Presence Of Trimethylolpropane Triacrylate Research Articles

Biodegradable cross-linked poly(L-lactide-co-ε-caprolactone) networks for ureteral stent formed by gamma irradiation under vacuum

The poly(L-lactide-co-ε-caprolactone) (PLCL) ureteral stent creeps and loses shape stability, increasing the risk of stent tube dislocation. The rubbery biodegradable cross-linked PLCL networks were prepared through gamma irradiation under vacuum in the presence of trimethylolpropane triacrylate (TMPTA), pentaerythritol tetraacrylate (PET4A), and pentaerythritol triacrylate (PETA). At a standard sterilization dose of 25 kGy, the gel content and network density of PLCL networks increased with increasing crosslinking agent content (1, 3, 5, 7 wt%), and crosslinking efficiency decreased in the order of PETA > PET4A > TMPTA. The average molecular weight (Mc¯) between two crosslinks ranged from 2000 to 105 g/mol. To perform the beneficial semi-interpenetrated polymer network and characterized by the principle, the networks were processed in several doses (25, 50, 75, 100, and 125 kGy). In place of the Charlesby-Pinner equation, the irradiation cross-linking followed the Chen-Liu-Tang equation. The PLCL network with 7 wt% PETA had a gel fraction of 83%, tensile strength of 34.7 MPa, and tensile set value as low as 5%. Furthermore, degradation in vitro was slowed down. Thus, PLCL networks with appropriate elasticity and flexibility, inherent biodegradability, and excellent biocompatibility can provide a promising alternative method for soft tissue repair engineering, such as ureteral stents.

Biodegradable cross‐linked poly(1,3‐trimethylene carbonate) networks formed by gamma irradiation under vacuum

AbstractRubbery biodegradable cross‐linked poly (1,3‐trimethylene carbonate) (PTMC) networks were prepared by gamma irradiation under vacuum in the presence of trimethylolpropane triacrylate (TMPTA), pentaerythritol triacrylate (PETA), and pentaerythritol tetraacrylate (PET4A). The effect of crosslinking agent, crosslinking agent content (1, 3, 5, 7 wt%), and irradiation dose (25, 50, 75, 100, 125 kGy) on PTMC networks were evaluated. The crosslinking efficiency of PETA was better than that of TMPTA and PET4A at a standard sterilization dose of 25 kGy. The PTMC network with gel fractions up to 92% ± 1% and tensile strength up to 26.0 ± 2.2 MPa could be obtained by adding 7 wt% PETA. The increase in irradiation dose reduced the gel content and network density, and led to a decrease in mechanical properties. The PTMC network extracted by ethanol showed better flexibility and mechanical properties. The irradiation crosslinking of PTMC with 7 wt% PETA followed the Chen–Liu–Tang equation instead of the Charlesby–Pinner equation. The incorporation of crosslinking agents improved the creep resistance and thermal stability, resulting in low permanent set values (5.5%). Furthermore, the enzymatic erosion rates of the networks decreased. Therefore, these PTMC networks can be utilized in a broad range of soft tissue engineering.

Radiation crosslinking of linear polyethyleneimine‐based nanoparticles grafted to poly(glycidyl methacrylate) via trimethylolpropane triacrylate as potential electronic packaging material

AbstractLinear polyethyleneimine (L‐PEI)‐based nanoparticles were synthesized via hydrolysis of poly‐2‐methyl‐2‐oxazoline (PMeOx), which was prepared by cationic ring‐opening polymerization of the oxazoline five‐membered ring. Herein, a kinetic study of the ring‐opening polymerization reaction is discussed. The nuclear magnetic resonance spectrum of PMeOx verified the presence of repeating units and terminal groups in the polymer's structure. Molar ratios of PEI and PMeOx were characterized using size exclusion chromatography with low‐polydispersity polymer chains as the controlled polymerization reaction. PEI and PMeOx exhibited narrow particle size distribution with hydrodynamic radii of 89 and 67 nm, respectively, as determined via dynamic light scattering analysis. In addition, atomic forces and scanning electron microscopy were used to investigate the topography of the PEI thin films. Poly(glycidyl methacrylate) P(GMA) was grafted onto a PEI chain in the presence of trimethylolpropane triacrylate (TMPTA) as the crosslinking agent to synthesize the P(GMA–PEI–TMPTA) tripolymer via free radical polymerization using gamma irradiation. The thermal characterization of the P(GMA–PEI–TMPTA) tripolymer was conducted using thermogravimetric analysis and differential scanning calorimeter. Generally, the thermal stability of the P(GMA–PEI–TMPTA) tripolymer was improved at low‐glycidyl methacrylate concentrations. The prepared tripolymer could be used as effective packaging materials for electronics industries.

Novel Potentiometric Sensor Based on Molecular Imprinted Polyacrylamide for the Determination of Shikimic Acid in Herbal Medicine

ABSTRACTA novel potentiometric sensor based on a molecular imprinted polymer was developed for the determination of shikimic acid in herbal medicine. The imprinted polymer was synthesized via bulk polymerization of the functional monomer in the presence of trimethylolpropane triacrylate as the cross-linker with 2,2′-azo-bisisobutyronitrile as the initiator and shikimic acid as the template. The sensing membrane was constructed by the inclusion of imprinted polymer in the polyvinyl chloride matrix. The effect of the identity of the imprinted polymer on the potentiometric response was observed. The optimal imprinted polyacrylamide was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The performance of the imprinted membrane based sensor, including the effects of pH, response time and selectivity coefficient, was investigated. The imprinted sensor exhibited a fast near-Nernstian response in the concentration range of 1 × 10−5 to 1 × 10−1 mol/L with a detection limit of 9 × 10−6 mol/L. The analytical performance of the sensor supported the direct determination of shikimic acid in herbs, and the obtained results were validated by ultraviolet-visible absorption spectrophotometry. Advantages of the potentiometric sensor include enhanced sensitivity, high selectivity, long-term stability and low-cost fabrication, suggesting the device offers promise for the analysis of Chinese herbal medicine.

In-situ Enhanced Toughening of Poly(ethylene terephthalate)/elastomer Blends via Gamma-Ray Radiation at Presence of Trimethylolpropane Triacrylate

Gamma-ray radiation has always been a convenient and effective way to modify the interfacial properties in polymer blends. In this work, a small amount of trimethylolpropane triacrylate (TMPTA) was incorporated into poly(ethylene terephthalate) (PET)/random terpolymer elastomer (ST2000) blends by melt-blending. The existence of TMPTA would induce the crosslinking of PET and ST2000 molecular chains at high temperatures of blending, resulting in the improvement in the impact strength but the loss in the tensile strength. When the PET/ST2000 blends were irradiated by gamma-ray radiation, the integrated mechanical properties could be enhanced significantly at a high absorbed dose. The irradiated sample at a dose of 100 kGy even couldn't be broken under the impact test load, and at the same time, has nearly no loss of tensile strength. Based on the analysis of the impact-fractured surface morphologies of the blends, it can be concluded that gamma-ray radiation at high absorbed dose can further in situ enhance the interfacial adhesion by promoting the crosslinking reactions of TMPTA and polymer chains. As a result, the toughness and strength of PET/ST2000 blend could be dramatically improved. This work provides a facial and practical way to the fabrication of polymer blends with high toughness and strength.

Tensile, flexural and morphological properties of electron beam-crosslinked LDPE–EPDM blends

The effect of electron beam (EB) irradiation on the tensile, flexural and morphological properties of low-density polyethylene (LDPE)/ethylene-propylene diene elastomer (EPDM) blends had been studied in the absence and presence of crosslink promoters, such as trimethylolpropane triacrylate (TMPTA) and triallyl cyanurate (TAC). Blends were prepared by melt mixing of LDPE and EPDM followed by EB irradiation at various doses. The gel fraction (%) of irradiated blends was increased with an increase in EPDM content as well as EB irradiation dose and consequently the tensile and flexural properties of the blends increased. The incorporation of crosslinking promoters accelerated the gel formation and improved the properties upon irradiation more efficiently. The phase morphology of fractured surface displayed immiscibility with a rough appearance before irradiation. But after irradiation, the surface became fine, smooth and uniform, which went on increasing upon irradiation, supporting the steady increase in mechanical properties. Surface appeared even smoother in the presence of TMPTA and TAC.

Electron Beam Crosslinking of EVA/ENR-50/HNTS Nanocomposites in the Presence of Trimethylol Propane Triacrylate, TMPTA

Ethylene vinyl acetate/ Epoxidised natural rubber/ Halloysite nanotube (EVA/ENR-50/HNT) nanocomposite was prepared through melt blending process using twin screw extruder at 120 oC and 50 rpm of screw speed. The ratio of EVA/ENR-50/HNT was fixed at 80:20:4. The nanocomposites were irradiated with a 3.0 MeV electron beam machine at doses ranging from 50 to 200 kGy in air at room temperature. The effect of irradiation dose and co-agent Trimethylol Propane Triacrylate (TMPTA) on tensile strength and gel content of EVA/ENR-50/HNT nanocomposite were studied. It was found that the tensile strength and gel fraction of the EVA/ENR-50/HNT nanocomposites increased with the increased of irradiation dose. In the presence of TMPTA, a better performance in tensile strength was achieved due to the increased efficiency of irradiation induce crosslinking of EVA/ENR-50/HNT nanocomposite.

The effects of electron beam irradiation on the thermal properties, fatigue life and natural weathering of styrene butadiene rubber/recycled acrylonitrile–butadiene rubber blends

The effects of electron beam (EB) irradiation on the thermal properties, fatigue life and natural weathering of styrene butadiene rubber/recycled acrylonitrile–butadiene rubber (SBR/NBRr) blends were investigated. The SBR/NBRr blends were prepared at 95/5, 85/15, 75/25, 65/35, or 50/50 blend ratios with and without the presence of a 3 part per hundred rubber (phr) of polyfunctional monomer, trimethylolpropane triacrylate (TMPTA). Results indicate that the crystallisation temperature ( T c) observed in polymeric blends is due to the alignment of polymer chains forming a semi-crystalline phase. Addition of TMPTA helps to align polymer chains through crosslinking. More crosslinking occurred between polymer blends with the help of TMPTA, upon irradiation. The improvement in fatigue life can also be associated with the stabilisation of SBR/NBRr blends upon irradiation and irradiation-induced crosslinking, which was accomplished with relatively low radiation-induced oxidative degradation in the presence of TMPTA. The tensile properties of both blends decreased over the periods of environmental exposure due to the effect of polymer degradation. After 6 months, the irradiated SBR/NBRr blends could not retain better retention [mainly with 25, 35 or 50 phr of recycled acrylonitrile–butadiene rubber (NBRr) particles] due to the samples becoming brittle over the long period of outdoor exposure.

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 (ML) of irradiated SBR/NBRr blend decreased, but the maximum torque (MH) 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.

Rheology and thermal properties of polypropylene modified by reactive extrusion with dicumyl peroxide and trimethylol propane triacrylate

AbstractTrimethylol propane triacrylate (TMPTA) and dicumyl peroxide (DCP) were used to modify polypropylene (PP) by reactive extrusion in a twin‐screw extruder. The effects of TMPTA concentration on oscillatory shear rheology, melt elongational rheology, and thermal properties were comparatively evaluated. Fourier transform infrared spectroscopy indicated that the grafting reaction took place and TMPTA had been grafted onto the PP backbone. Differential scanning calorimetric results showed that the crystallization temperatures of modified PPs were higher than those of the initial and degraded PPs. The rheological characteristics such as higher storage modulus (G′) at low frequency, increased degree of shear thinning, a plateau in tan δ–ω plot, and upturning at high viscosity in the Cole–Cole plots proved that the long‐chain branches have been added to the linear PP molecule. The melt elongational rheology showed that the modified PPs exhibit improved melt strength and increased elongational viscosity in the presence of TMPTA and DCP, which further confirmed the existence of long‐chain branching (LCB) in their backbone. According to the analytical results from oscillatory shear rheology and elongational rheology, it can be inferred that the LCB level in modified samples increases with an increase in TMPTA concentration. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:16–25, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20146

Effect of MAPP and TMPTA as compatibilizer on the mechanical properties of cellulose and oil palm fiber empty fruit bunch–polypropylene biocomposites

The effect of compatibilizers, namely, maleic anhydride grafted polypropylene (MAPP GR-205) and trimethylolpropane triacrylate (TMPTA), on the mechanical and morphological properties of the PP-cellulose (derived from oil palm empty fruit bunch fiber) and PP-oil palm empty fruit bunch fiber (EFBF) biocomposites has been studied. The ratio of PP : cellulose and PP : EFBF is fixed to 70 : 30 (wt/wt%) while the concentration of the compatibilizer is varied from 2.0 to 7.0 wt%. Results reveal that at 2.0 wt% of MAPP concentration, tensile strength of PP-EFBF biocomposite is significantly improved. This is due to the enhanced EFBF matrix adhesion resulting in an improvement in EFBF biocomposite performance. There are no significant changes observed in the PP-cellulose biocomposite properties upon the addition of MAPP. In contrast to the tensile strength, flexural modulus and impact strength are significantly improved with the addition of 2.0 wt% TMPTA to PP-cellulose biocomposite. The enhancement of mechanical properties in the presence of TMPTA is believed to be attributed to crosslinking of multifunctional monomer with the hydroxyl groups of cellulose.

Effects of gamma irradiation on the properties of flame-retardant EVM/magnesium hydroxide blends

The ethylene vinyl-acetate copolymer (EVM) rubber/magnesium hydroxide (MH) blend was crosslinked by 60Co irradiation in the presence of trimethylolpropane triacrylate. And the effects of gamma irradiation on the properties of irradiated EVM/MH blend were investigated through the measurements of the gel content, Vicat point, limiting oxygen index, UL-94, tensile properties, X-ray diffraction and thermogravimetric analysis. The test results show that the thermal, mechanical and flame-retardant properties of the EVM/MH blend all are markedly improved by 60Co irradiation.

Rheological properties of styrene–butadiene rubber filled with electron beam modified surface treated dual phase fillers

The rheological properties of styrene–butadiene rubber (SBR) loaded with dual phase filler were measured using Monsanto Processability Tester (MPT) at three different temperatures (100°C, 110°C and 130°C) and four different shear rates (61.3, 306.3, 613, and 1004.5 s −1). The effect of electron beam modification of dual phase filler in absence and presence of trimethylol propane triacrylate (TMPTA) or triethoxysilylpropyltetrasulphide (Si-69) on melt flow properties of SBR was also studied. The viscosity of all the systems decreases with shear rate indicating their pseudoplastic or shear thinning nature. The higher shear viscosity for the SBR loaded with the electron beam modified filler is explained in terms of variation in structure of the filler upon electron beam irradiation. Die swell of the modified filler loaded SBR is slightly higher than that of the unmodified filler loaded rubber, which is explained by calculating normal stress difference for the systems. Activation energy of the modified filler loaded SBR systems is also slightly higher than that of the control filler loaded SBR system.

Influence of Novel Electron Beam Modified Surface Treated Dual Phase Filler on Rheometric and Mechanical Properties of Styrene Butadiene Rubber Vulcanizates

Abstract Rheometric and mechanical properties, hysteresis and swelling behavior of the Styrene-Butadiene Rubber vulcanizates (SBR) filled with unmodified and novel electron beam modified surface treated dual phase fillers were investigated. Scorch time increases for these modified filler loaded vulcanizates due to introduction of quinone type oxygen on the surface. Electron beam modification of dual phase filler in the absence of trimethylol propanetriacrylate (TMPTA) or triethoxysilylpropyltetrasulphide (Si-69) significantly improves the modulus of the SBR vulcanizates, whereas the values of tensile strength and elongation at break drop. However, presence of TMPTA or silane slightly increases the modulus with significant improvement in tensile strength. This effect is more pronounced at higher loading of these modified fillers in SBR vulcanizates. These variations in modulus and tensile strength are explained by the equilibrium swelling data, Kraus plot and a new mathematical model interpreting the polymer-filler interaction. Hysteresis loss ratio of SBR vulcanizates loaded with irradiated fillers in absence and presence of TMPTA or silane increases due to highly aggregated structure of the filler.

Surface characterization of electron beam modified dual phase filler by ESCA, FT-IR and surface energy

Electron beam modification of carbon black (N220) and carbon-silica dual phase filler has been carried out at room temperature. The increase in oxygen to carbon ratio (O/C) determined by using Electron spectroscopy for chemical analysis (ESCA) is observed. Fourier transform infra-red spectroscopy (FT-IR) studies detect a new peak at 801 cm−1 upon electron beam irradiation, which is due to Si-C stretching in the case of modified dual phase fillers. The absence of the peak at 3400 cm−1 and the presence of the peak at 1720 cm−1 due to aliphatic ester stretching confirm the presence of trimethylol propane triacrylate (TMPTA) on the surface. Similarly, the absence of peak band at 3400 cm−1 confirms chemical interaction of triethoxysilylpropyl tetrasulphide (Si-69). A decrease in dispersive component (γsd) and an increase in polar component (γsp) of the surface energy corroborate surface oxidation.

Flammability of radiation cross-linked low density polyethylene as an insulating material for wire and cable

Various formulations of low-density polyethylene blended with ethylene vinyl acetate were prepared to improve the flame retardancy for wire and cable applications. The prepared formulations were cross-linked by γ-rays to 50, 100, 150 and 200 kGy in the presence of trimethylolpropane triacrylate (TMPTA). The effect of thermal aging on mechanical properties of these formulations were investigated. In addition, the influence of various combinations of aluminum trihydroxide and zinc borate as flame retardant fillers on the flammability was explored. Limiting oxygen index (LOI) and average extent of burning were used to characterize the flammability of investigated formulations. An improved flame retardancy of low density polyethylene was achieved by various combinations of flame ratardant fillers and cross-linking by gamma radiation.

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

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

Evidence of irradiation‐induced crosslinking in miscible blends of poly(vinyl chloride)/epoxidized natural rubber in presence of trimethylolpropane triacrylate

Evidence of irradiation‐induced crosslinking in miscible blends of poly(vinyl chloride)/epoxidized natural rubber in presence of trimethylolpropane triacrylate

Evidence of irradiation‐induced crosslinking in miscible blends of poly(vinyl chloride)/epoxidized natural rubber in presence of trimethylolpropane triacrylate

AbstractElectron‐beam initiated crosslinking of a poly(vinyl chloride)/epoxidized natural rubber blend (PVC/ENR), 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 gelation dose was determined by a method proposed by Charlesby. It was evident from the gelation dose, resilience, hysteresis, glass‐transition temperature (Tg), IR spectroscopy, and scanning electron microscopy studies that the miscible PVC/ENR blend underwent crosslinking by electron‐beam irradiation. The acceleration of crosslinking by the TMPTA was further confirmed in this study. Agreement of the results with a theory relating the Tg with the distance between crosslinks provided further evidence of irradiation‐induced crosslinking. The possible mechanism of crosslinking induced by the irradiation between PVC and ENR is also proposed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1914–1925, 2001

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

AbstractElectron‐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