Reactive Extrusion Technique Research Articles

Washable Antibacterial Modified Bio-based PA56 with High Toughness

An effective method was developed for the preparation of a washable antibacterial modified bio-based polyamide 56 (PA56) with high toughness by a simple reactive extrusion technique. In this work, polypentamethylene guanidine hydrochloride (PPMG), as a bio-based antibacterial reagent, was successfully grafted onto a bio-based PA56 polymer. The micromorphology of the samples was studied by scanning electron microscopy, which proved that the addition of ethylene-methyl acrylate-glycidyl methacrylate terpolymer (EMA) greatly improved the compatibility. In addition, the mechanical properties of the modified antibacterial bio-based polyamide were improved, especially the impact toughness of PA56-g-1.0 (1.0 wt % PPMG and 1.0 wt % EMA) could be 48% higher than pure PA56. When the content of PPMG was higher than 1.0%, the inhibition rates of the products against Escherichia coli and Staphylococcus aureus both reached over 99.99%, and such a high inhibition rate would still maintain after 30 washing times with hot water (90 °C) and detergent.

Improved compatibility of PLA/Starch blends with Binary functional monomers through UV-induced reactive extrusion

In this work, we chose starch as a biomass nucleating agent for PLA to enhance the crystalline properties without affecting the biodegradability of the composite. Under the synergistic effect of glycidyl methacrylate (GMA) and trimethylpropane triacrylate (TMPTA), biodegradable PLA/Starrch composites were prepared by a unique UV-induced reactive extrusion technique. GMA was grafted onto PLA with the help of TMPTA and the modified PLA enhanced compatibility with starch via epoxidation reaction during extrusion. The rheological properties, mechanical properties, and crystallization behavior of PLA/Starch composites were researched. The rheological and FITR results demonstrated that the introduction of GMA/TMPTA in PLA/Starch blends not only promoted the reactive compatibilization of PLA with starch but also produced a certain degree of chain branching effect. Meanwhile, starch provides heterogeneous nucleation sites for PLA crystallization, which improved the crystallization performance of PLA. In addition, the mechanical properties of the composite were improved. Compared with pure PLA, the tensile stress of the composite was increased by 116% and the elongation at break was increased by 118%. In summary, this work provides a new strategy for the preparation of PLA/starch composites, which is expected to expand the application of PLA in the packaging field.

Use of Water-Soluble Curcumin in TPS/PBAT Packaging Material: Interference on Reactive Extrusion and Oxidative Stability of Chia Oil

The reactive extrusion technique is efficient in the incorporation of bioactive compounds for active packaging development. The application of curcumin, a strong antioxidant in its pure, isolated form to obtain active packaging has already been investigated; however, the use of water-soluble curcumin (WSC) in thermoplastic starch/poly(butylene adipate-co-terephthalate) (TPS/PBAT) films has not yet been investigated. It is important to determine how WSC would affect starch esterification reaction during reactive extrusion (REx). The use of WSC at 0.5%wt led to an increase in tensile strength, elongation at break, and Young’s modulus. A reduction in starch esterification was observed; however, an improvement in TPS/PBAT compatibility was detected by infrared spectroscopy, X-ray diffraction, and scanning electron microscopy images. It is worth noting that WSC addition resulted in an increase in the film’s solubility and water vapor permeability, due to the hydrophilic character of the WSC. The films were used to package chia oil, and the oxidative stability data were evaluated by UV-Vis spectroscopy coupled with principal component analysis. The addition of WSC (0.5%wt) in the films led to the improvement of the oil oxidative stability, suggesting that using water-soluble curcumin may be a promising alternative to active packaging in the case of reactive extruded films.

Preparation and Properties of Nylon 6,6 Grafted Graphene Composites.

Nylon 6,6 composite fiber containing grafted graphene (nylon 6,6-g-graphene) was prepared by nylon and graphene grafted with acyl chloride (graphene-COCl) through extrusion reaction. Graphene-COCl was prepared through acid-treated reacting, graphene with thionyl chloride functional group. The chemical structure of nylon 6,6-g-graphene obtained using reactive extrusion technique was characterized using Fourier transform infrared spectrometer. It was found that this kind of composite fiber has the characteristics of less amount of graphene and excellent mechanical properties and has certain application prospects. Nylon 6,6-g-graphene dispersed evenly in the Nylon composite. But pristine graphene exhibited aggregate structure when composite was produced by pristine graphene through reactive extrusion. The composite reinforcement was increased obviously with the increase content of grafted graphene. After examined, the nylon/nylon 6,6-g-graphene with a certain content grafted graphene composite exhibited high level of reinforcement, and mechanical properties were improved.

Development and Characterization of Polyurethane and Acrylonitrile Butadiene Styrene and their Compatibilized Blends

Abstract Novel blends of polyurethane and acrylonitrile butadiene styrene, in both forms, compatibilized and uncompatibilized, were developed by melt reactive extrusion technique in a twin-screw extruder. This technique involved acrylonitrile butadiene styrene grafted maleic anhydride (ABS-g-MAH) as the compatibilizer. The objective of this study was to enhance the rigidity characteristics of polyurethane by melt blending acrylonitrile butadiene styrene into polyurethane using a compatibilizer. The blends were analyzed using different techniques to confirm the occurrence of compatibilization reaction between the parent polymers and the compatibilizer. It is observed that addition of the compatibilizer has improved the mechanical properties of the resultant blends.

Reactive Extrusion of Polyethylene Terephthalate Waste and Investigation of Its Thermal and Mechanical Properties after Treatment

This study investigates treating polyethylene terephthalate (PET) waste water bottles with different mass of ethylene glycol (EG) using reactive extrusion technique at a temperature of 260°C. The study puts emphases on evaluating the thermal, mechanical, and chemical characteristics of the treated polyethylene terephthalate. The properties of the treated PET from the extruder were analyzed using FT-IR, TGA, DSC, and nanoindentation. The melt flow indexes (MFI) of both treated and untreated PET were also measured and compared. Thermal properties such as melting temperature (Tm) for treating PET showed an inversely proportional behavior with the EG concentrations. The FT-IR analysis was used to investigate the formation of new linkages like hydrogen bonds between PET and EG due to the hydroxyl and carbonyl groups. Nanoindentation results revealed that both the mechanical characteristics, elastic modulus and hardness, decrease with increasing EG concentration. On the other hand, the melt flow index of treated PET exhibited an increase with increasing EG concentration in the PET matrix.

Comparison of static mixing reaction and reactive extrusion technique for ring-opening polymerization of l-lactide

In order to compare the static mixing reaction technique and the reactive extrusion technique for synthesizing poly(l-lactide) (PLLA), ring-opening polymerizations (ROPs) of l-lactide were performed in a tubular static mixing reactor (TSMR) and a twin-screw extruder (TSE), respectively. Compared with the results by using the TSE, the PLLA polymers obtained by using the TSMR had a smaller polydispersity index (PDI), higher molecular weight and optical purity. Additionally, the TMSR was also an energy-saving reactor. It provided reactants to have higher collision frequencies among molecules and an excellent mixing performance under lower shear rates. Therefore, the TSMR was an advantageous option to synthesize PLLA.

Optimizing the morphology, mechanical and crystal properties of in-situ polypropylene/polystyrene blends by reactive extrusion

In this study, in-situ polypropylene/polystyrene (PP/PS) blends were prepared via a reactive extrusion technique. Fourier transform infrared spectroscopy (FTIR) analysis confirmed the generation of polypropylene-grafted-polystyrene (PP-g-PS) copolymer in the reactive process. The morphology of the in-situ PP/PS blend tended to form a homogeneous structure, as observed by scanning electron microscopy (SEM). Owing to the introduction of PP-g-PS in the reactive extrusion, a remarkable enhancement of mechanical properties was achieved for the in-situ PP/PS blend. The elongation at break of the in-situ PP/PS blend with 15 wt% PS can reach 500 %, over 10 times higher than that of the normal PP/PS blend. Differential scanning calorimetry (DSC) showed an increased crystallization temperature of PP, which can be attributed to the heterogeneous nucleation effect of the PS and grafted PS. The analysis of wide angle X-ray diffraction (WAXD) indicated the development of beta crystals in the in-situ PP/PS blend.

Mechanically Robust and Transparent N-Halamine Grafted PVA-co-PE Films with Renewable Antimicrobial Activity.

Antimicrobial polymeric films that are both mechanically robust and function renewable would have broad technological implications for areas ranging from medical safety and bioengineering to foods industry; however, creating such materials has proven extremely challenging. Here, a novel strategy is reported to create high-strength N-halamine incorporated poly(vinyl alcohol-co-ethylene) films (HAF films) with renewable antimicrobial activity by combining melt radical graft polymerization and reactive extrusion technique. The approach allows here the intrinsically rechargeable N-halamine moieties to be covalently incorporated into polymeric films with high biocidal activity and durability. The resulting HAF films exhibit integrated properties of robust mechanical strength, high transparency, rechargeable chlorination capability (>300 ppm), and long-term durability, which can effectively offer 3-5 logs CFU reduction against typical pathogenic bacterium Escherichia coli within a short contact time of 1 h, even at high organism conditions. The successful synthesis of HAF films also provides a versatile platform for exploring the applications of antimicrobial N-halamine moieties in a self-supporting, structurally adaptive, and function renewable form.

Investigating the Degradation Behavior of LDPE-grafted Maleic Anhydride for Use as Compatibilizer in Environmentally Degradable Compositions

In this paper, we report the degradation behavior of a LDPE-grafted Maleic anhydride polymer prepared using a reactive extrusion technique. 70 ± 5 µm blown films were exposed to oxidative environments, and the degradation was followed by monitoring physico-chemical and morphological changes. The studies indicated that grafting with Maleic anhydride does not affect the degradation characteristics of the base polymer. Kinetic parameters of degradation, as estimated using non-isothermal TGA, were used to estimate the theoretical lifetime of the polymers, which remained unaltered due to grafting. The results, however, indicated that cobalt stearate, a typical pro-oxidant, led to massive degradation during thermal processing.

Reactive‐extrusion route for the closed‐loop recycling of poly(ethylene terephthalate)

AbstractThe effectiveness of the reactive extrusion technique was investigated for poly(ethylene terephthalate) to promote the concept of closed‐loop recycling, that is, the reuse of waste material in the initial application. More specifically, a chain‐extender system, consisting of pyromellitic dianhydride, polyol, and a catalyst, was employed, and its efficiency regarding the improvement of the recyclate quality was evaluated. Accordingly, rheological and thermal characterizations were performed and used as criteria of the modification induced in the polymer molecular structure during processing due to the counteracting degradation and chain‐extension reactions. In particular, the molecular weight, related to intrinsic viscosity and melt flow rate measurements, of modified poly(ethylene terephthalate) samples was found to increase with the additive content. Simultaneously, a decrease in the crystallinity was observed, attributed to the branching effect of the chain extender, which restricted the ability of the macromolecules to organize in the crystal structure. Beyond a critical concentration of the additive system, the molecular weight of the treated samples started to decrease again, and this was accompanied by a small increase in the crystallinity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1671–1678, 2007

A small-angle X-ray scattering study of the effect of chain architecture on the shear-induced crystallization of branched and linear poly(ethylene terephthalate)

The synchrotron-based small-angle X-ray scattering (SAXS) technique was used to investigate the shear-induced crystallization kinetics of branched/unbranched poly(ethylene terephthalate) (PET). Reactive extrusion of bottle-grade PET with the branching and chain-extension agents pyromellitic dianhydride and pentaerythritol results in enhanced rheological properties, such as higher melt strength and higher viscosity. In this study, six samples of PET were investigated: linear PET [intrinsic viscosity (IV) ≃ 0.76 dm3 g−1]; four branched PETs produced from linear PET by a reactive extrusion technique (IV ≃ 0.86–1.06 dm3 g−1); and a control PET (IV ≃ 0.73 dm3 g−1) extruded under the same conditions without reactive agents. SAXS data were recorded for the PET at the melt temperature and time-resolved SAXS data were recorded following the application of a step shear (53 s−1 for 2 s). As the PET IV was increased, the extent of shear-induced orientation increased, whilst the time taken for the polymer to initiate and complete crystallization decreased.

Environment friendly fluid loss additives to protect the marine environment from the detrimental effect of mud additives

The exploration and exploitation of hydrocarbon from the ocean dictate the use of environment friendly muds and mud additives to protect the existing wealths such as fishes, coastal areas and other habitats of the ocean. Hence, the preservation of the Australian as well as global ocean environments from the detrimental effects of muds and mud additives dictates the design of better environment friendly drilling mud systems using mud additives having no/negligible environmental impact. This paper describes the fluid loss characteristics of several starches and provides a comparative assessment with respect to a widely used modified starch. Experimental results indicate that some of the starches have static and dynamic fluid loss characteristics similar to or better than those of a widely used modified starch used by the mud industry. The static fluid loss properties measured after thermal treatment at different temperatures indicate that the newly developed starch products can be used as fluid loss additives for drilling boreholes having bottom hole temperature up to 150 °C. The products developed by gelatinization using a reactive extrusion technique have negligible impurities, need no solvent during gelatinization, produce no waste water as a by-product and thus are suitable for environment sensitive areas. The products have been developed from local resources and have lower manufacturing cost and thus expected to decrease the cost of drilling mud significantly.

Recycling of poly(ethylene terephthalate) into closed‐cell foams

AbstractThe increase of the elongational viscosity of recycled poly(ethylene terephthalate) (PET) is investigated with the aim of producing closed‐cell foams by means of a cost‐effective reactive extrusion technique. A recycled PET grade containing controlled contamination levels of polyvinyl chloride (PVC) and poylethylene (PE) is selected, and compared with virgin bottle‐grade PET as a reference. Reactive processing with a tetrafunctional epoxy additive induces randomly branched molecules with a lower degree of branching in recycled PET than in virgin PET, as shown by a molecular structure analysis. The corresponding increase in elongational viscosity is related to foaming experiments performed using supercritical CO2 in a pressurized vessel. Observations of foam microstructures reveal that modified virgin PET forms closed‐cell structures under a large variety of foaming conditions, as opposed to unmodified virgin and recycled PET, which collapse as a result of insufficient elongational resistance. Closed‐cell foams are also obtained using modified recycled PET, providing that the temperature at which the pressure is released is lowered to 260°. Recycling of PET into closed‐cell foams is thus achieved, although the processing window is slightly reduced compared to virgin PET.