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Oil spills have caused adverse effects on the environment calling for more efficient oil removal techniques. This study highlights the use of liquid natural rubber (LNR) as the main raw material to produce competitive and effective oil absorbents. The absorbents were produced via vulcanization with the aid of foaming agents and were then characterized in terms of morphology and oil absorption capacity. The morphology analysis shows that the absorbents formed have irregular pores of 450-500 μm in diameter. It was found that the oil absorption capacities of the absorbents decrease with increasing crosslinker concentration and when subjected to higher-viscosity oils. The sorption capacity of the absorbent is capped at 7.67 g g -1, while the reusability of the absorbents is up to 13 times. These LNR-based absorbents open up new opportunities for potential designs of better and renewable oil absorbents. [ABSTRACT FROM AUTHOR]

Thermoplastic mengkuang composites are an alternative material to solve environmental pollution issues associated with synthetic polymers. Mengkuang, or Pandanus atrocarpus, raw fiber was cut, dried, ground, and sieved to the required size. The fiber was filled into the matrix of natural rubber (NR) and high-density polyethylene (HDPE) by melt blending via internal mixer. The blend of HDPE/NR at 60/40 ratio with fiber sizes of 125 µm, 250 µm, and 500 µm were prepared at fiber contents of 10%, 20%, and 30%. The effects of fiber size and fiber content on the thermoplastic composite were investigated using tensile test, impact test, water absorption, and field emission scanning electron microscopy (FESEM). The maximum tensile strength and tensile modulus were obtained at 20% fiber content of 250 µm fiber size. Impact strength gradually decreased with the increased percentage of fiber content at fiber size, 125 µm and 250 µm. The highest tensile strain at break and lowest water absorption was observed at 10% fiber content for all sizes being studied. The effects of fiber size on water absorption, and percentage of fiber content on impact strength and tensile strain at break were statistically significant (p < 0.05). [ABSTRACT FROM AUTHOR]

The use of mengkuang fiber (MK) as a filler in NR/HDPE/MK bio-composite was investigated. The suitability of MK as reinforcing filler was studied in terms of the mechanical properties and phase morphology formed. Melt-blending was performed using an internal mixer (Haake Rheomix 600). The processing parameters identified were 135 °C temperature, 45 rpm rotor speed and 12 min processing time. The optimum MK loading in 40/60 of NR/HDPE blend was obtained at 20 wt.% with the tensile strength, tensile modulus, and impact strength of 12.4 MPa, 377 MPa and 17.2 kJ/m2, respectively. These results showed an enhancement in tensile strength of 10.7% compared to the unfilled NR/HDPE blend. The maximum impact strength obtained at 5% fiber loading was 23.5 kJ/m2, which was 7.8% higher compared to unfilled NR/HDPE blend. The FESEM micrographs showed good adhesion between MK fiber and matrix. These mechanical properties enhancements proved the suitability of mengkuang fiber as potential reinforcing filler in NR/HDPE blend. [ABSTRACT FROM AUTHOR]

Two mixed-matrix membranes (MMM) for gas permeability test were prepared by introducing inorganic fillers (silica (SiO2) and magnesium oxide (MgO)) in the composite blend of epoxidized natural rubber (ENR) and polyvinyl chloride (PVC). Inclusion of SiO2 and MgO particles in the membranes resulted in pores formation as observed through scanning electron microscopy. Thermal study demonstrated that there were interaction between the fillers and polymer matrix with SiO2 exhibited better interaction. SiO2 was also observed to disperse more evenly in the membrane compared to MgO. The permeability of carbon dioxide (CO2) and nitrogen (N2) gases was measured in order to determine the effects of SiO2 and MgO in CO2/N2 separation performance of the ENR/PVC/filler membranes. CO2 was found to exhibit higher permeability compared to N2 for all the membranes. The gas permeability of ENR/PVC/SiO2 membrane was significantly higher than ENR/PVC/MgO and ENR/PVC membranes. Interestingly, despite having lower permeability, MgO-filled membrane exhibited higher CO2/N2 selectivity. When compared to the Robeson’s upper bound, it was found that introduction of fillers had improved gas separation performance of ENR/PVC membrane. [ABSTRACT FROM AUTHOR]

Toughened unsaturated polyester resins (UPRs) were prepared using two different reactive rubbers, namely, liquid natural rubber (LNR) and liquid epoxidized natural rubber (LENR). The effect of varying amounts of LNR and LENR on the morphology, thermal, and mechanical properties of UPR were evaluated. Fourier Transform Infrared spectroscopy was used to investigate the probable crosslinking reaction and changes in the functional groups on crosslinking. Field emission scanning electron microscopy and infinite focus microscopy were used to study the morphology of fracture surfaces. Tensile test showed that both the rubber-modified resins (1.5 wt %) improved tensile strength. The viscoelastic properties and thermal stability of the toughened polyesters were evaluated using dynamic mechanical thermal analysis and thermogravimetric analysis, respectively. A slight reduction in the glass transition temperature (Tg) of the polyester was reported on the addition of both the rubbers. An increment in impact strength and fracture toughness was observed at 1.5 wt % for LNR and 4.5 wt % for LENR-modified UPR. The results showed that both the liquid rubbers improved the mechanical properties of UPR. However, LENR-modified UPR exhibited a more significant improvement in the mechanical properties compared to LNR-modified UPR. [ABSTRACT FROM AUTHOR]

Natural rubber (NR) is a high molecular weight natural polymer and can be degraded to liquid natural rubber (LNR) leaving certain functional groups at the end of chains. In this study, LNR samples prepared via oxidative degradation using H2O2 and NaNO2 as reagents were found to have different end groups depending on the pH of the reaction medium. In an acidic medium, LNR with hydroxyl terminal groups was formed as the degradation reaction was initiated by hydroxyl radicals produced from decomposition of peroxynitrite acid. In contrast, a redox reaction took place in an alkaline medium to yield LNR with carbonyl terminal groups. The mechanisms of reaction are discussed and proposed to explain the formation of different end groups when reaction carried out in acidic and alkaline media. Chain degradation in an acidic medium seems to be more effective than in an alkaline medium, and thus yields LNR with lower Mn. [ABSTRACT FROM AUTHOR]

Poly(p-phenylene-2,6-benzobisoksazole) (PBO) and natural rubber (NR)/high density polyethylene (HDPE) composites were melt-blended in a Haake internal mixer. The tensile strength, tensile modulus, and impact strength increased with fiber loading and optimized at 20%. Incorporation of clay into the NR/HDPE/PBO composites resulted in an improvement of tensile strength for NR/HDPE/PBO composites compared to the systems without clay. However, addition of clay was only effective at low contents (5-7.5%). Additional improvement of tensile strength, tensile modulus, and impact strength of the hybrid composite was observed on addition of liquid natural rubber (LNR). Scanning electron micrographs of the samples had indicated that the presence of clay decreased the domain size of the dispersed phase. Results on dynamic response showed that incorporation of clay and LNR into the composites had increased the storage modulus and reduced the tan δ. The shift of glass transition temperature ( T) to higher values for composites also indicated good interaction between the fiber and the matrix. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers. [ABSTRACT FROM AUTHOR]

Natural rubber/high-density polyethylene (NR/HDPE) blend with rice husk (RH) filler and liquid natural rubber (LNR) as the compatibilizer was prepared using an internal mixer at 140°C and 50 rpm. The reinforcing effect and compatibilizing performance of the added reagents in the composites were evaluated from the mechanical and thermal properties, and blend homogeneity. The tensile and impact strength decreased with RH loadings in the matrix, while the tensile modulus and hardness showed an opposite trend. The weak filler–matrix interaction, resulting in poor filler dispersion and large agglomerated particle size, caused those properties to decrease. However, the mechanical properties of the composites improved with the addition of NR or LNR into the matrix. The dissolution effect caused interactions between the phases, leading to an improvement in the compatibility in the blend. Changes in morphology resulted in the shift of T g of the amorphous part of NR to higher temperatures, as observed in differential mechanical analysis (DMA) thermograms. Scanning electron microscopy (SEM) micrographs of the fractured surface had also revealed the good RH–matrix interaction and, thus, the dispersion of particles in samples with added LNR. [ABSTRACT FROM AUTHOR]

The article focuses on a study which examined the effects of clay and liquid natural rubber on the mechanical properties and morphology of natural rubber and high-density polyethylene (NR/HDPE)-aramid composites. A description of hybrid composites is provided. Materials used in the study are described. The effect of Twaron loading on the tensile strength and tensile modulus is revealed. An illustration of the scanning electron micrograph of Twaron in NR/HDPE blend is presented. Conclusions of the study are discussed.

Highlights • Addition of cell-g-PMMA improves the mechanical properties of biocomposites. • Addition of cell-g-PMMA increases the water contact angle of biocomposites. • Degradation of biocomposites decreases with an increase in cell-g-PMMA content. • Weight loss after burial was higher for biocomposites than for the polymer alone. Abstract In this study, modified agave cellulose fibre combined by graft copolymerisation with methylmethacrylate was tested as a potential reinforcement for polylactic acid (PLA)-natural rubber/liquid natural rubber blends. Mechanical, morphological, thermal, wetting, and biodegradation characterisations were performed to assess the influence of cellulose-graft-polymethylmethacrylate (cell-g-PMMA) content on the properties of biocomposites. The addition of cell-g-PMMA improved the mechanical properties of the composites because of the chemical interaction between PLA and PMMA. Thermal stability decreased slightly upon cell-g-PMMA addition because of the low thermal stability of PMMA. A soil burial test revealed that the degradation of composites decreased with an increase in the cell-g-PMMA content. However, the weight loss after burial, which directly affected the water absorption capacity, was still higher for the cell-g-PMMA composites than for the polymer alone. [ABSTRACT FROM AUTHOR]

Abstract A novel macroporous and oleophilic Natural Rubber (NR) foam is prepared through a vulcanization process using methanol (CH 3 OH) as solvent at different compositions of crosslinking agent (Disulphur Dichloride, S 2 Cl 2). NR was firstly modified to reduce its molecular weight by photochemical oxidation method to produce Liquid Natural Rubber (LNR). This spongy-like foam made of LNR was firstly reported here, has produced interconnected open-cell structures with pore volume ranged from 1.83 mL/g to 4.28 mL/g and diameter sizes between 2.09 μm and 13.24 μm. The absorption capability of LNR-foam resembled to the cotton fiber-based sorbent where it absorbed most of oil products by up to 9.39 g/g. The porous materials reached the saturation limit within 5 min of low-viscosity oils, and 15 min for higher-viscosity oils. In a simulated oil slick system, this LNR macroporous and hydrophobic foams maintained its high oil absorption capacity in the ranged of 3.54 g/g to 9.39 g/g. About 90% of absorbed oil is being recovered and the LNR-foams are able to perform up to 20 absorption cycles which demonstrated a good reusability. Hence, this new type of natural-based modified absorbent has the potentials to be commercialized. Highlights • This research proposed facile method of preparing foams made of LNR. • The absorbent efficiency is comparable to the commercial items. • The LNR foams absorb more than 10 types of oils. • The reusability of LNR foams up to 10 cycles. [ABSTRACT FROM AUTHOR]

Abstract Blends of PLA-NR with and without liquid natural rubber (LNR) as a compatibilizer were prepared using a melt blending process. Thermal stability and biodegradability properties of poly(lactic acid)-natural rubber (PLA-NR) blends were studied using thermogravimetric analysis and compost soil burial tests. The sample surface morphology after each burial cycle was observed by digital microscopy. Water absorption tests were also conducted to study the effect of water absorption on the sample degradation rate. The pure PLA sample exhibits no weight loss before day 150; however, the addition of NR causes a significant weight loss as early as day 30. Both NR and LNR effectively increased PLA degradation, with compatibilized blends at 8 wt% LNR degrading faster than uncompatibilized blends; these results are attributed to the high water absorption as well as poor adhesion between matrix. Meanwhile, the poor thermal stability of PLA improves greatly with the incorporation of both NR and LNR. Several factors such as water absorption and the adhesion between matrix may directly influence the thermal stability and biodegradability of the compatibilized PLA-NR blend. These comparative studies support a direct role of NR and LNR in PLA degradation properties. Graphical abstract Image Highlights • Poly(lactic acid) (PLA) blends were prepared with natural rubber (NR). • Liquid natural rubber (LNR) was used as a compatibilizer for the blends. • Both NR and LNR increased the thermal stability and degradation of PLA. • The absorption of water was identified as a factor to affect biodegradability. • The functional groups in LNR affect the properties of PLA. [ABSTRACT FROM AUTHOR]

The effect of telechelic liquid natural rubber (TLNR) compatibilizer on natural rubber (NR) modified by melt-blending with poly(lactic acid) (PLA-NR) is studied using infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and notched Izod impact testing to determine the structural, thermal and mechanical properties. Scanning electron microscopy (SEM) is used to relate these properties to the morphology of the blends and fracture surface of the impact samples. Through this, it is revealed that the addition of LNR significantly improves the tensile and impact strength of PLA-NR, with the greatest compatibilization effect achieved with 6 wt% LNR. This improvement is confirmed through FTIR analysis to be due to a chemical interaction between LNR and PLA that improves the phase morphology of the blend. [ABSTRACT FROM AUTHOR]

Unsaturated polyester resin (UPR) has been modified with a liquid epoxidized natural rubber (LENR). The addition of LENR improves the toughness, but it is inevitably accompanied by a significant loss in stiffness, yield strength, and thermal resistance. Incorporation of a rigid material into the LENR–UPR blend, such as cellulose nanocrystal (CNC), provided a ternary polyester nanocomposites with desire mechanical properties. In the present work, the effects of different CNC and LENR content on the nanocomposite morphology and mechanical properties were examined. Morphological studies revealed that the size of the rubber particles is independent of the rubber content due to the chemical interaction of rubber and matrix; however, the size of the LENR particles increased with increasing CNC content. Tensile tests indicated that the blend’s tensile strength and elastic modulus could be further improved by incorporation of the CNCs. The high crystallinity and surface area of CNCs were the main factors for improvement of tensile properties of the blend. Moreover, the impact energy of the UPR improved when it was modified with the LENR, and even further improvement was achieved with the CNC addition to form nanocomposites. Dynamic mechanical thermal analysis (DMTA) showed that the storage modulus of nanocomposites with 1.5 wt% rubber content was lower than those with 4.5 wt% LENR; however, both samples showed a higher storage modulus than the neat UPR and the unfilled blend. The glass transition temperature ( T g ) of the UPR decreased with the LENR addition, but improved with the addition of CNCs. The nanocomposites prepared with a higher LENR content displayed better mechanical properties than those with low LENR content. [ABSTRACT FROM AUTHOR]

Abstract: The use of rice husk (RH) powder as a reinforcing filler in blends of natural rubber and high-density polyethylene (NR/HDPE) was studied via surface modification of the particle surface. The RH powder was pre-washed with sodium hydroxide (NaOH) prior to coating with liquid natural rubber (LNR) and reinforced by electron beam (EB) irradiation. The effects of the radiation dosage on the LNR-coated rice husk (RHr) as a reinforcing agent in the composite were evaluated from the mechanical and thermal properties, as well as from the blend homogeneity. The mechanical properties enhanced with the dosage of radiation on the RHr, and reached an optimum dose in the range 20–30kGy. The composites filled with radiated RHr showed the highest storage modulus (E′) and low tangent delta (tan δ) a radiation dosage of 30kGy. The scanning electron microscopy (SEM) micrograph of the fractural tensile surface showed that an effective RHr particle matrix interaction occurred in the RH powder at a radiation dosage of 20kGy. Improved RH filler–matrix interfacial bond strength and adhesion to the matrix were achieved by coating the RH powder and curing the rubber coat by electron beam irradiation. [Copyright &y& Elsevier]