Melt characteristics,mechanical, and thermal properties of blown film from modified blends of poly(butylene adipate‐co‐terephthalate) and poly(lactide)

Blown films from poly(butylene adipate‐co‐terephthalate) and poly(lactide) (PLA) blends were investigated. The blends were prepared in a twin‐screw extruder, in the presence of small amounts of dicumyl peroxide (DCP). The influence of DCP concentration on film blowing, rheological, mechanical, and thermal properties of the blends is reported in this article. Rheological results showed a marked increase in polymer melt strength and elasticity with the addition of DCP. As a consequence, the film homogeneity and the stability of the bubble were improved. The modified blend films, compared with the unmodified blend, showed an improvement in tensile strength and modulus with a slight loss in elongation. Fourier transform infrared and gel results revealed that chain scission and branching were more significant than crosslinking when the DCP loadings in the blends were not higher than 0.7%. A reduction in melt temperatures of PLA was observed due to difficulty in chain crystallization. The concentrations of DCP strongly affected the melting temperatures but had an insignificant effect on the decomposition behavior of the blends. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Rheological behavior of polyester blend and mechanical properties of the polypropylene–polyester blend fibers

The article deals with method of preparation, rheological properties, phase structure, and morphology of binary blend of poly(ethylene terephthalate) (PET)/poly(butylene terephthalate) (PBT) and ternary blends of polypropylene (PP)/(PET/PBT). The ternary blend of PET/PBT (PES) containing 30 wt % of PP is used as a final polymer additive (FPA) for blending with PP and subsequent spinning. In addition commercial montane (polyester) wax Licowax E (LiE) was used as a compatibilizer for spinning process enhancement. The PP/PES blend fibers containing 8 wt % of polyester as dispersed phase were prepared in a two‐step procedure: preparation of FPA using laboratory twin‐screw extruder and spinning of the PP/PES blend fibers after blending PP and FPA, using a laboratory spinning equipment. DSC analysis was used for investigation of the phase structure of the PES components and selected blends. Finally, the mechanical properties of the blend fibers were analyzed. It has been found that viscosity of the PET/PBT blends is strongly influenced by the presence of the major component. In addition, the major component suppresses crystallinity of the minor component phase up to a concentration of 30 wt %. PBT as major component in dispersed PES phase increases viscosity of the PET/PBT blend melts and increases the tensile strength of the PP/PES blend fibers. The impact of the compatibilizer on the uniformity of phase dispersion of PP/PES blend fibers was demonstrated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4222–4227, 2006     

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     

The role of specific interactions and transreactions on the compatibility of polyester ionomers with poly(ethylene terephthalate) and nylon 6,6

The compatibility of polyester ionomers with polar polymers (i.e., poly(ethylene terephthalate) and nylon 6,6) is under investigation for their potential use as minor component compatibilizers. Binary blends have been prepared by both solution and melt-mixed methods to determine the effect of melt-processing on blend compatibility. The effect of the sulfonate group and counterion type on compatibility was evaluated by blending sulfonated and nonsulfonated forms of the amorphous polyester ionomer with both nylon 6,6 and poly(ethylene terephthalate). The melting point and phase behavior of the blends were determined by differential scanning calorimetry (DSC) and environmental scanning electron microscopy (ESEM), respectively. A comparison of the melting behavior between the melt and solution blends suggests compatibility due to specific interactions for the ionomer/nylon 6,6 blends, and transesterification for the ionomer/poly(ethylene terephthalate) blends. The phase morphology of the melt blends is consistent with the results obtained by DSC analysis.     

PC/PETG共混物熔体的流变性能

采用熔融共混工艺制备了聚碳酸酯（PC）/聚对苯二甲酸乙二醇酯-1,4-环己烷二甲醇酯（PETG）共混物,测试了PC/PETG共混物的熔融指数,研究了共混物的复数黏度与剪切频率、温度以及物料组成的关系。结果表明,PETG的引入改善了PC的成型加工流变性能;PC/PETG共混物呈现出假塑性流体特性,表现出切力变稀的现象;共混物随着温度的升高,复数黏度下降,随着PETG含量的增加,共混物黏度呈现下降的趋势。     

PTT/PP共混物的性能研究

通过熔融共混制备了聚对苯二甲酸丙二酯/聚丙烯(PTT/PP=75/25)及其马来酸酐接枝PP(PP-g-MAH)增容共混物,研究了PTT/PP及其增容共混物的结晶性能、力学性能、流变性能和结晶形态。研究结果表明,PTT与PP共混能提高PP、PTT组分的结晶温度;对于增容共混物,随PP-g-MAH用量的增加,PP和PTT的结晶温度基本不变。加入PP使PTT拉伸强度降低,冲击强度提高;PP-g-MAH增容使共混物的拉伸和冲击强度都提高。增容共混物的熔体粘度明显降低,存在明显的剪切变稀现象,但熔体粘度与PP-g-MAH用量无关。在一定用量范围内,随PP-g-MAH用量的增加,PP分散相的尺寸变小。     

Non-isothermal crystallization kinetic of recycled PET and its blends with PBT modified with epoxy-based multifunctional chain extender

A fundamental understanding of crystallization behavior is essential for the processing of both virgin and recycled polymers. This research delves into the crystallization characteristics and non-isothermal crystallization kinetics of recycled polyethylene terephthalate (rPET) and its blends with poly butylene terephthalate (PBT), which have been modified using epoxy-based multifunctional chain extenders (CE). The preparation of rPET/PBT blends involved a twin-screw extruder, with varying weight ratios and different CE concentrations. Differential scanning calorimetry was employed to perform crystallization analysis on the samples. The results underscore the profound impact of blend composition on the thermal characteristics of the system, with CE exerting only a marginal influence. The glass transition temperatures (T_g) of the two polymers were measured at 49 and 79°C. During blending, the T_g values demonstrated variations relative to the proportions but did not adhere to the Fox equation. Furthermore, PBT was found to enhance the crystallization tendencies of rPET, resulting in an increase in relative crystallinity from 11% to 36%. Notably, the crystallization rate of PBT at 0.40 min⁻¹ exceeded that of rPET at 0.36 min⁻¹. PBT minimally affected the crystallization rate constant of rPET-dominant blends, while rPET significantly reduced the crystallization rate in PBT-dominant blends.     

The application of size-exclusion chromatography to study molecular-weight changes of flame-retardant fiber-reinforced polyesters

Reinforced plastics based on poly(cyclohexanedimethylene terephthalate) (PCT) are excellent for electrical and electronic applications, particularly in the manufacture of electrical connectors. PCT offers a high heat deflection temperature, low cost, and relative ease of processing. For the injection molding process, stability of the melt is an important consideration, especially for materials with high melting points such as PCT. The combination of the polyester resin with flame retardant additives, processing aids, and thermal stabilizers results in a number of competing reactions which can change the molecular weight and molecular-weight distribution (MWD) of the base polymer in the composite. Typical analytical techniques such as melt or dilute solution viscosity do not give adequate means of monitoring these changes so as to allow the polymer chemist to determine the effects of various additives on MWD. Size-exclusion chromatography (SEC), by virtue of providing information on the entire MWD, was found suitable to study molecular-weight changes in the melt due to both branching and chain cleavage, even when both phenomena occur simultaneously. Changes in the MWD over time at processing temperatures can be used to determine kinetic parameters and have been used to optimize PCT additive formulations for best processability and mechanical property retention.     

Thermal and crystallization behavior of engineering polyblends. II. Unfilled polyphenylene sulfide with poly(ethylene terephthalate)

The melting and crystallization behavior of blends of poly(phenylene sulfide) (PPS) with poly(ethylene terephthalate) (PET) has been investigated. The component polymers in the blend exhibited separate crystallization peaks and overlapping melting peaks. The nonisothermal DSC scans indicated that the crystallization parameters for PET become modified to a greater extent than do those for PPS in the blends. The PET crystallization peak became narrower with a higher heat of crystallization, suggesting a faster rate of crystallization as a result of blending with PPS. The isothermal crystallization studies revealed that the nucleation of PPS is facilitated by the presence of PET. This contention has been substantiated by polarized light microscopic observations. The spherulites of PPS were found to be smaller in the blends as compared to those in neat PPS. This enhancement in the nucleation of PPS has been attributed to the possibilities of chemical interactions between the component polymers. On the other hand, the increase in the rate of crystallization of PET has been attributed to the heterogeneous nucleation provided by the alreadycrystallized PPS. The melt crystallized blends exhibited slightly higher heats of fusion compared to the values computed from the rule of proportional additivity. © 1994 John Wiley & Sons, Inc.     

Miscibility assessment and thermal oxidative stability of blends of branched polyethylene and poly(1,2-butadiene)

Summary Poly(1,2-butadiene) promotes crosslinking of branched polyethylene, which indeed indicates partial miscibility of the two polymers. Dynamic mechanical spectroscopy and transmission electron microscopy of blends of branched polyethylene and poly(1,2-butadiene) indicated that the polymers are partially immiscible even in the blend with only 3% of poly(1,2-butadiene). The thermal oxidative stability at temperatures above the melting point of samples stabilized with antioxidants was essentially unaffected by the percentage concentration of poly(1,2-butadiene), whereas the stability towards external partial discharges was lower in crosslinked polyethylene blends containing poly(1,2-butadiene) than in pure crosslinked polyethylene.     

Two-Step Processing Method for Blending High-Performance Polymers with Notable Thermal and Rheological Differences: PEI and PBT

Blends between high-performance polymers (HPP) are barely studied, especially those produced by melting processing. In this work, it is proposed a novel methodology to prepare blends between polymers with notable processing temperature differences: poly(ether imide) (PEI) and poly(butylene terephthalate) (PBT). Processing parameters are settled after thermal and rheological evaluation of pure materials, those results suggest these blends need to be produced by steps. It is found a synergistic effect such as lowering PEI processing temperature and reducing PBT hydrolysis at high temperatures. Propose methodology allows to produce blends between HPP in the whole composition range with the same processing conditions.     

CDPTT/PTT共混体系的结构和性能研究

将含有间苯二甲酸丙二醇酯-5-磺酸钠(SIPT)阳离子可染聚对苯二甲酸丙二醇酯(CDPTT)与聚对苯二甲酸丙二醇酯(PTT)进行共混制备CDPTT/PTT共混聚酯,讨论了共混比例、共混时间和共混温度对CDPTT/PTT共混聚酯的序列结构、热稳定性、结晶性能的影响。结果表明:CDPTT/PTT的特性粘数([η])随共混温度和共混时间的增加而降低,共混温度对[η]的影响更大;CDPTT/PTT质量比为20/80时,[η]出现最小值。随着CDPTT/PTT共混比的增加,结晶度、熔点、热结晶温度逐渐减小。当CDPTT/PTT中SIPT摩尔分数小于2%时,晶粒尺寸随SIPT含量的增加而增加。     

Compatibilization of a poly(butylene terephthalate)/poly(ethylene octene) copolymer blends with different amounts of an epoxy resin

New toughened poly(butylene terephthalate) (PBT) materials were obtained by melt blending with 20 wt % poly(ethylene octene) (PEO) copolymer and different levels of a difunctional epoxy resin in a twin‐screw extruder followed by injection‐molding. The presence of neither PEO or epoxy influenced either the phase nature of the two amorphous phases of the blends or the crystallization process of PBT, despite the slight reaction of epoxy with PBT as stated by the observed torque increases. The addition of epoxy led to a decrease in the particle size that stopped due to the concomitant viscosity increase. Supertough PBT‐based blends with an impact strength more than 18‐fold that of PBT were obtained without previous chemical modification of any of the blend components at 1.0 wt % epoxy contents. The interparticle distance was the parameter that controlled notched toughness in these PBT/PEO blends. The adhesion at the interphase was the parameter on which the critical interparticle distance appeared to depend. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 260–269, 2004     

Influence of interchange reactions on the crystallization and melting behavior of nylon 6,6 blended with other nylons

The thermal behavior of blends of nylon 6,6, with an amorphous polyamide, Trogamid-T, and a semicrystalline polyamide, nylon 6,12, was studied. The blends were prepared both by solution blending and by melt blending, using a Maxwell extruder and a twin screw extruder. The concentration of the blends ranged from 75% to 95% by weight of nylon 6,6. Annealing the blend samples in the molten state in a differential scanning calorimeter (DSC) produced changes in the melting and crystallization behavior. This was attributed to transamidation reactions occurring between the blend components, leading to the formation of in-situ block copolymers. The length of the blocks decreased with annealing time, as suggested by reduced melting (T_m) and crystallization temperatures (T_c) and heat of fusion values. The changes in thermal behavior were dependent on the blending method, additive concentration, presence or absence of a catalyst, melt annealing time, and the extent of melt mixing. The extent of reaction, measured by the depression in equilibrium melting temperature, was linear with respect to the annealing time. The Trogamid-T containing blends appeared to be “nearly miscible” while those with nylon 6,12 were initially immiscible. The glass transition temperature (T_g) vs. the composition curve of the nylon 6,6/Trogamid-T blends showed a positive deviation from linear additivity, with the single T_g decreasing as a function of annealing time in the melt.     

Complex processing–morphology interrelationships during the reactive compatibilization of blends of poly(butylene terephthalate) with epoxide‐ containing rubber

Reactive processing of blends of poly(butylene terephthalate) (PBT) with the ethene–(methyl acrylate)–(glycidyl methacrylate) terpolymer (E–MA–GMA) is known to present a very complex reactivity since two competitive reactions take place spontaneously during melt blending, that is, blend compatibilization and rubber‐phase crosslinking. In this article, the effects of several processing parameters, such as the shear rate, the processing temperature, and the matrix viscosity, on the reactive processing of those blends were investigated in terms of the blend morphology and of the amount of copolymer formed at the blend interface. It was shown that the morphology development could be divided in two successive regimes: In the early stages of the mixing process, the particle size is essentially determined by the physical dispersion process, that is, breakup and coalescence, while, at longer mixing times, a further decrease in particle size is obtained as a result of the compatibilization reactions. The shift between the two regimes is progressive and intimately related to the processing conditions. Despite such a complexity, not only the blend morphology but also the elastic properties of the rubber particles can be controlled in a broad range by an adequate adjustment of the relative kinetics between both physical and chemical processes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 703–718, 2004     

Recycling poly(ethylene terephtalate) wastes: Properties of poly(ethylene terephtalate)/polycarbonate blends and the effect of a transesterification catalyst

The article addresses the issue of recycling of poly(ethylene terephtalate) (PET) by melt blending with polycarbonate (PC). PET/PC blends containing various amounts of the immiscible polymers were prepared in a twin‐screw extruder. Selected compositions were also prepared in the presence of an Sn‐based catalyst to assess the influence of transesterification during melt mixing. The degree of miscibility in the blends was studied using differential scanning calorimetry, scanning electron microscopy, and mechanical testing. PET/PC blends exhibit enhanced tensile properties in comparison to neat components for compositions of PET higher than 50% and these properties are improved by the addition of a transesterification catalyst. The PET/PC blend containing 20 wt% of PC, prepared with stannous octoate, shows the smallest size of the dispersed phase because of transesterification reactions that generate copolymer molecules at the interface between the immiscible polymers. The melting temperature of PET is decreased with the increase of the PC content in blends extruded in the presence of the catalyst. Also, the temperatures of the cold crystallization of PET are higher than those of similar blends without added catalyst. Both features give rise to better molding properties because of a shortening of the cooling time in the range of 50–90 wt% of PET. POLYM. ENG. SCI. 46:1378–1386, 2006. © 2006 Society of Plastics Engineers     

不同增韧剂对PBT增韧改性的研究

利用双螺杆挤出机,采用聚乙烯-辛烯弹性体(POE)、聚乙烯-辛烯弹性体接技马来酸酐(POE-g-MAH)以及聚丙烯(PP)作为增韧剂与聚对苯二甲酸丁二醇酯(PBT)进行熔融共混,研究了不同增韧剂POE、POE-g-MAH和POE-PP对PBT共混物的力学性能、相容性和熔融结晶行为的影响。通过拉伸、冲击、熔体质量流动速率、硬度等性能测试以及红外光谱、X射线衍射仪(XRD)、差示扫描量热仪(DSC)等综合测试。结果表明,加入增韧剂对PBT具有良好的增韧效果,其中以PBT/POE/PP的增韧效果最明显。当PBT∶POE∶PP质量比为7∶3∶1时,共混物的缺口冲击强度增加8倍,红外表征显示,增韧改性可提高PBT的相容性,XRD测试表明,增韧剂对PBT复合材料的晶体结构没有影响,通过熔融增韧,提高其力学性能和加工性能。DSC图显示,增韧剂的加入可使共混物的结晶度降低。扫描电镜(SEM)表明,增韧剂的加入增加界面了结合力,提高了共混体系相容性。     

Reactive blending as a tool for obtaining poly(ethylene terephthalate)-based engineering materials with tailored properties

The structure and properties of blends of poly(ethylene terephthalate) (PET) with poly(trimethylene terephthalate) (PTT) at PTT concentration ≤30 wt.%, obtained with three different methods: from solution, melt extrusion, and direct spinning, are investigated. Relationships between the method of preparation and properties of blends are established. All blends show glass transition temperature at values determined by composition, and crystallization properties also dependent on the preparation method. Blends obtained from solution show separated melting of components. For blends obtained from the melt only PET crystallizes. The melting temperature decreases with the residence time of the melt at high temperatures, due to occurrence of ester exchange reactions. It is shown that reactive blending of PET/PTT mixtures occurring during preparation is a versatile route for obtainment of engineering materials with good mechanical properties, high crystallinity, glass transition temperature lower than that of PET, and melting temperature that may be controlled by the processing conditions.     

回收PET共混物的非等温结晶和熔融行为

采用双螺杆挤出机制备了聚丙烯(PP)/回收聚对苯二甲酸乙二酯(r-PET)、r-PET/马来酸酐接枝PP(PP-g-MAH)和r-PET/甲基丙烯酸缩水甘油酯接枝PP(PP-g-GMA)共混物,并研究了共混物组成、熔融温度与时间以及降温速率对共混物非等温结晶与熔融行为的影响.结果表明,r-PET与PP共混,结晶温度均提高,这与组分间起到异相成核诱导结晶作用有关.r-PET结晶温度随PP-g-MAH用量增加而降低,但受PP-g-GMA用量影响较小;r-PET可提高PP-g-MAH结晶温度,但降低PP-g-GMA结晶温度.熔融温度提高,共混物中PP结晶温度和熔点均降低,r-PET熔融峰形和熔点取决于共混物的熔融温度及界面相互作用.     

Radiation crosslinking of poly(vinyl chloride)/epoxidized natural rubber blend: effect of lead stabilization of the poly(vinyl chloride) phase

The irradiation crosslinking of 50/50 poly(vinyl chloride)/epoxidized natural rubber blend was investigated in the presence of 1–5 parts per hundred resin (phr) tribasic lead sulfate (TBLS) with blends prepared at various mixing temperatures. The blends were irradiated using a 3.0 MeV electron accelerator at 0, 100 and 200 kGy irradiation doses. Changes in tensile strength, elongation at break and stress‐strain curves of the blends with the increase TBLS content and blending temperatures were observed before and after irradiation. The results on the tensile properties revealed the inhibition of the irradiation‐induced crosslinking by the TBLS although it stabilizes the blend against thermal and irradiation‐induced degradation. The Fourier transform infrared spectroscopy studies further confirmed these observations. Control on the thermal degradation of the blend during blending found to be crucial in achieving maximum enhancement in blend properties upon irradiation. Evidence from dynamic mechanical analysis was also used to support this contention. Addition of 2 phr TBLS and blending at 150 °C found to be adequate in order to achieve the best enhancement in blend properties through irradiation‐induced crosslinking. © 2001 Society of Chemical Industry