Incorporation of Magnetite in Toughened PLA Nanocomposite: Tensile and Thermal Stability

In this study, liquid natural rubber (LNR) toughened polylactic acid (PLA) incorporated with magnetite (Fe3O4) nanocomposites were fabricated via melt-compounding in an internal mixer and followed by hot/cold pressing. The effects of ultrasonic treatment time (1-3 hours) and Fe3O4 (0.5-4.0 wt%) nanoparticles loading on tensile, morphology and thermal stability were investigated. Based on tensile testing results, the ultrasonication time of 1 hour was served as the most suitable treatment period to achieve the optimum distribution of Fe3O4 within PLA/LNR matrix. Among the investigated nanoparticles loading, 1 wt% Fe3O4 nanocomposite presented the highest tensile strength of 23.7 MPa, Young’s modulus of 1293.5 MPa and strain at break of 2.8%. SEM micrographs showed that the over-treated nanocomposites with 2-3 hours and over-high nanoparticles loading had resulted in the formation of clusters in the matrix. With increasing Fe3O4 loading, the decomposition of PLA/LNR nanocomposites was initiated earlier.

Studies on reinforcing effect of industrial nano silica in chloroprene vulcanizates containing carboxy-terminated liquid natural rubber

Maleic anhydride was chemically attached to depolymerized natural rubber, and the product was named as carboxy-terminated liquid natural rubber (CTNR). The CTNR can act as a potential plasticizer in chloroprene (CR) vulcanizates. This paper describes the use of commercial nano silica (NS) as a promising cost-effective filler, which can enhance the tensile properties and ageing resistance of the CR vulcanizates incorporated with CTNR (CR-CTNR). The enhancement in properties may be attributed to the increased bound-rubber content owing to the large surface area of the nano-sized filler. The characteristics of the NS-filled CR vulcanizates containing CTNR (NS CR-CTNR) were compared with those containing amorphous silica. The NS CR-CTNR vulcanizates showed superior ageing and oil resistance due to the finer rubber filler interaction modified by ionic cross linking.

Preparation and characterization of liquid natural rubber through oxidative degradation with phenyl hydrazine and benzoyl peroxide-oxygen

The aim of this research was to synthesize liquid natural rubber (LNR) from Natural rubber (SIR-20) by chain scission method in the presence of oxygen gas and difference of peroxides, phenyl hydrazine and benzoyl peroxide. The chain scission reaction was conducted in solution of xylene in close system. SIR-20 was diluted xylene before flushing with oxygen and the addition of the peroxide. The degradation oxidation by the oxygen and the peroxides was processed at 60°C for 24 hours. The degradative oxidation product was re-precipitated by adding the excess of methanol and filtrated before dried in vacuum oven 60°C for 24 hours. The dried product was characterized by Fourier Transform Infra Red (FTIR). It was found that the liquid natural rubber product successfully degraded by chain scission process as shown the change of the peak area intensity of infrared absorption. It was showed the peaks area intensity of O-H and carbonyl group of liquid natural rubber spectra increased.

Hydrogenated Liquid Natural Rubber for Compatibility Enhancement of Poly(lactic acid) and Natural Rubber Blends

Non-catalytic hydrogenation of liquid natural rubber (LNR) via thermal decomposition of 2,4,6-trimethylbenzenesulfonylhydrazide (MSH) is reported in this study. Parameter studies of the hydrogenation reaction were performed by utilizing the combination of response surface methodology and central composite rotatable design (RSM/CCRD). The effects of each variable and the interaction between two variables (i.e. the MSH:LNR weight ratio and reaction time) were studied. Statistical analysis showed that the reaction time had significantly affected the hydrogenation percentage. A reduced quadratic model equation with the coefficient of determination (R2) value of 0.9875 was developed. The optimized condition as predicted by the software was compared with the experimental data, which deviated in only 0.67, hence indicating that this model was reliable and able to predict the hydrogenation percentage accurately. Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies were used to characterize the microstructure of LNR and hydrogenated liquid natural rubber (HLNR). HLNR was then used as compatibilizer to improve the miscibility of poly(lactic acid)/natural rubber blends. With an addition of 4% HLNR, the tensile strength and impact strength of the blends were slightly improved.

UTILIZATION OF BINARY BLENDS OF LIQUID NATURAL RUBBER AND POLYVINYL ACETATE IN EMULSION PAINT

Studies were conducted on blends of liquid natural rubber (LNR) and polyvinyl acetate (PVAc).The two polymers were characterized based on their physicochemical properties, and used in paint production. Results obtained showed that viscometric measurement and density of the polymers did not differ much. Five paints of different compositions labeled; Paint 1 (100% PVAc), Paint 2 (100% LNR), Paint 3 (75% LNR: 25% PVAc), Paint 4 (50% PVAc: 50% LNR), and Paint 5 (25% LNR: 75% PVAc) using standard emulsion paint formulation and method of production were employed. The paint samples were subjected to quality test. Most of the emulsion paint showed good quality test when compared by the Standard Organisation of Nigeria (SON). Paint 1 had an excellent viscosity and adhesion when compared with Paint 2 and other samples. Also, Paint 5 recorded 22.0poise for viscosity and 0.68kgf for adhesion when compared with other paint blends. This shows that, emulsion paint formulated blends of LNR/PVAc with percentage composition 25% LNR; 75%PVAc exhibited best performance characteristics in terms of test conducted. The results suggest that LNR and PVAc are compatible as binders in emulsion paint production. Therefore, LNR/PVAc blends could be used as binder in the coating industry as an alternative to PVAc binder based emulsion paint.

EVALUATION OF THE CHARACTERISTICS OF PLASTIC EXPLOSIVE ADHERED BY LIQUID NATURAL RUBBER

Plastic explosive (PBX) is an explosive that a polymer binder is used to reduce the sensitivity of high explosives for various applications. This paper presents the characteristics of the PBXs based on liquid natural rubber (LNR) and hexogen (RDX). The PBXs are prepared according to a modified formulation of the Composition C-4. The plasticity of the PBXs is determined according to the MIL-STD-650 method 211.1. The uniaxial compression of the PBXs examined by the STANAG 4443. The test of the sensitivity of PBXs to friction is carried out by STANAG 4487. The thermal stability is tested by the STANAG 4556 at 100 oC for 40 hours. The results indicated that the plasticity is found to be more than 0.018 in accordance with the MIL-C-45010A. Further, the modulus of elasticity, yield strength, and strain can be adjusted by the composition of the LNR binder. In addition, the frictional sensitivity of the PBXs is significantly reduced to more 360 N of the load. The thermal stability is in the range of 0.156 to 0.225 ml.g-1 and completely meets technical requirements. Therefore, the direction of using LNR as a binder for PBXs gives acceptable results for further researches.