Polypropylene Grafted With Maleic Anhydride Research Articles

Fused Filament Fabrication of WC-10Co Hardmetals: A Study on Binder Formulations and Printing Variables

This research explores the utilization of powder fused filament fabrication (PFFF) for producing tungsten carbide-cobalt (WC-10Co) hardmetals, focusing on binder formulations and their impact on extrusion force as well as the influence of printing variables on the green and sintered density of samples. By examining the interplay between various binder compositions and backbone contents, this study aims to enhance the mechanical properties of the sintered parts while reducing defects inherent in the printing process. Evidence suggests that formulated feedstocks affect the hardness of the sintered hardmetal—not due to microstructural changes but macrostructural responses such as macro defects introduced during printing, debinding, and sintering of samples. The results demonstrate the critical role of polypropylene grafted with maleic anhydride (PP-MA) content in improving part density and sintered hardness, indicating the need for tailored thermal debinding protocols tailored to each feedstock. This study provides insights into feedstock formulation for hardmetal PFFF, proposing a path toward refining manufacturing processes to achieve better quality and performance of 3D printed hardmetal components.

Defining the Effect of a Polymeric Compatibilizer on the Properties of Random Polypropylene/Glass Fibre Composites

Random polypropylene composites reinforced with short glass fibres have been successfully fabricated by melt-mixing. Polypropylene grafted with maleic anhydride (PP-g-MA) was added to the composites, which was expected to act as a compatibilizer and greatly limit the negative effects known to arise from the feeble polymer matrix/glass fibre interfaces. The effect of compatibilizer concentration on the structural, mechanical and thermal behaviour of the composites has been investigated. The results revealed an improvement of the glass fibre/matrix interaction upon the addition of the compatibilizer, which resulted in enhancing the overall material stiffness and the ability of the matrix to store energy. In particular, the lowering of the glass transition and the investigation of the fracture surfaces of the composites confirmed the improved PPR/fibre adhesion. Examination of the tensile elongation indicated the improvement of the Young’s modulus and yield strength with the addition of PP-g-MA, while the storage modulus was also shown to be significantly increased. These results confirmed the versatility and efficiency of the approach presented in this work to improve the thermomechanical properties and sustainability of PPR and promote its usage in industrial applications and commercial manufacturing.

POLYPROPYLENE/GRAPHENE OXIDE NANOCOMPOSITES: INFLUENCE OF ADDING POLYPROPYLENE GRAFTED WITH MALEIC ANHYDRIDE ON THE MECHANICAL PROPERTIES

In this work, graphene oxide (GO) was first obtained by chemical exfoliation. Then it was melted by hot compression with polypropylene grafted with maleic anhydride (PP-g-MA). The PP-g-MA/GO (1% and 3% GO wt.%) were applied to prepare polypropylene/PP-g-MA/GO nanocomposites by extrusion. Pelletized samples obtained by extrusion were stamped from plates obtained by compression in a bench press and these materials were characterized through FTIR and tensile tests. The GO was also characterized by Raman spectroscopy, X-ray diffraction and FTIR. The results indicated that GO acted as a plasticizer, reducing the mechanical property values in comparison with pure polypropylene.

Long-term experimental evaluation and molecular dynamics simulation of polypropylene/graphene oxide nanocomposite coating in 3.5 wt% NaCl solution

Most organic coatings lose their resistance over time. In this work, the super-hydrophobic polypropylene (PP) coating was developed by dip-coating method to avoid destructive agents penetration into the mild steel substrate and provide long-term corrosion protection. Graphene oxide (GO) was put in the PP matrix to improve corrosion durability by reducing wettability. PP grafted with maleic anhydride (PP-g-MAH) was also utilized to elevate the bond strength and adhesion of the coating to the undercoat. The PP coating formed in the solution contained 50 wt% PP-g-MAH and 0.1 wt% GO (named as PP/PP-g-MAH/GO-0.1) illustrated the best durability performance after 30 days of immersion by corrosion resistance of 5200 Ω·cm2, which is 25 times greater than the pure PP sample. Moreover, the positive effect of the GO on the efficiency of the PP/PP-g-MAH/GO-0.1 sample was proved by maintaining super-hydrophobicity after 1 week of immersion (water contact angle (WCA) of 152°). Furthermore, MD simulations were performed to verify the improvement of WCA owing to the presence of GO. The results reveal that this additive acted as an effective barrier against penetrating agents by growing WCA (50°).

Construction of highly anti-corrosion and super-hydrophobic polypropylene/graphene oxide nanocomposite coatings on carbon steel: Experimental, electrochemical and molecular dynamics studies

An anti-corrosion and super-hydrophobic coating of polypropylene (PP) was developed on mild steel surface to prevent the penetration of corrosive agents into the substrate. Additives such as polypropylene grafted with maleic anhydride (PP-g-MAH) and graphene oxide (GO) were introduced to the PP matrix to improve corrosion and hydrophobicity properties. The experimental results showed that the addition of PP-g-MAH and GO increased the compactness so that the PP coating obtained from the solution contained 1.5 g PP-g-MAH and 2 mg GO indicated the highest corrosion resistance (800 times greater than pure PP), the lowest surface roughness (87 nm) and average contact angle of 166◦. The MD results also illustrated that the presence of GO enhanced the density (compactness) from 0.80 to 0.85 g/cm3. The overall results confirmed that the made composite coating is highly effective in preventing the degradation of commonly used construction and building metals such as mild steel.

Behavior under electron irradiation of two clay-based polymer nanocomposites PPgMA/OMMT and PBS/OMMT

The effect of nanoparticles on the transport and trapping of electric charges as well as on the emission of secondary electrons from two nanocomposites subjected to electron irradiation in a scanning electron microscope (SEM) is studied experimentally. These nanocomposites are polypropylene grafted with maleic anhydride (PPgMA) and bio-based polybutylene succinate (PBS) filled with organically modified montmorillonite (OMMT) clay nanoparticles (i.e. cloisite 20: C20). Samples having 0%, 1%, 2%, 3% and 5% clay nanoparticles by weight are used.In order to determine the temporal evolution of the electrical charge trapped in each nanocomposite and that of its total electron emission yield (TEEY), simultaneous measurements of leakage and displacement currents, induced in the nanocomposites during and after electron irradiation, are performed using an appropriate device.Besides, broadband Dielectric Spectroscopy (BDS) is also used to study change of electrical characteristics of the neat polymeric matrices with the concentration of clay nanoparticles, namely dielectric constant and electrical conductivity.As surprising as it sounds, measurements indicate that not only the leakage current increases as the amount of clay nanoparticles increases but also the trapped charge. This behavior could be linked in particular to the change in the mobility of charge carriers due to the proliferation of interfaces between nanoparticles and neighboring materials (matrix). As the proliferation of interfaces is dependent on the state of dispersion of the clay nanoparticles within the host matrix, this state was studied using X-ray diffraction (XRD) analysis. The results highlight the impact of nanoparticle reinforcement on the electrical properties of studied polymers such as storage ability of electrical charges and also their transport.

Preparation of stiffer ternary blends of polypropylene/polyamide 6/biodegradable polymers with improved interfacial adhesion

AbstractBlends of polypropylene (PP), polyamide 6 (PA6), and biodegradable polymers (BPs) such as poly(D,L‐lactic acid) (PDLLA), poly(lactic acid‐co‐ε‐caprolactone) (poly[LA‐co‐ε‐CL]) and poly(ε‐caprolactone) (PCL) were prepared using a twin‐screw mini‐extruder. The composition of the blend PP/PA6 was fixed at a mass proportion of 70/30, and the compatibilized blends contain 5 wt% of each BP. The morphology observed through scanning electronic microscopy, the dynamic mechanical thermal properties (DMTA), and the biodegradation test after composting and performing optical microscopy (OM) of the blends were investigated. The blend PP/PA6 compatibilized with polypropylene grafted with maleic anhydride (PPMA) was also obtained and used as a reference. The results showed that the PP/PA6/PPMA revealed a more homogeneous morphology and resulted in higher modulus; nevertheless, the sample obtained with the lower molar mass PDLLA as an alternative for PPMA showed a storage modulus behavior close to the reference material. Poly(LA‐co‐ε‐CL) and PCL also showed changes in the morphology of the PA6 dispersed phase. Positive results were observed in the biodegradation test examined by OM for all samples containing BPs. The novelty of this work was to employ BPs as compatibilizing agents of the blends comprising PP/PA6, producing ternary blends with superior mechanical properties due to the better dispersion of the phases.

Study of thermal, morphological, barrier and viscoelastic properties of PP grafted with maleic anhydride (PP-g-MAH) and PET blends

Properties of polyethylene terephthalate (PET) and polypropylene (PP) can be enhanced by blending both in a specific proportion to get combined superior properties. To make a homogeneous blend, maleic anhydride functionalized PP (PP-g-MAH) was used as a compatibilizer in 60% PET blends. In all blends, PET’s percentage crystallinity was reduced as compared to pure PET because there were hindrances in chains packing because of the presence of PP chains. The addition of compatibilizer in PET and PP blend enhanced interactions resulted in a homogeneous blend with fewer voids. 2.5% of PP-g-MAH was observed to be the optimum value of compatibilizer in the blend of PET and PP. The decrease in free space inside the blend hindered water molecules' passage through the sheets. Owing to this, water vapor permeability of the blend was less compared to pure PET. The addition of the nonpolar PP also influenced the water transmittance rate of blended sheets.

Fabricating 3D printable BIIR/PP TPV via masterbatch and interfacial compatibilization

Fused deposition modeling is a highly promising and efficient additive manufacturing technology to fabricate the conceptual prototypes and functional components having complex geometries. Excellent melt flowability and strong bonding between the adjacent deposited filament are two vital physical indexes to evaluate 3D printable materials. In this work, using polypropylene grafted with maleic anhydride (PP-g-MA) as the compatibilizer, brominated butyl-rubber (BIIR)/polypropylene (PP) thermoplastic vulcanizate (BIIR/PP-TPV) with outstanding rheological, mechanical performance and 3D printability was fabricated via masterbatch procedure. For comparison, BIIR/PP-TPV without the compatibilizer was prepared via precompound procedure and masterbatch procedure, respectively. 3D printing properties, rheological, mechanical properties, and phase morphology of three types of TPV were compared. In the masterbatch procedure, the even dispersion of curing agents and the prolonged scorching time contribute to the homogenous crosslinking of BIIR and efficient formation of BIIR particles with a small size. The PP-g-MA locating in the interface region of BIIR/PP improves the compatibility of them. The superior rheology and low viscosity of PP-g-MA compatibilized TPV prepared by masterbatch procedure (mTPV-MA) are attributed to the low viscosity of PP-g-MA and small BIIR particle size. The low viscosity and higher polarity of mTPV-MA effectively improve the bonding strength between the adjacent layers of the printed product. This study may shed some new light on the preparation of 3D printable TPV.

Influence of the polarity of the matrix on the breakage mechanisms of lignocellulosic fibers during twin‐screw extrusion

AbstractIn a series of previous papers, models describing the breakage of lignocellulose fibers during melt mixing process were established and applied to predict fiber size changes when compounding composites in a twin‐screw extruder. Different types of fibers were studied (flax, hemp, sisal, etc), but always with the same matrix, namely polypropylene (PP) compatibilized with PP grafted with maleic anhydride (PP‐g‐MA). In the present study, the influence of the matrix was characterized, by comparing the results obtained with nonpolar PP and polar poly(butylene succinate) (PBS) of similar viscosity. For flax and hemp fibers, morphology changes (in length and diameter) were characterized along the screws under various processing conditions (screw speed and feed rate). Whatever the conditions, breakage was more important with the PBS matrix. Moreover, the rheological properties of the composites were also different, indicating specific interactions between fibers and matrices. Atomic force microscopy was used to measure the adhesion between the different matrices and AFM levers functionalized with nanocrystalline cellulose. The results confirmed a better interaction between the nanocrystalline cellulose and the PBS matrix compared to the PP one.

Effects of Compatibilizer and Airflow Field on the Formation of Helical Microfibers via Melt Blowing

ABSTRACTWe explore the approaches to improving the fabrication of melt‐blown helical microfibers, which have found the applications in sorption and filtration due to their unique morphology and excellent properties. To explore the effect of compatibilizer on the formation of helical microfiber, polypropylene (PP), polyurethane (TPU), and PP grafted with maleic anhydride (PP‐g‐MAH) are melt blown to fabricate microfibrous nonwovens. The results of rheological test and differential scanning calorimetry show that the addition of PP‐g‐MAH helps to increase the miscibility of the PP/TPU blends. Two die configurations are used to study the effect of airflow filed on the formation of helical microfibers. The computational fluid dynamics simulation results show that the modified swirl die intensifies the swirling strength of the melt blowing airflow. The addition of compatibilizer and modification of the airflow field both benefit the formation of helical microfibers from polymer blends. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 1423–1433

THERMOPLASTIC VULCANIZATES BASED ON DYNAMICALLY VULCANIZED POLYPROPYLENE/CARBOXYLATED NITRILE RUBBER BLENDS

ABSTRACT Thermoplastic vulcanizates (TPVs) based on polypropylene (PP) and carboxylated nitrile rubber (XNBR) with improved mechanical properties were prepared by dynamic vulcanization using dicumyl peroxide (DCP) in combination with N,N′-m-phenylene-bis-maleimide (BMI) as a cross-linking system. The effect of PP grafted with maleic anhydride (PP-g-MA) or with glycidyl methacrylate (PP-g-GMA) and triethylene-tetramine (TETA) as the compatibilizing systems on the mechanical, morphological, and dynamic mechanical properties of PP/XNBR blends was investigated. Experimental results revealed that PP-g-GMA has a better compatibilizing efficiency. Tensile strength and elongation at break presented a significant improvement with the addition of 2.5 to 7.5 phr of this functionalized PP. The improvement of the tensile properties was observed for all blend compositions studied. Also the tensile properties of the blends did not change considerably after three reprocessing cycles, confirming the efficiency of this system as a TPV. The presence of PP-g-GMA also resulted in an increase of the apparent melt viscosity of the corresponding TPVs, confirming the reactive compatibilization. A decrease in rubber particle size with the presence of PP-g-GMA was also observed by scanning electron microscopy.

Synergistic effect of the inclusion of glass fibers and halloysite nanotubes on the static and dynamic mechanical, thermal and flame retardant properties of polypropylene

Hybrid composites based on polypropylene (PP), glass fiber (GF) and halloysite nanotubes (HNT) were prepared in the presence of a compatibilizer, polypropylene grafted with maleic anhydride (PP-g-MAH), in a twin screw extruder. The properties of the micro composite (PP/GF), nanocomposite (PP/HNT) and hybrid composite (PP/GF/HNT) were studied and compared. The dispersion of the fillers in the base matrix and the effectiveness of the compatibilizer were ascertained by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and fourier transform infrared spectroscopy (FTIR). The tensile strength and modulus of the hybrid composite prepared in the presence of PP-g-MAH were found to be superior to those of the compatibilized micro and nanocomposites. Differential scanning calorimetry gave insight to the effect of the fillers on modifying the crystallization behavior of the base polymer. The combination of GF and HNT increased the crystallization temperature of PP phase in all the composites. The dynamic mechanical analysis proved that the fillers introduced in the polymer matrix restricted the relaxation of the PP polymer chains as evidenced by the rise in the glass transition temperature (Tg). The thermal stabilities of the hybrid composites were far superior to the neat polymer as the fillers formed an insulating layer delaying the degradation tendency and elevated the activation energy. The flammability of PP could be modified tremendously by the incorporation of the fillers as they reduced the burning rate and raised the limiting oxygen index values.

Polypropylene composite reinforced with fibrillated curaua fiber and using maleic anhydride as coupling agent

ABSTRACTCuraua fibers (CF) were fibrillated using high‐intensity ultrasonication, which is fast and uses water as a solvent. The fibrillated fibers (CFf) were used as reinforcement (20 wt %) in polypropylene composites processed by extrusion with or without 2 wt % of polypropylene grafted with maleic anhydride (PPMA). Fibrillation promotes an increase from 11.3 to 33.8 in the aspect ratio of the fiber. Sonication caused extraction of lignin and a decrease in the degree of crystallinity of the CF. Extrusion of the composites causes no additional fibrillation of the CF. A composite reinforced with CFf had tensile and flexural strength of 24.9% and 51.5%, respectively, higher than that of pristine PP. The use of PPMA and CFf in the composite promotes a further increase of 30% and 50.5% in these parameters, respectively. A thermal analysis of the composites using CFf with or without PPMA showed similar behavior. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44913.

Polyamide/Polypropylene/graphene oxide nanocomposites with functional compatibilizers: Morpho-structural and physico-mechanical characterization

Nanofilled polymeric matrices have demonstrated remarkable mechanical, electrical, and thermal properties. Compounding polymers with nanofiller is widely used for the preparation of new materials. Polyamide/polypropylene (PA/PP) composites are interesting because both components are relatively cheap, with advantageous properties, and are processable by melt blending. The compatibilisation of binary polymer compounds can be made by the addition of graft copolymer, segments of which have physical or chemical affinity with two immiscible homopolymers. In this case, polypropylene grafted with maleic anhydride (PP-g-MA) it was used. Polymer nanocomposites containing graphite have been considered as a new generation of composites materials due to their expected unique properties attributed to the high aspect ratio of the inorganic pellets. Combined effects of graphite treatment and compatibilizer polymers (PP-g-MA) on the structure and properties of PA/PP/PP-g-MA/graphene oxide composites were studies. The optimum formulation was used to prepare a series of nanocomposites under different technological conditions. The nanocomposites PA/PP/PP-g-MA/graphene oxide were characterized by scanning electron microscopy (SEM), Fourier transformation infrared spectrum (FT-IR) and physico-mechanical.

Tailoring the properties of PP/PA6 nanostructured blends by the addition of nanosilica and compatibilizer agents

The effectiveness of combining silica nanoparticles (NS) and polypropylene grafted with maleic anhydride (PPgMA) to stabilize the morphology and improve the properties of an immiscible PP/Nylon 6 blend was investigated. Blends of 80% polypropylene (PP) and 20% polyamide 6 (PA6) with a fixed amount of PPgMA and decreasing NS content were prepared by melt mixing. Two PPgMA compatibilizing agents with different grafting level and two modified NS, one hydrophilic and other hydrophobic, were employed. Used together, PPgMA and ∼4.0% of NS nanoparticles strongly reduced the PA6 droplet size, as a result of the preferential location of the NS at the interface avoiding drop coalescence. The effect was more remarkable when hydrophobic NS was added. Owing to the reduced droplet size, a fractioned crystallization of the PA6 dispersed phase was observed by DSC measurements, and self-nucleation experiments were carried out to elucidate the nature of the phenomenon. Despite the PA6 reduced size, the blends exhibited unsatisfactory mechanical performance. Thus, the NS content was decreased. In the end, a PP/PA6 blend stabilized with 1.6% hydrophobic NS and compatibilized with high grafting level PPgMA exhibited a fine-tuned morphology with enhanced ductility and barrier properties. NS nanoparticles act as outstanding stabilizers but do not promote interfacial adhesion between the phases. Therefore, the use of an optimal content of NS along with a compatibilizer yields a synergistic effect on the PP/PA6 blend.

Mechanism of highly improved electrical properties in polypropylene by chemical modification of grafting maleic anhydride

This paper reports excellent electrical properties in polypropylene grafted with maleic anhydride (PP-g-MAH) and a related mechanism of the enhanced electrical properties. The chemical structure of PP-g-MAH was analyzed and its effect on space charge accumulation, electrical breakdown strength and DC conductivity was studied. Compared with pure PP, the PP-g-MAH exhibits remarkably suppressed space charge accumulation, enhanced electrical breakdown strength and reduced conduction current. The mechanism enhancing the electrical properties was studied by measuring the trap level distribution. It can be explained that abundant deep traps are introduced in PP-g-MAH with the introduction of polar groups in MAH, which reduces the charge mobility and raises the charge injection barrier so as to suppress space charge accumulation. This investigation would contribute to propose a new material modification strategy for designing high-voltage direct current insulation material in addition to the inclusion of nanoparticles.

Linear and non-linear rheological behavior of polypropylene/polyamide blends modified with a compatibilizer agent and nanosilica and its relationship with the morphology

The morphology of immiscible 80/20 polypropylene/polyamide 6 (PP/PA) blends that contain different types of nanosilica and a compatibilizer agent was correlated with their linear and non-linear rheological behavior. Polypropylene grafted with maleic anhydride (PPgMA) was used as compatibilizer agent. Two types of modified silica nanoparticles were added to the blends, one hydrophilic (NSE) and the other hydrophobic (NSH). SEM and TEM microscopy were employed to observe the sea-island morphology of the 80/20 blends. The size of the PA droplets was reduced 12 times when the compatibilizer agent was added; and 25 times when hydrophobic nanosilica (NSH) was additionally included in the formulation. TEM results revealed that NSH particles are preferentially located at the PP-PA interface, whereas NSE particles remain inside the PA droplets. A good agreement between morphology and Small Amplitude Oscillatory Shear tests (SAOS) was observed. At low frequencies a suspension-like rheological behavior was identified for the blends containing nanosilica. The results at intermediate frequencies allowed the evaluation of the shape relaxation time of the droplets. Large Amplitude Oscillatory Shear tests (LAOS) results correlate well with droplets size. The coalescence promoted by flow was investigated, and in the case of the neat binary blend, coalesced blends were obtained. Employing LAOS results determined by measuring blends with a wide range of droplet sizes, an inversely proportional function of a characteristic LAOS parameter with the diameter of the droplets was obtained.

Morphology and dynamic mechanical properties of long glass fiber-reinforced polyamide 6 composites

Long glass fiber-reinforced polyamide 6 (LGF–PA6) composites were prepared by using self-designed impregnation device. Polypropylene grafted with maleic anhydride (PP-g-MAH) and polyolefin elastomer grafted with maleic anhydride (POE-g-MAH) were chosen as compatibilizers. Dynamic mechanical properties of LGF–PA6 composites were investigated by using dynamic mechanical analysis (DMA). The DMA measurement results showed that test frequency, long glass fiber content and compatibilizers had an influence on dynamic mechanical properties and glass transition temperature (Tg) of LGF–PA6 composites. The frequency had a complex influence on storage modulus (E′), loss modulus (E″) and loss tangent (tan δ). The Tg of the composites is shifted to high temperature with the increasing of test frequency and was affected insignificantly by the glass fiber content. Storage modulus and loss modulus (E″) increased with the increasing fiber content, while the tan δ decreased. The effect of the addition of PP-g-MAH and POE-g-MAH on the dynamic mechanical properties of LGF–PA6 composites was complex. Scanning electron microscopy (SEM) was used to investigate the morphology of the fractured composites surface. The SEM results suggested that the PP-g-MAH and POE-g-MAH both improved the fiber/matrix interface adhesion, which was consistent with the DMA measurement results.

The effect of compatibilizers and organically modified nanoclay on the morphology and performance properties of poly(acrylonitrile–butadiene–styrene)/polypropylene blends

In this study, poly(acrylonitrile–butadiene–styrene)/polypropylene (ABS/PP) blends with various compositions were prepared by melt intercalation in a twin‐screw extruder. Modifications of the above blends were performed by using organically modified montmorillonite (OMMT, Cloisite 30B) reinforcement as well as two types of compatibilizers, namely polypropylene grafted with maleic anhydride (PP‐g‐MAH) and ABS grafted with maleic anhydride (ABS‐g‐MAH). Increasing the PP content in ABS matrix seems to increase the melt flow and thermal stability of their blends, whereas a deterioration of the tensile properties was recorded. On the other hand, the addition of ABS to PP promotes the formation of the β‐crystalline phase, which became maximum at 30 wt% ABS concentration, and increases the crystallization temperature (Tc) of PP. A tendency for increase of Tc was also recorded by incorporation of the above compatibilizers, whereas the glass transition temperature (Tg) of PP and SAN phase in ABS was reduced. Regarding the Young's modulus, the greatest improvement was observed in pure ABS/PP blends containing organically modified nanoclay. However, in reinforced pure PP, the use of compatibilizers is recommended in order to improve the elastic modulus. The addition of OMMT to noncompatibilized and compatibilized ABS/PP blends significantly improves their storage modulus. POLYM. ENG. SCI., 56:458–468, 2016. © 2016 Society of Plastics Engineers