Ecofriendly latex films from cassava starch-filled radiation pre-vulcanized natural rubber latex

ABSTRACT

The demands of the usage of hazardous ingredients for sulfur curing system in latex industries decrease with an increase in health-conscious and environmental awareness. This work demonstrates the incorporation of cassava starch (CS) as biodegradable fillers with natural rubber latex (NRL) through a sulfur-free crosslinking technique using radiation pre-vulcanization natural rubber latex (RVNRL) in comparison to sulfur pre-vulcanized natural rubber latex (PvNRL). The 20% CS dispersion was prepared, and 5–25?phr of dispersed CS content were compounded with NRL and formed into films by the coagulant dipping method. Microstructures and crystallinity of the films were analyzed by scanning electron microscopy (SEM) and X-ray diffraction, and their mechanical properties of NRL/CS films were characterized by tensile and tear tests. The result revealed that the crystallinity of RVNRL films was lower than PvNRL films. The total bond of S?C from PvNRL contributes to high tensile strength compared to C?C intermolecular rubber bond from radiation vulcanization system. The trend of decrement of tensile properties from sulfur crosslinking was larger than radiation crosslinking, and both systems gave similar tensile behavior at 25?phr of CS content. This attributed to the better dispersion of CS in RVNRL as confirmed by SEM micrographs. It was found that the optimum tear strength of RVNRL/CS and PvNRL/CS films was obtained at 10 and 5?phr of filler content, respectively. The result presented in this study may facilitate a contribution to the current literature on the development of latex film by radiation pre-vulcanization for rubber industry in the future.     

Mechanical and electrical properties of radiation-vulcanized natural rubber latex with waste eggshell powder as bio-fillers

ABSTRACT

This work investigated the mechanical, physical, morphological, and electrical (volume) resistivity properties of radiation-vulcanized natural rubber latex (RVNRL) with additions of waste eggshell (WES) powder, which contained primarily CaCO₃ (calcite). The results showed that increasing gamma irradiation doses from 0 to 30?kGy in 10-kGy increments led to decreases in the swelling ratio and elongation at break but increases in the crosslink density, tensile modulus at 500% elongation, and tensile strength of the composites. The results also suggested that increasing the WES contents from 0 to 2, 4, or 6 parts per hundred parts of rubber by weight (phr) in the composites improved the tensile modulus at 500% elongation, tensile strength, hardness (Shore A), and electrical (volume) resistivity. In addition, after undergoing thermal aging at 70°C for 96?h, the tensile modulus and hardness (Shore A) increased, while the tensile strength and elongation at break decreased. This work also compared the properties of WES/RVNRL with commercial CaCO₃/RVNRL samples at the same 4-phr content. The results indicated that both composites had similar tensile properties, implying possible replacement of commercial CaCO₃ with WES powder as an effective reinforcing filler in RVNRL.     

Thermal and mechanical properties of gamma-irradiated prevulcanized natural rubber latex/low nitrosamines latex blends

Thermal and mechanical properties of blended radiation prevulcanized natural rubber latex (RVNRL) and low nitrosamines latex (LNL) were studied. RVNRL was blended with LNL at various composition ratios. From the tensile test, it was found that the optimum tensile value was attained at a total blending ratio of 70% RVNRL and 30% LNL. Latex blending with optimum tensile strength was then subjected to gamma irradiation at various doses with the presence and absence of methyl methacrylate (MMA) at 10?pphr. It was found that the gamma irradiation of latex blend with the presence of MMA could help increase further the tensile value. Composition of blending at a specific ratio and gamma irradiation at a specific dose has led to a significant improvement in the mechanical properties of the latex blend. The formation of grafting in the latex blend was characterized by Fourier transform infrared spectra (FTIR) spectroscopy and differential scanning calorimetry (DSC). FTIR spectroscopy confirmed that MMA could be grafted onto blended latex effectively under appropriate irradiation conditions. Two new peaks at 1731 and 1149?cm^?1 were observed after irradiation, indicating the presence of an ester group from poly(methyl methacrylate) (PMMA), which was grafted onto rubber chains. This finding was proved by the presence of new T_g in DSC analysis. The increase in new T_g indicates the movement of grafting chains, which are tightly bound onto rubber chains.     

A Comparative Study of the Dynamic-Mechanical Properties of Styrene Butadiene Rubber/Epoxidized Natural Rubber Dual Filler Nanocomposites Cured by Sulfur or Electron Beam Irradiation

The properties of (50/50?wt%) styrene butadiene rubber/epoxidized (50%) natural rubber (SBR/ENR50) blends containing nanoclay (NC, 5 or 10phr) without and with carbon black (CB 20phr) cured by sulfur or by electron beam (EB) irradiation (50 and 100kGy), were compared. A sulfur cured compound containing 35phr CB was prepared as a reference sample. Dynamic mechanical thermal analysis (DMTA) indicated that the sulfur cured sample containing 10phr NC and 20phr CB and the 100kGy irradiated sample with 5phr NC and 20phr CB had higher crosslink density, storage modulus, and tensile strength, and less loss factor and loss modulus, compared to the reference sample. Scanning electron microscopy (SEM) images of cryo- fractured surfaces confirmed the DMA and crosslink density results. We suggest a light weight 100kGy irradiated sample containing the lowest amount of NC and 20phr CB with a uniform distribution of the –C–C– bonds crosslinks, for high thermal stability applications and also for passenger cars tire treads, for its ice grip and wet skid properties especially for icy and wet roads, with improvements of 23% and 20%, respectively as compared to the reference sample.     

Effect of glycidyl methacrylateas compatibilizeron physico-chemical properties of gamma irradiated composites ofethylene propylene diene monomer rubber / styrene butadiene rubber/ground tire rubber

ABSTRACT

Composites of ethylene propylene diene monomer rubber (EPDM)/ styrene butadiene rubber (SBR)/ground tire rubber (GTR)(50/50/20) phr (part per hundred parts of rubber, by weight)loaded with different contents of glycidylmethacrylate (GMA) 2–6?phr. were irradiatedfrom 50 to 250?kGy. The physicochemical properties were investigated.

Irradiation dose and GMA improved physicochemical properties, the optimum content of GMA is 6?phr at a low dose of irradiation. These results were confirmed by scanning electron microscopy (SEM).     

Fe2O3 nanoparticles dispersed unsaturated polyester resin based nanocomposites: effect of gamma radiation on mechanical properties

ABSTRACT

In this work, unsaturated polyester resin (UPR) matrix based nanocomposite was fabricated using synthesized Fe₂O₃ nanoparticle as reinforcement and methyl ethyl ketone peroxide as curing agent by solution casting method. The Fe₂O₃ nanoparticles were synthesized using the sol–gel method and the formation of nanoparticle was confirmed by X-ray diffraction, Scanning electron microscope, Energy dispersive spectrometry analysis. Interactions between metal oxide nanoparticles and polymer molecules in fabricated nanocomposite were investigated by Fourier transform infrared spectrometer analysis. Pure UPR and Fe₂O₃/UPR composite were irradiated with various gamma radiation doses (0–15?kGy). At the 0?kGy (without radiation), the nanoparticles loaded composite showed better mechanical properties (increased in tensile strength and Young’s modulus and decreased in elongation) compared to that of pure UPR sheet. At the 5?kGy radiation dose, the tensile strength and Young’s modulus were further increased; whereas, the elongation was decreased in both samples.     

Natural rubber nanocomposites using polystyrene-encapsulated nanosilica prepared by differential microemulsion polymerization

In this study, nanocomposites of natural rubber (NR) and polystyrene (PS)-encapsulated nanosilica were prepared by latex compounding method. The nanolatex of PS-encapsulated silica was synthesized via in situ differential microemulsion polymerization. The resulted hybrid nanoparticles showed core-shell morphology with an average diameter of 40 nm. The silica hybrid nanoparticles were subsequently used as filler for the NR nanocomposite. The properties of NR were found to be improved as a result of the incorporation of PS-encapsulated nanosilica at 3 and 3-9 parts per hundred rubber (phr) for tensile strength and modulus at 300% strain, respectively, except the elongation at break, and up to 9 phr for flammability. The results from dynamic mechanical analyzer showed that the elastic properties of NR near the glass transition temperature increased with the inclusion of increasing concentration of the PS-encapsulated nanosilica, causing by the semi-interpenetrating nanostructure in the NR nanocomposites.     

Metal adsorption of gamma-irradiated carboxymethyl cellulose/polyethylene oxide blend films

Blend films of different ratios of carboxymethyl cellulose (CMC)/polyethylene oxide (PEO) were prepared by the solution casting method. To investigate the effect of irradiation on all properties of prepared blend, it was exposed to different gamma irradiation doses (10, 20, and 30?kGy). Physical properties such as gel fraction (GF) (%) and swelling (SW) (%) were investigated. It was found that the GF (%) increases with increasing irradiation dose up to 20?kGy, while SW (%) decreases with an increase in the irradiation doses for all blend compositions. Moreover, the structural and mechanical properties of the prepared films were studied. The results of the mechanical properties obtained showed that there is an improvement in these properties with an increase in both CMC and irradiation dose up to 20?kGy. The efficiency of metal ions uptake was measured using a UV spectrophotometer. The prepared films showed good tendency to absorb and release metal ions from aqueous media. Thus, the CMC/PEO film can be used in agricultural domain.     

Gamma induced changes in the structural and optical properties of Makrofol LS 1–1 polycarbonate

ABSTRACT

Samples from sheets of the polymeric material Makrofol LS 1–1 have been exposed to gamma radiation in the dose range 10–250?kGy. The modifications induced in Makrofol samples due to gamma irradiation have been studied through different characterization techniques such as intrinsic viscosity as a measure of the average molecular mass, Fourier Transform Infrared spectroscopy FTIR, refractive index and color difference studies. The results indicate that the crosslinking dominates at the dose range 50–250?kGy. The crosslinking reported by viscosity measurements is supported by the trend of the function groups present in the sample with the gamma dose. Also, the increase in intrinsic viscosity indicating an increase in the average molecular mass was associated with an increase in the refractive index. Additionally, the non-irradiated Makrofol samples showed significant color sensitivity towards gamma irradiation. The color intensity ΔE, which is the color difference between the non-irradiated sample and those irradiated with different gamma doses, increased (0–5.56) with increasing the dose up to 250?kGy, convoyed by an increase in the red and yellow color components.     

Study on the Reinforcing Effect of Milled Carbon Fibers in a Natural Rubber Based Composite

Milled carbon fibers (MCF) have been tested at 2, 4, and 6 phr in a standard natural rubber compound with 45 phr of N375 carbon black. A dramatic increase in the low elongation moduli was observed even with only 2 phr of MCF. The presence of MCF confers anisotropic properties to the rubber compounds that can be measured by an anisotropic factor σ, defined as the ratio between the modulus parallel to the MCF prevalent direction over the modulus orthogonal to the MCF prevalent direction. It has been shown that the presence of MCF is able to reduce the mechanical hysteresis and also the compression set of the natural rubber compound. However, the tear strength properties are affected negatively. The present study demonstrates the feasibility and the advantages derived by the utilization of the carbon fibers as extra reinforcing filler in rubber compounds.     

Dynamically Vulcanized Styrene-Butadiene Rubber/Ethylene-Vinyl Acetate Copolymer/High Impact Polystyrene Blends Compatibilized by Styrene-Butadiene-Styrene Block Copolymer

Thermoplastic vulcanizates (TPVs) based on styrene-butadiene rubber (SBR)/ethylene-vinyl acetate copolymer (EVA)/high-impact polystyrene (HIPS) blends were prepared by dynamic vulcanization, and the TPVs was compatibilized by styrene-butadiene-styrene block copolymer (SBS). The effects of SBS compatibilizer on mechanical, dynamic mechanical, and morphological properties of the TPVs were investigated systemically. Experimental results indicate that SBS had a good compatibilization effect on the SBR/EVA/HIPS TPVs. The tensile strength went through a maximum value at a compatibilizer resin content of 6 phr, and the elongation at break and tear strength increased with increasing SBS content. Morphology study shows that the vulcanized SBR particles were dispersed in the HIPS matrices. A rubber process analyzer reveals that the elastic modulus increased with increasing frequency and the incorporation of EVA in the TPVs led to the obvious decrease of elastic modulus; however, the further addition of compatibilizer SBS affected the elastic modulus less. The tan δ decreased continuously with increasing frequency. The addition of SBS in the TPVs led to enhanced hysteresis behavior and relatively high tan δ.     

Gamma radiation effects on mechanical properties and morphology of a polyurethane derivate from castor oil

In this study, an adhesive of a polyurethane derivate from castor oil was irradiated with gamma radiation from a ⁶⁰Co source, at doses from 0.2 to 25 kGy. This adhesive polyurethane is considered for use in hospital furniture because it does not liberate dangerous solvents. Hardness and elastic modulus were measured by instrumented indentation with a pyramidal Berkovich indenter, using loads from 0.08–40 mN with a nanoindenter XP. The instrumented indentation hardness was 110 MPa for an untreated sample, increasing to 124 MPa after irradiation with 25 kGy, at penetration depths of about 5 μm. The increases in elastic modulus induced by radiation were less pronounced. This polyurethane is naturally cross-linked and the relative modifications in the hardness are attributed to an additional cross-linking process induced by radiation. X-ray diffraction indicates a slight increase in crystallinity. The roughness measured by atomic force microscopy increases after gamma irradiation.     

Fabrication and characterization of jute fabrics reinforced polypropylene-based composites: effects of ionizing radiation and disaccharide (sucrose)

Composites were prepared successfully by compression molding technique using jute fabrics (reinforcing agent) and polypropylene (matrix). Jute fabrics were treated with disaccharide (sucrose) solution and composites were fabricated with the treated fabric and polypropylene. The fiber content of the prepared composites was 40% by weight. It was found that the sucrose (2% solution) decreased the tensile strength (TS) and elongation at break about 6% and 37%, respectively, but tensile modulus and impact strength improved about 27% and 32%, respectively. When gamma radiation was applied through the untreated and treated composites the mechanical properties were improved much higher in non-treated Jute/PP-based composites than that of sucrose treated composites. For 5.0?kGy gamma dose the highest mechanical properties were observed for non-treated composites. At 5.0?kGy gamma dose the improvement of TS was 14% and 2% for non-treated and sucrose treated composites, respectively. The water uptake property of the sucrose treated composites was performed up to 10 days and composites absorbed 18% water. The functional groups of the both composites were analyzed by Fourier transform infrared spectroscopy machine. The scanning electron microscopic images of the both composites were taken for the surface and fiber adhesion analysis.     

A radiochromic film based on leucomalachite green for high-dose dosimetry applications

A colorless polyvinyl butyral film (PVB) based on radiation-sensitive dye of leucomalachite green (LMG) was investigated as a high-dose dosimeter for gamma radiation processing applications in the dose range of 3–150 kGy. The useful applications for such dose range are food irradiation treatment, medical devices sterilization and polymer modification. Gamma irradiation of the film induces a significant intensity of green color, which can be characterized by a main absorption band at 627 nm and a small band at 425 nm. The variation in response of irradiated film stored in the dark and under laboratory light illumination was less than 3% during the first 6 days of storage. The response of film during irradiation was slightly influenced by relative humidity in the range of 12–76%; however, it was significantly affected by temperature in the range of 5–40 °C. The radiation chemical yield was reported to be 6.76 × 10⁻⁶ mol/J at the absorbed dose of 30 kGy for the film containing 6.5% of LMG dye. The overall uncertainty associated with routine dose monitoring would be less than 6% at a 95% confidence level if the dosimeter was being corrected for irradiation conditions and being calibrated with reference standard dosimeter in the production facility.     

Increased porous morphology and thermal degradation of electron beam-irradiated PVDF-HFP/LiCLO4 polymer electrolyte

The effect of 8?MeV energy electron beam radiation at 40, 80 and 120?kGy dosage on surface morphology and thermal properties of lithium perchlorate-doped poly (vinylidene fluoride-co-hexafluoropropylene) polymer electrolyte films have been studied. The field emission scanning electron microscopic image shows small-porous structured morphology for unirradiated film, but it changed drastically into large and deep porous structure as well as the size of spherulites is reduced for 120?kGy confirming the influence of irradiation on morphology. The atomic force microscope reveals the significantly changed surface roughness of unirradiated film from 116.8 to 123.4?nm with a hill-like pattern morphology for 120?kGy confirming the increased amorphousity after irradiation. The thermal study confirmed that the decrease in the melting point of unirradiated film 160.86–155.24°C for 120?kGy doses is attributed to the formation of defects by the chain scissioning process resulting in the degradation of polymer electrolytes at high dose.     

Influence of gamma radiation on optical properties of Halloysite nanotubes incorporated polycarbonate nanocomposites

In the current research investigation, polycarbonate/hallyosite nanotubes (PC/HNTs) nanocomposite (NC) films have been successfully fabricated by solution intercalation technique using ultrasound energy in facile way which helps complete exfoliation of the HNTs in the matrix. The effect of Gamma irradiation-induced modifications of PC/HNTs NC have been studied in the dose range 200–500?kGy, irradiated with Co⁶⁰ source. The NC films have been evaluated by UV–visible spectroscopy, Fourier Transform Infrared spectroscopy, X-ray diffraction and scanning electron microscopic techniques in order to probe the effect of gamma radiation on the structural behaviors. The obtained results have been indicated that as the Gamma irradiation dosage increases from 200 to 500?kGy, phenolic group forms through scissoring of ester link of PC, which may cause PC to degrade and lose their property. At lower dosage (200?kGy), the effect is less and at higher dosage (500?kGy), the effect is significant and at 300 and 400?kGy, the effect is moderate and NC films retained their properties. The irradiation effect is most significant and effective at the higher dosage range. UV–visible spectroscopy shows a noticeable reduction in the energy band gap due to gamma irradiation.     

聚丙烯/抗老化剂复合体系的γ-射线辐照降解研究

研究了聚丙烯(PP)及含有受阻酚类抗氧剂和受阻胺类光稳定剂复合体系的PP复合物经过γ-射线辐照后发生的结构变化及抗老化剂所起作用。实验利用红外光谱(FTIR)和示差扫描量热法(DSC)对PP的结构变化进行了系统表征。研究结果表明,当辐照剂量较小(50 kGy)时,纯PP及其复合物体系均未发生明显降解;当辐照剂量较大(≥50 kGy)时,PP及其复合物的羰基指数迅速提高,二者的结晶温度和熔融温度大幅度降低,说明PP发生了严重降解。在相同γ-射线辐照剂量条件下(≥50 kGy),PP复合物的羰基指数高于纯PP,而结晶温度以及熔融温度低于纯PP,表明高辐照剂量下抗老化剂复合物的存在不但没有阻止聚丙烯的降解,反而加快了降解的速率。     

Effect of gamma irradiation on HPMC/ZnO nanocomposite films

The present work looks into the structural, chemical, mechanical, optical and thermal modification in ZnO nanoparticle incorporated hydroxypropyl methylcellulose (HPMC) polymer films, induced by gamma irradiation. The irradiation process was performed in a gamma chamber at room temperature using Cobalt-60 source (average energy of 1.25?MeV) at different doses: 0, 50, 100, 150 and 200?kGy. The modifications in structural, chemical, mechanical, optical and thermal properties, due to gamma irradiation in HPMC/ZnO nanocomposite films, have been studied using wide angle X-ray scattering (XRD), Fourier transform infrared spectroscopy, universal testing machine, ultraviolet–visible spectrophotometry and thermogravimetric analysis. It is found that gamma irradiation improves the mechanical and thermal properties of nanocomposite films.     

Styrene Butadiene Rubber/Silicone Rubber Blends Filled With Dough Moulding Compound

Blends of styrene butadiene rubber (SBR)/methyl-vinyl silicone rubber (MVQ) filled with dough molding compound (DMC) were prepared and the effects of various amounts of the SBR, as a compatibilizer of MVQ and DMC, on the mechanical properties and the oxygen index of the DMC filled SBR/MVQ blends were investigated. Dynamic mechanical analysis (DMA) and infrared spectrum analysis (IR) of the DMC/SBR/MVQ blends were also investigated. The results showed that the mechanical properties of the DMC filled MVQ blends were improved when SBR was used as a compatibilizer; the best mass ratio was 60 phr (parts per hundred total rubber) DMC, 25 phr SBR and 75 phr MVQ. The volume electric resistivities of the DMC filled SBR/MVQ blends with various DMC mass ratios were all above 5.8?×?10¹² Ω?m; i.e., the electrical insulating property of the blends was excellent. Compared with the blends without DMC and the blends without SBR, the energy storage modulus and the peak area of the loss factor tan δ of the DMC reinforced SBR/MVQ blends were largest; the addition of DMC and SBR improved the thermal properties of the blends.     

Effect of disaccharide,gamma radiation and temperature on the physico-mechanical properties of jute fabrics reinforced unsaturated polyester resin-based composite

The jute fabrics reinforced unsaturated polyester resin (jute/UPR)-based composites were prepared successfully by the hand-lay-up technique. The percentage of jute fabrics was kept constant at 40% fiber (by weight). The disaccharide percentage was also kept constant at 2% (by weight), but at this percentage the mechanical properties were lower than the untreated composites. Gamma radiation dose was varied at 0, 2.5, 5 and 7.5?kGy for jute/UPR-based composites. At 5.0?kGy gamma dose highest TS, TM and Eb were obtained. The jute/UPR-based composites were treated under 30°C, 50°C and ?18°C for the measurement of mechanical properties. At low temperature (?18°C), the highest mechanical properties were observed. The water uptake properties were measured for disaccharide-treated and disaccharide-untreated composites up to 10 days, but no water was absorbed by the composites. The soil degradation test was carried out under 12 inch soil containing at least 25% water, but no significant decrease was observed for untreated and sucrose-treated composites. For the functional group analysis, FT-IR was carried out. For the fiber matrix adhesion analysis, the scanning electron microscopic image was taken.