Notched Charpy Impact Strength Research Articles

Phosphorus-Based Flame-Retardant Acrylonitrile Butadiene Styrene Copolymer with Enhanced Mechanical Properties by Combining Ultrahigh Molecular Weight Silicone Rubber and Ethylene Methyl Acrylate Copolymer.

The present work proposes to investigate the effect of an ultrahigh molecular weight silicone rubber (UHMW-SR) and two ethylene methyl acrylate copolymers (EMA) with different methyl acrylate (MA) content on the mechanical and fire performance of a fireproof acrylonitrile butadiene styrene copolymer (ABS) composite, with an optimum amount of ammonium polyphosphate (APP) and aluminum diethyl phosphinate (AlPi). ABS formulations with a global flame retardant weight content of 20 wt.% (ABS P) were melt-compounded, with and without EMA and UHMW-SR, in a Brabender mixer. During this batch process, ABS P formulations with UHMW-SR and/or EMA registered lower torque values than those of ABS P. By means of scanning electron microscopy (SEM), it was possible to observe that all ABS composites exhibited a homogenous structure without phase separation or particle agglomeration. Slightly improved interfacial interaction between the well-dispersed flame-retardant particles in the presence of EMA and/or UHMW-SR was also noticed. Furthermore, synergies in mechanical properties by adding both EMA and UHMW-SR into ABS P were ascertained. An enhancement of molecular mobility that contributed to the softening of ABS P was observed under dynamic mechanical thermal analysis (DMTA). An improvement of its flexibility, ductility and toughness were also registered under three-point-bending trials, and even more remarkable synergies were noticed in Charpy notched impact strength. Particularly, a 212% increase was achieved when 5 wt.% of EMA with 29 wt.% of MA and 2 wt.% of UHMW-SR in ABS P (ABS E29 S P) were added. Thermogravimetric analysis (TGA) showed that the presence of EMA copolymers in ABS P formulations did not interfere with its thermal decomposition, whereas UHMW-SR presence decreased its thermal stability at the beginning of the decomposition. Although the addition of EMA or UHMW-SR, as well as the combination of both in ABS P increased the pHRR in cone calorimetry, UL 94 V-0 classification was maintained for all flame-retarded ABS composites. In addition, through SEM analysis of cone calorimetry sample residue, a more cohesive surface char layer, with Si-O-C network formation confirmed by Fourier transform infrared (FTIR), was shown in ABS P formulations with UHMW-SR.

Branched thermotropic liquid crystal polymer with favourable processability and dielectric properties

Thermotropic Liquid Crystal Polymer (TLCP) has emerged as a promising material for 5G mm-wave antennas due to its low dielectric constant and loss at high frequencies. However, its low melt viscosity, inadequate melt elasticity, and rigid rod-like macromolecular chain with easy orientation pose a significant challenge in the production of isotropic films. In this study, in order to improve the melt viscosity and melt elasticity of TLCP, a multifunctional epoxide-based branching agent (ADR 4468) was applied to produce branched TLCP. The impact of the branched structure on linear viscoelastic, thermal, mechanical, and dielectric performance was investigated. Results from linear rheological characterizations indicated that complex viscosity and storage modulus of modified TLCP samples were significantly enhanced, indicating the presence of long-chain branches. The mechanical performance of modified samples was scarcely affected by the concentration of ADR 4468, with a tensile strength of approximately 245 MPa, and Charpy notched impact strength of approximately 30 KJ/m2. However, with an increase in ADR 4468 content, the dielectric constant increased (from 3.25 to 3.30 at 10 GHz) as well as the dielectric loss (from 1.36 × 10−3 to 2.14 × 10−3 at 10 GHz). Based on the overall performance, the optimal content of ADR 4468 was found to be about 2–3 wt%. These findings offer insights into the potential applications of modified TLCPs as substrates for 5G mm-wave antennas.

From Bottle Caps to Frisbee-A Case Study on Mechanical Recycling of Plastic Waste towards a Circular Economy.

This study demonstrates an open-loop recycling process of a specific post-consumer plastic waste stream. The targeted input waste material was defined as high-density polyethylene beverage bottle caps. Two methods of waste collection, informal and formal, were employed. Thereafter, materials were hand-sorted, shredded, regranulated, and then injection-molded into a flying disc (i.e., frisbee) as a pilot product. To observe the potential changes in the material throughout the entire recycling process, eight different test methods including melt mass-flow rate (MFR), differential scanning calorimetry (DSC), and mechanical tests were carried out on the various material states. The study showed that the informal collection led to a relatively higher purity in the input stream, which also appeared to have a 23% lower MFR value compared to that of the formally collected materials. The DSC measurements revealed a cross-contamination by polypropylene, which clearly affected the properties of all investigated materials. The cross-contamination led to a slightly higher tensile modulus in the recyclate, while the Charpy notched impact strength declined after processing by approximately 15% and 8% compared to those of the informal and formal input materials, respectively. All materials and the processing data were documented and stored online as a practical implementation of a digital product passport as a potential digital traceability tool. Furthermore, the suitability of the resulting recyclate to be used in transport packaging applications was also investigated. It was found that a direct replacement of virgin materials for this specific application is not possible without proper material modification.

In situ suspension polymerization of vinyl chloride/3-(trimethoxysilyl) propyl methacrylate (MPTMS) intercalated Mg-Al-layered double hydroxide: II. Morphological, thermal properties and diffusion behavior

A series of PVC composites were produced using an in-situ suspension polymerization method with an optimal amount of 5 wt% of MgAl(NO3) layered double hydroxide (LDH) or LDH-MPTMS, which is MPTMS-intercalated Mg-Al LDH. The physical, mechanical, and thermal properties of the composite samples were compared to pure PVC. Results from the Brabender® plastograph showed that the PVC grains produced with LDH-MPTMS had a longer thermal stability time and shorter fusion time. The addition of LDH-MPTMS nanosheets increased the gelation degree of PVC particles, resulting in a lower temperature/time requirement for processing. The thermal stability of the composite material was confirmed through a standard dehydrochlorination test, which demonstrated a 40% improvement in dehydrochlorination rate compared to pure PVC. This improvement was 12% higher than that observed in the PVC/LDH composite. TGA curves indicated a significant increase in the 5 and 50% weight loss temperatures of PVC resins with the addition of 5wt% LDH or LDH-MPTMS, with an approximate growth of 11°C. The glassy state storage modulus and Tg of the PVC/LDH-MPTMS composite were higher than those of pure PVC and the PVC/LDH composite. Mechanical analysis revealed that the PVC/LDH-MPTMS composites exhibited greater stiffness and toughness, as well as significantly higher Charpy notched impact strength, tensile strength, and Young’s modulus compared to both the PVC/LDH composite and pure PVC.

In-situ compatibilization of polyamide 6/polycarbonate blends through interfacial localization of silica nanoparticles

Nanoparticles are used to compatibilize immiscible polymer blends. The key to success is to localize nanoparticles at polymer-polymer interfaces. This work aims to use silica nanoparticles (SiO2) to compatibilize polyamide 6 (PA6)/polycarbonate (PC) blends. The strategy to ensure the interfacial localization of the SiO2 in the blends is to graft a methacrylic monomer onto the SiO2 and then copolymerize this methacrylic monomer with styrene (St) and 3-isopropenyl-α,α′-dimethylbenzyl isocyanate (TMI). When PA6 and PC are blended in the melt in the presence of the above surface modified SiO2 (denoted as SiO2-PST), PA6 chains are grafted onto the SiO2-PST to form PA6-SiO2-PST through a coupling reaction between the terminal amine group of the PA6 and the isocyanate moieties of the PST grafts which are partially miscible with the PC. It is shown that an optimum TMI content allows for the SiO2-PST to be preferentially localized at the interfaces between the PA6 and PC. This leads to a significant decrease in the PC domain diameter from 1.6 μm to 0.6 μm without and with the SiO2-PST, respectively. The presence of the SiO2-PST (0.5 wt% with an optimum TMI content) increases the tensile strength of the PA6/PC (70/30 by weight) from 64.1 to 79.6 MPa, the elongation at break from 84.7 to 284.7%, and the notched Charpy impact strength from 10.3 to 29.4 kJ/m2.

Relationship between interfacial shear strength and impact strength of injection molded short glass fiber-reinforced thermoplastics

Short glass fiber-reinforced thermoplastics (SGFRTPs) are being used to reduce carbon dioxide emissions from transportation equipment, especially domestic vehicles, because of their properties and because they are lighter than metal or ceramic materials. Interfacial shear strength (IFSS) strongly affects mechanical properties of SGFRTPs, such as the impact strength. In recent years, investigations of IFSS and impact strength have been very active. Positive correlation between these properties is often reported, but no clearly defined quantitative relation has been found. This study used the short beam method and the notched Charpy impact test to elucidate IFSS and the impact strength of injection-molded SGFRTPs with varying fiber contents: IFSS decreases concomitantly with increasing fiber content; the notched Charpy impact strength increases concomitantly with increasing fiber content. Fiber pull-out occurred along the entire fracture surface. Findings confirmed that fiber pull-out occurred with both crack initiation and propagation, indicating that energy absorption in the impact test was entirely attributable to the frictional energy necessary for fiber extraction. Based on this conclusion, a mechanical model was developed to explain the notched Charpy impact strength of SGFRTP injection molded products in terms of their IFSS, pull-out fiber length, and fiber orientation angle. The impact strength calculated using the predicted results shows good agreement with the experimentally obtained results.

Effects of blending poly(lactic acid) and thermoplastic polyester polyurethanes on the mechanical and adhesive properties in two-component injection molding

Abstract One possible way to increase the use of bioplastics and thus contribute to a more resource-efficient and sustainable economy is to broaden the application range of such bioplastics. Poly(lactic acid) (PLA) is a promising and commercially available bio-based and biologically degradable polymer, which exhibits a high strength and stiffness but is very brittle. Blending with other polymers can lead to an enhancement of the ductility of the PLA. The goal of this work was to show that blending of PLA with a bio-based thermoplastic polyester-urethane elastomer (TPU) increases the ductility of the compound and also affects the adhesion of the layers when the materials – the modified PLA compound and the TPU – are processed via two-component (2C) injection molding to form corresponding composite parts. The results show that both goals – the increased ductility as well as the increased adhesion between the polymeric phases in 2C parts – can be reached by compounding PLA with two different bio-based polyester-based TPUs. Tensile strength and Young’s modulus of the compounds decrease according to a linear mixing rule with the addition of TPU. Elongation at break and notched Charpy impact strength increase by 750 and 200%, respectively. By addition of the TPU, the surface free energies of the compounds were increased, especially the polar parts. This led to reduced interfacial tensions between the produced compounds and the neat TPUs and thus increased the adhesion between them. For the softer TPU the adhesion was so strong that the TPU showed a cohesive failure in the 90° peel test and thus could not be separated from the compound substrate at all. For the harder TPU the bonding strength increased by 140% upon the addition of this TPU inside the hard component.

Thermal, electrical and mechanical properties of carbon fiber/copper powder/carbon black reinforced hybrid Polyamide 6,6 composites

The development of low electrical and thermal properties of Polyamide (PA), which is used in place of metals in engineering applications, draws attention to the developments in various industrial disciplines. In this study, the effects of metal and carbon based fillers on the properties of Polyamide 6,6 (PA 6,6) were investigated. Especially, copper powder (Cu), carbon black (CB), carbon fiber (CF) and hybrid fillers (Cu/CB/CF) reinforced composites based on PA 6,6 were prepared by twin-screw extruder followed by injection molding. In the microstructure investigation, it was observed that the dispersion properties of used fillers were different in the PA 6,6 matrix. Both electrical and thermal conductivity of the PA 6,6 composites prepared were higher than pure PA 6,6. The highest electrical and thermal conductivity values were obtained as 7.97x10−2 S/cm and 0.73 W/mK for PA 6,6/CB30 and PA 6,6/CF/CB/Cu 10, respectively. The effects of the fillers on melting and crystallization behaviors and mechanical properties that affect the performance of PA 6,6 composites are also discussed. In general, the results showed that the mechanical properties of PA 6,6 composites were improved with the increase in the amount of hybrid filler. The highest tensile and notched Charpy impact strength were obtained as 252 MPa and 8.84 kJ/m2 in PA 6,6 composite with 30% carbon fiber reinforcement by volume. As a result, the tensile properties of PA 6,6 hybrid composite were found to be superior to PA 6,6/CF composite with the same amount of carbon fiber content.

Modified recycled polyamide 6,6 (r-PA 6,6) based on pelagic fishing nets and their physical properties

With the appropriate prescription of RPA66P (recycled polyamide 6,6 based on the pelagic fishing nets), HP-2225 (antioxidant), and SMA-1000 (chain extender), we have successfully manufactured a modified r-PA 6,6 with high melting temperature (252.5 °C), great heat distortion temperature (193.8 °C), high tensile strength (72.2 MPa), moderate elongation (55.0%), high flexural strength (104.7 MPa), good flexural modulus (2956.6 MPa), and excellent notched Charpy impact strength (14.19 kJ/m). Moreover, its preliminary feasible evaluation on injection-molded gearwheels of the bicycle chainwheel has also been executed, demonstrating that it is a potential engineering material with exceptional physical performances.

Influence of Recyclates on Mechanical Properties and Lifetime Performance of Polypropylene Materials

In Europe, the amount of plastic waste which was recycled and further processed into new products was only about 13 % in 2020. One option to process higher volumes of post-consumer recyclates into new products is blending with virgin materials. In order to investigate the effect of recyclates on rheological and structural material properties, a post-consumer polypropylene recyclate (PP-r) was added to a virgin polypropylene (PP-v) in different contents of 10 %, 25 % and 50 %, respectively. Mechanical and fracture mechanical properties were analysed and compared with initial conditions of the original virgin and recycled materials. In addition, the influence of two different recyclates (PP-r) was examined by using grades of a high (PP-r1) and low (PP-r2) melt flow rate (MRF). Results demonstrate that the blending of virgin material with recyclates had a clear influence on material properties. The MFR values increased with higher recyclate content. Tensile tests showed a reduction of the Young's modulus and the yield strength with increasing recycling content. While tensile test properties were significantly affected by a recycling content over 10 %, notched Charpy Impact strength started to change above 25 % and 50 % of PP-r1 and PP-r2, respectively. The resistance against slow crack growth (SCG) of the materials was analysed by the crack round bar (CRB) test. Results indicate that a small recyclate amount of 10 % does not significantly reduce the SCG resistance of the blend compared to the virgin material. However, the SCG resistance decreases dramatically with higher recyclate content.

Comparison of Properties with Relevance for the Automotive Sector in Mechanically Recycled and Virgin Polypropylene

Polypropylene (PP) has a high recycling potential. However, the properties of mechanically recycled PP (R-PP) have not been fully compared to those of virgin PP (V-PP). Therefore, in this study, properties of R-PP and V-PP were compared using data from recyclers, virgin plastic suppliers, and the literature. The properties of recyclates could not be directly correlated either with the properties of the virgin polymers from which the recyclates were made or the recycling parameters. It was found that the MFR of R-PP was higher; MFR R-PP had a median value (m) of 11 g/10 min while MFR V-PP had a median value of 6.3 g/10 min (at 230 °C and with 2.16 kg). In terms of mechanical properties, in many cases R-PP exhibited stiffer and more brittle behavior, with a slightly higher Young’s modulus (ER-PP = 1400 and EV-PP = 1200 MPa), a reduced elongation at break (ɛbR-PP = 4 l.-% and ɛbV-PP = 83 l.-%), and notched charpy impact strength (NCISR-PP = 4.8 and NCISV-PP = 7.5 kJ/m2). However, the values for every property had a broad distribution. In addition to existing information from the literature, our research sheds fresh light on the variation of the characteristics of recycled polypropylenes presently on the market.

Reinforcing potential of recycled carbon fibers in compatibilized polypropylene composites

Materials that are low cost and lightweight are essential for future automotive and aerospace industries. While carbon fibers have been shown to achieve high mechanical properties for high-end applications, their high cost has generated interest to find cost-effective alternatives. The recent advances in recycling carbon fibers has created an opportunity to develop low cost composite materials. Using a maleic anhydride grafted polypropylene (MA-g-PP), the interfacial adhesion between the polypropylene (PP) matrix and the recycled carbon fibers is greatly improved. The integration of 20 wt% recycle carbon fibers result in 2.4 times, 4.9 times, and 5.7 times enhancements in tensile strength, notched Charpy impact strength, and flexural modulus, respectively. This enhancements in mechanical properties are significantly higher than those reported in previous works. The addition of recycled carbon fibers also increases the heat deflection temperature (HDT) of the neat PP sample, indicating the higher resistance of the composite samples at high temperature. This work demonstrates the great potential of the recycled carbon fibers in manufacturing cost-effective and high-performance PP composites.

Hybrid Cellulose-Basalt Polypropylene Composites with Enhanced Compatibility: The Role of Coupling Agent.

This study deals with the development and optimization of hybrid composites integrating microcrystalline cellulose and short basalt fibers in a polypropylene (PP) matrix to maximize the mechanical properties of resulting composites. To this aim, the effects of two different coupling agents, endowed with maleic anhydride (MA-g(grafted)-PP) and acrylic acid (AA-g-PP) functionalities, on the composite properties were investigated as a function of their amount. Tensile, flexural, impact and heat deflection temperature tests highlighted the lower reactivity and effectiveness of AA-g-PP, regardless of reinforcement type. Hybrid formulations with basalt/cellulose (15/15) and with 5 wt. % of MA-g-PP displayed remarkable increases in tensile strength and modulus, flexural strength and modulus, and notched Charpy impact strength, of 45% and 284%, 97% and 263%, and 13%, in comparison with neat PP, respectively. At the same time, the thermo-mechanical stability was enhanced by 65% compared to neat PP. The results of this study, if compared with the ones available in the literature, reveal the ability of such a combination of reinforcements to provide materials suitable for automotive applications with environmental benefits.

Influence of sample thickness, curvature and notches on the Charpy impact strength - An approach to standardise the impact strength of curved test specimens and biological structures

The specimen geometry has a significant influence on the Charpy impact strength. This is often a problem when it comes to the analysis of materials that can only be prepared with a curved shape, or which, like some biological structures, are naturally given in curved form like nutshells. The question repeatedly arises to what extent the curvature influences the impact strength. Hence, the present study deals with the dependence of the specimen geometry like specimen thickness, curvature and notches on the impact properties of concrete, gypsum, polyurethane (PUR) and epoxy-based (EP) samples. Increasing sample thickness from 2 to 10 mm resulted in increased toughness for brittle materials, whereas more ductile materials did not show any significant change in toughness. Increasing span length showed an increase of the unnotched impact strength for brittle gypsum, while toughness increased for a more ductile PUR sample. For the curved specimens both, the unnotched and the notched Charpy impact strength could be shown to increase with a reduction of the specimen radius (higher curvature) while the notch-sensitivity was not significantly affected. Material-specific linear relationships between the impact strength and the curvature of the samples were found. These relationships were used to create a model to calculate the influence of the curvature on the impact strength. For all materials, the characteristic values of a normalised flat standard sample could be well predicted from measured values of curved specimens. This calculation approach was used to predict the impact strength of an isotropic biological sample (sweet potato) concerning a flat sample and different curved specimens. The results show a good trend with the measured values.

Reactive splicing compatibilization of immiscible polymer blends: Compatibilizer synthesis in the melt state and compatibilizer architecture effects

Reactive compatibilization is an effective method to improve the compatibility of immiscible polymer blends. The in-situ-formed graft/block copolymers should be thermodynamically located at the interface to bridge the neighboring phases. Unfortunately, they are often pulled out of the interface because of the asymmetric molecular structures. Here, we propose a new strategy to compatibilize immiscible polymer blends called reactive splicing compatibilization. Poly (styrene-co-glycidyl methacrylate) (SG) with high glycidyl methacrylate (GMA) content is used as the reactive backbone chain. Both poly (l-lactic acid) (PLLA) and poly (butylene adipate-co-terephthalate) (PBAT) molecular chains can be easily grafted onto the SG main backbone by the reaction of the terminal carboxylic acid groups with the epoxide groups in the melt. Direct melt blending SG with PLLA and/or PBAT leads to reactive compatibilizers with various molecular architectures, which are used for subsequent compatibilization of PLLA/PBAT blends. It was found that the compatibilizer architecture significantly affects the compatibilization efficiency. The best compatibilization occurs with a reactive compatibilizer of SG-g-PBAT with the SG to PBAT weight ratio of 1:2. The compatibilized PLLA/PBAT (50/50 w/w) blend has precise co-continuous phase morphology with very few micelles. The blend exhibits extremely high Charpy notched impact strength of 90.2 kJ/m2 and tensile strength of 33.3 MPa. The principle of the facile splicing compatibilization strategy is highly applicable to many other immiscible blends with both components containing reactive groups.

Formation of high-density polyethylene–poly(ethylene-octene) core–shell particles in recycled poly(ethylene terephthalate) by reactive blending

Recycled poly(ethylene terephthalate) (R-PET)/high-density polyethylene (HDPE)/glycidyl methacrylate grafted poly(ethylene-octene) (mPOE) blends, in which the binary (HDPE/mPOE) dispersed phase was of a HDPE core-mPOE shell structure, were prepared. For this purpose, HDPE-g-mPOE graft copolymers were prepared in HDPE/mPOE blends via reactive extrusion with the presence of the free radical initiator dicumyl peroxide (DCP). Then, R-PET was blended with the HDPE/mPOE blends by melt extrusion. The effect of the DCP and mPOE content in the HDPE/mPOE blends on the phase morphology and mechanical properties of the R-PET/HDPE/mPOE blends were studied systematically. It was found that the blends containing reactive compatibilizer exhibited the encapsulation of the HDPE by the mPOE, forming core–shell particles dispersed phase morphology. The graft chains of HDPE-g-mPOE-g-PET formed by the in situ reaction between R-PET and mPOE phases reduced the interfacial tension. Consequently, the dispersed phase morphology was observed to form smaller diameter core–shell particles. The resultant blends exhibited an effect on both the thermal and mechanical properties. Differential scanning calorimetric analysis showed the dispersed phase particles could act as a nucleating agent in the R-PET matrix to improve the crystallization temperature, while the graft copolymers formed in the compatibilized R-PET/HDPE/mPOE blend decreased the nucleation activity. Notched Charpy impact strength and elongation at break of the R-PET were improved by forming the core–shell particles dispersed phase morphology.

Direct Compounding Injection Molding and Resulting Properties of Ternary Blends of Polylactide, Polybutylene Succinate and Hydrogenated Styrene Farnesene Block Copolymers

Direct compounding injection molding of ternary blends of polylactide (PLA), polybutylene succinate (PBS) and a hydrogenated styrene farnesene block copolymer (HSFC) was investigated for different blend compositions. Morphological analysis by atomic force microscopy and scanning electron microscopy showed a heterogeneous morphology of the ternary blends, with coexisting droplets of HSFC and PLA respectively PBS. Particle sizes analysis of the minor phases in the ternary blends showed mean values in the range of ∼1 μm, which is discussed in correlation to the rheological properties of the blend components as obtained by high pressure capillary rheometry. In result, with increasing HSFC content, the ternary blends showed a significant increase in notched Charpy impact strength (acN). In concrete, for the ternary blends with 15 wt% of HSFC a maximum acN of 15.8 kJ/m2 was found. At the same time, incorporation of the HSFC resulted only in a moderate reduction in elastic modulus and tensile strength.

Effect of D‐lactide content of annealed poly(lactic acid) on its thermal, mechanical, heat deflection temperature, and creep properties

AbstractIn our research, the effect of D‐lactide content in injection‐molded and annealed poly(lactic acid) (PLA) was investigated for crystallinity as well as crystalline forms (less‐ordered α′ and more‐ordered α crystalline forms) and thus on the mechanical, heat deflection temperature (HDT), and creep properties. Three different PLA grades 3052D, 3001D, and 3100HP were investigated with D‐lactide contents of 4%, 1.4%, and 0.5%, respectively. The injection‐molded PLA specimens were then postproduction annealed in a heat chamber at 80–140 °C for 1 h to develop various crystallinities and various ratios of α′ and α crystal forms. It was demonstrated that not only annealing but also the D‐lactide content significantly influences the crystallization, crystal structure, and accordingly properties of PLA like notched Charpy impact strength, HDT, and creep characteristics. Higher HDT, impact properties, and creep resistance could be reached by using PLA with lower D‐lactide content with a certain annealing temperature range to develop definite crystal structures. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47103.

Monitoring of Injection Molding Tool Corrosion and Effects of Wood Plastic Compound's Moisture on Material Properties

Abstract Before injection molding, wood polymer composites (WPC) normally have to be dried to achieve optimal quality of the injected parts as well as to avoid corrosion of the mold. Based on a literature study, there are currently no published investigations dealing with the dependency of WPC properties on the initial moisture content of the compound's pellets. Further, it is known that water and wood in combination with high temperatures can lead to corrosion of steel parts, but a systematic analysis of the impact of WPC injection molding on tool corrosion has not been found in the literature. For the present study, a compound with 68 wt% (weight percent) polypropylene, 30 wt% wood flour and 2 wt% coupling agent was produced and tested in injection molding trials. Specimens according to ISO 527-2 were produced from WPC with defined moisture contents, respectively. Compound moisture, already at very low contents, had significant negative effects on the tested mechanical properties, namely tensile modulus and strength, unnotched and notched Charpy impact strength and heat deflection temperature. Corrosion trials were performed for different tool steel qualities. The severity of corrosion correlates with the amount of chromium (Cr) in the alloys tested.

Compatibilization of poly(lactic acid)/high impact polystyrene interface using copolymer poly(stylene‐ran‐methyl acrylate)

ABSTRACTIn this work, a surfactant‐free emulsion polymerization method was utilized to synthesize poly(styrene‐ran‐methyl acrylate) (PSMA) at a styrene/(methyl acrylate) mole ratio of 75/25 with the aim to compatibilize high impact polystyrene (HIPS)/poly(lactic acid) (PLA) interface. HIPS/PLA blends with different PSMA contents were prepared. Their phase morphologies, mechanical properties, and rheological and crystallization behaviors were investigated using scanning electron microscopy, tensile tests, rotational rheometry, and differential scanning calorimetry. The rheological results showed that the complex viscosity, storage moduli, and loss moduli of PLA/HIPS blends were enhanced with increasing PSMA content. A decrease in the degree of crystallinity of PLA in PLA/HIPS blends with the addition of PSMA was observed in the differential scanning calorimetry results. It was also revealed that the addition of a small amount of PSMA can effectively improve the compatibility and thus the interfacial adhesion of the PLA/HIPS blends, thereby reducing the size of the HIPS dispersion phase. When 1 wt % of PSMA was used, compared with the PLA/HIPS blends without PSMA, the tensile strength and notched Charpy impact strength of PLA/HIPS blends were improved by 95.3% and 104.8%, respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45799.