The effect of trimethylol propane tetraacrylate (TMPTA) and organoclay loading on the properties of electron beam irradiated ethylene vinyl acetate (EVA)/natural rubber (SMR L)/organoclay nanocomposites

Ethylene vinyl acetate (EVA)/natural rubber (SMR L)/organoclay nanocomposites were prepared by melt blending technique with 0–10 phr organoclay loading and 3 phr TMPTA. Electron beam initiated crosslinking on these samples was carried out using a 3.0 MeV electron beam machine with doses ranging from 50 to 200 kGy. XRD results proved that dispersion of organoclay in the nanocomposites was slightly improved by irradiation with TMPTA. This was further supported by transmission electron microscopy images, where the nanoscale dispersion of organoclay was more homogenous throughout the irradiated polymer matrix compared to nonirradiated samples. TMPTA also increased the gel fraction yield, tensile properties and thermal stability of the irradiated neat EVA/SMR L and its nanocomposites. TMPTA was found to act as a crosslink initiator, which promotes crosslink bridges via free radical mechanism in EVA/SMR L matrix. SEM observation shows that the fracture behavior of the irradiated neat EVA/SMR L and its nanocomposites with TMPTA is significantly different compared to the fracture behavior of the nonirradiated neat EVA/SMR L. The distinct failure surface structure formed in the irradiated samples with TMPTA explains the overall higher value of tensile properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and Properties of Ethylene Vinyl Acetate (EVA)/Organoclay/Compatibilizer Nanocomposites: Effects of Organoclay Loading and Methyl Ethyl Ketone

Ethylene vinyl acetate (EVA)/organoclay/compatibilizer nanocomposites were produced using a melt compounding technique in an internal mixer, Haake Rheometer, at 120°C and 50 rpm rotor speed. Effects of organoclay loading (from 2 to 10 phr—parts per hundred of resin and methyl ethyl ketone (MEK), used as a compatibilizer, on the processing properties, tensile properties, morphology, thermal degradation, and water absorption behavior of EVA/organoclay nanocomposites were studied. Results indicate that the presence of organoclay increase the processing torque, tensile properties, thermal degradation, and resistance to water absorption. The optimum organoclay loading was achieved at 2 phr. This was caused by the dispersion state of individual silicate layers (intercalation/exfoliation) in EVA matrix. The intercalation/exfoliation structure affects the properties of EVA/organoclay nanocomposites as evidenced from the morphology studies such as x-ray diffraction (XRD) and transmission electron microscopy (TEM) evaluation. The addition of MEK has the ability to improve the tensile properties, thermal degradation, and slightly reduces the resistance of water permeation of EVA/organoclay nanocomposites. The enhanced properties were seen as a result of the better matrix and filler interaction. The EVA/organoclay/MEK nanocomposites shows better intercalation/exfoliation of individual silicate layers in the EVA matrix as indicated by TEM. Moreover, the XRD evaluation shows that intercalation/exfoliation of the organoclay was formed in the EVA matrix.     

Effects of different preparation methods on the properties of poly[ethylene‐co‐(vinyl acetate)]/(Standard Malaysian natural rubber)/organoclay nanocomposites

Poly[ethylene‐co‐(vinyl acetate)] (EVA)/(Standard Malaysian natural rubber) (SMR L)/organoclay nanocomposites were prepared by using melt intercalation and solution blending methods. In both preparation methods, the EVA: (SMR L) ratio was prefixed at 50:50, while the organoclay loading was varied from 0 to 10 phr. The effects of two different processing routes and organoclay loading on the morphology, tensile, properties thermal properties, and flammability of the nanocomposites were studied. X‐ray diffraction results and transmission electron microscopy images proved that solution blending promotes better dispersion of organoclay than melt intercalation. Thus, the nanocomposites prepared by the solution‐blending method exhibited higher values of tensile strength, stress at 100% elongation (M100), and thermal stability. The M100 value and thermal stability improved proportionally with the increase of organoclay content, owing to the demobilizing effect and the barrier properties of the organoclay. The optimum tensile strength value was achieved at a 2‐phr organoclay loading. Further increases in loading decreased the strength of the nanocomposites. Tensile fracture surfaces of the nanocomposites prepared by both methods showed different fracture behavior, as evidenced by scanning electron microscopy images. Flammability decreased when the organoclay loading increased for the nanocomposites prepared by both methods. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers     

Organoclay Filled Natural Rubber Nanocomposites: The Effects of Filler Loading

Organoclay filled natural rubber (NR) nanocomposites were prepared using a laboratory two-roll mill. The effect of organoclay loading up to 10 phr was studied. The vulcanized nanocomposites were subjected to mechanical, thermal, and swelling tests. The results indicated that the tensile strength and elongation at break reached optimum at 4 phr of organoclay loading, and the incorporation of organoclay increased the tensile modulus and hardness of NR nanocomposites. The thermal degradation was shifted to a higher temperature and the weight loss decreased with incorporation of organoclay. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were employed to characterize the microstructure of NR nanocomposites. Results from TEM and XRD show the formation of intercalated and exfoliated individual silicate layers of organoclay filled NR nanocomposites particularly at low filler loading (< 4 phr).     

Effect of electron beam irradiation on the properties of ethylene‐(vinyl acetate) copolymer/natural rubber/organoclay nanocomposites

The effects of electron beam (EB) irradiation on the morphology, crosslink density, and tensile properties of EVA/SMR L (Standard Malaysian Rubber)/organoclay nanocomposites prepared by a melt‐blending technique were investigated. All the samples were irradiated by using a 3.0‐MeV EB apparatus with doses ranging from 50 to 200 kGy. Organoclay loading was varied from 0 to 10 phr (parts by weight per hundred parts of resin). X‐ray diffraction results and transmission electron microscopy images proved that the dispersion of organoclay in the nanocomposites was slightly improved by EB irradiation. The gel fraction yield for the nanocomposites increased with irradiation dose but decreased with organoclay loading. However, at 200 kGy, the gel fraction yield was almost the same at all organoclay loadings. Tensile strength and stress at 100% elongation increased proportionally with the irradiation dose. Elongation at break of the nanocomposites increased up to 100 kGy but then decreased at higher irradiation doses. The intercalation and exfoliation of the organoclay, the barrier effect, and the Hofmann degradation of the modification agent are the three major factors leading to the improvement of the properties of the irradiated nanocomposites. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers     

Properties of Halloysite Nanotube (HNT) Filled SMR L and ENR 50 Nanocomposites

Various HNTs loading filled SMR L and ENR 50 were prepared. Addition of HNTs caused increments in scorch time, cure time, tensile modulus, and thermal stability of nanocomposites. Optimum tensile strength of nanocomposites was achieved at 20 phr loading. Elongation at break, swelling percentage, and fatigue life decreased with increasing HNTs loading. ENR 50 nanocomposites show shorter scorch time, longer cure time, and lower curing rate index than SMR L nanocomposites. ENR 50 nanocomposites also show higher tensile modulus and thermal stability than SMR L nanocomposites. SEM images show that HNTs can be dispersed more uniformly at lower filler loading.     

The Effect of Epoxidized Natural Rubber (ENR-50) or Polyethylene Acrylic Acid (PEA) as Compatibilizer on Properties of Ethylene Vinyl Acetate (EVA)/Natural Rubber (SMR L) Blends

The effect of epoxidized natural rubber (ENR) or polyethylene acrylic acid (PEA) as a compatibilizer on properties of ethylene vinyl acetate (EVA)/natural rubber (SMR L) blends was studied. 5 wt.% of compatibilizer was employed in EVA/SMR L blend and the effect of compatibilizer on tensile properties, thermal properties, swelling resistance, and morphological properties were investigated. Blends were prepared by using a laboratory scale of internal mixer at 120°C with 50 rpm of rotor speed. Tensile properties, thermal properties, thermo-oxidative aging resistance, and oil swell resistance were determined according to related ASTM standards. The compatibility of EVA/SMR L blends with 5 wt.% of compatibilizer addition or without compatibilizing agent was compared. The EVA/SMR L blend with compatibilizer shows substantially improvement in tensile properties compared to the EVA/SMR L blend without compatibilizer. Compatibilization had reduced interfacial tension and domain size of ethylene vinyl acetate (EVA)/natural rubber (SMR L) blends.     

Ethylene‐vinyl acetate copolymer/multiwalled carbon nanotube/organoclay nanocomposites

Ethylene‐vinyl acetate copolymer (EVA) was melt‐mixed with multiwalled carbon nanotubes (MWCNTs) and organoclays, and the effects of simultaneous use of organoclays and MWCNTs on the surface resistivity and tensile properties of EVA nanocomposites were investigated. The surface resistivity of EVA/MWCNT nanocomposite with 1 phr of MWCNT is out of our measurement range (above 10¹² Ω/square). With increasing content of organoclay from 0 to 3 phr, the surface resistivity of the EVA/MWCNT/organoclay nanocomposites with 1 phr MWCNT remains out of our measurement range. However, the surface resistivity of the nanocomposite decreases to 10⁶ Ω/square with addition of 5 phr organoclay. The tensile properties of EVA/MWCNT/organoclay nanocomposites with 1 phr MWCNT and 5 phr organocaly are similar to those of EVA/MWCNT nanocomposites with 5 phr MWCNT except tensile modulus. POLYM. COMPOS. 2012. © 2012 Society of Plastics Engineers     

Preparation,characterization, and application of NR/SBR/Organoclay nanocomposites in the tire industry

The natural rubber/styrene butadiene rubber/organoclay (NR/SBR/organoclay) nanocomposites were successfully prepared with different types of organoclay by direct compounding. The optimal type of organoclay was selected by the mechanical properties characterization of the NR/SBR/organoclay composites. The series of NR/SBR/organoclay (the optimal organoclay) nanocomposites were prepared with various organoclay contents loading from 1.0 to 7.0 parts per hundreds of rubber (phr). The nearly completely exfoliated organoclay nanocomposites with uniform dispersion were confirmed by transmission electron microscopy (TEM) and X‐ray diffraction (XRD). The results of mechanical properties measurement showed that the tensile strength, tensile modulus, and tear strength were improved significantly when the organoclay content was less than 5.0 phr. The tensile strength and the tear strength of the nanocomposite with only 3.0 phr organoclay were improved by 92.8% and 63.4%, respectively. It showed organoclay has excellent reinforcement effect with low content. The reduction of the score and cure times of the composites indicated that the organoclay acted as accelerator in the process of vulcanization. The incorporation of a small amount of organoclay greatly improved the swelling behavior and thermal stability, which was attributed to the good barrier properties of the dispersed organoclay layers. The outstanding performance of co‐reinforcement system with organoclay in the tire formulation showed that the organoclay had a good application prospect in the tire industry, especially for the improvement of abrasion resistance and the reduction of production cost. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Oxygen permeability and the mechanical and thermal properties of (low‐density polyethylene)/poly (ethylene‐co‐vinyl acetate)/organoclay blown film nanocomposites

Various (low‐density polyethylene)/poly(ethylene‐co‐vinyl acetate) (LDPE/EVA) nanocomposites containing organoclay were prepared by one‐ and two‐step procedures through melt blending. The resultant nanocomposites were then processed via the film blowing method. From the morphological point of view, X‐ray diffraction and optical microscopy studies revealed that although a prevalent intercalated morphology was evident in the absence of EVA, a remarkable increase of organoclay interlayer spacing occurred in the EVA‐containing systems. The advantages of the addition of EVA to the LDPE/organoclay nanocomposites were confirmed in terms of oxygen barrier properties. In other words, the oxygen transmission rates of the LDPE/EVA/organoclay systems were significantly lower than that of the LDPE/organoclay sample. The LDPE/EVA/organoclay films had better mechanical properties than their counterparts lacking the EVA, a result which could be attributed to the improvement of the organoclay reinforcement efficiency in the presence of EVA. Differential scanning calorimetry and thermogravimetric analysis experiments were performed to follow the effects of the EVA and/or organoclay on the thermal properties of LDPE. Finally, the films produced from the two‐step‐procedure compound showed enhanced oxygen barrier properties and mechanical behavior as compared to the properties of the films produced via the one‐step procedure. J. VINYL ADDIT. TECHNOL., 19:132–139, 2013. © 2013 Society of Plastics Engineers     

Effect of organoclay content on the mechanical properties of ethylene‐vinyl acetate copolymer/ multi‐walled carbon nanotube/organoclay foams

The main objective of this study is to obtain ethylene‐vinyl acetate copolymer (EVA)/multi‐walled carbon nanotube (MWCNT)/organoclay foams with improved mechanical properties without increase of their density, compared with EVA/MWCNT foams. MWCNT content was fixed at 5 phr in this study. To achieve the objective, EVA was melt‐mixed with MWCNTs and organoclays in a bench kneader. And the obtained EVA/MWCNT/organoclay mixtures were mixed with chemical blowing agent and cross‐linking agent in a two roll‐mill. After being mixed in a two roll‐mill, the mixtures were put in a mold and the foams were obtained by compression‐molding. The effect of organoclay content on the mechanical properties and surface resistivity of EVA/MWCNT (5 phr)/organoclay foams was investigated. The addition of 1 phr organoclays to the EVA/MWCNT (5 phr) foams resulted in the improvement of tensile strength, 100% tensile modulus, tear strength, and compression set without increase of the density. However, further increase in content of organoclay (3 phr) leaded to a deterioration of mechanical properties. Therefore, determining the optimal content of organoclay was very important in order to achieve the main objective of this study. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Natural rubber/poly(ethylene‐co‐vinyl acetate)‐blend‐based nanocomposites

Natural rubber (NR)/poly(ethylene‐co‐vinyl acetate) (EVA) blend–clay nanocomposites were prepared and characterized. The blend nanocomposites were prepared through the melt mixing of NR/EVA in a ratio of 40/60 with various amounts of organoclay with an internal mixer followed by compression molding. X‐ray diffraction patterns revealed that the nanocomposites formed were intercalated. The formation of the intercalated nanocomposites was also indicated by transmission electron microscopy. Scanning electron microscopy, used to study the fractured surface morphology, showed that the distribution of the organoclay in the polymer matrix was homogeneous. The tensile modulus of the nanocomposites increased with an increase in the organoclay content. However, an increase in the organoclay content up to 5 phr did not affect the tensile strength, but the organoclay reduced this property when it was increased further. This study also indicated that a low silicate content dispersed in the blend matrix was capable of increasing the storage modulus of the material. The addition of the organoclay also increased the decomposition temperature of the NR/EVA blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 353–362, 2006     

Effect of compatibilizer and organoclay content on structure,thermal, and mechanical properties of poly(butylene succinate)/(Ethylene acrylic acid)/Organoclay nanocomposites

Poly(butylene succinate) (PBS)/(ethylene acrylic acid) (EAA)/organoclay nanocomposites were prepared by using the melt intercalation technique. EAA was used as compatibilizer and organoclay was used as inorganic filler. X‐ray diffraction and transmission electron microscopy results indicated the addition of compatibilizer led to a large increase in basal spacing of nanocomposites and better overall dispersion of organoclay in the PBS matrix. However, the basal spacing was found to be invariant as the organoclay content increased. The differential scanning calorimetry analyses revealed that the incorporation of the organoclay and EAA and the variation of organoclay content altered the melting behavior and crystallization properties of PBS. Storage and loss modulus of virgin matrix increased with the incorporation of organoclay and EAA, and a maximum for the nanocomposite with 9 wt% organoclay. Moreover, the glass transition temperatures also increased for the various organoclay‐containing samples. Mechanical properties showed an increase with the incorporation of organoclay and EAA. The 5 wt% organoclay‐filled PBS gave the highest tensile strength and notched Izod impact strength among all the composites. Further increments in organoclay loading reduced the tensile strength and notched impact strength of nanocomposites, which was thought to be the result of agglomeration. However, increments in clay loading enhanced the flexural strength and flexural modulus of nanocomposites, with a maximum at 9 wt% organoclay. J. VINYL ADDIT. TECHNOL., 23:219–227, 2017. © 2015 Society of Plastics Engineers     

Preparation of Cu(II)-Immobilized Chitosan (CIC) and Preliminary Urea Uptake Study

The effect of filler loading and size on commercially available silica (Vulcasil C) and value added silica (ultrafine) as filler in SMR L grade natural rubber were studied. Vulcasil C with particle size ranged from 10 µm–20 µm whilst ultrafine (1 µm–3 µm) was loaded in SMR L compound at 4 different loadings. The curing characteristics, tensile properties and swelling behavior were studied. At similar filler loading, ultrafine-filled vulcanizates exhibited shorter scorch time and cure time. It also shows higher tensile strength and elongation at break up to 20 phr filler loading and exhibit lower swelling ratio compared to Vulcasil C-filled vulcanizates.     

The Effect of Filler Loading and Epoxidation on Paper-Sludge-Filled Natural Rubber Composites

The effect of filler loading and epoxidation on curing characteristics, dynamic properties, tensile properties, morphology, and rubber-filler interactions of paper-sludge-filled natural rubber compounds have been studied. Two different types of natural rubber, SMR L and ENR 50, having 0% and 50% of epoxidation and conventional vulcanization were used. Paper sludge was used as a filler and the loading range was from 0 to 40 phr. Compounding was carried out using a laboratory-sized two-roll mill. The scorch time for both rubber compounds decreased with filler loading. The cure time was found to decrease with increasing filler content for SMR L vulcanizates, whereas for ENR 50, the cure time seemed to be independent of the filler loading. Dynamic properties, i.e., maximum elastic torque, viscous torque, and tan delta, increase with filler loading in both grades of natural rubber. Results also indicate that both rubbers show increment in tensile modulus but inverse trend for elongation at break and tensile strength. However, for a fixed filler loading, ENR 50 compounds consistently exhibit higher maximum torque, modulus at 100% elongation, and modulus at 300% elongation, but lower elongation at break than SMR L compounds. In the case of tensile strength, ENR 50 possesses higher tensile strength than SMR L at 10 to 20 phr, but the difference is quite small at 30 and 40 phr. These findings might be associated with better rubber-filler interaction between the polar hydroxyl group of cellulose fiber and the epoxy group of ENR 50.     

Effects of Filler Loading and Different Preparation Methods on Properties of Cassava Starch/Natural Rubber Composites

Cassava starch-filled natural rubber (NR) composites were prepared by using direct blending and co-coagulation method. The effects of two different method and cassava starch loading on morphology, mechanical properties and thermal properties of cassava starch/NR composites were studied. X-ray diffraction results and scanning electron microscopy images proved that co-coagulation method promotes better dispersion of cassava starch than direct blending method. The composites prepared by co-coagulation method exhibited higher values of tensile strength, tear strength, hardness, and thermal stability. The optimum value of tensile strength and tear strength of cassava starch/NR composites were achieved at a 10 phr cassava starch loading.     

Effect of vinyl acetate content on the mechanical and thermal properties of ethylene vinyl acetate/MgAl layered double hydroxide nanocomposites

Ethylene vinyl acetate (EVA)/Mg‐Al layered double hydroxide (LDH) nanocomposites using EVA of different vinyl acetate contents (EVA‐18 and EVA‐45) have been prepared by solution blending method. X‐ray diffraction and transmission electron microscopic studies of nanocomposites clearly indicate the formation of exfoliated/intercalated structure for EVA‐18 and completely delaminated structure for EVA‐45. Though EVA‐18 nanocomposites do not show significant improvement in mechanical properties, EVA‐45 nanocomposites with 5 wt % DS‐LDH content results in tensile strength and elongation at break to be 25% and 7.5% higher compared to neat EVA‐45. The data from thermogravimetric analysis show that the nanocomposites of EVA‐18 and EVA‐45 have ≈10°C higher thermal decomposition temperature compared to neat EVA. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Microstructure,rheological behavior,and properties of poly(lactic acid)/poly(butylene succinate)/organoclay nanocomposites

Nanocomposites made of poly(lactic acid), poly(butylene succinate), and organically modified montmorillonite were prepared by melt blending in a twin screw extruder. The influence of the organoclay content on nanocomposite properties was investigated. The nanocomposite structure has been characterized by various techniques at different scales. X‐ray diffraction showed an intercalated structure whereas rheological investigations in small amplitude oscillatory shear indicated a partial exfoliation. It was also shown that organoclay was evenly dispersed in the matrix even though some large aggregates were also observed. The mechanical properties of nanocomposites were measured in uniaxial tensile test. Oxygen and water vapor permeability was also characterized. It was shown that dispersed organoclay and aggregates have a direct impact on mechanical properties and permeability. An increase of Young's modulus by 41% and a decrease of permeability by 40% could be obtained with 7 wt % organoclay. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40364.     

Synthetic aliphatic biodegradable poly(butylene succinate)/clay nanocomposite foams with high blowing ratio and their physical characteristics

Poly(butylene succinate) (PBS)/organoclay nanocomposites were prepared by both solution blending and melt mixing methods. In addition, nanocomposites of PBS/organoclay were also prepared by a two‐step process where the solution blended mixture is subsequently compounded in the melt state using a torque rheometer (SOAM method). We then investigated thermal and mechanical properties of the PBS/organoclay nanocomposite at first and determined an optimum organoclay content for the preparation of nanocomposite foams. All PBS/organoclay nanocomposite foams are found to possess closed spherical‐shaped cells without any rupture when examined by an optical microscopy. The blowing ratio also increased with the increase in the blowing temperature and time, with the maximum blowing ratio of 19. Furthermore, the addition of a small amount of organoclay is found to allow the cell size to follow Gaussian distribution. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Preparation of poly(lactic acid)/poly(ethylene glycol)/organoclay nanocomposites by melt compounding

Poly(lactic acid) (PLA)/organoclay nanocomposites were prepared by melt compounding in a co‐rotating twin screw extruder. Two types of commercialized organoclay (dimethyl benzyl stearyl ammonium ion and dimethyl distearyl ammonium ion intercalated between clay platelets named as Clay A and Clay B, respectively) and two grades of poly(ethylene glycol) (PEG) with different molecular weight (M_w = 2,000 and 300,000–500,000 named as PEG2k and PEG500k, respectively) were used in this study. The Young's modulus improved by the addition of organoclay to PLA matrix. The Young's modulus decreased with the addition of PEG to PLA/organoclay nanocomposites. The tensile strength and elongation of PLA/Clay B nanocomposites increased with the addition of PEG2k. The effect of the addition of PEG on d‐spacing of PLA/organoclay nanocomposites is dependent upon the kind of organoclay. The sizes of clay agglomerations in PLA/PEG/organoclay nanocomposites are larger than those of PLA/organoclay ones in the same organoclay. Addition of PEG to PLA/organoclay nanocomposites during melt compounding will not be useful for the preparation of PLA/organoclay having fully exfoliated clay platelets. The shear thinning properties of the nanocomposites are independent of the addition of PEG. On the whole, PEG2k is good plasticizer for PLA/organoclay nanocomposites. POLYM. COMPOS. 27:256–263, 2006. © 2006 Society of Plastics Engineers