Crystallisation kinetics of novel branched poly(ethylene terephthalate): a small‐angle X‐ray scattering study

Three types of poly(ethylene terephthalate) (PET) were investigated: linear (unprocessed) bottle‐grade PET (intrinsic viscosity, IV ～ 0.82 dL g^?1); a branched PET produced from linear PET by reactive extrusion with 0.4% w/w pyromellitic dianhydride and pentaerythritol in 5:1 molar ratio (IV ～ 0.97 dL g^?1); and a control sample produced from the same linear PET by extrusion under the same conditions without the reactive agents (IV ～ 0.71 dL g^?1). A key finding is that the reactive extrusion process, presumably as a consequence of branching and branch distribution, significantly modifies the crystallisation kinetics and changes the final morphology. Using small‐angle X‐ray scattering (SAXS) and differential scanning calorimetry (DSC), the crystallisation kinetics of PET was monitored from the melt (270 °C) to a crystallisation temperature of either 205 or 210 °C. The IV of the branched PET was ～ 21% greater than that of the unprocessed PET, and the rate of melt crystallisation (from DSC measurements) was 510 s for the branched, 528 s for the control, and 640 s for the unprocessed PET. The lamellae spacings measured from the equilibrium SAXS patterns were ～160 ± 10 Å for the branched PET and ～180 ± 10 Å for the unprocessed PET. Such properties offer the potential for new applications requiring high‐melt‐strength PET. Copyright © 2006 Society of Chemical Industry     

UV‐curable pressure‐sensitive adhesives derived from functionalized soybean oils and rosin ester

Functionalized plant oils such as epoxidized soybean oil (ESO) are widely used in plastic industries as additives and are available for more value‐added applications. Pressure‐sensitive adhesive (PSA) derived from petroleum feedstocks has a huge market ranging from tapes to packaging. Here we show a sustainable PSA derived from ESO/dihydroxyl soybean oil (DSO)/rosin ester (Sylvalite) via UV‐initiated copolymerization. The ether crosslinks derived from cationic polymerization of ESO and copolymerization between ESO and DSO (or rosin ester) were demonstrated using ¹H NMR, 2D ¹H–¹H COSY NMR, electrospray ionization mass spectrometry and thermal analyses (differential scanning calorimetry and thermogravimetric analysis). The PSA was formulated by modulating the ratio of ESO/DSO/rosin ester to achieve high performance. At a UV dose of 5.1–5.4 J cm^?2 and 0.3–3% (w/w) of a photoinitiator, i.e. [4‐(2‐hydroxy‐1‐tetradecyloxy)‐phenyl]phenyliodonium hexafluoroantimonate, the PSA at a ratio (by weight) of 1:1:0.7 (ESO/DSO/rosin ester) recorded the highest peel and loop tack strength, which was comparable to a commercial PSA, Scotch Magic Tape, and showed much stronger shear strength (>30 000 min) than the commercial tape (10 000 min). The high‐shear rheological behavior and excellent thermal stability of the PSA were also demonstrated. © 2012 Society of Chemical Industry     

Novel anion‐exchange organic‐inorganic hybrid membranes prepared through sol‐gel reaction and UV/thermal curing

Anion‐exchange organic‐inorganic hybrid membranes were prepared through sol‐gel reaction and UV/thermal curing of positively charged alkoxysilane and the alkoxysilane containing acrylate or epoxy groups. Properties of prepared hybrid membranes were varied by control of the molar ratio of the precursors. It was shown that the thermal degradation temperatures (T_d) of the membranes were in the range of 212–226°C, water uptakes in the range of 9.6–14.6% and IEC values in the range of 0.9–1.6 mmol g^?1. The hybrid membranes show high permeability to anions, as reflected by the high static transport number (t_?) of the anion (Cl^?). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Synthesis,characterization, thermal stability,and compatibility properties of poly(vinyl p‐nitrobenzal acetal)‐g‐polyglycidylazides

A series of energetic polymers, poly(vinyl p‐nitrobenzal acetal)‐g‐polyglycidylazides (PVPNB‐g‐GAPs), are obtained via cross‐linking reactions of poly(vinyl p‐nitrobenzal acetal) (PVPNB) with four different molecular weights polyglycidylazides (GAPs) using toluene diisocyanate as cross‐linking agent. The structures of the energetic polymers are characterized by ultraviolet visible spectra (UV‐Vis), attenuated total reflectance‐Fourier transform‐infrared spectroscopy (ATR‐FT‐IR), ¹H nuclear magnetic resonance spectrometry (¹H NMR), and ¹³C nuclear magnetic resonance spectrometry (¹³C NMR). Differential scanning calorimetry (DSC) is applied to evaluate the glass‐transition temperature of the polymers. DSC traces illustrate that PVPNB‐g?2^#GAP, PVPNB‐g?3^#GAP, and PVPNB‐g?4^#GAP have two distinct glass‐transition temperatures, whereas PVPNB‐g?1^#GAP has one. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) are used to evaluate the thermal decomposition behavior of the four polymers and their compatibility with the main energetic components of TNT‐based melt‐cast explosives, such as cyclotetramethylene tetranitramine (HMX), cyclotrimethylene‐trinitramine (RDX), triaminotrinitrobenzene (TATB), and 2,4,6‐trinitrotoluene (TNT). The DTA and TGA curves obtained indicate that the polymers have excellent resistance to thermal decomposition up to 200°C. PVPNB‐g?4^#GAP also exhibits good compatibility and could be safely used with TNT, HMX, and TATB but not with RDX. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42126.     

Crystallization behavior and UV‐protection property of PET‐ZnO nanocomposites prepared by in situ polymerization

The aim of this study was to investigate the crystallization behavior and UV‐protection property of polyethylene terephthalate (PET)‐ZnO nanocomposits. PET‐ZnO nanocomposites containing 0.5–3.0 wt % of ZnO were successfully synthesized by in situ polymerization. The Fourier transformed infrared (FTIR) spectroscopy indicated the silane coupling agent was anchored onto the surface of ZnO. Scanning electron microscope (SEM) images showed ZnO particles were dispersed homogeneously in PET matrix with amount of 0.5–1.0 wt %. Differential scanning calorimetry (DSC) results exhibited that the incorporation of ZnO into PET resulted in increase of the melting transition temperature (T_m) and crystallization temperature (T_c) of PET‐ZnO nanocomposites. The crystallization behavior of PET and PET‐ZnO nanocomposites was strongly affected by cooling rate. ZnO nanoparticles can act as an efficient nucleating agent to facilitate PET crystallization. UV–vis spectrophotometry showed that UV‐ray transmittance of PET‐ZnO nanocomposites decreased remarkably and reached the minimum value of 14.3% with 1.5 wt % of ZnO, compared with pure PET whose UV‐ray transmittance was 84.5%. PET‐ZnO nanocomposites exhibited better UV‐protection property than pure PET, especially in the range of UVA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Oxo‐biodegradability of high‐density polyethylene films containing limited amount of isotactic polypropylene

Limited amount of isotactic polypropylene (iPP) is added to high‐density polyethylene (HDPE) containing 1% w/w an oxo‐biodegradable additive and extruded and converted to films. The films are put under UV irradiation for different periods of time. Irradiation of the films for 6 weeks imposes remarkable effects on viscosity average molecular weight (M_v) and carbonyl index (CI) of them. M_v decreases from 3.4 × 10⁵ to 4.7 × 10⁴ g mol^?1 for neat HDPE films; from 3.1 × 10⁵ to 3.3 × 10⁴ g mol^?1 for the films containing oxo compound, and from 1.5 × 10⁵ to 2.6 × 10⁴ g mol^?1 for the films containing oxo compound and 1% w/w iPP. Carbonyl index of the neat HDPE films increases from 4 to 8.7 while for the sample containing only the oxo compound it increases from 4.5 to 7.3 and for the sample containing both oxo compound and iPP it decreases from 12.0 to 8.8. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) indicate more cracks and uniform degradation in the samples containing iPP and oxo compound. Thermogravimetric analysis (TGA/DTG) of the samples shows that the samples containing iPP and oxo compound have lower decomposition temperature after UV irradiation. Finally, it can be said that the presence of iPP in HDPE matrix containing oxo compound can improve HDPE oxo‐biodegradablity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45843.     

Influence of LiClO4 on the thermal,mechanical, and morphological properties of P(DMS‐co‐EO)/ P(EPI‐co‐EO) blends

The UV‐vis absorption, thermal analysis, ionic conductivity, mechanical properties, and morphology of a blend of poly(dimethylsiloxane‐co‐ethylene oxide) [P(DMS‐co‐EO)] and poly(epichlorohydrin‐co‐ethylene oxide) [P(EPI‐co‐EO)] (P(DMS‐co‐EO)/P(EPI‐co‐EO) ratio of 15/85 wt %) with different concentrations of LiClO₄ were studied. The maximum ionic conductivity (σ = 1.2 × 10^?4 S cm^?1) for the blend was obtained in the presence of 6% wt LiClO₄. The crystalline phase of the blend disappeared with increasing salt concentration, whereas the glass transition temperature (T_g) progressively increased. UV‐vis absorption spectra for the blends with LiClO₄ showed a transparent polymer electrolyte in the visible region. The addition of lithium salt decreased the tensile strength and elongation at break and increased Young's modulus of the blends. Scanning electron microscopy showed separation of the phases between P(DMS‐co‐EO) and P(EPI‐co‐EO), and the presence of LiClO₄ made the blends more susceptible to cracking. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1230–1235, 2004     

Investigations of the electrical conduction mechanisms of polyaniline‐DBSA/poly(acrylonitrile‐butadiene styrene) blends

The electrical properties of Al/PANI‐DBSA/ABS/Au blend with PANI (5%) w/w have been investigated by using of current‐voltage (I‐V) measurements, in a temperature range of 100–313 K. The analysis of I‐V characteristics in the forward direction was based on thermionic emission mechanism for applied electrical field till ～3 × 10² V/cm. The thickness dependence of the current‐voltage relationship, clearly demonstrates that the electrical current for larger fields is space charge limited current (SCLC). Temperature dependences of the ideality factor, barrier height, and series resistance have been calculated. The mobility of carriers which is temperature dependent was calculated using the trap free SCLC as 1.53 × 10^?4 cm² V^?1 s^?1 at room temperature. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40688.     

Interpenetrating polymer networks of poly(butyl methacrylate) and poly(α‐terpineol‐co‐styrene): Synthesis and characterization

Simultaneous interpenetrating polymer networks (IPNs) based on poly(butyl methacrylate) and poly(α‐terpineol‐co‐styrene) were synthesized with azobisisobutyronitrile (AIBN) as the initiator and divinyl benzene as the crosslinking agent in xylene under an inert nitrogen atmosphere. Fourier transform infrared spectra provided structural evidence for the IPNs, indicating characteristic frequencies of ester groups of butyl methacrylate at 1723 cm^?1 and alcoholic groups of α‐terpineol at 3436 cm^?1. Scanning electron microscopy revealed threadlike network structures. Properties such as percentage swelling and average molecular weight between crosslinks were direct functions of the copolymer and initiator (AIBN) concentrations and inverse functions of the monomer (butyl methacrylate) and crosslinking agent (divinyl benzene) concentrations. Differential scanning calorimetry showed an IPN glass‐transition temperature at 80.2°C. The thermal decompositions of the IPNs were established with the help of thermogravimetric analysis. The value of the activation energy, calculated from thermogravimetric analysis with the Coats and Redfern equation, was 23 kJ/mol. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 343–352, 2006     

Crosslinking studies on poly(ethylene terephthalate‐co‐1,4‐phenylene bisacrylate)

Several compositionally different poly(ethylene terephthalate‐co‐1,4‐phenylene bisacrylate) (PETPBA) copolymers were melt spun into fibers. The resulting fibers were subjected to UV irradiation to induce crosslinking. Evidence of crosslinking was obtained from FTIR, solid‐state ¹³C‐NMR, thermal analysis, and solubility. Irradiation of the fiber results in an increased glass‐transition temperature, reduced thermal shrinkage, and enhanced modulus retention at elevated temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1698–1702, 2004     

Synthesis and characterization of oligosalicylaldehyde‐graft‐oligoaniline and its beginning oligomers

Conjuge bonding oligosalicylaldehyde‐graft‐oligoaniline (OSA‐graft‐OA) was synthesized from the polycondensation reaction of oligosalicylaldehyde (OSA) with oligoaniline (OA). There were various functional groups such as ? OH, ? NH and ? CH?N in the structure of the graft cooligomer. The physical properties of graft‐co‐oligomers such as melting temperature and solubility were studied: number‐average molecular weight, mass‐average molecular weight, and a polydispersity index of OA, OSA, and fractions of the graft cooligomers [(OSA‐graft‐OA)‐I] and [(OSA‐graft‐OA)‐II] were found to be 740, 780 g mol^?1,1.05; 3700, 5990 g mol^?1, 1.62; 990, 2770 g mol^?1, 2.80 and 1300, 4100 g mol^?1, 3.15, respectively. The FTIR and UV‐Vis spectra of the graft cooligomer were compared with those of beginning oligomers. The spectral analyses results showed that the OSA‐graft‐OA synthesized from the polycondensation reaction of aromatic amine with aldehyde that have long oligophenol macromolecule bonded each other with an azomethine bridge through oligophenylamine side chains. The thermal stability of the graft cooligomer and oligomers were measured by thermogravimetric analysis (TG) under an air atmosphere. According to TG analyses, the carboneous residues of the [(OSA‐graft‐OA)‐I) (soluble in ethanol) and (OSA‐graft‐OA)‐II) (soluble in toluene)] were 23 and 40%, respectively, at 1000°C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 218–226, 2002     

Poly(hydroxyethyl methacrylate‐co‐glycidyl methacrylate) reactive membrane utilised for cholesterol oxidase immobilisation

Poly(2‐hydroxyethyl methacrylate‐co‐glycidyl methacrylate) p(HEMA–GMA) membrane was prepared by UV‐initiated photopolymerisation of 2‐hydroxyethyl methacrylate (HEMA) and glycidyl methacrylate (GMA) in the presence of an initiator, azobisisobutyronitrile (AIBN). Cholesterol oxidase was immobilised directly on the membrane by forming covalent bonds between its amino groups and the epoxide groups of the membrane. An average of 53 µg of enzyme was immobilised per cm² of membrane, and the bound enzyme retained about 67% of its initial activity. Immobilisation improved the pH stability of the enzyme as well as its temperature stability. The optimum temperature was 5 °C higher than that of the free enzyme and was significantly broader. The thermal inactivation rate constants for free and immobilised preparations at 70 °C were calculated as k_{i (free)} 1.06 × 10^?1 min^?1 and k_{i (imm)} 2.68 × 10^?2 min^?1, respectively. The immobilised enzyme activity was found to be quite stable in the repeated experiments. © 2002 Society of Chemical Industry     

A novel positive‐type photosensitive polyimide based on soluble block copolyimide showing low dielectric constant with a low‐temperature curing process

A soluble block copolyimide (Bco‐PI) was prepared by direct one‐pot polycondensation of 2,2‐bis‐(3‐amino‐4‐hydroxyphenyl)hexafluoropropane, 2,2‐bis[4‐(4‐aminophenoxy)phenyl]hexafluoropropane, and cyclohexane‐tetracarboxylic dianhydride in the presence of γ‐valerolactone and a pyridine catalyst system using γ‐butyrolactone as the solvent. The thermal transmission temperature (T_g) of Bco‐PI was 282°C. By having the curing process occur at 250°C, which was below the T_g, colorless and transparent films could be obtained. The film showed excellent optical characteristics. Such properties could not be attained by the conventional high‐temperature thermal imidization process of poly(amic acid). The hydroxy groups in the polyimide backbone gave the Bco‐PI the potential to become alkaline. To the Bco‐PI was added 15 wt % ester of 2,3,4‐trihydroxybenzophenone with 1,2‐naphthoquinone‐(2) diazide‐5‐sulfonic acid (NT200) as the photoreactive compound. The system worked as a positive‐type photosensitive polyimide (PSPI). The sensitivity and contrast of the PSPI system were 220 mJ/cm² and 1.27, respectively, when exposed to UV light, followed by development with a 5% tetramethylammonium hydroxide (TMAH) aqueous solution at room temperature. After curing at 250°C for 1 h, the average refractive index of Bco‐PI with and without NT200 was 1.5543 and 1.5563, and the optically estimated dielectric constant of the polyimides was 2.66 and 2.67, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4240–4246, 2006     

Advanced oxidation processes for the degradation of p‐hydroxybenzoic acid 2: Photo‐assisted Fenton oxidation

Oxidation of p‐hydroxybenzoic acid in aqueous solution by the photo‐assisted Fenton reaction (Fe²⁺ + H₂O₂ + UV) has been studied. The effects of ferrous ion concentration (0.05, 0.14 and 0.29 mmol dm^?3), temperature (10, 20, 30 and 40 °C), and initial hydrogen peroxide concentration (0.7, 1.4, 2.2 and 2.9 mmol dm^?3) on the p‐hydroxybenzoic acid conversion were established. Experimental results indicate that the kinetics of this oxidation process fits pseudo‐first‐order kinetics well. The overall kinetic rate constant was split into two components: direct oxidation by UV radiation (photolysis) and oxidation by free radicals (mainly OH·) generated in the system. The importance of these two reaction paths for each specific value of ferrous ion concentration, temperature and initial hydrogen peroxide concentration was evaluated. A semi‐empirical expression is proposed for the overall reaction rate which takes into account both oxidation pathways and is a function of operating variables. © 2001 Society of Chemical Industry     

Sequence analysis and fiber properties of a blend of poly(ethylene terephthalate) and poly(ethylene terephthalate‐co‐4,4′‐bibenzoate)

Blends of poly(ethylene terephthalate) (PET) and poly(ethylene terephthalate‐co‐4,4′‐ bibenzoate) (PETBB) are prepared by coextrusion. Analysis by ¹³C‐NMR spectroscopy shows that little transesterification occurs during the blending process. Additional heat treatment of the blend leads to more transesterification and a corresponding increase in the degree of randomness, R. Analysis by differential scanning calorimetry shows that the as‐extruded blend is semicrystalline, unlike PETBB15, a random copolymer with the same composition as the non‐ random blend. Additional heat treatment of the blend leads to a decrease in the melting point, T_m, and an increase in glass transition temperature, T_g. The T_m and T_g of the blend reach minimum and maximum values, respectively, after 15 min at 270°C, at which point the blend has not been fully randomized. The blend has a lower crystallization rate than PET and PETBB55 (a copolymer containing 55 mol % bibenzoate). The PET/PETBB55 (70/30 w/w) blend shows a secondary endothermic peak at 15°C above an isothermal crystallization temperature. The secondary peak was confirmed to be the melting of small and/or imperfect crystals resulting from secondary crystallization. The blend exhibits the crystal structure of PET. Tensile properties of the fibers prepared from the blend are comparable to those of PET fiber, whereas PETBB55 fibers display higher performance. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1793–1803, 2004     

Preparation and kinetic analysis of PS‐b‐PBA block copolymer by 4‐oxo‐TEMPO capped polystyrene macroinitiators

Polystyrene‐block‐poly(n‐butyl acrylate) block copolymers were prepared from 4‐oxo‐2,2,6,6‐tetramethylpiperidinooxy (4‐oxo‐TEMPO) capped polystyrene macroinitiators at a high temperature, 165°C. It was found that the number‐average molecular weight of PBA chains in block copolymers could reach above 10,000 rapidly at early stage of polymerization with a narrow polydispersity index of 1.2–1.4, but after that, the polymerization seemed to be retarded. Furthermore, according to the kinetic analysis, the concentration of 4‐oxo‐TEMPO was increased mainly by the hydrogen transfer reaction of hydroxylamine (4‐oxo‐TEMPOH) to growing radicals during polymerization. This increase in 4‐oxo‐TEMPO concentration could retard the growth of polymer chains. The rate constant of the hydrogen transfer reaction of 4‐oxo‐TEMPOH to growing radicals, k_H, estimated by the kinetic model is about 9.33 × 10⁴M^‐1s^?1 at 165°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Syntheses and properties of the PET‐co‐PEA copolyester

An aliphatic‐aromatic random‐block copolyester of poly(ethylene terephthalate) (PET), and poly(enthylene adipate) (PEA), PET‐co‐PEA, was synthesized via melt polycondensation. The chemical structure of the products were characterized by two kinds of spectroscopic techniques (Fourier transform infrared and ¹H‐NMR). The thermal properties of the copolyester were characterized by thermogravimetry analysis, differential scanning calorimetry, wide‐angle X‐ray diffraction, and polarized optical microscopy. It was found that the crystallization ability, melting point, glass transition temperature of the random‐block coplyester decreased apparently. Meanwhile, the tensile strength and hydrolysis performance were measured as well. The result showed that the random‐block copolyesters PET‐co‐PEA displayed excellent properties in elasticity and strength. In addition, the potential degradability was found in hydrolysis measurement. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44967.     

Cationization of cellulose/polyamide on UV protection,bio‐activity,and electro‐conductivity of graphene oxide‐treated fabric

In this work, cationized cotton/nylon fabric was treated with reduced graphene oxide (rGO) to produce highly conductive fabric. The fabric was cationized with 3‐chloro‐2‐hydroxy propyl trimethyl ammonium chloride to attract more anionic GO. The fabric was then treated with GO followed by reduction with sodium dithionite. The results of energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, and X‐ray photoelectron spectroscopy indicated entire coverage of the fabric surface with rGO. The color of fabrics changed to gray‐black and the electrical resistance decreased to 0.6 × 103 Ω sq^?1. The washing fastness was measured according to ISO 105‐CO5 for color change and also electrical resistance of the samples demonstrated well stability of rGO on the fabric surface. The antibacterial activities of the treated fabrics improved against Gram‐negative bacteria including Escherichia coli (84.8%) and Pseudomonas aeruginosa (96.4%) and also Gram‐positive bacteria consisting Staphylococcus aureus (100%) and Enterococcus faecalis (98.4%). Further, the treated fabrics indicated an excellent UV reflectance of 100%. Finally heating of the cationized rGO fabric at 220 °C displayed a lower electrical resistance of 0.5 × 103 Ω sq^?1. The thermogravimetric analysis showed that heating has a slight effect on the dimensional thermal stability of the treated fabric as shrunk 2.43%. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45493.     

A single‐phase full‐color emitting phosphor Na3Sc2(PO4)3:Eu2+/Tb3+/Mn2+ with near‐zero thermal quenching and high quantum yield for near‐UV converted warm w‐LEDs

A single‐phase full‐color emitting phosphor Na₃Sc₂(PO₄)₃:Eu²⁺/Tb³⁺/Mn²⁺ has been synthesized by high‐temperature solid‐state method. The crystal structure is measured by X‐ray diffraction. The emission can be tuned from blue to green/red/white through reasonable adjustment of doping ratio among Eu²⁺/Tb³⁺/Mn²⁺ ions. The photoluminescence, energy‐transfer efficiency and concentration quenching mechanisms in Eu²⁺‐Tb³⁺/Eu²⁺‐Mn²⁺ co‐doped samples were studied in detail. All as‐obtained samples show high quantum yield and robust resistance to thermal quenching at evaluated temperature from 30 to 200°C. Notably, the wide‐gamut emission covering the full visible range of Na₃Sc₂(PO₄)₃:Eu²⁺/Tb³⁺/Mn²⁺ gives an outstanding thermal quenching behavior near‐zero thermal quenching at 150°C/less than 20% emission intensity loss at 200°C, and high quantum yield‐66.0% at 150°C/56.9% at 200°C. Moreover, the chromaticity coordinates of Na₃Sc₂(PO₄)₃:Eu²⁺/Tb³⁺/Mn²⁺ keep stable through the whole evaluated temperature range. Finally, near‐UV w‐LED devices were fabricated, the white LED device (CCT = 4740.4 K, Ra = 80.9) indicates that Na₃Sc₂(PO₄)₃:Eu²⁺/Tb³⁺/Mn²⁺ may be a promising candidate for phosphor‐converted near‐UV w‐LEDs.     

Phase structure and properties of poly(ethylene terephthalate)/high‐density polyethylene based on recycled materials

Blends based on recycled high density polyethylene (R‐HDPE) and recycled poly(ethylene terephthalate) (R‐PET) were made through reactive extrusion. The effects of maleated polyethylene (PE‐g‐MA), triblock copolymer of styrene and ethylene/butylene (SEBS), and 4,4′‐methylenedi(phenyl isocyanate) (MDI) on blend properties were studied. The 2% PE‐g‐MA improved the compatibility of R‐HDPE and R‐PET in all blends toughened by SEBS. For the R‐HDPE/R‐PET (70/30 w/w) blend toughened by SEBS, the dispersed PET domain size was significantly reduced with use of 2% PE‐g‐MA, and the impact strength of the resultant blend doubled. For blends with R‐PET matrix, all strengths were improved by adding MDI through extending the PET molecular chains. The crystalline behaviors of R‐HDPE and R‐PET in one‐phase rich systems influenced each other. The addition of PE‐g‐MA and SEBS consistently reduced the crystalline level (χ_c) of either the R‐PET or the R‐HDPE phase and lowered the crystallization peak temperature (T_c) of R‐PET. Further addition of MDI did not influence R‐HDPE crystallization behavior but lowered the χ_c of R‐PET in R‐PET rich blends. The thermal stability of R‐HDPE/R‐PET 70/30 and 50/50 (w/w) blends were improved by chain‐extension when 0.5% MDI was added. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009