Melt Polymerization Research Articles

Methodology for development of new active barrier PET copolymers

ABSTRACTActive barrier developments for poly(ethylene terephthalate) (PET) are among important approaches being used to achieve improvements in the polyester's barrier properties. This work utilized two active barrier materials and their PET copolymers, synthesized by melt polymerization of terephthalic acid (TPA) with ethylene glycol (EG) and active oxygen scavengers: monoolein (MO) or 3‐cyclohexene‐1,1‐dimethanol (CHEDM), in separate compositions. The oxidizable monomers and their copolymers were characterized with respect to changes resulting from their reactions with oxygen. Evaluations of their infrared and nuclear magnetic resonance spectra established that the monomers as well as their PET copolymers underwent first order reactions and had rate constants ranging from 0.03 to 0.08 day−1. The only volatile oxidation product of MO was acetaldehyde and no volatile products resulted from oxidation of CHEDM. In comparison to unmodified PET, the PET/MO and PET/CHEDM copolymers achieved respective oxygen barrier property improvements of about 30 and 40%. Results from this study have shown that the oxidation kinetics of pure monomers of this type may be used for evaluation of their effectiveness and suitability as active barrier materials, without the need to synthesize their corresponding PET copolymers. This is significant and work is continuing to include other moieties that will interact with higher levels of oxygen and react at faster rates. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4273–4283, 2013

Synthesis and characterization of p-benzophenoneoxycarbonylphenyl acrylate by means of experimental measurements and theoretical approaches, and bulk melt polymerization

This multidisciplinary study deals with not only the synthesis of p-benzophenoneoxycarbonylphenyl acrylate (BPOCPA) in the xylene solvent and production of Poly(BPOCPA) by bulk melt polymerization and solution methods but also the characterization of BPOCPA experimentally (by DCS, UV, IR, 1H NMR and PL) and theoretically (with DFT method, B3LYP) method for the first time. The FTIR and 1H NMR measurement results verify that the synthesis of the BPOCPA is performed in the yield of 57wt% without any impurities. Moreover, DSC melting point belonging to the monomer is found to be about 131.1°C when the C and H contents are noted to be 71.397% and 3.554%, respectively. As for the UV–vis spectrometer findings, the absorption wavelength λmax is observed at 344nm due to the effective π–π* conjugated segments in the title compound. The optical band gap energy is observed to be about 3.22eV, confirming the presence of the strong electronic donating groups in the monomer. Furthermore, PL spectrum shows that the compound exhibits strong fluorescence centered at 464.4nm with a large Stokes shift of 120.4nm. Moreover, the theoretical calculation results indicate that the structure is quite stable but obtains high electronic donor ability for the electrophilic attack (intermolecular interactions), favored by the experimental findings of UV–vis and PL measurements. Theoretical electronic absorption spectra values are also discussed clearly.

Single-step synthesis of internally functionalizable hyperbranched polyethers

Radical catalyzed thiol-ene reaction has become a useful alternative to the Hüisgen-type azide-yne click reaction as it helps expand the variability in reaction conditions as well as the range of clickable entities. In this study, the direct generation of a hyperbranched polyether (HBPE) having decyl units at the periphery and a pendant allyl group on every repeat unit of the polymer backbone is described; the allyl groups serve as a reactive handle for postpolymerization modifications and permits the generation of a variety of internally functionalized HBPEs. In this design, the AB2 monomer carries two decylbenzyl ether units (B-functionality), an aliphatic OH (A-functionality) and a pendant allyl group within the spacer segment; polymerization of the monomer readily occurs at 150 °C via melt transetherification process by continuous removal of 1-decanol under reduced pressure. The resulting HBPE has a hydrophobic periphery due to the presence of numerous decyl chains, while the allyl groups that remain unaffected during the melt polymerization provides an opportunity to install a variety of functional groups within the interior; thiol-ene click reaction with two different thiols, namely 3-mercaptopropionic acid and mercaptosuccinic acid, generated interesting amphiphilic structures. Preliminary field emission scanning electron microscope (FESEM) and Atomic Force Microscopy (AFM) imaging studies reveal the formation of fairly uniform spherical aggregates in water with sizes ranging from 200 to 400 nm; this suggests that these amphiphilic HBPs is able to reconfigure to generate jellyfish-like conformations that subsequently aggregate in an alkaline medium. The internal allyl functional groups were also used to generate intramolecularly core-crosslinked HBPEs, by the use of dithiol crosslinkers; gel permeation chromatography traces provided clear evidence for reduction in the size after crosslinking. In summary, we have developed a simple route to prepare core-clickable HBPEs and have demonstrated the quantitative reaction of the allyl groups present within the interior of the polymers; such HB polymeric systems that carry numerous functional groups within the core could have interesting applications in analyte sequestration and possibly sensing, especially from organic media. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4125–4135

High molecular weight poly(ethylene-2,5-furanoate); critical aspects in synthesis and mechanical property determination

Furan-2,5-dicarboxylic acid (FDCA) is a widely advocated renewable substitute for terephthalic acid (TA). Preparation of high molecular weight FDCA based polyesters by an industrially common combination of melt polymerization and subsequent solid state post condensation is described. Ultimately, poly(ethylene 2,5-furanoate) (PEF) with absolute Mn = 83,000 g mol−1 is obtained, determined by triple detection Size Exclusion Chromatography. The bulk polymer properties of FDCA based polyesters, necessary to evaluate their industrial potential were determined the Young's modulus of PEF is determined to be 2450 ± 220 MPa and the maximum stress 35 ± 8 MPa. The influence of crystallinity on the mechanical properties as function of temperature was determined by dynamic mechanical thermal analysis. A detailed differential scanning calorimetry study on the crystallization behavior of high molecular weight PEF allowed to calculate the equilibrium melting temperature (Tm0) of 239.3 and 239.7 °C for the first and second melting peak, respectively. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4191–4199

Synthesis, Characterization and Ring-Opening Polymerization of Macrocyclic Aryl Ketone Oligomers Containing the Phthaloyl Moiety

Preparation of macrocyclic aryl ketone oligomers containing the phthaloyl moiety by Friedel-Crafts acylation reaction is described. Detailed structural characterization of these oligomers confirmed the cyclic nature by a combination of MALDI-TOF-MS and GPC analyses. The cyclic aryl ketone oligomers are amorphous and readily undergo anionic ring-opening polymerization in the melt by using potassium 4, 4-biphenoxide as the initiator, producing linear, high molecular weight poly (ether ketone) s with excellent thermal stability.

A biodegradable thermoset polymer made by esterification of citric acid and glycerol

A new biomaterial, a degradable thermoset polymer, was made from simple, economical, biocompatable monomers without the need for a catalyst. Glycerol and citric acid, nontoxic and renewable reagents, were crosslinked by a melt polymerization reaction at temperatures from 90 to 150°C. Consistent with a condensation reaction, water was determined to be the primary byproduct. The amount of crosslinking was controlled by the reaction conditions, including temperature, reaction time, and ratio between glycerol and citric acid. Also, the amount of crosslinking was inversely proportional to the rate of degradation. As a proof-of-principle for drug delivery applications, gentamicin, an antibiotic, was incorporated into the polymer with preliminary evaluations of antimicrobial activity. The polymers incorporating gentamicin had significantly better bacteria clearing of Staphylococcus aureus compared to non-gentamicin gels for up to 9 days.

Solid state polymerization of poly(lactic acid): Some fundamental parameters

Poly(lactic acid) (PLA) was submitted to solid state polymerization (SSP) in a fixed bed reactor under nitrogen flow, so as to examine technique efficiency for increasing the molecular weight and hence permitting the reduction of the melt polymerization residence times. In order to use a suitable starting material, SSP prepolymers of low and medium molecular weight were first prepared through solid state hydrolysis of commercial PLA grade under acidic and alkaline conditions. During these degradation runs, hydrolysis involved the random scission of ester groups in the polymer backbone, while the relevant kinetics and the resulting thermal properties were also examined. In a subsequent step, the prepolymers obtained were subjected to SSP at three temperatures, approximately 2.5–25.0 °C below their melting point. The process achieved an increase of up to 1.7 times the initial molecular weight, however, with different trends depending on the prepolymer characteristics, reaction temperature and time, as well as the pH of the hydrolysis medium. In addition to molecular weight build up, the effect of the SSP process on end product thermal properties was also investigated.

Structure–Property Relationship of CaO-MgO-SiO2 Slag: Quantitative Analysis of Raman Spectra

The quantitative structural information such as the relative abundance of silicate discrete anions (Q n units) and the concentration of three types of oxygens, viz. free-, bridging- and nonbridging oxygen can be obtained from micro-Raman spectra of the quenched CaO-SiO2-MgO glass samples. Various transport properties such as viscosity, density, and electrical conductivity can be expected as a simple linear function of “ln (Q3/Q2),” indicating that these physical properties are strongly dependent on a degree of polymerization of silicate melts. The methodology outlined in the current study can be extended to predict the physicochemical properties of silicate melts in ferrous and non-ferrous metallurgical processes.

Advanced Polymerization and Properties of Biobased High Tg polyester of Isosorbide and 1,4-Cyclohexanedicarboxylic Acid through in Situ Acetylation

The synthetic problems associated with melt polymerizations to form homopolyesters of isosorbide (ISB) and rigid diacids could potentially be solved by using catalyst systems with acetic anhydride (Ac2O). A catalyst consisting of dibutyltin oxide, germanium oxide, and Ac2O exhibited excellent performance characteristics in syntheses of a high-molecular-weight homopolyester of ISB and cis/trans-1,4-cyclohexanedicarboxylic acid (CHDA), also referred to as poly(isosorbide cis/trans-1,4-cyclohexanedicarboxylate) (PICD). The acetylation of ISB using Ac2O during esterification decreased the steric hindrance of ISB and accelerated the chain growth of PICD. Gel permeation chromatography data confirmed the formation of a high-molecular-weight PICD (71 100 weight-average molecular weight and 14 300 number-average molecular weight) using 0.02 mol of Ac2O. The glass transition temperature of PICD was almost 131 °C at 0.02 mol of Ac2O and decreased with increasing amounts of Ac2O due to the breaking of the rigid ring of ISB at higher concentrations of Ac2O. The structure of opened ring ISB was confirmed using two-dimensional nuclear magnetic resonance (NMR) and distortionless enhancement by polarization transfer NMR.

말단캡핑제를 이용한 폴리카보네이트의 분자량 특성 조절

말단캡핑제(end capping agent) 6종류에 대해 폴리카보네이트를 용융중합법으로 제조하였다. 합성된 폴리카보네이트의 화학구조는 FT-IR 스펙트럼을 이용하여 확인하였다. 평균분자량 및 분자량분포도, 유리전이 온도 및 열분해 온도는 GPC, DSC와 TGA를 이용하여 측정하였다. 말단캡핑제의 화학구조에 따라 평균분자량이 증가 또는 감소를 나타내었으며, 말단캡핑제로 4-tert-butylphenol (TBP)이 사용되었을 때 최적의 분자량 조절 결과를 나타내었다. 말단캡핑제의 함량이 증가할수록 평균분자량은 감소하였고, 4-tert-butylphenol이 0.05 - 0.1 mol%가 첨가될 때 폴리카보네이트의 대형 사출물 가공에 적합한 20,000 - 30,000 정도의 수평균분자량을 나타내었다. 폴리카보네이트의 용융점도와 유리전이온도는 분자량이 감소할수록 감소하였다. 말단캡핑제의 투입방법 변경은 PC의 분자량분포도에 영향을 주었고, power law index의 감소를 보여주었다. Polycarbonates (PCs) with six different end capping agents were synthesized from melt polymerization. Chemical structure of the synthesized PC was determined by FT-IR spectroscopy. The average molecular weight and distribution, glass transition and thermal degradation temperatures were determined by GPC, DSC and TGA. Average molecular weight changed with the chemical structure of end capping agent, and 4-tert-butylphenol was estimated as the optimum end capping agent. The average molecular weights of PCs decreased with the concentration of the agent, the number average molecular weight was observed as 20,000 - 30,000 when 0.05-0.15 mol% of 4-tert-butylphenol added in PCs. The melt viscosities and glass transition temperature of the PCs decreased with molecular weight. The change for adding method of the agent affected on both the molecular weight distribution and decrease in power law index.

Solubility and partitioning behavior of Au, Cu, Ag and reduced S in magmas

Experiments have been conducted at 200MPa, 800–1030°C, and fO2 0.8 log units below the Ni–NiO buffer to determine the solubility of Au, Cu and Ag in silicate melts and pyrrhotite. The metal activities were imposed by using Au965Ag020Cu015 alloy capsules. Sulfur-free and sulfur-bearing systems were studied with otherwise identical melt compositions to assess the relative effect of S on the solubility of these metals. The data show that the major element composition of the silicate melt only moderately affects the solubility of Au, Ag and Cu between basalt and dacite, yielding solubilities identical within 50% relative. In comparison, solubilities in the rhyolite melts are lower by a factor of 1.5–2.5 for Cu and higher by up to a factor of 5 for Ag, depending on the aluminum saturation index of the melt. The solubilitiy of Ag significantly increases with increasing peraluminousity above an aluminum saturation index of 1. The effect of melt composition is significant on the solubility of Au in S-bearing melts, in part due to its effect on the sulfur concentration at sulfide saturation. The effect of S is the most pronounced in peralkaline rhyolites and mafic melts, and minimal in peraluminous rhyolites. The solubilities of all three metals significantly decrease with decreasing temperature. The concentration of sulfur in the melt at sulfide saturation and its volatile/melt partition coefficient are primarily determined by the FeO activity in the melt and the activity coefficients of dissolved FeS species, which appear to correlate with the degree of melt polymerization. The volatile/melt partition coefficient of reduced S increases from 79±4 (1σ) to 635±80 as the melt composition changes from basalt to slightly peraluminous rhyolite, and from 225±13 to 776±148 as the aluminium saturation index increases from 0.7 to 1.1 in rhyolites.At 1000°C, pyrrhotite/silicate melt partition coefficients for Cu increase from 540±30 (1σ) to 1140±110 from basalt to dacite, whereas the partition coefficients for Ag are nearly constant at 50±10. The partition coefficients of Au increase from 180±20 to 900±210 from basalt to dacite. Pyrrhotite/rhyolite melt partition coefficients for Cu, Ag and Au increase by about an order of magnitude as temperature drops from 1000°C to 800°C.At typical S concentrations for arc magmas (500–2000μg/g), the budget of Ag in the magma will not be controlled by pyrrhotite, whereas primary control on the Au and Cu budget by pyrrhotite may only be relevant in intermediate to felsic magmas.

Development of active barrier systems for poly(ethylene terephthalate)

AbstractCopolymers of Poly(ethylene terephthalate) (PET) were synthesized by the melt polymerization of terephthalic acid (TPA) with ethylene glycol (EG) and with each of the active oxygen scavengers; monoolein (MO) and 3‐cyclohexene‐1,1‐dimethanol (CHEDM) in separate compositions. Proton nuclear magnetic resonance spectroscopy (1H NMR) and 2D correlation spectroscopy (COSY) indicated that PET had reacted with both MO and CHEDM at their hydroxyl end groups. Oxygen barrier properties of the MO and CHEDM copolymers exhibited improvements of up to 40%, in comparison to an unmodified commercial PET. Effects of the oxygen scavengers on the copolymers' physical properties were investigated in terms of their crystallization, melting, and rheological behaviors. Both types of copolymers showed decreases in peak melting temperatures with increased scavenger concentrations and also crystallized more slowly as the scavenger concentrations increased. The PET/MO copolymer showed non‐Newtonian rheological behavior with higher MO concentration; while the PET/CHEDM copolymers showed Newtonian behavior within the studied range of CHEDM concentrations. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Synthesis and chain extension of hydroxyl‐terminated poly(lactic acid) oligomers and application in the blends

AbstractHydroxyl‐terminated poly(lactic acid) prepolymer (LA prepolymer) were prepared via L‐lactic acid as monomer, 1,4‐butanediol as blocking agent and Sn(II) octoate as catalyst by direct melt polymerization. Then the LA prepolymer was blended with starch followed by in situ chain extending reaction using different content of TDI as chain extender, producing the high molecular weight of poly(ester urethane) in the blends. The LA prepolymer/starch‐TDI blends were characterized by GPC, 1H‐NMR, SEM, DSC, tensile strength testing, and water resistance. The SEM results of cross‐section show that, compared with the simple PLA/starch blends, almost the starch granules were completely covered by ploy(ester urethane) in the LA prepolymer/starch‐TDI blends system. In comparison to the simple PLA/starch blends, the mechanical properties of LA prepolymer/starch‐TDI blends were increased, such as tensile strength increasing from 18.6 ± 3.8 to 44.2 ± 6.2 Mpa, tensile modulus increasing from 510 ± 62 to 1,850 ± 125 Mpa and elongation at break increasing from 1.8 ± 0.4 to 4.0 ± 0.5 %, respectively. This is attributed to high weight of poly (ester urethane) was formed via in situ reaction of the end of hydroxyl (LA prepolymer) and isocyanate groups and the starch granules were easily covered by ploy(ether urethane) via in situ polymerization in the blends. Moreover, covalent linkage was formed between the two phases interfaces. As a result, the interfacial adhesion was enhance and improved the mechanical property. In addition, the water resistance of LA prepolymer/starch‐TDI blends was much better that of the simple PLA/starch blends. POLYM. COMPOS., 2013 © 2013 Society of Plastics Engineers

Use of over the counter oral relief aids or dietary supplements for the ring-opening polymerization of lactide

Over the counter oral relief aids or dietary supplements, namely calcium carbonate, calcium hydroxyapatite, magnesium oxide, zinc oxide, Tums® and Pepto-Bismol® have been investigated in the melt ring-opening polymerization of lactide and a direct comparison with that involving tin(II) octanoate has been made. Of these, Pepto-Bismol® is shown to be the most active and comparable to tin octanoate. The active ingredient in Pepto-Bismol® is bismuth subsalicylate and when this is employed as the initiator similar results are obtained in melt polymerizations which suggests it could be employed as an alternative to the commercially used tin(II) octanoate.

Influence of Al2O3/SiO2 Ratio on Viscosities of CaO^|^ndash;Al2O3^|^ndash;SiO2 Melt

The influence of Al2O3/SiO2 ratio on viscosity of CaO-Al2O3/SiO2 melt was investigated by the rotating cylinder method in this study. Three groups of compositions with different CaO contents of 0.35, 0.4 and 0.45 were studied. From the experimental results, it was concluded that viscosity always first increases and then decreases as gradually increasing Al2O3/SiO2 ratio. The appearance of viscosity maximum may be resulted from the opposite variation tendencies of mean bond strength and the degree of polymerization of melt with Al2O3/SiO2 ratio. When substituting SiO2 by Al2O3, the mean bond strength decreases because of the weak Al-O bond relative to Si-O bond, which decreases viscosity; while the degree of polymerization is enhanced by the charge compensation effect of Al3+ ion, which increases viscosity. Our new proposed viscosity model can well describe the viscosity variation of CaO-Al2O3-SiO2 melt.

Fully Isohexide-Based Polyesters: Synthesis, Characterization, and Structure–Properties Relations

Here we present a novel series of biobased polyesters solely based on renewable isohexide building blocks, synthesized via melt polymerization. The recently developed isoidide dicarboxylic acid (IIDCA) was polymerized with rigid renewable diols such as isosorbide (IS), isomannide (IM), isoidide (II), and the novel 2,5-methylene-extended isoidide dimethanol (IIDML). Both IIDCA and IIDML were developed to increase the reactivity of the isohexide building block, while retaining rigidity and hence the beneficial effects on Tg. Compared to the parent isohexides, IIDML showed a markedly higher reactivity, resulting in three to four times higher weight-average molecular weight (Mw) values of the synthesized polyesters. The molecular structure of the novel polyesters was analyzed by 1H, 13C and 2D-COSY NMR techniques, confirming that the stereoconfigurations of the isohexide moieties were preserved under the applied polymerization conditions. The II/IS-based polyesters have high Tg values noted of 70 and 85 °C, r...

Formation of extended ionomeric network by bulk polymerization of l,d-lactide with layered-double-hydroxide

We report the formation of an ionomeric network in a poly(l,d-lactide) hybrid nanocomposite, (PLDLA-HYB) during in-situ melt polymerization of l,d-lactide in the presence of magnesium/aluminum layered-double-hydroxide (LDH) without added catalyst.The effect of LDH mass loading and reaction time on molecular mass and yield of soluble poly(l,d-lactide) (PLDLA-SOL) present in the hybrid was investigated for a better understanding of the conflicting roles of LDH in polymerization and degradation of PLDLA-SOL. High molecular mass PLDLA-SOL is obtained through initiation of polymerization by LDH. However an additional insoluble organic–inorganic fraction, INSOL, is also observed within the product when PLDLA-SOL is extracted using methylene chloride as solvent. It is proposed that INSOL is an ionomeric network comprising hydrogen-bonded, or otherwise co-ordinated, lactic acid monomer salts of magnesium, together with PLDLA in a 24%–76% mass ratio.

An Investigation of Polyamides Based on Isoidide-2,5-dimethyleneamine as a Green Rigid Building Block with Enhanced Reactivity

Novel, semicrystalline polyamides and copolyamides were synthesized from a new carbohydrate-based diamine, namely isoidide-2,5-dimethyleneamine (IIDMA). In combination with 1,6-hexamethylene diamine (1,6-HDA) as well as the biobased sebacic acid (SA) or brassylic acid (BrA), the desired copolyamides were obtained via melt polymerization of the nylon salts followed by a solid-state polycondensation (SSPC) process. Depending on the chemical compositions, the number average molecular weights (Mn) of the polyamides were in the range of 4000–49000 g/mol. With increasing IIDMA content in the synthesized copolyamides, their corresponding glass transition temperatures (Tg) increased from 50 °C to approximately 60–67 °C while the melting temperatures (Tm) decreased from 220 to 160 °C. The chemical structures of the polyamides were analyzed by NMR and FT-IR spectroscopy. Both differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) analyses revealed the semicrystalline character of these nove...

Oxalic Amidines – Protonation Studies and Activity in Lactide Polymerisation

AbstractThe oxalic amidine N,N′‐dimethyl‐N,N′‐diphenyl‐1,2‐bis[4‐tolylimino]ethane‐1,2‐diamine was used to synthesise a chloridozinc complex and two monoprotonated species either with chloride or triflate counterions. The compounds have been structurally characterised by X‐ray crystallography. Proton affinities have been determined by quantum chemical calculations to investigate why only the iminium protonated species is selectively formed upon mild protonation. To better understand the coordination properties of the ligand, different possible coordination modes of the ligand to zinc chloride have been investigated by DFT calculations. The chloridozinc complex was applied as a catalyst in the melt polymerisation of rac‐lactide and exhibited high activity combined with excellent agreement between the obtained and calculated molecular weights.

Catalytic behavior of silyl-amide complexes for lactide polymerization

A series of silyl-amide complexes (=M{N(SiMe3)2}2) were examined as the catalysts for the ring-opening polymerization (ROP) of L-lactide. The catalytic activity of the silyl-amide complexes for zinc was compared with that of the silyl-amide complexes of tin in order to clarify the structural effects on the catalytic behavior. In the tin complexes, the addition of 1-dodecanol made the polymerization rate of L-lactide faster and suppressed the initiation with the N(SiMe3)2 ligands. The 1H NMR analysis revealed that the rates of ligand exchange for the N(SiMe3)2 and 1-dodecanol are different between the zinc and tin complexes. Based on this finding, melt polymerizations of L-lactide was conducted with the zinc catalyst to synthesize high-molecular-weight poly(L-lactide). The M n of the obtained polymer was found to become higher than 60,000 Da, which is required for the industrial application of polylactide, in a short reaction time. Open image in new window