Study on electron‐beam‐irradiated (linear low‐density polyethylene)/(soya powder) blends under outdoor exposure

Linear low‐density polyethylene was blended with soya powder, and the blends were compatibilized with epoxidized natural rubber having 50 mol% of epoxidation. The content of soya powder was varied from 0 to 40 wt%. The blends were irradiated at 30 kGy with an electron beam. Degradation of the irradiated blends was evaluated by exposing the samples to an outdoor environment according to ISO 877.2. The degradation was monitored by changes in the tensile, morphological, and thermal properties, as well as the molecular structure and weight loss. The tensile strength and elongation at break (Eb) of the exposed samples decreased as a function of exposure period. The irradiated blends exhibited higher retention of tensile strength and Eb than nonirradiated blends after 1 year of exposure. The crystallinity of the irradiated blends increased upon exposure, though the nonirradiated blends showed higher crystallinity indicating higher degradability. Weight loss of the irradiated blends showed less change after 6 months of outdoor exposure, but significant change was observed after 1‐year exposure. The molecular weight changes of the irradiated blends exhibited the same trend as weight loss. All the results confirmed that the degradability of the irradiated blends was comparable to that of the nonirradiated blends upon long‐term outdoor exposure. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers     

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     

Effect of trimethylolpropane triacrylate (TMPTA) on the properties of irradiated epoxidized natural rubber (ENR‐50), ethylene‐(vinyl acetate) copolymer (EVA), and an ENR‐50/EVA blend

The effect of trimethylolpropane triacrylate (TMPTA) monomer on the tensile properties, dynamic mechanical properties, and morphology of irradiated epoxidized natural rubber (ENR‐50), ethylene‐(vinyl acetate) copolymer (EVA), and an ENR‐50/EVA blend was investigated. The ENR‐50, EVA, and ENR‐50/EVA blend were irradiated by using a 3.0‐MeV electron‐beam apparatus at doses ranging from 20 to 100 kGy. The improvement of tensile properties and morphology with irradiation indicated the advantage of having irradiation‐induced crosslinks in these materials. Observation of the properties studied confirmed that TMPTA was efficient in enhancing the irradiation‐induced crosslinking of ENR‐50, EVA, and the ENR‐50/EVA blend. Addition of TMPTA improved the adhesion between the ENR‐50/EVA blend phases by forcing grafting and crosslinking at a higher irradiation dose (100 kGy). J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers.     

Curing Characteristics and Mechanical and Morphological Properties of Styrene Butadiene Rubber/Virgin Acrylonitrile-Butadiene Rubber (SBR/vNBR) and Styrene Butadiene Rubber/Recycled Acrylonitrile-Butadiene Rubber (SBR/rNBR) Blends

Curing characteristics and mechanical and morphological properties of styrene butadiene rubber/virgin acrylonitrile-butadiene rubber (SBR/vNBR) and styrene butadiene rubber/recycled acrylonitrile-butadiene rubber (SBR/rNBR) were investigated. Results indicated that the curing characteristics, such as scorch time, t₂, and cure time, t₉₀, of SBR/vNBR and SBR/rNBR blends decreased with increasing vNBR and rNBR content. At similar blend ratios, particularly up to 15 phr, SBR/rNBR blends exhibited higher t₂ and t₉₀ compared with SBR/vNBR blends. Minimum torque (ML) and maximum torque (MH) of SBR/vNBR blends significantly increased with increasing vNBR content. For SBR/rNBR blends, ML increased with increasing rNBR content, but MH exhibited the opposite trend. Tensile strength, elongation at break (E_b), resilience, and fatigue decreased with increasing virgin and recycled NBR content in both blends. Up to 15 phr, the tensile strength, E_b and fatigue life (Kc) of SBR/rNBR blends were higher than in SBR/vNBR blends. The M100 (stress at 100% elongation), hardness, and cross-linking density of both blends also showed an increasing trend with increasing vNBR and rNBR content. The scanning electron microscopy study indicates that rNBR exhibited a weak rNBR-SBR matrix interaction particularly when more than 15 phr of rNBR was used, thus decreasing the mechanical properties of SBR/rNBR blends.     

Electron‐beam processing of nylon 6 and HNBR blends. Part II: development of high strength,heat‐ and oil‐resistant thermoplastic elastomers

The effects of electron‐beam irradiation on morphology, mechanical properties and on the heat and hot oil resistance of the thermoplastic elastomeric blend of 30:70 and 70:30, nylon 6 and hydrogenated nitrile rubber (HNBR) were investigated over the dose range 0–8 Mrad. The insoluble content of blends increased with increase in the radiation dose. The morphology of the blend was studied in scanning electron microscopy, with special reference to the effect of radiation prior to processing via injection molding. Irradiated pellets showed better mechanical properties after injection molding compared with irradiated sheets at low radiation dose. The observed differences in mechanical properties are explained on the basis of morphology of the blend. The blend properties were also found to have a strong dependence on nylon content. It was found that the blends rich in nylon had superior mechanical properties, hot oil and solvent resistance, whereas blends with higher HNBR content had better set and heat resistance. The effect of radiation on interaction in these blends was also evaluated and was found to induce possible inter‐chain crosslinking in the blends. Copyright © 2006 Society of Chemical Industry     

The Effect of Electron Beam (EB) Irradiation in Presence of TMPTA on Cure Characteristics and Mechanical Properties of Styrene Butadiene Rubber/Recycled Acrylonitrile-Butadiene Rubber (SBR/NBRr) Blends

The effect of electron beam (EB) irradiation on the cure characteristics and mechanical properties of unirradiated and irradiated SBR/NBRr blends were investigated. The SBR/NBRr blends were prepared at 95/5, 85/15, 75/25, 65/35, and 50/50 blend ratio with and without the presence of a polyfunctional monomer, trimethylolpropane triacrylate (TMPTA). Results indicated that the scorch time t₂, cure time t₉₀ and minimum torque (M_L) of irradiated SBR/NBRr blend decreased, but the maximum torque (M_H) particularly at 35 and 50 phr of NBRr (recycled NBR) increased with the presence of TMPTA. The stress at 100% elongation (M100), hardness, cross-linking density and tensile strength (particularly after 15 phr of NBRr content) of irradiated SBR/NBRr blends increased after irradiation but the elongation at break (EB) and resilience decreased. The irradiated SBR/NBRr blends showed lower thermal stability than non-irradiated blends. Scanning electron microscopy proved the enhancement in tensile strength when more NBRr were added in SBR matrix where the irradiated surfaces demonstrate more irregularity with increasing crack branching (fracture planes are located at different heights) due to the increased of cross-linked density.     

Physical properties of polyamide 6/H‐NBR blends and the effects of dynamic vulcanization on them

Polyamide 6 (PA 6) and hydrogenated nitrile rubber (H‐NBR) were blended with various blend ratios in a brabender plasticoder at 240°C/100 rpm. The processing characteristics with a mixing torque of the blends were investigated. The effect of the blend ratio on physical properties such as tensile strength, Young's modulus, elongation at break, permanent set, hardness, and swelling behavior of blends was analyzed. Most mechanical properties were found to decrease with an addition of H‐NBR. The morphology of the blends was observed, and the results show a two phase system where the component with high proportions exists as a continuous phase. A cocontinuous phase was observed in blend ratios of 50/50 and 40/60. Dynamic mechanical properties were observed to study a viscoelastic property of the blends. In addition, the effect of dynamic vulcanization with peroxide on physical properties was studied, and the influence of peroxide on PA 6 was also examined. It was found that the peroxide can have an effect on PA 6 as well as act as a crosslinker to H‐NBR. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The Effects of PP-g-MA on the Physical Properties and Morphology of Polypropylene (PP)/Recycled Acrylonitrile Butadiene Rubber (rNBR) Blends

Polypropylene-grafted maleic anhydride (PP-g-MA) was used to enhance the compatibility of polypropylene (PP) and recycled acrylonitrile butadiene rubber (rNBR) blends. The blends were prepared by melt mixing using a Haake Rheomix Polydrive R 600/610 mixer at 180°C. The processing torque was used to investigate the mixing process. The better mixing of compatibilized blends (PP/rNBR-MA) was evidence by the higher stabilization torque. Compared to uncomapatibilized PP/rNBR blends, tensile properties and oil resistance of compatibilized PP/rNBR were improved. SEM micrographs of tensile fractured surfaces showed better dispersion and better interfacial adhesion between the phases of compatibilized blends compared to uncompatibilized counterparts.     

Improvement of Physicochemical Properties of Rubber Blends Between Nonirradiated and Irradiated Rubber Latexes by Radiation Vulcanization

Abstract

Nonirradiated natural rubber latex (NRL) and irradiated (12 kGy) rubber latex were blended in ratios of 100:0, 85:15, 65:35, 50:50, 35:65, 15:85, and 0:100 (v/v) to improve properties of the rubber latex. The blends were irradiated using different irradiation doses (0–20 kGy) in the presence of a radiation vulcanization accelerator (RVA), normal butyl acrylate (n-BA). The physicochemical properties of the nonirradiated latex, irradiated latex, and blend films were determined after leaching with distilled water. It was observed that the tensile strengths of the blend films increases with an increase in the content of the irradiated proportion and radiation doses. The composition of the blends and the doses of radiation were optimized. The maximum tensile strength (31.41 MPa) was found for the 50:50 composition of the blend with a 5 kGy radiation dose. The 100:0 blends, when irradiated, give the highest tensile strength (27.69 MPa) with 12 kGy but a 15:85 nonirradiated blend gives the tensile strength of 26.18 MPa.     

Electron‐beam irradiation of poly(vinyl chloride)/epoxidized natural rubber blends in presence of trimethylolpropane triacrylate

Electron‐beam initiated crosslinking of poly(vinyl chloride)/epoxidized natural rubber blends, which contained trimethylolpropane triacrylate (TMPTA), was carried out over a range of irradiation doses (20–200 kGy) and concentrations of TMPTA (1–5 phr). The gel content increased with the irradiation dose and the TMPTA level, although the increase was marginal at higher doses and higher TMPTA levels. Blends containing 3–4 phr TMPTA achieved optimum crosslinking, which in effect caused the maximum tensile strength (TS) at a dose of 70 kGy. A further addition of TMPTA caused a decline in the TS above 40 kGy that was due to embrittlement, which is a consequence of excessive crosslinking and the breakdown of the network structure. The possible formation of a more open network as a result of the breakdown of the network structure was further confirmed by the modulus results. Dynamic mechanical analysis (tan δ curve) and scanning electron microscopy studies on samples irradiated at 0 and 200 kGy were undertaken in order to gain further evidence on the irradiation‐induced crosslinking. The plasticizing effect of TMPTA prior to irradiation and the formation of microgels upon irradiation were also discussed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1926–1935, 2001     

High‐density polyethylene/ultrahigh‐molecular‐weight polyethylene blend. I. The processing,thermal, and mechanical properties

Various blend ratios of high‐density polyethylene (HDPE) and ultrahigh‐molecular‐weight polyethylene (UHMWPE) were prepared with the objective of determining their suitability as biomaterials. Although the presence of HDPE in the blends enabled melt processing, the presence of UHMWPE helped to improve the toughness of the resulting blends. The processability of the blends was investigated with the Brabender torque, which was used as an indication of the optimum blend conditions. The blends were characterized with differential scanning calorimetry. The mechanical tests performed on the blends included tensile, flexural, and impact tests. A 50:50 (w/w) blend yielded optimum properties in terms of the processability and mechanical properties. The tensile property of the 50:50 blend was intermediate between those of HDPE and UHMWPE, but the strain at break increased 200% in comparison with that of both neat resins. The energy at break of the 50:50 blend revealed an improvement in the toughness. The fracture mechanism was also investigated with scanning electron microscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 413–425, 2005     

A comparative study of polypropylene/(chloroprene rubber) and (recycled polypropylene)/(chloroprene rubber) blends

The blends of virgin polypropylene (PP) and recycled polypropylene (RPP) with chloroprene rubber (CR) have been prepared. The effect of different blend ratios on tensile properties, swelling behavior, morphology, and crystallinity of both blends of virgin and RPP was investigated. The tensile strength and Young's modulus of both blends decreased with increasing CR in blend ratios but the elongation at break was increased. It was found that the tensile properties of PP/CR blends were better than the RPP/CR blends. The PP/CR blends showed the lower value of swelling index. The scanning electron micrograph of the tensile fractured surface of PP/CR blends indicates that a higher energy is needed to cause failure compared with RPP/CR blends. The differential scanning calorimery results indicated that the degree of crystallinity of PP/CR blends also was found to be higher than RPP/CR blends. J. VINYL ADDIT. TECHNOL., 21:122–127, 2015. © 2014 Society of Plastics Engineers     

Effect of blend ratio on cure characteristics,tensile properties,thermal and swelling properties of mica‐filled (ethylene‐propylene‐diene monomer)/(recycled ethylene‐propylene‐diene monomer) (EPDM/r‐EPDM) blends

(Ethylene‐propylene‐diene monomer)/(recycled ethylene‐propylene‐diene monomer) (EPDM/r‐EPDM) blends filled with constant mica loading were compounded at various blends ratios (i.e., 90/10, 80/20, 70/30, 60/40, and 50/50). Results indicated that scorch time decreased with increasing r‐EPDM content, whereas curing time, minimum torque, and maximum torque show the opposite trend. The tensile strength, stress at 100% elongation, and elongation at break value increased with increasing r‐EPDM loading in the blend systems and the optimum properties occurred at 70/30 EPDM/r‐EPDM blends ratio. The thermal stability of EPDM/r‐EPDM blends increased with increasing r‐EPDM content in the blends but the swelling percentage showed the opposite trend with a greater addition of r‐EPDM content in the blends. J. VINYL ADDIT. TECHNOL., 21:1–6, 2015. © 2014 Society of Plastics Engineers     

Fracture behavior of die‐drawn toughened polypropylenes

The Leeds die‐drawing process has been used to make oriented sheets of toughened polypropylenes. Die‐drawn oriented sheets were produced by drawing at 110°C to draw ratios of 4, 6, and 10. Comparative measurements have been undertaken of the plane stress fracture toughness at room temperature using the essential work of fracture method for isotropic and oriented polypropylene homopolymer and the two polypropylene blends containing 10 and 25% of a polyethylene‐based elastomer. In the isotropic state, the blend containing 25% elastomer exhibited higher fracture toughness than the homopolymer and the 10% blend. The oriented sheets were tested both parallel (cracks perpendicular to the draw direction) and perpendicular (cracks parallel to the draw direction). For the latter case of cracks parallel to the draw direction, the fracture toughness of all the materials decreased with increasing draw ratio and up to a draw ratio of 4 the 25% blend exhibited higher fracture toughness than the other two materials. At higher draw ratios, however, the unfilled polypropylene was tougher than the blends. When tested parallel to the draw direction, all three materials failed with the cracks growing slowly initially followed by sudden rupture. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1336–1345, 2003     

Comparison Properties of Natural Rubber (SMR L)/Ethylene Vinyl Acetate (EVA) Copolymer Blends and Epoxidized Natural Rubber (ENR-50)/Ethylene Vinyl Acetate (EVA) Copolymer Blends

Mixing torque, morphology, tensile properties and swelling studies of natural rubber/ethylene vinyl acetate copolymer blends were studied. Two series of unvulcanized blends, natural rubber/ethylene vinyl acetate (SMRL/EVA) copolymer blend and epoxidized natural rubber (50% epoxidation)/ethylene vinyl acetate (ENR-50/EVA) copolymer blend were prepared. Blends were prepared using a laboratory internal mixer, Haake Rheomix polydrive with rotor speed of 50 rpm at 120°C. Results indicated that mixing torque value and stabilization torque value in ENR-50 blends are lower than SMRL blends. The process efficiency of ENR-50/EVA blends is better due to less viscous nature of the blend compared to SMRL/EVA blends as indicated in stabilization torque graph. Tensile properties like tensile strength, M100 (modulus at 100% elongation) and E _b (elongation at break) increase with increasing EVA fraction in the blend. At the similar blend composition, ENR-50 blend shows better tensile properties than SMRL blends. In oil resistance test, swelling percentage increased with immersion time and rubber composition. At a similar immersion time, ENR-50 blends exhibit better oil resistance compared to SMRL blends. Scanning electron microscopy (SEM) of tensile fractured surface indicated that EVA/ENR-50 blends need higher energy to cause catastrophic failure compared to EVA/SMRL blends. In etched cryogenically fractured surface, size and distribution of holes due to extraction of rubber phase by methyl ethyl ketone (MEK) were studied and holes became bigger as rubber composition increased due to coalescence of rubber particle.     

Swelling and mechanical properties of (acrylonitrile‐butadiene rubber)/(hydrogenated acrylonitrile‐butadiene rubber) blends with precipitated silica filled in gasohol fuels

This work studied the effects of hydrogenated acrylonitrile‐butadiene rubber (HNBR) and precipitated silica (PSi) loadings in acrylonitrile‐butadiene rubber (NBR) filled with 60 parts per hundred of rubber (phr) of carbon black (CB) for oil‐resistant seal applications in contact with gasohol fuel. The cure characteristics, mechanical properties, and swelling behavior of HNBR/NBR blends reinforced with PSi before and after immersion in ethanol‐based oils (E10, E20, and E85) were then monitored. This work studied the effects of PSi loading in rubber compounds on the mechanical properties of the rubber blends. The results suggested that the scorch time of CB‐filled NBR/HNBR was not affected by HNBR loading, but the cure time, Mooney viscosity, and torque difference increased with HNBR content. The swelling of the blends in E85 oil were relatively low compared with those in E10 and E20 oils. The recommended NBR/HNBR blend ratio for oil‐resistant applications was 50/50. Tensile strength and elongation at break before and after immersion in gasohol oils increased with HNBR loading, and the opposite effect was found for tensile modulus and hardness. PSi filler had no effect on scorch time, but decreased the cure time of the blends. The swelling level of the blends slightly decreased with increasing PSi content. The recommended silica content for optimum reinforcement for black‐filled NBR/HNBR blend at 50/50 was 30 phr. The results in this work suggested that NBR/HNBR blends reinforced with 60 phr of CB and 30 phr of silica could be potentially used for rubber seals in contact with gasohol fuels. J. VINYL ADDIT. TECHNOL., 22:239–246, 2016. © 2014 Society of Plastics Engineers     

Preparation and properties of molded blends of wheat gluten and cationic water‐borne polyurethanes

Cationic water‐borne polyurethanes (CWPU) were prepared and blended with wheat gluten (WG) in aqueous dispersion. The freeze‐dried blend powders of WG/CWPU were thermally compression‐molded into sheets. The tensile strength of the WG/CWPU blends decreased with increasing CWPU content, showing a relationship between the composition of the sheets and their mechanical properties. FTIR spectra reveal that the free carbonyl in the blend results in a decrease in the hydrogen‐bonding interaction of the WG. SEM images show that the morphology of the cross‐sections of the blends is homogenous. The dynamic thermal behavior of the blends illustrates that the WG is plasticized by CWPU, with the result that the relaxation transition of the WG becomes broader and the temperature transition of WG changes slightly. The water resistance of the WG was also improved by blending it with the CWPU. Biodegradation of the blends in soil resulted in a loss in mass of the samples of more than 60% w/w after burial for 15 days. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The effect of irradiation on morphology and properties of the PET/HDPE blends with trimethylol propane trimethacrylate (TMPTA)

The mechanical properties of poly(ethylene terephthalate)/high-density poly(ethylene) (PET/HDPE) blends were improved by γ-ray irradiation combined with using a cross-linking agent—trimethylol propane trimethacrylate (TMPTA). The effect of the weight ratio of PET/HDPE, the content of TMPTA and the absorbed dose on the phase morphology and the mechanical properties of the PET/HDPE blends were investigated through scanning electron microscopy (SEM), gel fraction, Fourier transform infrared spectroscopy (FTIR), tensile and impact tests. SEM images showed that the phase structure changed significantly as TMPTA coexistence. The results of tensile and impact tests indicated that their mechanical properties depended on their structures. FTIR spectra suggested that a new structure of HDPE-g-PET was generated. When the weight ratio of PET/HDPE blend was 80/20, the content of TMPTA was 1 wt% and the absorbed dose was 30 kGy, the tensile strength, elongation at break and impact strength of irradiated blends were improved greatly compared with non-irradiated blends.     

Morphology and tensile properties of crosslinked nanocomposite foams of low‐density polyethylene and poly(ethylene‐co‐vinyl acetate) blends

This paper studies the morphology and tensile properties of nanocomposite foams of blends of low‐density polyethylene (LDPE) and poly(ethylene‐co‐vinyl acetate) (EVA). Preparations of LDPE/EVA nanocomposites were conducted in an internal mixer, and then samples were foamed via a batch foaming method. Morphology of the nanocomposite blends and nanocomposite foams was studied by X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy. Morphological observations showed that nanoparticle dispersion in the polymeric matrix was affected by the blend ratio in a way such that EVA‐rich samples had a better dispersion of nanoclay than LDPE‐rich ones. In addition, the tensile properties of the nanocomposite foams were related to different variables such as blend ratio, clay content, and foam density. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers     

Improvement of compatibility of poly(ethylene terephthalate) and poly(ethylene octene) blends by γ‐irradiation

Blends of poly(ethylene terephthalate) (PET) and poly(ethylene octene) (POE) were prepared by melt blending with various amounts of trimethylolpropane triacylate (TMPTA). The mechanical properties, phase morphologies, and gel fractions at various absorbed doses of γ‐irradiation have been investigated. It was found that the toughness of blends was enhanced effectively after irradiation as well as the tensile properties. The elongation at break for all studied PET/POE blends (POE being up to 15 wt %) with 2 wt % TMPTA reached 250–400% at most absorbed doses of γ‐irradiation, approximately 50–80 times of those of untreated PET/POE blends. The impact strength of PET/POE (85/15 wt/wt) blends with 2 wt % TMPTA irradiated with as little as 30 kGy absorbed dose exceeded 17 kJ/m², being approximately 3.4 times of those of untreated blends. The improvement of the mechanical properties was supported by the morphology changes. Scanning electron microscope images of fracture surfaces showed a smaller dispersed phase and more indistinct inter‐phase boundaries in the irradiated blends. This indicates increased compatibility of PET and POE in the PET/POE blends. The changes of the morphologies and the enhancement of the mechanical properties were ascribed to the enhanced inter‐phase boundaries by the formation of complex graft structures confirmed by the results of the gelation extraction and Fourier Transform Infrared analyses. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013