica content of 30 phr. In comparison with silica filled compound without silane coupling agent, shorter scorch and cure times, lower Payne effect and higher tensile strength of silica filled natural rubber were achieved with the presence of interfacial modifier at 2.4 parts per hundred parts of rubber (phr). This was attributed to an active reaction of silanol groups with interfacial modifier and compatibility between modifier and natural rubber. For HTNR-treated compound to obtain optimum properties, mixing should be carried out at initial mixing temperature of 300C, mixing time of 12minutes, and rotor speed of 60rpm. However, TESPT is more effective than HTNR because it imposes better properties than HTNR.

Physical Properties of Poly(lactic acid)/Hydroxyl Terminated Natural Rubber Blends

SummaryThe objective of the study is to use hydroxyl‐terminated natural rubber (HTNR) as the toughening modifier for poly(lactic acid) (PLA). Photochemical degradation of natural rubber by ultraviolet radiation from high pressure mercury vapor lamp was used as depolymerization and hydroxylation of natural rubber. Molecular weight of HTNR was 25,000 () and estimation of hydroxyl number of HTNR according to ASTM D4274‐11 was 2.04 mg KOH/g. The present of hydroxyl group was confirmed by FT‐IR, 1H‐NMR and 13C‐NMR spectrum. HTNR was blended with PLA in the ratio of 100/0, 100/3, 100/5, 100/10, and 100/15. Tensile and impact tests were carried out according to ASTM D638 and D256 respectively. It was found that tensile strength and tensile modulus of the PLA/HTNR blends were not significantly decreased whereas elongations at break were increased up to about 9 times compared with neat PLA. For impact properties, the results showed that impact strength of PLA was significantly increased up to 4 times with an addition of 10 wt% HTNR. SEM micrographs of the blends showed well disperse of HTNR particles and the occurrence of ductile fracture.

Hydroxyl Terminated Natural Rubber (HTNR) as a Binder in Solid Rocket Propellant

Controlled degradation of deproteinized natural rubber by oxidative method using cobaltous leading to the formation of telechelic liquid natural rubber (TLNR) has been the subject of study in the current work. Hydroxyl-terminated natural rubber (HTNR) having number-average molecular weights (Mn) below 10,000 gmol-1 were synthesized at temperatures 60°C using Cobalt bis (acetyl acetonate) (Co) in the presence of ethanol and Sodium borohydride. The HTNR were characterized structurally by using Fourier Transform Infrared (FTIR), Gel Permeation Chromatography (GPC) and Nuclear Magnetic Resonance (NMR) spectroscopy. From the FTIR and GPC analysis, one hour reaction showed the lowest Mn around 6691 gmol-1 comparable to Hydroxyl terminated polybutadiene (HTPB) which were 7708 gmol-1. As the reaction time increases the Mn also increase up to 8 hours of reaction. FTIR indicated that the synthesized HTNR contained hydroxyl end groups. The study showed the optimum percentage of Cobalt bis (acetyl acetonate) is 5% which produce the lowest molecular weight. Next, the HTNR underwent crosslinking reaction with isophore diisocyanate (IPDI). Then, metal fuel (aluminium powder, Al), oxidizer (ammonium perchlorate, AP) and HTNR were mixed together and went through compression process to produce solid rocket propellant. Burning rate obtained from HTNR samples were 2.78 mms-1 which were equivalent to HTPB samples which is 2.94 mms-1.

Development of Solid Rocket Propellant based on Isophorone Diisocyanate – Hydroxyl Terminated Natural Rubber Binder

In this work, a novelty solid propellant based on Isophorone Diisocyanate (IPDI) with Hydroxyl Terminated Natural Rubber (HTNR) binder network was successfully developed. The preparation of Liquid Natural Rubber (LNR) by chemical degradation Deprotenized Natural Rubber (DPNR) using cobaltous was carried out. From the FTIR spectroscopy, a broad hydroxyl group peak at 3444cm-1 was obtained from HTNR. Rubber network depict a strong carbonyl group C=O at 1714cm-1 and amine group N-H at 3433cm-1. NMR analysis also proves that there was hydroxyl group presence in the sample where broad peak at range 1-3 ppm and 3.5 ppm peak for -HOCH2CH2CH2-. Four different mol ratio of HTNR with IPDI was carried out to find the best formulation with good properties as propellant. Flory-Rehner equation depict that only slightly increasing occur with higher IPDI mol ratio but mixing with Ammonium Perchlorate (AP) and Aluminium Powder (AL) significantly improve the crosslink density. Melting point for HTNR is near to room temperature and it increase abruptly after crosslink with IPDI up to range of 148-150 °C. For all formulation, cross section morphology showed occurrence of porosity and brittle type of failure however HTNR has good contact with AL and AP. 2 : 1 molar ratio depict the best burning rate but the combustion characteristic shows less energy and spark compared to HTPB binder.

Natural Rubber Based Fuel Rich Propellant for Ramjet Rocket

Development of fuel rich propellants for air-breathing propulsion is one of the frontier areas of research. This carries less oxidiser than the normal propellants, uses ram air for complete combustion and is heavily metallised. Studies were conducted at VSSC for the development of hydroxyl-terminated natural rubber (HTNR)-based Mg and Mg-Al alloy-filled polyurethane systems. The HTNR prepolymer was modified to make it free of acid functionality so as to avoid reaction with the metals and was then reacted with calculated amount of propylene oxide in the presence of tertiary amine catalyst at room temperature. Various levels of Mg and Mg-Al alloy were used in different compositions and the effect on propellant characteristics was studied. TMP and butane diol were used for higher crosslinking, chain extension, etc and their effects were evaluated. Propellant compositions using 30-35 per cent by weight of Mg/Mg-Al alloy with the modified prepolymer have been developed. They exhibit good processibility and mechanical properties. The feasibility of room temperature curing was attempted. Motors weighing 2 kg with 100 mm OD and 200 mm length were successfully static-tested in the primary mode for performance evaluation.

Thermoset polyurethanes from hydroxyl‐terminated natural rubber

Thermoset polyurethanes from hydroxyl‐terminated natural rubber

Development and evaluation of a novel binder based on natural rubber and high-energy polyurethane/composite propellants

Hydroxyl terminated natural rubber (HTNR) was prepared by the depolymerization of masticated natural rubber in the presence of H2O2 in toluene. Probable mechanisms leading to the formation of side reaction products are proposed based on the analytical data. A comparative study of some formulation variables was made for their effect in improving the flow characteristics and mechanical properties of an aluminized polyurethane (PU) propellant system based on HTNR. This PU system has also been compared for its theoretical performance characteristics with some other state-of-the-art systems.