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1.
Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) was blended with poly(lactic acid) (PLA) with various reactive processing agents to decrease its brittleness and enhance its processability. Three diisocyanates, namely, hexamethylene diisocyanate, poly(hexamethylene diisocyanate), and 1,4‐phenylene diisocyanate, were used as compatibilizing agents. The morphology, thermomechanical properties, and rheological behavior were investigated with scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, tensile testing, dynamomechanical thermal analysis in torsion mode (dynamic mechanical analysis), and oscillatory rheometry with a parallel‐plate setup. The presence of the diisocyanates resulted in an enhanced polymer blend compatibility; this led to an improvement in the overall mechanical performance but did not affect the thermal stability of the system. A slight reduction in the PHBV crystallinity was observed with the incorporation of the diisocyanates. The addition of diisocyanates to the PHBV–PLA blend resulted in a notable increase in the final complex viscosity at low frequencies when compared with the same system without compatibilizers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44806.  相似文献   

2.
A batch processing method is used to fabricate foams comprising of a blend of poly(lactic acid) (PLA) and Novatein, a protein‐based thermoplastic. Various compositions of Novatein/PLA are prepared with and without a compatibilizer, PLA grafted with itaconic anhydride (PLA‐g‐IA). Pure Novatein cannot form a cellular structure at a foaming temperature of 80 °C, however, in a blend with 50 wt % of PLA, microcells form with smaller cell sizes (3.36 µm) and higher cell density (8.44 × 1021 cells cm?3) compared to pure PLA and blends with higher amounts of PLA. The incorporation of 50 wt % of semicrystalline Novatein stiffens the amorphous PLA phase, which restrains cell coalescence and cell collapse in the blends. At a foaming temperature of 140 °C, NTP30–PLA70 shows a unique interconnected porous morphology which can be attributed to the CO2‐induced plasticization effect. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45561.  相似文献   

3.
This study is focused on the development and analysis of the thermal and structural behavior of nanocrystalline cellulose (NCC)‐based bionanocomposites (BCs). Nanocrystalline cellulose was prepared by controlled acid hydrolysis of oil palm empty fruit bunch fibers. The resulting NCC was surface modified using TEMPO‐mediated oxidation and solvent exchange methods for surface functionalization and also to improve dispersion of fillers. Solvent exchange NCC reinforced polymer blend containing poly(lactic acid)/poly‐(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) was prepared by using solution casting technique at various NCC loading percentages. The addition of NCC resulted in the improvement of structural, thermal, and mechanical properties of BCs as compared to that of the polymer blend. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44328.  相似文献   

4.
Poly(lactic acid) (PLA), a physical blend of PLA and thermoplastic cassava starch (TPCS) (PLA‐TPCS), and reactive blends of PLA with TPCS using maleic anhydride as compatibilizer with two different peroxide initiators [i.e., 2,5‐bis(tert‐butylperoxy)‐2,5‐dimethylhexane (L101) and dicumyl peroxide (DCP)] PLA‐g‐TPCS‐L101 and PLA‐g‐TPCS‐DCP were produced and characterized. Blends were produced using either a mixer unit or twin‐screw extruder. Films for testing were produced by compression molding and cast film extrusion. Morphological, mechanical, thermomechanical, thermal, and optical properties of the samples were assessed. Blends produced with the twin‐screw extruder resulted in a better grade of mixing than blends produced with the mixer. Reactive compatibilization improved the interfacial adhesion of PLA and TPCS. Scanning electron microscopy images of the physical blend showed larger TPCS domains in the PLA matrix due to poor compatibilization. However, reactive blends revealed smaller TPCS domains and better interfacial adhesion of TPCS to the PLA matrix when DCP was used as initiator. Reactive blends exhibited high values for elongation at break without an improvement in tensile strength. PLA‐g‐TPCS‐DCP provides promising properties as a tougher biodegradable film. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46140.  相似文献   

5.
Poly(lactic acid) (PLA)/thermoplastic polyurethane (TPU) blends were prepared via a melt‐blending process with or without the addition of a 3‐aminopropyl triethoxysilane (APTES) compatibilizer at different dosages. The addition of the compatibilizer showed improved compatibility between TPU and PLA; this led to an enhanced dispersion of TPU within the PLA matrix. With the addition of 1‐phr APTES, the crystallization behavior did not vary much, but this exacerbated the formation of a second melting temperature for PLA at higher temperature. However, the addition of 5‐phr APTES into the PLA/TPU blends depressed the crystallization temperature and resulted in a melting temperature depression phenomena with the disappearance of the second melting peak because of the lubricated effect of low‐molecular‐weight species of APTES. The addition of a low dosage of APTES improved the impact strength further from 29.2 ± 1.4 to 40.7 ± 2.7 J/m but with a limited improvement in the tensile properties; this indicated that a higher dispersion of the dispersed phase did not always improve all of the mechanical properties because of the low‐molecular‐weight nature of the compatibilizer used. The physical properties of the added modifier needed to be considered as well. A low dosage of APTES (1 phr) also increased the viscosity because of the improved interaction between TPU and PLA at all of the investigated shear rate regions, but a higher dosage of compatibilizer induced another plasticizing effect to reduce the viscosity. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42322.  相似文献   

6.
Poly(lactic acid) (PLA) is a biobased polymer made from biomass having high mechanical properties for engineering materials applications. However, PLA has certain limited properties such as its brittleness and low heat distortion temperature. Thus, the aim of this study is to improve toughness of PLA by blending with poly(butylene succinate‐co‐adipate) (PBSA), the biodegradable polymer having high toughness. Polymer blends of PLA and PBSA were prepared using a twin screw extruder. The melt rheology and the thermal property of the blends were examined. Further the blends were fabricated into compression molded parts and melt‐spun fiber and were subjected to tensile and impact tests. When the PBSA content was low, PBSA phase was finely dispersed in the PLA matrix. On the other hand, when the PBSA content was high, this minor phase dispersed as a large droplet. Mechanical properties of the compression molded parts were affected by the dispersion state of PBSA minor component in PLA matrix. Impact strength of the compression molded parts was also improved by the addition of soft PBSA. The improvement was pronounced when the PBSA phase was finely dispersed in PLA matrix. However, the mechanical property of the blend fibers was affected by the postdrawing condition as well as the PBSA content. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41856.  相似文献   

7.
Reactive interfacial compatibilization is the most efficient way to prepare super-tough poly (lactic acid) (PLA) materials. Introducing a post-reactive group into a toughening agent that can react with PLA is the key issue. Herein, we reported a series of fully bio-based polyesters (PBSePM) synthesized with sebacic acid, diethyl malate, 1,3-propanediol, and 1,4-butanediol via transesterification in one pot. Super-tough PLA materials can be obtained by reactively blending with PBSePM in the presence of hexamethylene diisocyanate (HDI). In the processing, the side hydroxyl group of the PBSePM reacted with HDI and formed polyurethane elastomer to improve the toughness of PLA. Moreover, the in-situ formed PLA-g-PBSePM grafted copolymer enhanced the interfacial adhesion. With increasing diethyl malate moiety in PBSePM, the PBSePM phase morphology transformed from co-continuous phase structure to semi-continuous and “sea-island” phase structure. When adding 20 wt% PBSePM, all PLA/PBSePM blends have a notched impact strength higher than 53 kJ m−2, suggested a super toughness effect. Maximum impact strength of 83 kJ m−2 was realized while the PBSePM containing 20% diethyl malate moiety. In addition, super-tough PLA materials can be achieved by only adding 15 wt% PBSePM20, exhibited a highly efficient toughening effect.  相似文献   

8.
The packaging industry is searching for alternative materials to attain environmental sustainability. Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate (PHBV) is a semicrystalline polymer that meets this sustainability goal since it is bioderived and biodegradable. However, its brittle nature and relatively high water permeation and transmission rates make it unsuitable for packaging applications. In addition, PHBV has poor mechanical, thermal, and rheological properties above 160 °C, limiting its use in cast sheets and thermo‐formed packaging applications. To improve these properties, new blends of PHBV with high molecular weight natural rubber at 5, 10, 15, and 25% by weight were fabricated, and physico‐chemical properties of the blends were characterized. The rubber in the blends aided in the following: increased thermal stability since the complex viscosities of the blends were improved by one log over pure PHBV at 170 °C, created more uniform melting peaks attesting to improved homogeneity, decreased water permeation to a level similar to that of traditional thermoplastics; increased the elongation at break, and stabilized the Young's modulus. Therefore, these blends can potentially be used in‐place of traditional, petroleum‐based thermoplastics in cast sheets and thermoforms. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43937.  相似文献   

9.
Natural rubber (NR) grafted with poly(vinyl propionate) (NR-g-PVP) was prepared by emulsion polymerization. The monomer content was set at 5, 10, 20, and 30 wt%. The chemical structure of NR-g-PVP was confirmed by 1H-NMR and FTIR techniques. The grafting parameters of purified NR-g-PVP were evaluated. Binary (PLA/NR and PLA/NR-g-PVP) and ternary (PLA/NR/NR-g-PVP) blends were prepared by melt blending using a twin-screw extruder. The percentage of grafted PVP on NR affected morphology, thermal and mechanical properties of the blends. In binary blends, 5% grafting showed the greatest improvement of toughness and ductility with PLA, whereas there was no improvement in the mechanical properties of PLA/NR blend from using NR-g-PVP as a compatibilizer. The mechanical properties of the blends are related to mutual compatibility of the components. Good interfacial adhesion and proper particle size of NR were the key factors contributing to mechanical properties.  相似文献   

10.
In this research work, biocomposites based on a ternary system containing softwood Kraft lignin (Indulin AT), poly‐L ‐lactic acid (PLLA) and polyethylene glycol (PEG) have been developed. Two binary systems based on PLLA/PEG and PLLA/lignin have also been studied to understand the role of plasticizer (i.e., PEG) and filler (i.e., lignin) on the overall physicomechanical behavior of PLLA. All samples have been prepared by melt‐blending. A novel approach has also been introduced to improve the compatibility between PLLA and PEG by using a transesterification catalyst under reactive‐mixing conditions. In PEG plasticized PLLA flexibility increases with increasing content of PEG and no significant effect of the molecular weight of PEG on the flexibility of PLLA has been observed. Differential scanning calorimetry and size‐exclusion chromatography along with FTIR analysis show the formation of PLLA‐b‐PEG copolymer for high temperature processed PLLA/PEG systems. On the other hand, binary systems containing lignin show higher stiffness than PLLA/PEG system and good adhesion between the particles and the matrix has been observed by scanning electron microscopy. However, a concomitant good balance in stiffness introduced by the lignin particles and flexibility introduced by PEG has been observed in the ternary systems. This study also showed that high temperature reactive melt‐blending of PLLA/PEG leads to the formation of a segmented PLLA‐b‐PEG block copolymer. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

11.
Biodegradable blown films comprising of poly(lactide) (PLA) and poly(butylene adipate‐co‐terephthalate) (PBAT) were produced using epoxy functionalized‐poly(lactide) (EF‐PLA) reactive modifiers for rheological enhancement and compatibilization. The epoxy groups on the EF‐PLA modifiers react with PBAT forming an in situ copolymer that localizes at the blend interphase resulting in compatibilization of the polymer blend components. The EF‐PLA modified polymer blends have improved melt strength and the resultant films showed better processability as seen by increased bubbled stability. This allowed for blown films with higher PLA content (70%) compared to the unmodified control films (40%). The static charge build‐up typically experienced with PLA film blowing was decreased with the inclusion of EF‐PLA yielding films with better slip and softness. The compatibilization effect of the EF‐PLA modifiers resulted in significant improvement in mechanical properties. For example, dart test performance was up to four times higher than the control, especially at higher PLA concentrations. Therefore, the rheological enhancement and compatibilization effects of the EF‐PLA reactive modifiers make them ideally suited to create high PLA content films. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43310.  相似文献   

12.
Biodegradable poly(lactic acid) (PLA)/poly(butylene adipate-co-terephthalate) (PBAT) blends and PLA/PBAT/Al2O3 nanocomposites were fabricated via solution blending. The influence of PBAT and Al2O3 content on the thermal stability, flexural properties, impact strength, and morphology of both the PLA/PBAT blends and the PLA/PBAT/Al2O3 nanocomposites were investigated. The impact strength of the PLA/PBAT/Al2O3 nanocomposites containing 5 wt% PBAT increased from 4.3 to 5.2 kJ/m2 when the Al2O3 content increased from 0 to 1 wt%. This represents a 62% increase compared to the impact strength of pristine PLA and a 20% increase compared to the impact strength of PLA/PBAT blends containing 5 wt% PBAT. Scanning electron microscopy imaging revealed that the Al2O3 nanoparticles in the PLA/PBAT/Al2O3 nanocomposites function as a compatibilizer to improve the interfacial interaction between the PBAT and the PLA matrix.  相似文献   

13.
The effect of polyethylene glycol (PEG) on the mechanical and thermal properties of poly(lactic acid) (PLA)/poly(butylene succinate) (PBS) blends was examined. Overall, it was found that PEG acted as an effective plasticizer for the PLA phase in these microphase‐separated blends, increasing the elongation at break in all blends and decreasing the Tg of the PLA phase. Significant effects on other properties were also observed. The tensile strength and Young's modulus both decreased with increasing PEG content in the blends. In contrast, the elongation at break increased with the addition of PEG, suggesting that PEG acted as a plasticizer in the polymer blends. Scanning electron microscope images showed that the fracture mode of PLA changed from brittle to ductile with the addition of PEG in the polymer blends. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43044.  相似文献   

14.
Natural rubber (NR) is a renewable bio‐based polymer, while poly(butylene succinate) (PBS) belongs to the family of biodegradable renewable polymers. In this article, novel polyurethanes (PUs) were prepared using hydroxyl telechelic natural rubber (HTNR) and hydroxyl telechelic poly(butylene succinate) (HTPBS) as soft segments, and using toluene‐2,4‐diisocyanate (TDI) and 1,4‐butanediol (BDO) as hard segment. HTPBS oligomers of = 2000 and 3500 g mol?1 were synthesized by bulk polycondensation of succinic acid (SA) with BDO. The polyurethane materials were obtained by casting process after solvent evaporation. The influence of the hard segment content and the molecular weight of HTPBS on the materials’ thermo‐mechanical properties were investigated by means of tensile testing, DSC, TGA, and DMTA. The obtained polyurethanes were amorphous with phase separations between hard and soft segments as well as between HTNR and HTPBS segments, and they exhibited good physical properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42943.  相似文献   

15.
One of the most significant limitations to widespread industrial implementation of emerging bioplastics such as poly(lactic acid) and poly(hydroxyalkanoate) (PHA) is that they do not match the flexibility and impact resistance of petroleum‐based plastics like poly(propylene) or high‐density poly(ethylene). The basic goal of this research is to identify alternative, affordable, sustainable, biodegradable materials that can replace petroleum‐based polymers in a wide range of industrial applications, with an emphasis on providing a solution for increasing the flexibility of PHA to a level that makes it a superior material for bioplastic nursery‐crop containers. A series of bio‐based PHA/poly(amide) (PA) blends with different concentrations were mechanically melt processed using a twin‐screw extruder and evaluated for physical characteristics. The effects of blending on viscoelastic properties were investigated using small‐amplitude oscillatory shear flow experiments to model the physical character as a function of blend composition and angular frequency. The mechanical, thermal, and morphological properties of the blends were investigated using dynamic mechanical analysis, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, and tensile tests. The complex viscosity of the blends increased significantly with increasing concentration of PHA and reached a maximum value for 80 wt % PHA blend. In addition, the tensile strength of the blends increased markedly as the content of PHA increased. For blends containing PA at >50 wt %, samples failed only after a very large elongation (up to 465%) without significant decrease in tensile strength. The particle size significantly increased and the blends became more brittle with increasing concentration of PHA. In addition, the concentration of the PA had a substantial effect on the glass relaxation temperature of the resulting blends. Our results demonstrate that the thermomechanical and rheological properties of PHA/PA blends can be tailored for specific applications, and that blends of PHA/PA can fulfill the mechanical properties required for flexible, impact‐resistant bio‐based nursery‐crop containers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42209.  相似文献   

16.
The effect of the mixing condition in a mill‐type mixer on the thermal property and the crystal formation of the poly(l ‐lactide)/poly(d ‐lactide) blends is investigated. The blends melt‐mixed at 200 and 210 °C under application of a high shear flow tend to show a single melting peak of the stereocomplex crystal (SC) in the differential scanning calorimetry first and second heating processes without indicating the trace of the melting of homo‐chiral crystal. The mixing at an elevated temperature causes a serious thermal degradation. Further kneading of the blends at an elevated temperature higher than Tm of SC causes the transesterification between the same enatiomeric chains forming block copolymers of l ‐ and d ‐chains. This block copolymer acts as a nucleating agent of SC and the compatibilizing agent between poly(l ‐lactide) and poly(d ‐lactide) and promotes the formation of SC. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45489.  相似文献   

17.
The reactive blends were prepared by the blending of poly(lactic acid) (PLA) with poly(butylene succinate) (PBS) in the presence of dicumyl peroxide (DCP) as a radical initiator in the melt state. The gel fractions, morphologies, crystallization behaviors, and rheological and mechanical properties of the reactive blends were investigated. Some crosslinked/branched structures were formed according to the rheological measurement and gel fraction results, and the crosslinked/branched structures played the role of nucleation site for the reactive blends. The PLA–PBS copolymers of the reactive blends acted as a compatibilizer for the PLA and PBS phases and, hence, improved the compatibility between the two components. Moreover, it was found that the reactive blends showed the most excellent mechanical properties as the DCP contents were 0.2 and 0.3 phr. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39580.  相似文献   

18.
Blending of poly (lactic acid) (PLA)/functionalized gum arabic (FG) in presence of dicumyl peroxide (DCP) presents a simple process to produce film using melt extrusion (recycle time ~ 4 min, screw speed ~60 rpm) at 180°C with tailored characteristics. The FTIR investigation shows that the confirmation of grafting of PLA chains on FG through formation of new C─C linkage. Properties of fabricated films such as morphological, mechanical, UV barrier and contact angle are examined to develop film with improved interfacial interaction, increased toughness, UV–C blocking effect (~95%) and hydrophobicity (~14%). Polarized optical microscopy (POM) studies reveal that PLA/1FG with and without DCP has more crystal density as compared to PLA at 120°C. This melt extrusion permits straightforward, feasible bionanocomposite film and has great potential as a modification with DCP assists to overcome particular drawbacks of FG.  相似文献   

19.
A serials of fully bio‐based poly(ethylene dodecanedioate‐2,5‐furandicarboxylate) (PEDF) were synthesized from Dodecanedioic acid (DDCA), 2,5‐Furandicarboxylic acid (2,5‐FDCA), and ethylene glycol through a two‐step procedure consisted of transesterification and polycondensation. After their chemical structures were confirmed by Nuclear Magnetic Resonance and Fourier Transform Infrared Spectroscopy, their thermal, mechanical, and biodegradation properties were investigated in detail. Results showed that the chemical composition of PEDFs could be easily controlled by the feeding mole ratio of DDCA to FDCA and they possessed the characteristic of random copolyester with the intrinsic viscosity ranged from 0.82 to 1.2 dL/g. With the varied mole ratio of DDCA to FDCA, PEDFs could be changed from semicrystalline thermoplastic to the completely amorphous elastomer, indicated by the elongation at break ranged from 4 for poly(ethylene 2,5‐furandicarboxylate) to 1500% for amorphous PEDF‐40. The amorphous PEDF‐30 and PEDF‐40 showed satisfactory shape recovery after cyclic tensile test, which was the typical behavior for elastomer. Enzymatic degradation test indicated that all the PEDFs were biodegradable and the degradation rate was heavily affected by their chemical compositions. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46076.  相似文献   

20.
This work focuses on phase morphology and properties of immiscible poly(lactic acid)/ethylene‐propylene‐diene rubber (PLA/EPDM) blends compatibilized with organic montmorillonite (OMMT). Effect of OMMT loading on phase morphology, mechanical properties, and blown film bubble stability was investigated. Transmission electron micrographs show that a large number of OMMT nanolayers locate at interfacial region between PLA and EPDM phase, as well as in EPDM phase due to higher affinity of OMMT with EPDM. Scanning electron micrographs show that EPDM domain size decreases largely with increasing OMMT loading, which is associated with reduction of interfacial energy and inhibition of coalescence by the OMMT locating at the interface, acting as an emulsifier to enwrap the discrete domains. As OMMT loading increases from 0 to 1 phr, elongation at break increases from 20.4 to 151.7% and notched impact strength is enhanced from 8.2 to 31.7 kJ?m?2. The reduced EPDM domain is the main reason for enhanced toughness of PLA/EPDM/OMMT samples according to crazing with shear yielding mechanism. However, with more than 2 phr of OMMT, the toughness decreases largely due to excessive stress concentration and OMMT aggregation. Attempts were made to produce ductile films from the PLA/EPDM/OMMT nanocomposites by using blown film extrusion. Improvement in blown film bubble stability and tensile ductility of PLA/EPDM/OMMT films also shows that OMMT is an efficient compatibilizer, as well as a processing aid for PLA/EPDM blends. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44192.  相似文献   

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