Notched Izod Impact Strength Research Articles

Miscible blends of chemically‐modified poly(phenylene oxides) with styrene copolymers containing polar groups

AbstractPoly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) is well‐known to be miscible with polystyrene, but immiscible with styrene copolymers containing polar groups. Certain nitrated‐PPOs (NPPOs) were found to be miscible with copolymers of styrene/acrylonitrile (SANs), copolymers of styrene/maleic anhydride (SMAs), a terpolymer of α‐methylstyrene/styrene/acrylonitrile (α‐MS/S/AN), and a copolymer of o‐ and p‐chlorostyrene (PCS). Also, certain simultaneously nitrated‐ and chlorinated‐PPOs (NCPPOs) were found to be miscible with SANs, SMAs and PCS whereas immiscible with the α‐MS/S/AN. The miscibility was indicated by the presence of a single composition‐dependent glass‐transition temperature for a given blend across the entire range of blend compositions tested. The miscibility of the aforementioned NPPOs and NCPPOs blends with SAN1 and SMA1 is attributed to hydrogen bonding of hydroxy groups of NPPOs and NCPPOs with nitrile groups and carbonyl groups, respectively, based on the literature information. The hydroxy groups were generated during nitration and simultaneous nitration/chlorination of PPO as a result of nucleophilic chain scission. Miscible blends of ‐NPPO/SAN and ‐NPPO/SMA with ABS1 showed a substantially better balance of the following properties than a comparable immiscible‐NPPO/SAN blend and a ‐PPO/SAN blend with ABS1: notched Izod impact strength, tensile properties, heat distortion temperature and gasoline stress‐crack resistance.Highlights Nitration and simultaneous nitration/chlorination of PPO generated hydroxyl end groups. Certain NPPOs and NCPPOs were miscible with SANs, SMAs and PCS. Miscibility indicated by a single composition dependent Tg for a given blend. Miscibility attributed to hydrogen bonding of respective functional groups. Impact‐modified miscible‐NPPO/SAN blends and ‐NPPO/SMA blends with ABS1 as impact modifier had good key properties.

Preparation and Properties of PA10T/PPO Blends Compatibilized with SEBS-g-MAH.

Plant-derived PA10T is regarded as one of the most promising semi-aromatic polyamides; however, shortcomings, including low dimensional accuracy, high moisture absorption, and relatively high dielectric constant and loss, have impeded its extensive utilization. Polymer blending is a versatile and cost-effective method to fabricate new polymeric materials with excellent comprehensive performance. In this study, various ratios of PA10T/PPO blends were fabricated via melt blending with the addition of a SEBS-g-MAH compatibilizer. Molau test and scanning electron microscopy (SEM) were employed to study the influence of SEBS-g-MAH on the compatibility of PA10T and PPO. These studies indicated that SEBS-g-MAH effectively refines the domain size of the dispersed PPO phase and improves the dispersion stability of PPO particles within a hexafluoroisopropanol solvent. This result was attributed to the in situ formation of the SEBS-g-PA10T copolymer, which serves as a compatibilizer. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) results showed that the melting-crystallization behavior and thermal stability of blends closely resembled that of pure PA10T. Dynamic mechanical analysis (DMA) revealed that as the PPO content increased, there was a decrease in the glass transition temperature and storage modulus of PA10T. The water absorption rate, injection molding shrinkage, dielectric properties, and mechanical strength of blends were also systematically investigated. As the PPO content increased from 10% to 40%, the dielectric loss at 2.5 GHz decreased significantly from 0.00866 to 0.00572, while the notched Izod impact strength increased from 7.9 kJ/m2 to 13.7 kJ/m2.

Ultrahigh strength and toughness of polylactide added with EGMA elastomer of a small amount processed via pressure-induced flow above the glass transition temperature

Elastomer toughening is widely recognized as a highly effective strategy for enhancing the mechanical performance of plastics. However, the improvement in toughness generally comes at the cost of a drastic sacrifice in tensile strength. In this work, ethylene–acrylic ester-glycidyl methacrylate random terpolymer (EGMA) of a small amount of 5 % in mass was applied as a toughening agent of polylactide (PLA), with the assistance of a pressure-induced flow processing at above the glass transition temperature. The obtained PLA blend showed simultaneously improved tensile strength and impact toughness. The tensile strength and Young′s modulus maintained at a relatively high level of 58 MPa and 2.1 GPa, respectively, and the notched Izod impact strength reached up to 54 kJ/m2, which was 27 times higher than that for neat PLA (1.9 kJ/m2). The increased toughness was primarily attributed to a synergistic effect of the reduced crystal sizes, reduction in phase domain sizes and enhanced interfacial interactions. This study provided a cost-effective and feasible approach to achieving strong and super-tough PLA materials, which held a significant potential for PLA widespread applications.

Exploring the Effects of Nano-CaCO3 on the Core-Shell Structure and Properties of HDPE/POE/Nano-CaCO3 Ternary Nanocomposites.

To address the dilemma of the stiffness and toughness properties of high-density polyethylene (HDPE) composites, titanate coupling agent-treated CaCO3 nanoparticles (nano-CaCO3) and ethylene-octene copolymer (POE) were utilized to blend with HDPE to prepare ternary nanocomposites via a two-sequence-step process. Meanwhile, a one-step process was also studied as a control. The obtained ternary nanocomposites were characterized by scanning electron microscopy (SEM), Advanced Rheometrics Expansion System (ARES), Dynamic Mechanical Analysis (DMA), wide-angle X-ray diffraction analysis (WXRD), and mechanical test. The SEM results showed one or two CaCO3 nanoparticles were well-encapsulated by POE and were uniformly dispersed into the HDPE matrix to form a core-shell structure of 100-200 nm in size by the two-step process, while CaCO3 nanoparticles were aggregated in the HDPE matrix by the one-step method. The result of the XRD showed that the nano-CaCO3 particle played a role in promoting crystallization in HDPE nanocomposites. Mechanical tests showed that the synergistic effect of both the POE elastomer and CaCO3 nanoparticles should account for the balanced performance of the ternary composites. In comparison with neat HDPE, the notched impact toughness of the ternary nanocomposites of HDPE/POE/nano-CaCO3 was significantly increased. In addition, the core-shell structure absorbed the fracture impact energy and prevent further propagation of micro-cracks, thus obtaining a higher notched Izod impact strength.

Enhanced mechanical performance of jute-glass fiber reinforced epoxy composite: Fabrication, analysis, and comparison

This study centers on fabricating and analysing a composite material by integrating jute and glass fibers reinforced with epoxy, and subsequently comparing its performance to composites formed using jute and glass fibers individually as well as reinforced with epoxy. The mechanical properties of the composites, including tensile strength, notched Izod impact strength, and Rockwell hardness were tested. Additionally, the surface morphology of the samples was analyzed using scanning electron microscopy (SEM). The experimental results indicate that the jute/glass fiber composite exhibited a 37% increase in tensile strength, 396% increase in impact strength, and a 60% increase in hardness when compared to the jute/jute composite. The SEM analysis revealed that the jute specimens displayed more cracks resulting from delamination, while the glass fiber composite experienced failure mainly due to breakage in the glass fibers.

Improvement of mechanical properties of highly ZnO‐filled polyethylene composites by dual‐compatibilizer for hydrogen sulfide permeation inhibition

AbstractTransportation of acidic fluids containing hydrogen sulfide (H2S) by flexible reinforced thermoplastic pipes can cause safety problems due to diffusion of H2S in the pipe. Herein, high‐density polyethylene (HDPE) composites are prepared with a large amount of zinc oxide (ZnO) particles as absorbent fillers by melt‐mixing via introducing maleic anhydride‐grafted polyethylene (PE‐g‐MAH) and maleic anhydride‐grafted poly(ethylene‐co‐octene) (POE‐g‐MAH) as dual‐compatibilizer. By controlling the mass ratio of the two compatibilizers, ZnO particles can be encapsulated by PE‐g‐MAH and POE‐g‐MAH so that mechanical properties of the prepared HDPE/ZnO composites are improved owing to enhanced compatibility between the filler and the resin. By adding PE‐g‐MAH and POE‐g‐MAH with total 10 wt% in a mass ratio of 1/3, the HDPE/ZnO composite containing 50 wt% ZnO exhibits 37.3 ± 3.8 MPa of yield strength, 576 ± 16 MPa of flexural modulus, and 84.4 ± 1.4 kJ m−2 of notched Izod impact strength corrected to 311 ± 24.9 kJ m−2. After exposure in H2S at 0.1 MPa for 7 days, the diffusion distance of H2S in the composite is 659 ± 17 μm, demonstrating a high barrier ability on H2S via absorption. This study provides a feasible method for preparation of polymer composites with suitable mechanical properties for inhibiting H2S permeation in reinforced thermoplastic pipes.

Mechanically strong and fully transparent PMMA composite with greatly improved toughness and impact strength incorporating PEBA nanofibrils

Improving the tensile toughness and impact strength of poly(methyl methacrylate) (PMMA) involves a trade-off, the improvements often come at the expense of reduced tensile strength, stiffness, transparency, and other crucial properties. In this article, we report a facile method to enhance the tensile toughness and impact strength of PMMA simultaneously, without sacrificing its tensile strength, stiffness, transparency, glass transition temperature, and scratch resistance. We demonstrate that the inclusion of only 3 wt% of polyether block amide elastomer (PEBA) nanofibrils (diameters ranging from ∼ 20 to 164 nm) in PMMA and ∼ 0.6 wt% of a random ethylene-glycidyl methacrylate copolymer (E-GMA) selectively at the interface resulted in a remarkable increase of ∼ 169 % in its elongation at break, ∼188 % in tensile toughness, and ∼ 87 % in notched Izod impact strength. Importantly, by incorporating such a minimal content of rubbery materials, these improvements were attained without compromising any of its major properties. Herein, we also demonstrate that multiple crazing was the primary toughening mechanism in the composites at a slow deformation speed (i.e., tensile testing), while rubber cavitation and subsequent ductile shear yielding of the surrounding matrix (enabled by the presence of E-GMA at the interface) was the most dominant at a high deformation speed (i.e., notched Izod impact testing). The high-performance composites presented herein possess immense potential for use in applications requiring a unique combination of attributes such as high strength, stiffness, tensile toughness, impact strength, and optical transparency.

Time- and temperature-dependent mechanical and rheological behaviours of injection moulded biodegradable organoclay nanocomposites

Injection moulded specimens were produced from biodegradable poly(butylene succinate) (PBS)/organomodified montmorillonite (OMMT) nanocomposites, after melt compounding in different compositions. WAXD studies demonstrated that the OMMT formed similar intercalation levels in the 2.5–10 w/w% additive ratio range. It was also proved by rotational rheometry that the nanoclay stacks form physical network above 5 w/w% concentration, which significantly influence the viscoelastic properties of the melt. The value of zero shear viscosity also changed accordingly, starting to increase above 5 w/w% nanoclay content. The OMMT content reduced the creep sensitivity measured in molten state.X-ray and DSC investigations showed that OMMT inhibits the crystallisation of PBS, resulting in a decrease in crystallinity at higher nanoclay ratios. As a result, the room temperature creep increased with the OMMT ratio.The Young's modulus linearly increases in the entire concentration range exceeding 1.2 GPa at 10 w/w% nanoclay content. The value of yield strength does not change significantly (35–40 MPa), but the strain at yield – which characterises stiffness – and the notched Izod impact strength already decrease at 2.5 w/w% OMMT content, but further increasing the nanoclay content has minor effect. However, the nanocomposite with 10 w/w% OMMT can be a real alternative to polypropylene (PP) and high-density polyethylene (HDPE) injection moulded products based on its mechanical properties.To characterise the effect of OMMT on dynamic mechanical properties, the S (Stiffening effectiveness), L (Loss effectiveness) and D (Damping effectiveness) indices were introduced to quantitatively describe the nanoclay effect intensity in each temperature range.

Improving the flame retardancy properties of PLA/PC blends

Polylactic acid/Polycarbonate (PLA/PC) blend was prepared via twin screw extruder by taking the bio-based content as much as possible and the better mechanical, thermal, and impact properties into consideration. Flame retardant (FR) performance of the PLA/PC blend was improved by using the mixture of ammonium polyphosphate, triphenyl phosphate, and zinc borate. FR properties of PLA/PC blend was evaluated according to the UL 94 test standard. The variations in tensile and flexural strength, and Izod-notched impact strength values were determined. In order to reduce the total amount of flame retardant additive, instead of using a mixture of TPP and APP (weight ratio of 2/1) at 21 wt% weight fraction, 1 wt% Zinc borate together with 18 wt% TPP-APP mixture was used and obtained V0 rating for the thickness of 1.5 mm. It was reported that weight fraction of flame retardant additives (APP and TPP) was successfully reduced by using a mixture of APP, TPP and ZnB without degrading the mechanical properties such as tensile and flexural strengths. Using less total FR additive weight (19 wt%) led to 15 and 24% higher tensile and flexural strength values, respectively, compared to higher FR additive weight (21 wt%).

Supertoughened Polylactide via the Addition of Low Content Poly(ε-caprolactone) and Tensile Deformation above the Glass Transition Temperature

Polylactide (PLA) is considered as an ideal alternative of petroleum-based plastics due to its high tensile strength and biodegradability. However, the low impact strength limits its extensive application in the engineering field. In this work, a supertough binary PLA blend was fabricated through pre-stretching above the glass transition temperature to a certain pre-strain. The biodegradable and biocompatible poly(ε-caprolactone) (PCL) was used as a toughening modifier for the PLA/PCL 95/5 (wt/wt) blend. It was found that the impact strength increased with the increase in pre-strain. The highest notched Izod impact strength reached 251 kJ/m2 at the pre-strain of 400%, nearly 132 times of that for neat PLA (1.9 kJ/m2). To our knowledge, such fabulous impact toughness has not been referred in literature. Even at the pre-strain of 150%, the blend exhibited a sufficiently high notched Izod impact strength of 149 kJ/m2. Small-angle X-ray scattering demonstrated a typical structural feature of combination of PLA shish-kebabs and oriented PCL lamellar stacks due to strain-induced crystallization. The wide-angle X-ray diffraction indicated that PLA crystals had high orientation at the pre-strain of 200% and above. The crystallinity of the PLA matrix increased with the increase in pre-strain, which was consistent with the increasing trend of impact strength. The high orientation of shish-kebabs and increased crystallinity of PLA matrix were the key factors for drastically toughening PLA. This work provides a feasible and effective method to manufacture competitive PLA materials, which can be extended to improve impact toughness of other brittle glassy polymers.

Carbon Nanotube-, Boron Nitride-, and Graphite-Filled Polyketone Composites for Thermal Energy Management.

In order to improve the thermal conductivity of 30 wt % synthetic graphite (SG)-filled polyketones (POKs), conductive fillers such as multiwall carbon nanotubes (CNTs) and hexagonal boron nitride (BN) were used in this study. Individual and synergistic effects of CNTs and BN on 30 wt % synthetic graphite-filled POK on thermal conductivity were investigated. 1, 2, and 3 wt % CNT loading enhanced the in-plane and through-plane thermal conductivities of POK-30SG by 42, 82, and 124% and 42, 94, and 273%, respectively. 1, 2, and 3 wt % BN loadings enhanced the in-plane thermal conductivity of POK-30SG by 25, 69, and 107% and through-plane thermal conductivity of POK-30SG by 92, 135, and 325%. It was observed that while CNT shows more efficient in-plane thermal conductivity than BN, BN shows more efficient through-plane thermal conductivity. The electrical conductivity value of POK-30SG-1.5BN-1.5CNT was obtained to be 1.0 × 10-5 S/cm, the value of which is higher than that of POK-30SG-1CNT and lower than that of POK-30SG-2CNT. While BN loading led to a higher heat deflection temperature (HDT) than CNT loading, the hybrid fillers of BNT and CNT led to the highest HDT value. Moreover, BN loading led to higher flexural strength and Izod-notched impact strength values than CNT loading.

Inorganic Filled Polycarbonate-Polybutylene Terephthalate Composites

A series of inorganic filled polycarbonate (PC) - polybutylene terephthalate (PBT) composites were prepared. The effects of various inorganic fillers, viscosity level of the PC and PBT resins, and also the blend ratio of PC to PBT, on the properties and stability of the composites were studied and are described. The results showed that the viscosities of PC and PBT had little impact on the mechanical properties of the composites. The melting stability of the composites was characterized by the difference of Melt Flow Index (△MFI) with composition, and it was found that the melting stability was improved significantly by using the resin (PC or PBT) of high viscosity as opposed to the medium one. With the increase of PC-to-PBT ratio, the increased Notched Izod Impact Strength of the composites and the reduced Melt Flow Index (MFI), Heat Deflection Temperature (HDT) and the density of the composites were observed. The “brittle-ductile transition” was found at various blend ratios of PC to PBT. The composition ratio of the critical point in this study was PC/PBT(45/30).

Influence of interfacial compatibilization caused by epoxidized cardanol on the toughness of poly (lactic acid)/flax fiber blends

Poly (lactic acid) (PLA)/flax fiber/cardanol (or epoxidized cardanol) blends were prepared by mould injection. Epoxidized cardanol was effective on toughening PLA/flax fiber blends. The maximum notched Izod impact strength of PLA/flax fiber/epoxidized cardanol (80/10/10) blend reached 10.42 ± 0.61 kJ/m2 i.e. two fold of PLA/flax fiber (90/10) blend (5.18 ± 0.23 kJ/m2). Also, the elongation at break of PLA/flax fiber/epoxidized cardanol (85/5/10) blend was promoted to 43.76 ± 8.58 %, which was over four fold of PLA/flax fiber (95/5) blend (9.94 ± 1.65 %). The improved interfacial compatibility caused by epoxidized cardanol was presumed to be responsible for the superior toughness.

Fabrication of outstanding mechanical performance engineered poly (lactic acid)/thermoplastic poly(ester)urethane in-situ nanofiber composites with a large-scale industrial innovation methodology

As one of the most promising biodegradable materials, poly(lactic acid) (PLA) is seriously restricted by its notorious brittleness and weak heat distortion resistance. Hitherto, the possibility of effectively toughening PLA while simultaneously maintaining high strength and stiffness has hardly been realized on an industrial scale. In this work, an innovative industrial methodology was applied to manufacture high-performance engineered (95-x) poly(l-lactic acid)/5poly(d-lactic acid)/xthermoplastic poly(ester)urethane ((95-x)L/5D/xT) nanofiber composites. The in-situ formed TPU nanofibers (TNFs) combined with sterocomplex crystals (SCs) generating synergistic effects significantly improve the crystallization behavior and elasticity of melt. The compatibility between PLA matrix and TNFs in (95-x)L/5D/xT nanofiber composites was significantly reinforced by constructing bundle structures. The bundle structure is composed of rigid PLA hybrid crystals tightly bundled with a handle of oriented TNFs with good interfacial compatibility, bundle structures interlink with each other forming 3D strengthening-toughening bundle structures contributing to the mechanical performance. The notched Izod impact strength of 80L/5D/15T and 75L/5D/20T nanofiber composites prodigiously increase to 74.8 and 98.7 kJ/m2, which is 27.7 and 35.6 times higher than that of neat PLLA. Meanwhile, the nanofiber composites can maintain balanced tensile yield strength, good Young's modulus, and obtain advantaged heat distortion resistance of 1132 MPa at 100 °C. Compared with reported PLA/elastomer blends, neat biodegradable plastics, general-purpose and engineering plastics, the efficient industrial-scale manufactured 80L/5D/15T and 75L/5D/20T nanofiber composites possessing outstanding mechanical performance of super toughness, balanced strength, good Young’s modulus and advantaged heat distortion resistance. It has immense potential to substitute non-degradable petroleum-based engineering plastics as structural materials in harsh environments, thereby reducing CO2 emissions and reducing pollution caused by discarded non-degradable petroleum-based plastics.

Effect of Nanoalumina on Physical and Thermal Properties of Polypropylene-Glass Fiber Reinforced Nanocomposites

The present study examines the effect of nanoalumina on the mechanical and thermal properties of glass fiber and elastomer reinforced PP/EPDM/GF/Al2O3 with an aim to develop suitable composite material for orthotics. In present study, PP/GF, PP/EPDM/GF composite and PP/EPDM/GF/Al2O3 nanocomposites with specific composition were fabricated using melt-blending technique. Prepared composites were characterized through scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The mechanical characteristics including tensile strength, tensile modulus, notched Izod impact strength and elongation at break of the prepared composite were studied in accordance with ASTM guidelines. PP/EPDM/GF/Al2O3 composites showed the mechanical properties of PP/EPDM/GF/Al2O3 composites showed 62%, 145%, 15% and 165% enhancement in tensile strength, tensile modulus, notched Izod impact strength and elongation at break, respectively as compared to PP/GF composites. The mechanical properties and thermal properties of PP/EPDM/GF/Al2O3 were also compared with PP/EPDM/GF composites. The use of nanoalumina significantly and brilliantly balances the complimentary tensile and elongation properties in PP/EPDM/GF/Al2O3 composite, which is an essential requirement for fabricating composite material capable of being thermoformed to orthotic devices.

Development and characterization of a recycled nylon fiber reinforced and nano-fly ash hybridized high impact performance polypropylene composite for sustainability

The pursuit of a renewable and recyclable material to reduce carbon footprint is the need of the hour for a safe and secure future of flora and fauna. This study explores the reinforcement potential of pre-treated recycled nylon fiber (NF) with CaCl2, NaOH and silane in a polypropylene (PP) matrix. Silane coating over the fiber surface was confirmed from FTIR and surface morphology. Interfacial interactions among NF and PP were further strengthened by adding nano-structured cetrimonium bromide (CTAB) treated fly ash (FA). A positive hybridization effect of FA was observed on such hybrid composites, apparent from an increment of ∼29% in tensile, ∼49% in flexural, and ∼970% in notched Izod impact strength. FE-SEM analysis showed good dispersion and distribution of reinforcements into the base matrix, establishing excellent interfacial adhesion. DSC analysis showed an increase in crystallization temperature (∼125°C) and a decrease in melting temperature of all the composites, while TGA confirms a reduction in the activation energy of all the composites.

Supertough polylactide-based materials with fast shrinking property by stereocomplex crystallites through in situ reactive blending

Polylactide (PLA), one of the most innovative biopolymers with excellent performance, can be produced from plant-derived resources. However, the brittleness of PLA limits its further applications. In this work, supertough poly(L-lactide) (PLLA)-based materials with fast shrinking property have been prepared by blending PLLA, poly(D-lactide) (PDLA), and ethylene-acrylic ester-glycidyl methacrylate random terpolymer (EGMA). It was confirmed that PLLA and PDLA can react with EGMA to form a strong interfacial interaction. With the addition of PDLA component, the EGMA phase structure changed from a sea-island structure to a cocontinuous-like phase structure, and the stereocomplex (SC) crystallites appeared at the interface between PLLA matrix and EGMA phase. Compared to pristine PLLA, the ternary blend containing 70 wt% PLLA, 10 wt% PDLA, and 20 wt% EGMA exhibited high notched Izod impact strength (83.9 KJ/m2) and high elongation at break (242 %). XRD results indicate that only SC crystallites can be found in these PLLA/PDLA/EGMA blends. Interestingly, these supertough PLLA-based material films can shrink in hot water within 2 s without changing the mechanical property even after three stretching-shrinking cycles. The presence of SC crystallites and strong interfacial interaction between EGMA and PLLA matrix leads to significantly enhanced toughness, which opens a new path for high-performance PLLA-based materials in medical and packaging areas.

Enhanced interfacial adhesion for effectively stress transfer inducing the plastic deformation of matrix towards high-toughness PC/PBT/EMA-GMA blends

The interfacial adhesion between polycarbonate (PC) and polybutylene terephthalate (PBT) is improved by in-situ grafting reaction during melt blending, and the high toughness polycarbonate/polybutylene terephthalate/ethylene-methyl acrylate-glycidyl methacrylate (PC/PBT/EMA-GMA) blend is prepared. The results indicate that the matrix changes from brittleness to toughness gradually, and the impact toughness of the blends are greatly improved with the addition of EMA-GMA. When 4 wt % EMA-GMA is added, the toughness of the samples reaches the optimal value with the notched Izod impact strength and elongation at break reaching 79.3 kJ/m2 and 226.0%, which are 13.7 and 3.5 times of PC/PBT blends, respectively. The phase morphology, the effect of in-situ reactions on the relaxation behaviors of chains, and the mechanical properties of samples are systematically investigated. In the process of in-situ reactive blending, the EMA-GMA that is distributed between PC and PBT promoted the formation of interface layer, and the size of dispersed phase PBT decreased relatively. Meanwhile, the structure of PBT core coated by EMA-GMA soft shell is formed, which is conducive to producing the matrix ligaments and transmitting the stress. The toughening mechanism is mainly related to the reduced dispersed phase size, efficient stress transfer, and massive plastic deformation induced by the matrix ligaments throughout the matrix. This work provides a feasible method for the preparation of high toughness PC/PBT blend, and also it is of great significance to guide the preparation of other high toughness polymer blends.

Water boosts reactive toughening of PET

During melt-processing, the molecular weight of poly(ethylene terephthalate) PET, being prone to hydrolytic degradation, decreases proportionally with its initial moisture content. Therefore, to avoid undesired deterioration of the physical and mechanical properties, PET granules or recyclates are generally dried (the residual moisture must be generally lower than 500 ppm) just prior to melt-processing. In this research, in contrast to the general practice, PET granules with increasing moisture content in the range of 30-3520 ppm, as conditioned in a climate chamber, were melt blended with a constant amount (13%) of ethylene-butyl acrylate-glycidyl methacrylate (EBA-GMA) type reactive terpolymer by twin screw extrusion. It was found that moisture boosts the reactive toughening process, and consequently, the notched Izod impact strength increases by up to 600%. Notched impact strength higher than 50 kJ/m2 was reached only by using PET with optimal (1710 ppm) moisture level instead of fully dried granules, as starting material. It is also noteworthy that the tensile strength and stiffness of the blends showed little variation over the examined moisture content range. Scanning electron microscopic analyses show that the size of the dispersed phase decreases continuously with the increasing initial moisture content of PET, which is explained by the increasingly effective interfacial compatibilisation with the terpolymer. Compatibilisation reactions are accelerated by the low-molecular-weight PET chains of increased reactivity that are formed in situ in the presence of moisture during melt-processing. The observed phenomenon can be advantageously utilized for upgrading recycling technology.

Magnetic polypropylene composites with selectively localized reactive nano-Fe3O4 in toughener of POE-g-MAH: Towards super toughness, high flexibility and balanced strength

Herein, a new magnetic super-tough polypropylene (PP) composite was developed via one-step melt blending with maleic anhydride grafted ethylene-octene copolymer (POE-g-MAH) and reactive nano-Fe3O4. The reactive nano-Fe3O4 with polyamide (PA) tails (PA-Fe3O4) was prepared by in situ ring-opening polymerization PA with amino-modified Fe3O4. By regulating the ratio of POE-g-MAH to PA-Fe3O4, PA-Fe3O4 nanoparticles can selectively and uniformly distribute in the POE-g-MAH phase, reinforcing the POE-g-MAH phase and reducing its processing viscosity synchronously as a new plasticizer and compatibilizer. Meanwhile, a cocontinuous morphology was formed in the PP/POE-g-MAH/PA-Fe3O4 composite at a low elastomer content, contributing to the dramatically enhanced toughness of the PP matrix without deteriorating the processing flowability. In particular, adding 4 wt% PA-Fe3O4 into PP/POE-g-MAH (weight ratio: 80/20), the notched Izod impact strength of the composite reached 74.2 kJ/m2, which was enhanced by approximately 247%. In addition, these super-tough PP composites have excellent flexibility and room temperature soft magnetic performance. This study provides a novel and feasible strategy to fabricate magnetic polymer composites with excellent mechanical properties via manipulating the morphology of the composites.