Reactive Blending Research Articles

Sericin cocoon bio-compatibilizer for reactive blending of thermoplastic cassava starch

Cassava starch was blended with glycerol to prepare thermoplastic starch (TPS). Thermoplastic starch was premixed with sericin (TPSS) by solution mixing and then melt-blended with polyethylene grafted maleic anhydride (PEMAH). The effect of sericin on the mechanical properties, morphology, thermal properties, rheology, and reaction mechanism was investigated. The tensile strength and elongation at break of the TPSS10/PEMAH blend were improved to 12.2 MPa and 100.4%, respectively. The TPS/PEMAH morphology presented polyethylene grafted maleic anhydride particles (2 μm) dispersed in the thermoplastic starch matrix, which decreased in size to approximately 200 nm when 5% sericin was used. The melting temperature of polyethylene grafted maleic anhydride (121 °C) decreased to 111 °C because of the small crystal size of the polyethylene grafted maleic anhydride phase. The viscosity of TPS/PEMAH increased with increasing sericin content because of the chain extension. Fourier-transform infrared spectroscopy confirmed the reaction between the amino groups of sericin and the maleic anhydride groups of polyethylene grafted maleic anhydride. This reaction reduced the interfacial tension between thermoplastic starch and polyethylene grafted maleic anhydride, which improved the compatibility, mechanical properties, and morphology of the blend.

Corn starch reactive blending with latex from natural rubber using Na+ ions augmented carboxymethyl cellulose as a crosslinking agent

A mixture of corn starch and glycerol plasticizer (CSG) was blended with latex natural rubber (LNR) and carboxymethyl cellulose (CMC). The addition of 10 phr of CMC improved the Young’s modulus (6.7 MPa), tensile strength (8 MPa), and elongation at break (80%) of the CSG/LNR blend. The morphology of the CSG/LNR/CMC blends showed a uniform distribution of LNR particles (1–3 µm) in the CSG matrix. The addition of CMC enhanced the swelling ability and water droplet contact angle of the blends owing to the swelling properties, interfacial crosslinking, and amphiphilic structure of CMC. Fourier transform infrared spectroscopy confirmed the reaction between the C=C bond of LNR and the carboxyl groups (–COO−) of CMC, in which the Na+ ions in CMC acted as a catalyst. Notably, the mechanical properties of the CSG/LNR/CMC blend were improved owing to the miscibility of CSG/CMC and the CMC/LNR interfacial reaction. The CSG/LNR/CMC biodegradable polymer with high mechanical properties and interfacial tension can be used for packaging, agriculture, and medical applications.

On-line ATR-MIR for real-time quantification of chemistry kinetics along the barrel in extrusion-based processes

This work deals with the development and validation of an on-line infrared spectroscopic set-up for the real time quantification of the melt extrudate during reactive extrusion based processes. The arrangement consists of an infrared spectrophotometer operating in attenuated total reflectance ATR-FTIR, fitted on-line, along the extruder barrel. The setting helps understand the effects of extrusion process parameters and the reaction conversion during development of polymer blends and compound in-processing. The ATR-FTIR spectroscopic probe has been coupled along with an extruder to analyze/understand the process during operation in the MID region of the infrared spectrum. The ATR-FTIR prototype probe was calibrated and validated using off-line measurements. The probe is interfaced to the extruder through to a probe holder unit (PHU), also described herein. The on-line ATR-FTIR measurements were conducted at various locations (L/D) along the length of the extruder. Polymer blends of PP/PA6 in various compositions were investigated and reactive blend of PP-g-AA/PA6 were used to validate the on-line measurements compared to the standard off-line ATR-FTIR analysis.

Hydrolytic degradation of isosorbide-based polycarbonates: Effects of terminal groups, additives, and residue catalysts

The hydrolysis degradation of bisphenol-A polycarbonate (BPA-PC), isosorbide (ISB)-co-1,4-cyclohexanedimethanol (CHDM) polycarbonate (IcC-PC), and BPA-PC/IcC-PC reactive blends were systematically investigated. The terminal hydroxyl groups of BPA-PC, thermally derived chemical structure on IcC-PC chains, and derivatives from phosphite antioxidants trigger severe hydrolysis degradation. 1H-NMR analysis shows that carbonate groups connected to the BPA unit are most susceptible to hydrolysis, followed by ISB and CHDM units, demonstrating that the acidity of monomers plays a key role in the hydrolysis degradation of polycarbonates. Residual catalysts may cause significant hydrolysis in BPA-PC/IcC-PC reactive blends. Hydrolysis prefers to occur on the exo position of ISB unit with a low steric hindrance rather than on the endo position with a high electrophilicity, indicating that the residual catalyst acts as a Lewis acid and likely promotes hydrolysis through coordination mechanism. The hydrolysis resistance of BPA-PC/IcC-PC blends with a Na-based catalyst is lower than that of blends with K- and Cs-based catalysts because of the strong coordination ability.

High fire-safety phosphorus-containing polyethylene terephthalate with well-balanced comprehensive performances by reactive blending with liquid crystalline copolyester

With increased public awareness of fire-safety, flame retardant materials have been widely used and developed. Among them, a polyester called CPET, synthesized by the copolymerization of polyethylene terephthalate and 2-carboxyethyl (phenyl) phosphinic acid, has a good fire-safety and has been employed in the manufacture of synthetic fibers. However, the fabricated fiber made of CPET simultaneously possessing good flame retardancy and mechanical properties is a dilemma. Herein, we resolve this problem through the reactive blending of CPET with a type of thermotropic liquid crystal copolyester (PPDT) and subsequently solid-state polymerization (SSP). Thus, the fire-safety of the CPET/PPDTSSP blend improves greatly. The peak heat release rate, total heat release, and total smoke release decrease by 31.2%, 16.3%, and 11.0%, respectively, compared with those of CPET. Meanwhile, the CPET/PPDTSSP shows better crystallization and mechanical properties than CPET. The strength at yield and Young’s modulus of CPET/PPDTSSP increase by 20.0% and 15.8%, respectively. This blend shows great potential in the fabrication of fire-safety fibers with high strength.

Morphology, Thermo-Mechanical Properties and Biodegradibility of PCL/PLA Blends Reactively Compatibilized by Different Organic Peroxides.

Reactive blending is a promising approach for the sustainable development of bio-based polymer blends and composites, which currently is gaining more and more attention. In this paper, biodegradable blends based on poly(ε-caprolactone) (PCL) and poly(lactic acid) (PLA) were prepared via reactive blending performed in an internal mixer. The PCL and PLA content varied in a ratio of 70/30 and 55/45. Reactive modification of PCL/PLA via liquid organic peroxides (OP) including 0.5 wt.% of tert-butyl cumyl peroxide (BU), 2,5-dimethyl-2,5-di-(tert-butylperoxy)-hexane (HX), and tert-butyl peroxybenzoate (PB) is reported. The materials were characterized by rotational rheometer, atomic force microscopy (AFM), thermogravimetry (TGA), differential scanning calorimetry (DSC), tensile tests and biodegradability tests. It was found that the application of peroxides improves the miscibility between PCL and PLA resulted in enhanced mechanical properties and more uniform morphology. Moreover, it was observed that the biodegradation rate of PCL/PLA blends reactively compatibilized was lower comparing to unmodified samples and strongly dependent on the blend ratio and peroxide structure. The presented results confirmed that reactive blending supported by organic peroxide is a promising approach for tailoring novel biodegradable polymeric systems with controllable biodegradation rates.

Reaction Mechanism and Mechanical Property Improvement of Poly(Lactic Acid) Reactive Blending with Epoxy Resin.

Polylactic acid (PLA) was melt-blended with epoxy resin to study the effects of the reaction on the mechanical and thermal properties of the PLA. The addition of 0.5% (wt/wt) epoxy to PLA increased the maximum tensile strength of PLA (57.5 MPa) to 67 MPa, whereas the 20% epoxy improved the elongation at break to 12%, due to crosslinking caused by the epoxy reaction. The morphology of the PLA/epoxy blends showed epoxy nanoparticle dispersion in the PLA matrix that presented a smooth fracture surface with a high epoxy content. The glass transition temperature of PLA decreased with an increasing epoxy content owing to the partial miscibility between PLA and the epoxy resin. The Vicat softening temperature of the PLA was 59 °C and increased to 64.6 °C for 0.5% epoxy. NMR confirmed the reaction between the -COOH groups of PLA and the epoxy groups of the epoxy resin. This reaction, and partial miscibility of the PLA/epoxy blend, improved the interfacial crosslinking, morphology, thermal properties, and mechanical properties of the blends.

Synthesis and characterization of starch/fiber-based bioplastic composites modified by citric acid-epoxidized palm oil oligomer with reactive blending

In the present work, starch and empty fruit bunch-based bioplastic composites were modified with epoxidized palm oil (EPO) or citric acid-epoxidized palm oil (CEPO) oligomer using melt blending in order to improve the mechanical and water resistance properties. As evidenced by the FTIR, CEPO generated strong interactions with starch/fibers via citric acid-inspired esterification reaction. The X-ray diffraction patterns of the composites were apparently changed by CEPO because of the crosslinking effect. The SEM micrographs showed that EPO was immiscible with starch and hence migrated to the composite’s surface. The compatibility between starch and CEPO was obviously improved. EPO contributed to a noticeable decrease in melting temperature (Tm) of the composites, while CEPO improved Tm due to its crosslinking effect. As a result, the blending of CEPO in the composites led to the higher evolution in the tensile strength and young’s modulus than EPO. The tensile strength and young’s modulus of the control sample increased from 3.67 MPa to 6.90 MPa and from 27.19 MPa to 88.74 MPa, respectively, after the addition of 0.75 wt% CEPO. Higher concentrations of EPO or CEPO toughened the composites. The water sensitivity and permeability of the composites were also slightly reduced upon the addition of both oils. This study proposed a simple and effective modification technique by utilizing the CEPO oligomer to fabricate the bioplastic composites with superior properties.

Self-Reinforcement via 1D Nanostructure Formation during Melt Blending of Thermoplastics and Thermoplastic Elastomers with Nanophase-Separated UHMWPE/HDPE Wax Reactor Blends

Self-Reinforcement via 1D Nanostructure Formation during Melt Blending of Thermoplastics and Thermoplastic Elastomers with Nanophase-Separated UHMWPE/HDPE Wax Reactor Blends

Reactive compatibilization of poly(hydroxybutyrate-co-hydroxyvalerate)/polyvinyl alcohol blends

ABSTRACT In this work, di(tert-butylperoxyisopropyl)benzene (DB) and multifunctional Epoxide compound (ECE) were incorporated into Poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV)Modified polyvinyl alcohol (mPVOH) (70/30, 30/70) in an internal mixer to improve the compatibility of PHBV/PVOH blend. Prior to blending, glycerol and Maleic anhydride (MA) were added to PVOH (mPVOH). FTIR spectra indicated the reaction of MA grafted PVOH. The addition of DB and ECE showed higher torque values and better interfacial adhesion than nonreactive and reactive blends with DB or ECE. Tensile strength and elongation at break were increased for all reactive blends. The matrix dominated the crystallization whereas the minor phase was not crystallized upon cooling.

Advances in the hydration of reactive MgO cement blends incorporating different magnesium carbonates

Hydration of reactive magnesia cement (RMC) is limited by the formation of a Mg(OH)2 surface-layer on unreacted MgO particles. This study improved RMC hydration by using magnesium acetate (MA), along with hydromagnesite (H) and magnesite (M) as RMC replacements. While MA accelerated hydration and resulted in the formation of needle-like artinite, inclusion of M led to rosette-like crystals. The accumulated nucleation and growth of low-crystallinity Mg(OH)2 on H particles in a bird nest-like arrangement was observed for the first time in literature. This low-crystallinity Mg(OH)2 could be prone to carbonation. The replacement of up to 40% RMC with M in the presence of MA improved the compressive strength of RMC samples by 240%. This performance enhancement was supported by microstructure densification via the compact formation of hydrate and carbonate phases, defining M as a feasible partial RMC substitute.

Structure and properties of in situ reactive blend of polylactide and thermoplastic starch

In this study, in situ reactive extrusion of polylactide and thermoplastic starch modified with chloropropyl trimethoxysilane coupling agent (PLA/mTPS) is proposed. The success of covalent bond formation between PLA matrix and mTPS phase is clarified by two-dimensional nuclear magnetic resonance (2D-NMR) spectroscopy with 1H1H TOCSY mode. This chemically bound PLA with starch gives the remarkable compatibility in the PLA/mTPS film, with not only a decreased glass transition temperature (47 °C) but also an increased crystallinity of PLA (Χc of 50%). It consequently increases oxygen barrier significantly and also enhances the film flexibility as observed from the drastic increase of elongation at break (from 3% to 50%). Moreover, the PLA/mTPS 60/40 (w/w) film exhibits the accelerated degradation as compared with pure PLA film.

A New Era in Engineering Plastics: Compatibility and Perspectives of Sustainable Alipharomatic Poly(ethylene terephthalate)/Poly(ethylene 2,5-furandicarboxylate) Blends.

The industrialisation of poly(ethylene 2,5-furandicarboxylate) for total replacement of poly(ethylene terephthalate) in the polyester market is under question. Preparation of high-performing polymer blends is a well-established strategy for tuning the properties of certain homopolymers and create tailor-made materials to meet the demands for a number of applications. In this work, the structure, thermal properties and the miscibility of a series of poly(ethylene terephthalate)/poly(ethylene 2,5-furandicarboxylate) (PET/PEF) blends have been studied. A number of thermal treatments were followed in order to examine the thermal transitions, their dynamic state and the miscibility characteristics for each blend composition. Based on their glass transition temperatures and melting behaviour the PET/PEF blends are miscible at high and low poly(ethylene terephthalate) (PET) contents, while partial miscibility was observed at intermediate compositions. The multiple melting was studied and their melting point depression was analysed with the Flory-Huggins theory. In an attempt to further improve miscibility, reactive blending was also investigated.

Low Warpage Nanophase-Separated Polypropylene/Olefinic Elastomer Reactor Blend Composites with Digitally Tuned Glass Fiber Orientation by Extrusion-Based Additive Manufacturing

Among thermoplastics, polypropylene (PP) is outstanding with respect to its high versatility in terms of its tailoring property profiles for diversified applications, high resource and energy effic...

Thermal stabilization of polyoxymethylene by copolymerization and modified phenolic stabilizer: examining the effects of catalyst, retardant, and stabilizer

ABSTRACT Due to the low stability of oxymethylene units and their high heat sensitivity, polyoxymethylene (POM) shows weak thermal resistance. Therefore, by using a stabilizer the thermal stability of POM would be improved. In this study, the in-situ ring-opening copolymerization of 1,3,5-trioxane (TOX) as a monomer and 1,3-dioxolane (DOX) as a comonomer was investigated which was carried out in the presence of phosphotungstic acid (PTA) as the catalyst and the reactive antioxidant during the reactive blending. Then POM samples were characterized by Fourier-transform Infrared spectroscopy (FTIR), and Hydrogen Nuclear Magnetic Resonance spectroscopy (1H-NMR). Also, to scrutinize the crystallinity and the thermal degradation of POM Differential scanning calorimetry (DSC) and Thermogravimetric analysis (TGA) were performed, respectively. The Crystalline structure of the samples was also studied by X-ray diffraction (XRD). According to the results, The synthesized polymer had a hexagonal structure and the best quantity of catalyst was 50 ppm. The presence of retardant improved the thermal resistance of POM while the addition of 1 wt.% of stabilizer as an optimum amount has no upward or ascending effect.

Stable Co-Continuous PLA/PBAT Blends Compatibilized by Interfacial Stereocomplex Crystallites: Toward Full Biodegradable Polymer Blends with Simultaneously Enhanced Mechanical Properties and Crystallization Rates

Constructing stable co-continuous morphology of commercial immiscible polymer blends remains an ongoing challenge in terms of complex presynthetic routes, multiple parameter dependency, and intrinsic instability of phase morphology. Herein, we demonstrate a full biodegradable polymer blend, poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate), where hitherto inaccessible co-continuous with asymmetric compositions (70/30) can be obtained with the assistance of interfacial stereocomplex crystallites (i-SCs) through reactive blending. By taking full advantages of this unprecedented compatibilizer, nanostructured co-continuous blends with synergistically enhanced comprehensive performance are achieved. First, due to the “rigid” i-SC, co-continuous morphology is induced through a simple melt blending procedure; second, considerable augmentation of the crystallization rate of the PLA matrix is accomplished on account of the in situ formed nucleation agent (i.e., i-SC); third, a super toughened material with simultaneously enhanced tensile strength, ductility, and impact strength can be acquired, resulting from the i-SC-induced co-continuous morphology; and fourth, i-SC can function as a “rigid” supporting layer between phases even above 200 °C, resulting in significantly enhanced morphology stability in melt. The versatile, facile, and practical strategy offers an industrially relevant technique to fabricate super-robust and fully biobased polymer materials.

Digitally Tuned Multidirectional All-Polyethylene Composites via Controlled 1D Nanostructure Formation during Extrusion-Based 3D Printing

Fused filament fabrication (FFF) of polyethylene (PE) reactor blends containing high amounts of nanophase-separated disentangled ultrahigh molar mass polyethylene (UHMWPE) generates self-reinforced...

Toughening of polylactide by in-situ reactive compatibilization with an isosorbide-containing copolyester

Polylactide (PLA)/poly(1,4-cyclohexanedimethylene isosorbide terephthalate) (PEICT) blends were prepared by melt processing. Oligomer, with multiple epoxy functional groups, were introduced as a reactive compatibilizer to enhance interfacial adhesion of the two blend components. The reaction between the reactive compatibilizer and blend components was confirmed by infrared spectroscopy and rheological analysis. The improved compatibility of the blends reduced interfacial tension between polymer components, yielding a co-continuous phase morphology from a sea–island morphology. The added PEICT improved the impact strength of PLA to 22.5 kJ/m2 at 40% loading. After compatibilization and the impact strength of PLA/PEICT blends increased to 44.1 kJ/m2, showing that increased interfacial adhesion improved energy transfer between the polymers.

Review on transesterification in polycarbonate–poly(butylene terephthalate) blend

AbstractVarious polycarbonate ‐ poly(butylene terephthalate) polyester (PC‐PBT) blend prepared by reactive melt blending primarily in extruder with range of temperature and time are discussed in this review article. In the melt blended PC‐PBT blend system, transesterification plays a major role in formation of PC‐PBT blend. Transesterification reactions between these two polymers have been analyzed by proper polymer sample, end‐capped or having reactive chain end group. The kinetics of mechanism is a function of temperature and PC‐PBT ratio. Trace catalyst residue present in PBT catalyzes the transesterification reaction. As the extent of transesterification is increased, it forms various composition of copolymer. Inhibition in the transesterification reaction of PC‐PBT blend has been observed when different type of alkyl, aryl, and alkyl‐aryl group of phosphite are introduced into it, otherwise there has been collateral change in the morphology, thermal, and mechanical property of blend. Therefore, this PC‐PBT blend has been an interesting topic of research in academia and industries.

A Comparison on Biodegradation Behaviour of Polylactic Acid (PLA) Based Blown Films by Incorporating Thermoplasticized Starch (TPS) and Poly (Butylene Succinate-co-Adipate) (PBSA) Biopolymer in Soil

The comparative study of biodegradation of various blown films obtained from Poly (lactic) acid (PLA) has been studied via soil burial method. A total of 3-different types of films prepared from neat PLA and the reactive blends containing poly butylenes succinate-co-adipate (PBSA), and thermoplasticized starch (TPS); namely VPLA, PLA/PBSA, PLA/TPS respectively were the subjects of investigation. Several analytical techniques including weight loss method and analysis of mechanical properties were performed in each seven days interval until ninety days to elucidate the biodegradation in soil. The tensile modulus of VPLA and PLA/PBSA blown films were deteriorated to the tune of 60.32% and 71.28% respectively within 28 days, while PLA/TPS blown films recorded a significant reduction of 75.31% in the modulus value within 21 days of soil exposure compared to unexposed blown film samples. Similarly, blown films of PLA/TPS reported the highest rate of weight loss in the order of 40.06% in 90 days of soil burial with an estimated half-life of 103 days in soil environment compared to its counterparts. The depletion in both mechanical properties and weight of the film samples suggesting the occurrence of biodegradation in the real soil environment. Scanning electron microscopy (SEM) revealed the formation of coarse morphology for all three types of soil buried samples which trace of microbial action appeared on PLA/TPS films. Fourier transform infrared microscope (FTIR) showed the decrease in carbonyl index and variation in the intensities of carbonyl and hydroxyl peaks irrespective of the film samples after 90 days of soil exposure. Gel permeation chromatography (GPC) documented reduction in molecular weight and variation in polydispersity index (PDI) of post-exposed soil samples. The elemental analysis exhibited that the percentage of organic carbon and hydrogen content of all the films decreased while the oxygen percentage increased after soil burial due to the biodegradation of film specimens. Both Differential scanning calorimetry (DSC) and X-ray diffraction analysis (XRD) reported increase in crystallinity for soil exposed samples indicating the initiation of degradation kinetics preferably at the amorphous region of film composition. It has also been inferred that the biodegradation mechanism of VPLA and PLA/PBSA blown films predominantly driven by hydrolysis of ester bond. Contrastingly, the biodegradation kinetics in case of PLA/TPS film has been proceeded with microbial assimilation of TPS component which further thrived on hydrolysis of PLA component of the blown film system.