Effects of size and shape of dispersed poly(butylene terephthalate) on isothermal crystallization kinetics and morphology of poly(lactic acid) blends

Poly(lactic acid)/poly(butylene terephthalate) (PLA/PBT) blends with 3, 5, and 10 wt % of PBT were produced in a twinscrew extruder, with the addition of ethylene-glycidyl methacrylate copolymer as compatibilizer. An uncompatibilized PLA/PBT blend with 5 wt % of PBT was prepared for comparison studies. The epoxy reactive groups in the compatibilizer allowed modification of the interfacial tension in the blends and reduced the PBT dimensions. The crystallinity of the blends was studied, and its influence on mechanical properties was analyzed. Tensile tests showed an increase in strain at break from 3% for neat PLA to 49% for PLA with 3 wt % PBT, while the tensile modulus dropped from 3.59 GPa to 3.35 GPa for the same samples. Izod results showed a transition from a brittle behavior of PLA to a ductile one for compatibilized blends. These results indicate that the nanometer-size dispersed phase was effective in changing the deformation behavior of the matrix without a significant loss of modulus. V C 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45951.

Section: Mechanical Testingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…[1][2][3] They have attracted great interest as a substitute for traditional petroleumbased thermoplastics, because they have the possibility of solving environmental problems. [1][2][3]5 It is widely used for biomedical and packing applications because of its excellent optical properties and very low toxicity. However, it is a relatively brittle thermoplastic and has a low crystallization rate.…”

Section: Introductionmentioning

confidence: 99%

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Development of biodegradable PLA/PBT nanoblends

Santos

Costa

Pessan

2017

“…The polymer has been viewed as one of the most promising alternatives to substitute the traditional petropolymers and is widely used in applications such as biomedical, consumer goods, and packaging materials where biodegradability is crucial for environmental reasons. PLA has been considered for such applications because of its renewability, competitive cost, good mechanical properties, transparency, and biocompatibility . In addition, PLA also can be melt‐processed with the standard thermoplastic processing equipment such as extrusion, calendaring, thermoforming, and injection molding …”

Section: Introductionmentioning

confidence: 99%

“…In addition to its inherent brittleness another major drawback of PLA is its slow crystallization rate during the normal processing conditions involving high cooling rates . PLA, therefore, often unable to develop significant crystallinity and the final products of PLA obtained by the standard thermoplastic processing equipment are usually of low crystallinity even amorphous not suitable for engineering applications that require better mechanical properties and thermal‐dimensional stability.…”

Section: Introductionmentioning

confidence: 99%

Isothermal crystallization kinetics and spherulite morphologies of poly(lactic acid)/ethylene acrylate copolymer blends

Taib

Tham

2017

Isothermal crystallization kinetics and spherulite morphologies of partially immiscible blends of poly(lactic acid) (PLA) and ethylene acrylate copolymer (EAC) were investigated by differential scanning calorimetry (DSC) and polarized optical microscopy. The DSC data obtained was analyzed using the Avrami equation. Crystallization kinetics of PLA from the melt was strongly influenced by the blend composition and the crystallization temperature. At a given crystallization temperature, the overall crystallization rate value was greater in the blends than in PLA suggesting that the presence of EAC enhanced crystallization of PLA. Polarized optical micrographs showed that the crystallization of PLA initially took place at the PLA/EAC interface. At high EAC content (>1 wt %), EAC domains acted as hindrance to crystallization reducing the overall crystallization rate of PLA in the blends. Based on the DSC analysis, the crystallization rate was maximum when PLA blend with 1 wt % EAC was isothermally crystallized at 103 °C. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45487.

Modification of dry‐spun Suplon polyimide fibers by mixed‐acid oxidation and their effects on the properties of polypropylene‐resin‐based composites

Chen

Long

Zhang

et al. 2017

In this study, the effects of mixed-acid oxidation on the contents of surface elements, morphology, fiber fineness, mechanical properties, mass change rate, chemical structure, and microaggregate structure of dry-spun Suplon polyimide (PI) fibers were systematically investigated with wet chemical treatment with HNO 3 /H 2 SO 4 . Experiments investigating both the improvement in the O/C ratio of the fiber surface elements and the changes in other performance features were conducted through the functional modification of the fibers. Meanwhile, the causes of specific changes in the mechanical properties of the oxidized PI-fiber-reinforced polypropylene-resin-based composites were studied and are discussed. The results of this study demonstrate that the treatment of the fibers with HNO 3 /H 2 SO 4 mixed-acid oxidation resulted in significant changes in the properties of the fibers; these changes included an uneven surface, increased specific surface area and surface roughness, a locally etched surface, increased surface energy and O/C ratio, an enhanced wettability, an increased fiber fineness, reduced mechanical properties, and a mass gain in the fibers. Although the chemical structures of the fibers treated by oxidized HNO 3 /H 2 SO 4 were not significantly changed compared to those of the untreated fibers, the microscopic aggregation of the treated fibers changed to some degree, and the ratio of the amorphous regions significantly increased. Taken together, the functional modification of the PI fiber surface was achieved efficiently through the use of a suitable HNO 3 /H 2 SO 4 oxidation process and with other performance features of the fibers taken into account. This was favorable for the enhancement of the interfacial properties of the polypropylene fibers and the matrix resins, and thus, the modification improved the mechanical properties of the composites.