Melt complex viscosity and molecular weights for homo-polypropylene modified by grafting bifunctional monomers under electron beam irradiation

High melt viscosity polypropylene was manufactured by grafting bifunctional monomers, HDDA (1,6-hexanediol diacrylate) and TPGDA (tripropyleneglycol diacrylate), onto homo-polypropylene under an electron beam irradiation. Melt complex viscosity (η^∗) of modified polypropylene was sensitive to irradiation dose and monomer content. The melt viscosity of the polypropylene modified with TPGDA increased to 132,290 Pa s (at 190 °C and 0.1 rad/s of frequency) from 5039 Pa s for virgin homo-polypropylene. TPGDA monomer could give higher melt viscosity at low dosages than HDDA monomer, probably due to the structural feature of TPGDA with three numbers of methyl groups.Modified polypropylene with high melt complex viscosity had a broad molecular weight distribution with remarkable shift to higher molecular weight leading to high values of both and . Melt viscosity of modified polypropylene could be properly correlated by the equation , where the term gave a dominant effect for the estimation of η^∗.     

High-melt-strength polypropylene with electron beam irradiation in the presence of polyfunctional monomers

High-melt-strength polypropylene (PP) was achieved with irradiation by an electron beam generated from an accelerator in the presence of polyfunctional monomers (PFM). Among 16 PFMs, the relatively shorter molecular chain bifunctional monomers such as 1,4-butanediol diacrylate (BDDA) and 1,6-hexanediol diacrylate (HDDA) were the most effective for enhancing the melt strength of PP. The concentration and dose of the HDDA to obtain the high melt strength PP in irradiation under nitrogen gas atmosphere were 1.5 mmol/100 g PP and 1 kGy, respectively. DSC measurement and dynamic mechanical analysis showed that the thermal behavior of the high-melt-strength PP was different from that of the original PP. Crystallinity and crystallization temperature during cooling after heating were lower and higher in high melt strength PP than original PP, respectively. Elongational viscosity at 180°C of the high-melt-strength PP showed a remarkable increase at a certain elongational time with constant strain rate, demonstrating the typical property of high-melt-strength samples. This implies that a few higher molecular chains of PP, formed by intermolecular combination of its chain by HDDA in irradiation, give higher melt strength to induce entanglement of molecular chains. © 1996 John Wiley & Sons, Inc.     

Part 5. Influence of additives containing heteroatoms on the reactivity of butyl acrylate

The radiation‐induced polymerization of n‐butyl acrylate (nBuA) in the presence of small amounts of organic compounds containing heteroatoms has been investigated to evaluate the tentative explanations proposed to account for the differences in initiation rate observed between tripropyleneglycol diacrylate (TPGDA) and hexanediol diacrylate (HDDA), when subjected to electron‐beam (EB) polymerization. The progress of monomer conversion as a function of increasing dose was monitored by transmission infrared spectroscopy applied to thin films submitted to incremental exposure to EB radiation. Miscible organic additives expected to favour hydrogen abstraction, or free radical generation as a consequence of easy carbon–halogen bond scission, were thus introduced in nBuA at a concentration of 2 wt%. The kinetic changes were examined at low monomer conversion. The presence of di‐n‐butyloxide, diisopropyloxide or diisopropylsulfide was shown not noticeably to affect the conversion–dose dependence for EB‐irradiated nBuA. n‐Butyl chloride or bromide caused a noticeable reduction of nBuA reactivity; this was even greater for the iodide at the same 2 wt% concentration. n‐Butanol (nBuOH) was shown to sensitize nBuA consumption when present at a low concentration (2 wt%), but the enhancement of the polymerization rate was not as high for a larger nBuOH content (10 wt%). These results are discussed in the light of the radical anion mechanism for the radiation‐initiated polymerization of acrylate monomers. The absence of a significant sensitizing effect from additives known to enhance free‐radical formation supports the minor contribution of homolytic bond scission to the initiation mechanism. The observed effects of nBuOH at low concentration, indicate that trace amounts of protonic contaminants can exert a strong influence on the efficiency of initiation by the radical‐anion mechanism. © 2001 Society of Chemical Industry     

Using mixture experimental design to study the effect of multifunctional acrylate monomers on UV cured epoxy acrylate resins

An epoxy acrylate resin was synthesized and the resin was used along with different multifunctional acrylate monomers, i.e. trimethylol propane triacrylate (TMPTA), tripropylene glycol diacrylate (TPGDA), 1,6-hexanedioldiacrylate (HDDA). The effect of the chemical structure of the monomers on some of the physical–mechanical properties of the resins and their cured films, such as viscosity, T_g, hardness and scratch resistance was studied. To minimize the number of experiments, mixture method was used as an appropriate tool for experimental design.     

Influence of polyfunctional monomer on melt strength and rheology of long‐chain branched polypropylene by reactive extrusion

Long chain branching (LCB) were added to linear polypropylene (PP) using reactive extrusion in the presence of selected polyfunctional monomers (PFMs) and a peroxide of dibenzoyl peroxide (BPO). Fourier Transformed Infrared spectra (FTIR) directly confirmed the grafting reaction occurred during the reactive extrusion process. Various rheological plots including viscosity curve, storage modulus, Cole‐Cole plot, and Van‐Gurp plots, confirmed that the LCB structure were introduced into modified PPs skeleton after modification. In comparison with linear PP, the branched samples exhibited higher melt strength, lower melt flow index, and the enhancement of crystallization temperature. The LCB level in modified PPs and their melt strength were affected by the type of PFM used and could be controlled by the PFM properties and structure. PFMs with lower boiling points, such as 1, 4‐butanediol diacrylate (BDDA), could not produce LCB structure in modified PP skeleton. The shorter molecular chain bifunctional monomers, such as 1,6‐hexanediol diacrylate (HDDA), favored the branching reaction if their boiling points were above the highest extrusion temperature. And some polar groups, such as hydroxyl, in the molecule of PFM were harmful to the branching reaction, which might be attributed to the harm of the polarity of groups to the dispersion of PFM in PP matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Mechanical properties study of photocured paperboard surface treated with aliphatic epoxy diacrylate

In order to improve the quality of paperboard (a well‐known packing material) surface by photocuring method, different formulations were developed with aliphatic epoxy diacrylate (EA‐1020) oligomer along with reactive monomers of various functionalities. The reactive monomers are tripropylene glycol diacrylate (TPGDA), a difunctional monomer, and trimethylol propane triacrylate (TMPTA), a trifunctional monomer. 2‐Benzyl‐2‐dimethylamino‐1(4morpholinophenyl) butanone‐1 (Irgacure 369), a photoinitiator (2%), was incorporated into the formulations to initiate photocuring reaction. The formulated solutions were coated on clean glass plate and irradiated under UV radiation of different intensities. Different physical properties like pendulum hardness and gel content of the cured films were studied. The formulation containing TMPTA showed better properties. After characterization of the films, these formulations were applied on paperboard surfaces and cured under the same UV radiation. Various physicomechanical properties such as pendulum hardness, tensile properties, surface gloss, adhesion, abrasion, and water uptake were studied. The best performance was obtained at 12 passes of radiation with 18% TMPTA‐containing formulation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1774–1780, 2003     

Investigation on multifunctional monomer modified polypropylene and its foamability

1,6‐Hexanediol diacrylate (HDDA), pentaerythrithyl tetramethacrylate (PETMA), and triallyl‐isocyanurate (TAIC) were used as representative monomers to modify polypropylene (PP) in the presence of dicumyl peroxide (DCP) in a mixer. Fourier transformed infrared spectroscopy (FTIR) results confirmed that all the three polyfunctional monomers have been grafted on PP backbone. The shape of torque curves suggested the occurrence of grafting and/or crosslinking structure. The rheological behaviors of HDDA modified PP showed the highest G′ and lowest tan δ at low frequency, shear‐thinning shifted to lower frequency in η*–ω plot, as well as more deviation from semicircle characteristic of linear PP at high viscosity in Cole–Cole plot. And, the improvement of the mechanical properties followed the order as below: TAIC < PETMA < HDDA. Meanwhile, the foamability of the modified PP samples was also investigated. The cellular structure and morphology of the obtained foams were observed by scanning electron microscopy (SEM), and the results indicated that the foamability of the three modified PPs followed the same order, demonstrating HDDA modified PP foam possessed the highest cell density and expansion ratio, and the most well‐defined closed cell structure and uniformly cellular morphology. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1675–1681, 2013     

Curing of crust leather by ultraviolet radiation with urethane acrylate: Role of pigment

Eight different formulations were developed with four diacrylate reactive monomers such as tripropylene glycol diacrylate (TPGDA), 1,4‐butanediol diacrylate (BDDA), 1,6‐hexanediol diacrylate (HDDA), and 2‐ethylene glycol dimethacrylate (EGDMA) and aromatic urethane diacrylate (M1100) in order to modify the crust leather surface. To study the effect of pigment on the performance of ultraviolet (UV)‐cured leather surface, 1% pigment (congored) was incorporated in the formulations. Irgacure 369 (2%) was also used in the formulation as photoinitiator. The gel content, tensile strength, elongation at break, and pendulum hardness of UV‐cured thin films with and without pigment was studied. The films without pigment produced better properties. Among all the diluents, BDDA‐containing films showed the best performance. Different properties of UV‐coated leather surface such as pendulum hardness, tensile strength, elongation, gloss (at 20° and 60°), adhesion, and abrasion were studied. Effect of gloss on simulating weathering was also performed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 692–697, 2002     

Surface modification of polypropylene sheets by UV‐radiation grafting polymerization

1,6‐Hexanediol diacrylate (HDDA) was grafted onto polypropylene (PP) substrates in the presence of benzophenone (BP) and isopropylthioxanthone (ITX) photoinitiators, and then polyurethane acrylate formulations were coated onto the HDDA‐g‐PP substrates, using UV radiation. The amount grafted and the grafting efficiency of the polymerizations were determined gravimetrically. The effects of the photoinitiator concentration and the UV radiation intensity on the physicochemical surface properties and the grafting efficiency of the UV‐radiation grafting polymerizations were characterized in detail using contact‐angle measurements, Fourier transform infrared spectroscopy with attenuated total internal reflection, and scanning electron microscopy. The results showed that the amount grafted and the surface polarity of the HDDA‐g‐PP substrates both increased linearly with increasing BP photoinitiator concentration and UV radiation intensity, and that the addition of a small amount of ITX markedly enhanced both parameters, probably due to photosensitization. The adhesion of the UV‐cured coating onto the HDDA‐g‐PP substrates was evaluated using the crosshatch adhesion test. The results indicated that the amount of HDDA grafted onto the PP substrates should exceed about 1 mmol/cm² for satisfactory adhesion with the UV‐cured coating. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1446–1461, 2006     

Dispersion of γ-methacryloxypropyltrimethoxysilane-functionalized zirconia nanoparticles in UV-curable formulations and properties of their cured coatings

Highly dispersible zirconia (ZrO₂) nanocrystals were functionalized with γ-methacryloxypropyltrimethoxysilane (MPS) and dispersed in trimethylolpropane triacrylate (TMPTA), 1,6-hexandiol diacrylate (HDDA), tripropyleneglycol diacrylate (TPGDA) and aliphatic polyurethane oligomer (PU)/TPGDA mixtures, respectively. The dispersion behavior of MPS-functionalized ZrO₂ (MPS-ZrO₂) as well as its mechanical reinforcement for the PU/TPGDA matrixes was investigated. It was found that the dispersion of MPS-ZrO₂ nanoparticles in UV-curable formulation strongly depends on the ZrO₂ load, the grafting density of MPS, the composition of organic matrix and the type of monomer. A critical ZrO₂ load beyond which phase separation of MPS-ZrO₂ nanoparticles takes place exists for all cases. MPS-ZrO₂ nanoparticles are more efficient to improve the pendulum hardness and scratch resistance of PU/TPGDA-based coatings that contains higher amount of TPGDA, being presumably due to quicker increase of the cross-linking density of the coatings. Additionally, a completely transparent TPGDA-based nanocomposite coating with ZrO₂ load of as high as 60 wt.% can be obtained, and has absolutely high refractive index of 1.78.     

Effect of electron beam irradiation on the dielectric properties of fluorocarbon rubber

Terpolymeric fluorocarbon rubber (68 wt.-% fluorine, 1.4 wt.-% hydrogen) was subjected to electron beam irradiation using 1,1,1-trimethylolpropane triacrylate (TMPTA), tripropylene glycol diacrylate (TPGDA), and pentaerythritol tetracrylate as radiation sensitizers. Compared to the original sample both the dielectric constant and the dielectric loss factor decrease for samples treated to a certain dose level, beyond which there is an increase. Similar improvement in dielectric properties is observed at relatively higher levels of TMPTA, owing to the increased degree of crosslinking. Among the various polyfunctional monomers used as radiation sensitizers, both the dielectric constant and the dielectric loss factor are higher for systems based on TPGDA due to the reduced crosslink density.     

Acrylate-based photosensitive resin for stereolithographic three-dimensional printing

In this article, we report an acrylate-based three-dimensional (3D) printing stereolithography rapid-prototyping photosensitive resin with a low viscosity, small volumetric shrinkage, high photoreactivity, and excellent strength. The resin was a compound prepared with bisphenol A epoxy acrylate (BAEA) as the main matrix, 1,6-hexanediol diacrylate (HDDA) and tri(propylene glycol) diacrylate (TPGDA) as reactive diluents, pentaerythritol triacrylate (PETA) as the crosslinking agent, and 2-hydroxy-2-methyl propiophenone (1173) and diphenyl(2,4,6-trimethyl benzoyl)phosphine oxide (TPO) as photoinitiators. The photocuring kinetics of the resins with different photoinitiator types and loadings were studied via real-time IR spectroscopy, which provided insights into the optimization of photoinitiator composition and printing parameter settings. The results show that the content change of each component affected the viscosity of the photosensitive resin; this was accompanied by fluctuations in the volume shrinkage and mechanical strength of the cured products. Although an increase in the molar ratio of the reactive diluent remarkably reduced the viscosity of the photosensitive resin and thereby boosted photopolymerization, it also caused an increase in the volume shrinkage and a sacrifice of mechanical strength. Finally, as shown by a comparison of the other samples we studied, the resin composed of 30 mmol HDDA, 50 mmol TPGDA, 10 mmol PETA, 10 mmol BAEA, 2.5 mol % TPO, and 2.5 mol % 1173 achieved the best viscosity of 239.53 mPa s at 25 °C, the minimum shrinkage rate of 4.36%, and the maximum tensile strength of 43.19 MPa. The 3D printing curing products had the closest size to the design dimensions of the computer-aided design model; this indicated that the resin seemed to be a most promising candidate for 3D printing applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47487.     

Synthesis and characterization of palm‐based resin for UV coating

The production of UV curable acrylated polyol ester prepolymer from palm oil and its downstream products offer potential and promising materials for applications such as polymeric film preparation and coatings. In this study, palm olein polyol was reacted with acrylic acid in the presence of a catalyst and inhibitors via condensation esterification process. The reaction temperature of 80°C and the stirring rate of 400 rpm produce a homogeneous product. Based on iodine value result, the suitable amount of p‐toluene sulfonic acid monohydrate used as catalyst was 3.0% (w/w) of palm olein polyol. Different UV curable formulations have been investigated using the synthesized prepolymers with monomers and a small amount of photoinitiator. Monomers used were 1,6‐hexanediol diacrylate (HDDA) and trimethylolpropane triacrylate (TMPTA) while photoinitiator used was 1‐hydroxy cyclohexyl phenylketone (Irgacure 184). The mixtures were cured to make thin polymeric films under UV radiation with doses between 2 and 14 passes (energy per pass is 0.6 J/cm²). Coating and curing was carried out on glass for pendulum hardness and FTIR analysis. Pendulum hardness of the film prepared using monomer HDDA and the prepolymer previously synthesized using 3.0% catalyst was 24.5%. The radiation dose needed was 14 passes. The highest pendulum hardness of 49.4% was achieved using monomer TMPTA and the prepolymer synthesized using 2.0% catalyst. The radiation dose needed was 10 passes. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Coating characteristics of electron beam cured bisphenol A diglycidyl ether diacrylate resin containing 1,6-hexanediol diacrylate on wood surface

Electron beam curing of bisphenol A diglycidyl ether diacrylate resin (BDGDA) mixed with varying amount of 1,6-hexanediol diacrylate monomer (HDDA) was investigated using low energy DC electron beam accelerator. Cured coating films were analyzed by Fourier transformed infrared spectroscopy (FTIR), gel fraction, swelling ratio and thermogravimetric (TG) techniques. The wood surfaces cured with different coating compositions were tested for their end use performance properties like gloss, pencil hardness, scratch resistance, mar resistance, abrasion resistance, chemical resistance, steam resistance and cigarette burn resistance. FTIR studies indicated that the density of acrylate functionality and degree of curing increased with the HDDA content in the feed mixture. This observation was supported by gel fraction and swelling studies as well. The thermal stability, pencil hardness, mar resistance, abrasion resistance and solvent resistance properties of coating were observed to improve with the incorporation of HDDA. However, there was significant decrease in gloss and scratch resistance at higher HDDA content. The coating showed excellent steam and stain resistance but poor resistance to cigarette burns.     

Dynamic mechanical properties of electron beam modified fluorocarbon rubber

The dynamic mechanical properties of electron beam modified fluorocarbon rubbers (terpolymer: F content, 68% and H, 1.4%; copolymer: F content, 65% and H, 1.9%) were studied. With an increase in the radiation dose, the loss tangent maximum decreases and the glass transition temperature increases. The influence of the polyfunctional vinyl monomer, trimethylolpropane triacrylate (TMPTA), is to decrease the loss tangent value, especially at higher doses. At a particular level of the multifunctional monomers tripropylene glycol diacrylate (TPGDA), TMPTA, and tetramethylolmethane tetracrylate, the dynamic mechanical thermal analysis indicated the lowest degree of crosslinking for the system based on TPGDA. MgO-based systems register a decrease of the loss tangent peak height and an increase in the storage moduli compared to the control rubber. The results are explained on the basis of gel fraction, scission reactions, and structural changes as measured with the help of IR-attenuated total reflectance spectroscopy. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2079–2087, 1998     

Effect of alkali and ultraviolet (UV) radiation pretreatment on physical and mechanical properties of 1,6‐hexanediol diacrylate–grafted jute yarn by UV radiation

To improve the physicomechanical properties of jute yarn, grafting with 1,6‐hexanediol diacrylate (HDDA) monomer was performed by a UV radiation technique. A series of HDDA solutions of various concentrations in methanol were prepared. A small quantity of photoinitiator (Darocur‐1664) was also added to HDDA solutions. To optimize the conditions for grafting, the effects of monomer concentration, soaking time, and radiation doses were studied by varying the number of soaking times along with variation of monomer concentrations and UV radiation intensities. The extent of polymer loading and the mechanical properties like tensile strength (TS), elongation at break (Eb), and tensile modulus of both treated and untreated jute were investigated. The highest tensile strength, polymer loading, and modulus were achieved with 5% HDDA concentration, 5 min soaking time, and the 4th pass of UV radiation. This set of conditions was selected as optimum and produced enhanced tensile strength (67%), modulus (108%), and polymer loading (11%) over those of virgin fiber. To further improve the mechanical properties the jute yarns were pretreated with alkali (5% NaOH) solution and after that the alkali‐treated yarn were treated under UV radiation of various intensities. The pretreated samples were grafted with optimized monomer concentration (5% HDDA). Increased properties of alkali + UV‐pretreated and grafted samples such as polymer loading (12%), tensile strength (103%), elongation at break (46%), and modulus (114%) were achieved over those of virgin jute yarn. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 18–24, 2004     

A polymerizable photosensitizer and its photopolymerization kinetics

A previously reported polymerizable benzophenone photosensitizer, 2‐methacryloxyethyl 4‐benzoylbenzoate (MEBB), was synthesized and characterized. The photopolymerization kinetics of methyl α‐hydroxymethylacrylate (MHMA) and 1,6‐hexanediol diacrylate (HDDA) initiated with MEBB or benzophenone (BP) in the presence or absence of amine co‐initiators were determined by photo‐differential scanning calorimetry. The results indicate that benzophenone with a p‐carbonyl substitutent is more efficient in photoinitiation when compared to the non‐substituted benzophenone analogue. The final monomer conversions in the presence of amine co‐initiators are slightly higher than without them. Copyright © 2005 Society of Chemical Industry     

Rheology and thermal behavior of long branching polypropylene prepared by reactive extrusion

Long‐chain branching polypropylene (LCB‐PP) was achieved by reactive extrusion in the presence of bifunctional monomer [1,6‐hexanediol diarylate (HDDA)] and peroxide of dicumyl peroxide (DCP). Influences of HDDA and DCP concentrations on the branching efficiency were comparatively evaluated. Fourier transformed infrared spectroscopy (FTIR) results indicated that the grafting reaction took place, and HDDA has been grafted on PP skeleton. In comparison with initial PP, some modified samples showed lower melt flow index because of a large number of LCB in their skeleton. Several rheology plots were used to investigate the rheological properties of the initial PP and modified PPs, and the rheological characteristics confirmed the LCB in modified PPs skeleton. DSC results showed that the crystallization temperatures of modified PPs were higher than those of initial PP and degraded PP, suggesting that the modified PPs had long‐chain branched structure. The contrastive investigation in the rheology of modified PPs suggested that proper concentrations of HDDA and DCP were more beneficial to producing LCB during reactive extrusion. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Improvement of hydrophilicity of polypropylene by liquid-phase mutual irradiation of acrylics

N-butanol was found to promote the inclusion of methyl acrylate and methyl methacrylate in polypropylene, but did not affect the uptake of acrylic acid in the polymer. Polymerization of the monomers was, however, not significantly affected by the use of this swelling agent. The monomer exchange process followed by a liquid phase mutual irradiation has proved to be very effective in enhancing the polymerization of all three monomers on polypropylene. Optimum radiation doses for effective polymerization of the monomers were found to be around 3.2 Mrad for methyl acrylate and around 4.8 Mrad for methyl methacrylate and acrylic acid. Surface wettability of the film and moisture regain of the fiber were tremendously improved with all monomers regardless of the swelling agent and temperatures. Also, a low radiation dose of 1.6 Mrad was as effective as the higher doses. Methyl acrylate and methyl methacrylate modified fibers showed no marked changes in strength and elongation, but did result in a harsher hand. Acrylic acid modified fibers increased greatly in elongation, decreased to a greater extent in strength, and softened in hand.     

Synthesis and photopolymerizations of new hydroxyl-containing dimethacrylate crosslinkers

Two new hydroxyl-containing di(meth)acrylate monomers were synthesized from the reaction of methyl α-chloromethylacrylate (MCMA) and of ethyl α-chloromethylacrylate (ECMA) with glycerol. The monomers were obtained as mixtures of two isomers in different ratios and in combination with the analogous trimethacrylate monomers. Each monomer was isolated by column chromatography. The photopolymerization of these isomer mixtures and the trimethacrylate monomers was investigated individually by photodifferential scanning calorimetry (photoDSC) at room temperature using 2,2′-dimethoxy-2-phenyl-acetophenone (DMPA) as a photoinitiator. The effect of hydrogen bonding on the rates of polymerizations and conversions was examined. The results obtained for the synthesized monomers were compared to the values obtained for commercial monomers. It was observed that the hydroxyl-containing dimethacrylates polymerize much faster and to considerably higher conversion than the trimethacrylate monomers. The maximum rates of polymerization of the hydroxyl-containing monomers were higher than that of the hexanediol dimethacrylate (HDDMA), comparable to glycerol dimethacrylate and lower than hexanediol diacrylate (HDDA) and 3-(acryloyloxy)-2-hydroxypropyl methacrylate (AHM).