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

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

Microstructure and crystallization of melt‐mixed poly(ethylene terephthalate)/poly(ethylene isophthalate) blends

Physical blends of poly(ethylene terephthalate) (PET) and poly(ethylene isophthalate) (PEI), abbreviated PET/PEI (80/20) blends, and of PET and a random poly(ethylene terephthalate‐co‐isophthalate) copolymer containing 40% ethylene isophthalate (PET₆₀I₄₀), abbreviated PET/PET₆₀I₄₀ (50/50) blends, were melt‐mixed at 270°C for different reactive blending times to give a series of copolymers containing 20 mol % of ethylene isophthalic units with different degrees of randomness. ¹³C‐NMR spectroscopy precisely determined the microstructure of the blends. The thermal and mechanical properties of the blends were evaluated by DSC and tensile assays, and the obtained results were compared with those obtained for PET and a statistically random PETI copolymer with the same composition. The microstructure of the blends gradually changed from a physical blend into a block copolymer, and finally into a random copolymer with the advance of transreaction time. The melting temperature and enthalpy of the blends decreased with the progress of melt‐mixing. Isothermal crystallization studies carried out on molten samples revealed the same trend for the crystallization rate. The effect of reaction time on crystallizability was more pronounced in the case of the PET/PET₆₀I₄₀ (50/50) blends. The Young's modulus of the melt‐mixed blends was comparable to that of PET, whereas the maximum tensile stress decreased with respect to that of PET. All blend samples showed a noticeable brittleness. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3076–3086, 2003     

Blends of poly(ethylene terephthalate) and poly(butylene terephthalate)

Commercial grade poly(ethylene terephthalate), (PET, intrinsic viscosity = 0.80 dL/g) and poly(butylene terephthalate), (PBT, intrinsic viscosity = 1.00 dL/g) were melt blended over the entire composition range using a counterrotating twin‐screw extruder. The mechanical, thermal, electrical, and rheological properties of the blends were studied. All of the blends showed higher impact properties than that of PET or PBT. The 50:50 blend composition exhibited the highest impact value. Other mechanical properties also showed similar trends for blends of this composition. The addition of PBT increased the processability of PET. Differential scanning calorimetry data showed the presence of both phases. For all blends, only a single glass‐transition temperature was observed. The melting characteristics of one phase were influenced by the presence of the other. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 75–82, 2005     

Recycled poly(ethylene terephthalate)/linear low‐density polyethylene blends through physical processing

Poly(styrene‐ethylene/butylene‐styrene) (SEBS) was used as a compatibilizer to improve the thermal and mechanical properties of recycled poly(ethylene terephthalate)/linear low‐density polyethylene (R‐PET/LLDPE) blends. The blends compatibilized with 0–20 wt % SEBS were prepared by low‐temperature solid‐state extrusion. The effect of SEBS content was investigated using scanning electron microscope, differential scanning calorimeter, dynamic mechanical analysis (DMA), and mechanical property testing. Morphology observation showed that the addition of 10 wt % SEBS led to the deformation of dispersed phase from spherical to fibrous structure, and microfibrils were formed at the interface between two phases in the compatibilized blends. Both differential scanning calorimeter and DMA results revealed that the blend with 20 wt % SEBS showed better compatibility between PET and LLDPE than other blends studied. The addition of 20 wt % of SEBS obviously improved the crystallizibility of PET as well as the modulus of the blends. DMA analysis also showed that the interaction between SEBS and two other components enhanced at high temperature above 130°C. The impact strength of the blend with 20 wt % SEBS increased of 93.2% with respect to the blend without SEBS, accompanied by only a 28.7% tensile strength decrease. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effects of electron beam irradiation on poly(ethylene 2,6‐naphthalate)/poly(ethylene terephthalate) blends

The effect of electron beam (EB) irradiation on the properties and compatibility of poly(ethylene 2,6‐naphthalate) (PEN)/poly(ethylene terephthalate) (PET) blends was investigated. Upon EB irradiation, PEN/PET blends underwent transesterification reactions, resulting in the formation of more random copolymers from the original binary pair. The degree of transesterification increased with dose rate, and all of the irradiated blends exhibited a single glass transition temperature. This indicated that transesterification reactions promoted by EB irradiation led to the formation of a single phase. Transesterification reactions promoted by EB irradiation led to more random copolymers, and the reduced regularity in the irradiated blends decreased the melting temperature. A higher degree of randomness and lower number‐average sequence lengths for the blend systems indicated that a more random chain structure was formed in the blends. The rheological measurements demonstrated that the irradiated PEN/PET blends were miscible. EB irradiation could promote transesterification reaction, thus enhancing the compatibility of PEN/PET blends.     

Crystallization behavior and mechanical properties of polypropylene random copolymer/poly(ethylene‐octene) blends

New polymer blends of polypropylene random copolymer (PP‐R) and poly(ethylene‐octene) (POE) were prepared by melt‐blending process using a corotating twin‐screw extruder. The POE content was varied up to 35%. The toughening efficiency of POE for PP‐R was evaluated by the mechanical properties of the resulted PP‐R/POE blends. The crystallization behavior and morphology of the blends were also studied. Results show that POE acts as nucleation agent to induce the crystallization of PP‐R matrix at higher crystallization temperature. Super‐toughened PP‐R/POE blends (Izod impact strength more than 500 J/m) can be readily achieved with only 10 wt % of POE. The high toughness of PP‐R/POE is attributed to cavitation and shear yielding of matrix PP‐R, as revealed by the morphology studies. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Biodegradable blends of high molecular weight poly(ethylene oxide) with poly(3‐hydroxypropionic acid) and poly(3‐hydroxybutyric acid): a miscibility study by DSC,DMTA and NMR spectroscopy

The miscibility of high molecular weight poly(ethylene oxide) blends with poly(3‐hydroxypropionic acid) and poly(3‐hydroxybutyric acid) (P(3HB)) has been investigated by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and high‐resolution solid state ¹³C nuclear magnetic resonance (NMR). The DSC thermal behaviour of the blends revealed that the binary blends of poly(ethylene oxide)/poly(3‐hydroxypropionic acid) (OP blends) were miscible over the whole composition range while the miscibility of poly(ethylene oxide)/poly(3‐hydroxybutyric acid) blends (OB blends) was dependent on the blend composition. OB blends were found to be partly miscible at the middle P(3HB) contents (25 %, 50 %) and miscible at other P(3HB) contents (10 %, 75 % and 90 %). Single‐phase behaviour for OP blends and phase separation behaviour for OB blends were observed from DMTA. The results from NMR spectroscopy revealed that the two components in the OP50 blend were intimately mixed on a scale of about 35 nm, while the domain sizes in the OB blend with a P(3HB) content of 50 % were larger than about 32 nm. © 2000 Society of Chemical Industry     

Properties of poly(ethylene terephthalate) and maleic anhydride-grafted polypropylene blends by reactive processing

The properties of poly(ethylene terephthalate) (PET) and polypropylene (PP) blends and PET/maleic anhydride-grafted PP (MAgPP) reactive blends were investigated. Two blend systems were immiscible based on tan δ measured by dynamic mechanical analyzer (DMA). In case of PET/MAgPP blends, the reaction of ester groups of PET and MA sites on MAgPP occurred during melt mixing at 280°C for 30 min. The reaction was confirmed by a new peak between the glass transition temperatures of PET-rich and MAgPP-rich phase on tan δ curves, as well as from the rheological properties. From the morphology, the improvement of the dispersibility in PET/MAgPP reactive blends was observed. The modulus of PET/MAgPP blends was higher than that of PET/PP blends, and the strength of PET/MAgPP blends showed the good adhesion compared with the PET/PP blends. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 389–395, 1998     

Miscibility of block copolymers of poly(ε‐caprolactone) and poly(ethylene glycol) with poly(3‐hydroxybutyrate) as well as the compatibilizing effect of these copolymers in blends of poly(ε‐caprolactone) and poly(3‐hydroxybutyrate)

Atactic poly(3‐hydroxybutyrate) (a‐PHB) and block copolymers of poly(ethylene glycol) (PEG) with poly(ε‐caprolactone) (PCL‐b‐PEG) were synthesized through anionic polymerization and coordination polymerization, respectively. As demonstrated by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) measurements, both chemosynthesized a‐PHB and biosynthesized isotactic PHB (i‐PHB) are miscible with the PEG segment phase of PCL‐b‐PEGs. However, there is no evidence showing miscibility between both PHBs and the PCL segment phase of the copolymer even though PCL has been block‐copolymerized with PEG. Based on these results, PCL‐b‐PEG was added, as a compatibilizer, to both the PCL/a‐PHB blends and the PCL i‐PHB blends. The blend films were obtained through the evaporation of chloroform solutions of mixed components. Excitingly, the improvement in mechanical properties of PCL/PHB blends was achieved as anticipated initially upon the addition of PCL‐b‐PEG. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2600–2608, 2001     

PEN/PET共混物结晶行为研究

用差示扫描量热法(DSC)研究了不同共混比例PEN/PET共混物的熔体结晶行为,并进行了等温结晶动力学测定。结果表明:随着两种组分向中间比例(50/50)靠近,共混物的熔融温度越低,结晶速率也越慢。     

Effect of poly(ethylene glycol) on the solid‐state polymerization of poly(ethylene terephthalate)

Poly(ethylene glycol) (PEG) and end‐capped poly(ethylene glycol) (poly(ethylene glycol) dimethyl ether (PEGDME)) of number average molecular weight 1000 g mol^?1 was melt blended with poly(ethylene terephthalate) (PET) oligomer. NMR, DSC and WAXS techniques characterized the structure and morphology of the blends. Both these samples show reduction in T_g and similar crystallization behavior. Solid‐state polymerization (SSP) was performed on these blend samples using Sb₂O₃ as catalyst under reduced pressure at temperatures below the melting point of the samples. Inherent viscosity data indicate that for the blend sample with PEG there is enhancement of SSP rate, while for the sample with PEGDME the SSP rate is suppressed. NMR data showed that PEG is incorporated into the PET chain, while PEGDME does not react with PET. Copyright © 2005 Society of Chemical Industry     

Impact modification of waste PET by polyolefinic elastomer

Waste poly(ethylene terephthalate) [PET] and a polyolefinic elastomer (POE), Engage? 8150, were melt blended in a co‐rotating twin screw extruder having initial distributive mixing followed by high shearing/stretching. Compositions having POE up to 10% with and without poly(ethylene‐co‐acrylic acid), as a compatibilizer were studied. The blends were characterized for mechanical, thermal and rheological properties as well as for morphological characteristics. Incorporation of POE improved the impact properties of PET very significantly. © 2003 Society of Chemical Industry     

Modification of bismaleimide resin by poly(ethylene phthalate‐co‐ethylene terephthalate), poly(ethylene phthalate‐co‐ethylene 4,4′‐biphenyl dicarboxylate), and poly(ethylene phthalate‐co‐ethylene 2,6‐naphthalene dicarboxylate)

Aromatic polyesters were prepared and used to improve the brittleness of bismaleimide resin, composed of 4,4′‐bismaleimidodiphenyl methane and o,o′‐diallyl bisphenol A (Matrimid 5292 A/B resin). The aromatic polyesters included PEPT [poly(ethylene phthalate‐co‐ethylene terephthalate)], with 50 mol % of terephthalate, PEPB [poly(ethylene phthalate‐co‐ethylene 4,4′‐biphenyl dicarboxylate)], with 50 mol % of 4,4′‐biphenyl dicarboxylate, and PEPN [poly(ethylene phthalate‐co‐ethylene 2,6‐naphthalene dicarboxylate)], with 50 mol % 2,6‐naphthalene dicarboxylate unit. The polyesters were effective modifiers for improving the brittleness of the bismaleimide resin. For example, inclusion of 15 wt % PEPT (MW = 9300) led to a 75% increase in fracture toughness, with retention in flexural properties and a slight loss of the glass‐transition temperature, compared with the mechanical and thermal properties of the unmodified cured bismaleimide resin. Microstructures of the modified resins were examined by scanning electron microscopy and dynamic viscoelastic analysis. The toughening mechanism was assessed as it related to the morphological and dynamic viscoelastic behaviors of the modified bismaleimide resin system. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2352–2367, 2001     

Enhanced dynamic mechanical and shape‐memory properties of a poly(ethylene terephthalate)–poly(ethylene glycol) copolymer crosslinked by maleic anhydride

Dimethyl terephthalate (DMT) and ethylene glycol (EG) were used for the preparation of poly(ethylene terephthalate) (PET), and poly(ethylene glycol) (PEG) was added as a soft segment to prepare a PET–PEG copolymer with a shape‐memory function. MWs of the PEG used were 200, 400, 600, and 1000 g/mol, and various molar ratios of EG and PEG were tried. Their tensile and shape‐memory properties were compared at various points. The glass‐transition and melting temperatures of PET–PEG copolymers decreased with increasing PEG molecular weight and content. A tensile test showed that the most ideal mechanical properties were obtained when the molar ratio of EG and PEG was set to 80:20 with 200 g/mol of PEG. The shape memory of the copolymer with maleic anhydride (MAH) as a crosslinking agent was also tested in terms of shape retention and shape recovery rate. The amount of MAH added was between 0.5 and 2.5 mol % with respect to DMT, and tensile properties and shape retention and recovery rate generally improved with increasing MAH. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 27–37, 2002     

Thermal and mechanical properties of poly(methyl methacrylate) and ethylene vinyl acetate copolymer blends

A series of poly(methyl methacrylate) (PMMA) blends have been prepared with different compositions viz., 5, 10, 15, and 20 wt % ethylene vinyl acetate (EVA) copolymer by melt blending method in Haake Rheocord. The effect of different compositions of EVA on the physico‐mechanical and thermal properties of PMMA and EVA copolymer blends have been studied. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) has been employed to investigate the phase behavior of PMMA/EVA blends from the point of view of component specific interactions, molecular motions and morphology. The resulting morphologies of the various blends also studied by optical microscope. The DSC analysis indicates the phase separation between the PMMA matrix and EVA domains. The impact strength analysis revealed a substantial increase in impact strength from 19 to 32 J/m. The TGA analysis reveals the reduction in onset of thermal degradation temperature of PMMA with increase in EVA component of the blend. The optical microscope photographs have demonstrated the PMMA/EVA system had a microphase separated structure consisting of dispersed EVA domains within a continuous PMMA matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effect of gamma irradiation on the thermal and dyeing properties of blends based on waste poly(ethylene terephthalate) blends

The effect of gamma irradiation on the properties of virgin, waste poly(ethylene terephthalate) (PET), and their blends was characterized by IR spectroscopy, thermogravimetric analysis and differential scanning calorimetry. The dye affinity for disperse dyes of the different PET polymers, before and after gamma irradiation was also studied. The results showed that the thermal stability of virgin, waste PET, and their blends was improved after gamma irradiation. The dye affinity for the disperse dye in terms of color intensity was improved after the exposure to gamma irradiation. The dye ability with disperse dye, in terms of color intensity (ΔE*), for virgin/waste PET (80/20%) blend, as an example, was improved by ～ 53 and 98% after the exposure to doses 30 and 50 kGy of gamma irradiation, respectively. In conclusion, the modification of waste PET or its blends with virgin PET by gamma irradiation may provide a practical method for the recycling to obtain useful products. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Melting and crystallization behavior of poly(ethylene terephthalate) and poly(m‐xylylene adipamide) blends

The crystallization and melting behaviors as well as the crystalline morphologies of Poly(ethylene terephthalate)/Poly(m‐xylylene adipamide) (PET/MXD6) blends have been examined and characterized with the aid of differential scanning calorimetry (DSC) and wide angle x‐ray diffraction (WAXD). The isothermal and nonisothermal crystallization behaviors of the blends were studied as functions of the contents of MXD6, catalyst concentrations, and the effects of the interchange reactions between PET and MXD6. Wide angle x‐ray scattering has been used to examine the crystalline morphologies of the PET/MXD6 blends, to characterize their crystalline and amorphous phases, and to determine crystallite sizes in the blends. Results indicate that the catalyst has both catalyzing and nucleation effects on the PET/MXD6 blends, with the extents of each effect dependent upon the content of catalyst. In addition the crystalline morphology was found to be dominated by the MXD6 content as well as the crystallization temperature. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Compatibility in immiscible polysulfone/poly(ethylene terephthalate) blends

Polysulfone (PSU)/poly(ethylene terephthalate) (PET) blends were obtained by direct injection molding across the composition range. Their phase behavior, thermal properties, morphology, and mechanical properties were measured. The blends were composed of a pure PSU amorphous phase and either a pure PET phase in PSU‐poor blends, or a PET‐rich phase with some dissolved PSU in PSU‐rich blends. The morphology of the dispersed phase was mostly spherical with some elongated particles in the PET‐rich blends. A slight synergistic behavior was observed in the Young's modulus, mainly in the 90/10 blend, which is probably due to orientation effects. The presence of some broken particles indicated some interfacial adhesion. The ductility values were approximately linear with composition. This was generally the case in PSU‐rich blends, and was attributed to the higher level of PSU in the PET‐rich phase. Although embrittlement was seen in blends with 30% of the second component, the ductility of the two pure components did not significantly decrease after annealing due to the presence of low amounts (up to 10%) of another component of the blend. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2193–2200, 2004     

High molecular weight poly( -lactide) and poly(ethylene oxide) blends: thermal characterization and physical properties

The miscibility of high molecular weight poly( -lactide) PLLA with high molecular weight poly(ethylene oxide) PEO was studied by differential scanning calorimetry. All blends containing up to 50 weight% PEO showed single glass transition temperatures. The PLLA and PEO melting temperatures were found to decrease on blending, the equilibrium melting points of PLLA in these blends decreased with increasing PEO fractions. These results suggest the miscibility of PLLA and PEO in the amorphous phase. Mechanical properties of blends with up to 20 weight% PEO were also studied. Changes in mechanical properties were small in blends with less than 10 weight% PEO. At higher PEO concentrations the materials became very flexible, an elongation at break of more than 500% was observed for a blend with 20 weight% PEO. Hydrolytic degradation up to 30 days of the blends showed only a small variation in tensile strength at PEO concentrations less than 15 weight%. As a result of the increased hydrophilicity, however, the blends swelled. Mass loss upon degradation was attributed to partial dissolution of the PEO fraction and to an increased rate of degradation of the PLLA fraction. Significant differences in degradation behaviour between PLLA/PEO blends and (PLLA/PEO/PLLA) triblock-copolymers were observed.     

Drug release from poly(ortho esters)–poly(ethylene glycol) polyblend

A polyblend of poly(ortho esters)–poly(ethylene glycol) (POE–PEG) was prepared. The release behavior of the acetanilide‐loaded film of the POE–PEG polyblend was studied. Blending POE with water‐soluble PEG can promote the release of drug in pH 7.4 PBS buffer at 37°C, while POE has plasticizing effect on PEG. Infrared and X‐ray diffraction studies reveal that there is some interaction between POE and acetanilide. The SEM micrographs disclose that the porosity of the drug‐loaded film enhances with an increase immersing time. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 303–309, 1999