Extrusion Injection Moulding Research Articles

Sliding wear performance of novel millet husk reinforced polypropylene composites

The current research aims to investigate the influence of novel millet husk, finger millet husk (FMH), and barnyard millet husk (BMH) as fillers on the sliding wear performance of polypropylene (PP) composites. The composites were prepared with 10 wt% loading of FMH and BMH by the extrusion injection molding (EIM) process. The sliding wear testing was performed at different combinations of sliding velocity (0.5, 1, and 1.5 m/sec), load (10, 20, and 30 N), and sliding distance (300 m) against the 1000-µm silicon carbide abrasive paper as counter surface. It was observed from the micrographs that FMH and BMH established improved adhesion with the PP matrix and lowered the specific wear rate. At higher load and velocity values, tribofilm development was observed, which lowered the rate at which composites wear out. The wear mechanism, bonding behavior, and worn-out surface have also been discussed and supported with surface analysis using a scanning electron microscope.

Ultrasonic Welding of Banana/ Bagasse Based Polypropylene Composites

ABSTRACT The usage of natural fiber–reinforced composites (NFRCs) may help the global fraternity in achieving their long-term goal of developing sustainable products having minimum effect on ecosystem, during and at the end of their service life. The primary manufacturing processes such as injection molding, hand-layup, and compression moulding have been extensively used to fabricate products with simpler profiles. However, the fabrication of complex products necessitates secondary manufacturing processes. In current investigation, the short fiber (banana and bagasse)–based polypropylene composites (10, 15, and 20 wt.%) were fabricated using extrusion-injection moulding process. Banana fiber–based composites recorded 1.8%, 4.7%, and 3.25%, higher tensile strength than bagasse fiber–based composites at 10, 15, and 20 wt.% fiber loading, respectively. However, bagasse fiber–based composites performed distinctly better in flexural properties. Field emission scanning electron microscopy and thermogravimetric analysis were employed to analyze the failure mechanisms and thermal degradation behavior (analyzed at 5%, 25%, 50%, and 75% weight loss) of the fabricated composites. The ultrasonic welded joints of banana fiber–based composites recorded higher failure load prior to the fracture as compared to bagasse fiber–based composites upto 15% fiber loading. It was established that ultrasonic welding can be successfully employed for joining of NFRCs.

Hot-Plate welding behavior of Sisal and Jute Polypropylene composites

ABSTRACT The recent global pandemic has created a grave concern and awareness about the importance of the environment. The researchers/engineers/scientists are now focusing their efforts on the development of technologies that can ensure the sustainable growth of communities. Materials are at the core of every technological advancement. Natural fiber-based composites are a class of sustainable materials being used in diverse engineering applications, ranging from automotive to household goods. The processing methods, such as hand lay-up, injection, and compression molding are used extensively to fabricate simple composite parts. However, for complex/intricate product designs, the parts/components are made independently and these are assembled to get the final product. Joining thus becomes an inevitable process ensuring the assembly of parts/components. In the current experimental investigation, the hot-plate welding (HPW) behavior of sisal/jute fiber (both woven and short) reinforced polypropylene (PP) composite specimens fabricated using direct compression molding(DCM) and Extrusion injection molding (EIM) have been analyzed. The process parameters optimization has been achieved using the Taguchi experimental design approach. The hot plate welded joints of jute/sisal/PP composites were further investigated on the basis of their flexural and tensile properties. The failed joint specimens were characterized using TGA and XRD characterization techniques to analyze any changes occurred in their thermal degradation and crystalline behavior during welding process. The failure mechanisms of the joints have been thoroughly analyzed using SEM micrographs.

Processing and characterization of pineapple fiber reinforced recycled polyethylene composites

Abstract The current research investigation is a step towards the use of recycled plastics with natural fiber for developing sustainable composites. In this experimental investigation, pineapple fiber (20% wt.) was selected as reinforcement, and virgin HDPE and recycled HDPE were selected as matrix material. Composites were fabricated by the Extrusion Injection Molding (EIM) process. The mechanical characteristics of fabricated composites (vHDPE + 20PF and rHDPE + 20PF) were determined in terms of tensile and flexural properties as per the ASTM standards. The results show a minor variation in tensile and flexural properties of vHDPE + 20PF and rHDPE + 20PF. SEM images of the fractured surface of fabricated composites, after the tensile test, showed fiber breakage which confirmed that fibers are participating in load-bearing. It may be due to good adhesion between fiber and polymer. The thermogravimetric analysis gives a limiting value of temperature (240 °C) for the processing of composites. Recycling of polymer also has no significant effect on the crystalline nature of fabricated composites.

PLA/banana fiber based sustainable biocomposites: A manufacturing perspective

In the present experimental investigation, biocomposites based on short banana fiber (20 wt%) and poly-lactic acid were fabricated using three different processing techniques, namely direct injection molding (DIM), extrusion injection molding (EIM) and extrusion compression molding (ECM). The thermal and mechanical characterization as well as dynamic mechanical analysis has been performed to understand and compare the performance of the developed biocomposites. FTIR analysis has been conducted to investigate the presence and type of interfacial interaction in the biocomposites. XRD analysis was conducted to investigate the structure and to measure the crystallinity of the biocomposites. A significant improvement in the mechanical (tensile and flexural properties), dynamic mechanical properties (storage modulus, loss modulus, and tan delta) and crystallinity of the biocomposites fabricated by EIM were observed. A novel approach was used to examine the orientation and distribution of the fibers within the developed biocomposites. The fiber damage in terms of breaking, bending, twisting and formation of the clusters have been observed. Scanning Electron Microscopy (SEM) analysis revealed that the fiber pull-out and fracture are dominating the failure of biocomposite under loading.

Processing of PLA/sisal fiber biocomposites using direct- and extrusion-injection molding

ABSTRACTThe processing strategy adopted to develop biocomposites plays a significant role in determining their characteristics. The present experimental investigation explores the feasibility of using direct-injection molding (D-IM) process for processing of sisal fiber (3 mm and 8 mm) reinforced poly-lactic acid biocomposites with a fiber weight fraction of 30%. For a comparative analysis, mechanical and morphological behavior of biocomposites developed using D-IM process is compared with biocomposites developed using extrusion-injection molding (E-IM) process. The mechanical behavior in terms of tensile, flexural and impact properties is compared and discussed in relation to extracted fiber morphology and fiber orientation as well as dispersion within the developed biocomposites. Morphological investigation of extracted fibers revealed severe fiber attrition and fiber length variation during E-IM process as compared with D-IM process. However, short sisal fiber (3 mm) reinforced biocomposites developed using both the processes exhibit uniform fiber dispersion and orientation, resulting in comparable mechanical properties. The tensile and flexural strength of D-IM-SF biocomposites increased remarkably by 34.7% and 15.9%, respectively, as compared with D-IM-LF biocomposites. Similarly, the tensile and flexural modulus of D-IM-SF biocomposites increased significantly by 92.5% and 56.7%, respectively, as compared with D-IM-LF biocomposites. However, D-IM process incorporating long fibers exhibit better impact properties.

Characterization of Heterogeneity and Spatial Distribution of Phases in Complex Solid Dispersions by Thermal Analysis by Structural Characterization and X-ray Micro Computed Tomography

PurposeThis study investigated the effect of drug-excipient miscibility on the heterogeneity and spatial distribution of phase separation in pharmaceutical solid dispersions at a micron-scale using two novel and complementary characterization techniques, thermal analysis by structural characterization (TASC) and X-ray micro-computed tomography (XμCT) in conjunction with conventional characterization methods.MethodComplex dispersions containing felodipine, TPGS, PEG and PEO were prepared using hot melt extrusion-injection moulding. The phase separation behavior of the samples was characterized using TASC and XμCT in conjunction with conventional thermal, microscopic and spectroscopic techniques. The in vitro drug release study was performed to demonstrate the impact of phase separation on dissolution of the dispersions.ResultsThe conventional characterization results indicated the phase separating nature of the carrier materials in the patches and the presence of crystalline drug in the patches with the highest drug loading (30% w/w). TASC and XμCT where used to provide insight into the spatial configuration of the separate phases. TASC enabled assessment of the increased heterogeneity of the dispersions with increasing the drug loading. XμCT allowed the visualization of the accumulation of phase separated (crystalline) drug clusters at the interface of air pockets in the patches with highest drug loading which led to poor dissolution performance. Semi-quantitative assessment of the phase separated drug clusters in the patches were attempted using XμCT.ConclusionTASC and XμCT can provide unique information regarding the phase separation behavior of solid dispersions which can be closely associated with important product quality indicators such as heterogeneity and microstructure.

Creating Drug Solubilization Compartments via Phase Separation in Multicomponent Buccal Patches Prepared by Direct Hot Melt Extrusion-Injection Molding.

Creating in situ phase separation in solid dispersion based formulations to allow enhanced functionality of the dosage form, such as improving dissolution of poorly soluble model drug as well as being mucoadhesive, can significantly maximize the in vitro and in vivo performance of the dosage form. This formulation strategy can benefit a wide range of solid dosage forms for oral and alternative routes of delivery. This study using buccal patches as an example created separated phases in situ of the buccal patches by selecting the excipients with different miscibility with each other and the model drug. The quaternary dispersion based buccal patches containing PEG, PEO, Tween 80, and felodipine were prepared by direct hot melt extrusion-injection molding (HME-IM). The partial miscibility between Tween 80 and semicrystalline PEG-PEO led to the phase separation after extrusion. The Tween phases acted as drug solubilization compartments, and the PEG-PEO phase had the primary function of providing mucoadhesion and carrier controlled dissolution. As felodipine was preferably solubilized in the amorphous regions of PEG-PEO, the high crystallinity of PEG-PEO resulted in an overall low drug solubilizing capacity. Tween 80 was added to improve the solubilization capacity of the system as the model drug showed good solubility in Tween. Increasing the drug loading led to the supersaturation of drug in Tween compartments and crystalline drug dispersed in PEG-PEO phases. The spatial distribution of these phase-separated compartments was mapped using X-ray micro-CT, which revealed that the domain size and heterogeneity of the phase separation increased with increasing the drug loading. The outcome of this study provides new insights into the applicability of in situ formed phase separation as a formulation strategy for the delivery of poorly soluble drugs and demonstrated the basic principle of excipient selection for such technology.

Microstructure, thermomechanical properties, and electrical conductivity of carbon black‐filled nylon‐12 nanocomposites prepared by selective laser sintering

AbstractSelective laser sintering (SLS) is employed to fabricate a multifunctional polymer nanocomposite comprising Nylon‐12 reinforced with carbon black (CB) at a loading of 4% by weight. The heat distortion temperature (HDT), viscoelastic properties, and the electrical conductivity of this nanocomposite are compared to those obtained via extrusion injection molding (Ex‐IM). The HDT of the nanocomposites made by the two methods are found to be nearly identical. The electrical conductivity of the nanocomposite made by SLS is five orders of magnitude higher than that obtained through Ex‐IM. The storage modulus of the SLS‐processed nanocomposite is at least one order of magnitude higher than that of the nanocomposite made by Ex‐IM, for all the frequencies tested. The observed differences in properties and the effects of the processing methods on the polymer's molecular weight, its crystallization characteristics, and the dispersion of CB within the polymer matrix are investigated using X‐ray diffraction, differential scanning calorimetry, and scanning electron microscopy. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers

Thermal properties of extruded injection‐molded poly(lactic acid) and milkweed composites: Degradation kinetics and enthalpic relaxation

AbstractTo determine the degree of compatibility between poly(lactic acid) (PLA) and different biomaterials, PLA was compounded with milkweed fiber, a new crop oil seed. After oil extraction, milkweed remaining cake retained approximately 10% residual oil, 47% protein, and 10% moisture. The fiber (300 μm) was added at 85 : 15 and 70 : 30 PLA : Fiber and blended by extrusion (EX) followed by injection molding (IM). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used for testing the composites. After melting in the DSC sealed pans, composites were cooled by immersion in liquid nitrogen and aged (stored) at room temperature for 0, 7, 15, and 30 days. After storage, samples were heated from room temperature to 180°C at 10°C/min. The pure PLA showed a glass transition (Tg) at 60.3°C and the corresponding ΔCp was 0.464 J/g/°C followed by crystallization and melting transitions. The enthalpic relaxation (ER) of neat PLA and composites steadily increased as a function of storage time. Although the presence of fiber had little effect on ER, IM reduced it. The percentage crystallinity of neat unprocessed PLA dropped by 95 and 80% for the EX and IM, respectively. The degradation activation energy (Ea) of neat PLA exhibited a significant drop in nitrogen environment, whereas increased in air, indicating PLA resistant to heat degradation in the presence of oxygen. Overall, IM appeared to decrease Ea of the composites, whereas milkweed significantly reduced Ea values in nitrogen environment. Enzymatic degradation of the composites revealed higher degradation rate for the EX samples versus IM, whereas 30% milkweed exhibited higher weight loss compared to the 15%. The degradation mechanism was observed by looking at the percent conversion as a function of Ea from the TGA data, where multisteps degradation occurred mostly in air. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Influence of Separation and Processing Systems on Morphology and Mechanical Properties of Hemp and Wood Fibre Reinforced Polypropylene Composites

ABSTRACT The separation processes of natural fibres and the technique of composite processing influence the fibre degradation, length and herewith the composites properties in a wide range. Different separation processes (mechanical, refiner and enzymatic separation) were investigated with hemp and partially with flax and wheat straw. Selected fibres were mixed with PP in a cascade mixer (heat-cooling mixer system) or compounded in a twin screw extruder and formed into test specimens by injection moulding with 40 wt.% fibre content. Thermomechanical processed hemp fibre-PP composites showed higher mechanical properties in cascade mixer process compared to twin-screw extruder or agglomerated process. Wood fibre reinforced polypropylene composites containing hard wood fibre were prepared by extrusion-injection moulding, mixer-injection moulding, compression moulding and direct extrusion (profile) process with 30 wt.% and 50 wt.% fibre contents. It is seen that extrusion-injection moulding process showed best properties compared to other processes in maximum cases.

Structure and properties of amorphous polyamide/liquid crystalline polyester blends

AbstractAmorphous polyamide (AP)/liquid crystalline polyester (VA) blends were obtained by extrusion‐injection molding (EI) throughout the whole composition range. The phase behavior, chemical nature and morphology of the blends were studied, and the mechanical properties discussed and compared with those of the 10 and 30% VA blends obtained by direct injection molding (DI). The blends showed two almost pure slightly reacted amorphous phases. The apparently higher reaction level of the EI blends, although small, led to a more homogeneous, fine and fibrillated morphology, attributed to a lower interfacial tension. Significant synergisms in the modulus of elasticity (up to 25%) and in the tensile strength (up to 40%) were seen in EI blends. The similar values of both specific volume and orientation in the blends and in the pure components suggest that the contribution to the modulus of the dispersed VA rigid particles is greater than that due to the proportion of VA in the blend. The 10% VA DI blend showed a similar behavior in these two properties, indicating that the DI procedure is preferred, provided that only stress‐related properties are sought. At 30% VA content, the moduli of elasticity were similar by the two molding processes, but the clearly lower tensile strength and lower ductility of the easier DI procedure, means that the more complex, but more effective, EI procedure is the one of choice for high performance materials.