High flow compression molding for recycling discontinuous long fiber thermoplastic composites

2020 ◽  
Vol 54 (23) ◽  
pp. 3343-3350
Author(s):  
Éric Léger ◽  
Benoit Landry ◽  
Gabriel LaPlante
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compression Molding ◽  
High Flow ◽  
Low Flow ◽  
Thermoplastic Composites ◽  
Direction Parallel ◽  
Significant Difference ◽  
Long Fiber Thermoplastic ◽  
Flow Compression

An investigation into high flow compression molding for recycling thermoplastic discontinuous long fiber composites is presented. High flow recycled panels and conventional low flow baseline panels were produced with a large rectangular (2:1 aspect ratio) mold. Flow was induced in the recycled panels by stacking cut sections of conventionally produced baseline panels in the center of the mold cavity, representing 25% initial coverage. High flow compression molded panels were found to exhibit significantly higher than baseline tensile strength (+50%) and modulus (+31%) when tested in the direction parallel to flow. When tested in the direction perpendicular to flow, the opposite effect was found, with reductions in tensile strength (−42%) and modulus (−37%). However, when the average results of both directions are compared to baseline, no significant difference was found between the recycled and baseline panels. This severe anisotropic redistribution of mechanical properties suggests chip orientation is affected by flow. Additionally, micrographic analysis revealed that high flow molding induces intra-ply chip shearing and a reduction in resin rich regions within panels. Baseline panels also exhibited in-plane anisotropy, despite initial random distribution of chips and no or near no flow induced during molding. In this case, mechanical properties favored the direction perpendicular to that of the recycled panels.

Experimental Investigation of Stratasys J750 PolyJet Printer: Effects of Orientation and Layer Thickness on Mechanical Properties

2019 ◽  
Author(s):  
Xingjian Wei ◽  
Abhinav Bhardwaj ◽  
Chin-Cheng Shih ◽  
Li Zeng ◽  
Bruce Tai ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Ultimate Tensile Strength ◽  
Layer Thickness ◽  
Axial Direction ◽  
Limited Information ◽  
Direction Parallel ◽  
Control Factors ◽  
Significant Difference

Abstract The J750 PolyJet printer is the newest model of full-color, multi-material 3D printer from Stratasys. Currently, limited information is available about the effects of control factors on mechanical properties such as elastic modulus, ultimate tensile strength, and elongation. In this study, the effects of two control factors, orientation and layer thickness, on mechanical properties of samples printed by the Stratasys J750 printer are investigated. The results show that orientation significantly affects mechanical properties. Specifically, samples printed with its axial direction parallel to the direction of printing have the highest elastic modulus, and elongation, whereas samples printed with its axial direction perpendicular to the direction of printing have the highest ultimate tensile strength. Also, layer thickness makes a significant difference for mechanical properties, and larger layer thickness leads to higher ultimate tensile strength and elongation. These results would be valuable to researchers and practitioners who use J750.

Stir zone material flow patterns during friction stir welding of heavy gauge AA5056 workpieces and stability of its mechanical properties

2021 ◽  
Vol 23 (4) ◽  
pp. 140-154
Author(s):  
Tatiana Kalashnikova ◽  
◽  
Vladimir Beloborodov ◽  
Kseniya Osipovich ◽  
Andrey Vorontsov ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Friction Stir Welding ◽  
Elevated Temperatures ◽  
Thin Sheet ◽  
Stir Zone ◽  
Clear Correlation ◽  
Material Structure ◽  
Friction Stir ◽  
Significant Difference

Introduction. Friction stir welding and processing are almost identical processes of severe plastic deformation at elevated temperatures. These technologies differ mainly in the purpose of its use: the formation of a hardened surface layer or producing a welded joint. However, it is known that both during welding and during processing of heavy gauge workpieces temperature gradients occur. As a result, the conditions of adhesive interaction, material plastic flow, and the formation of the stir zone change as compared to thin-sheet workpieces with fundamentally different heat dissipation rates. In this connection, the purpose of the work is to determine the regularities of the structure formation and stability of the mechanical properties in different directions in the material of 35-mm-thick aluminum-magnesium alloy samples produced by friction stir welding/processing. Research Methodology. The technique and modes of friction stir welding and processing of AA5056 alloy workpieces with a thickness of 35 mm are described. Data on the equipment used for mechanical tests and structural research are given. Results and discussion. The data obtained show the excess mechanical properties of the processing zone material over the base metal ones in all studied directions. Material structure heterogeneities after friction stir welding/processing of heavy gauge workpieces have no determining effect on the stir zone properties. At the same time, there is no clear correlation between the tensile strength values and the load application direction, nor is there any significant difference in mechanical properties depending on the location of the samples inside the stir zone. The average ultimate tensile strength values in the vertical, transverse, and longitudinal directions are 302, 295 and 303 MPa, respectively, with the yield strength values of 155, 153 and 152 MPa, and the relative elongation of 27.2, 27.5, 28.7 %.

Effects of Probenecid on Renal Function in Surgical Patients Anesthetized with Low-flow Sevoflurane

2001 ◽  
Vol 94 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Hideyuki Higuchi ◽  
Hiroki Wada ◽  
Yumi Usui ◽  
Kohichiro Goto ◽  
Masuyuki Kanno ◽  
...  
Keyword(s):  
Urinary Excretion ◽  
Biochemical Markers ◽  
High Flow ◽  
Surgical Patients ◽  
Low Flow ◽  
Sevoflurane Anesthesia ◽  
Compound A ◽  
Significant Difference ◽  
Beta 2 ◽  
Beta 2 Microglobulin

Background Dehydrofluorination of sevoflurane by carbon dioxide absorbents in anesthesia machines produces compound A, which is nephrotoxic in rats. Several clinical studies indicate that prolonged low-flow sevoflurane anesthesia is associated with an increased urinary excretion of biochemical markers, such as protein. Probenecid, a competitive inhibitor of organic anion transport, diminishes compound A nephrotoxicity in rats. The purpose of the present study was to examine the effects of low- and high-flow sevoflurane anesthesia on urinary excretion of biochemical markers in humans and to examine the effects of probenecid on urinary excretion of these markers. Methods Elective surgical patients (n = 64) were assigned to four groups (n = 16 each): low-flow sevoflurane plus probenecid (LSP), low-flow sevoflurane (LS), high-flow sevoflurane plus probenecid (HSP), and high-flow sevoflurane (HS). Probenecid (2.0 g) was administered orally 2 h before the induction of anesthesia in both the LSP and HSP groups. Nothing was administered orally 2 h before the induction of anesthesia in either the LS or HS groups. All patients underwent prolonged low-flow (1 l/min) or high-flow (6 l/min) sevoflurane anesthesia. Urinary excretion of protein, albumin, beta(2)-microglobulin, glucose, and N-acetyl-beta-d-glucosaminidase was measured for up to 7 days postoperatively. Results Sevoflurane doses were similar in all four groups. There were no differences in blood urea nitrogen, creatinine, or creatinine clearance among the four groups after anesthesia. Average values for urinary excretion of protein, beta(2)-microglobulin, and N-acetyl-beta-d-glucosaminidase in the LS group were significantly higher than those in the other groups (LSP, HSP, HS; P < 0.05). There was no significant difference between the LS and LSP groups in average values for urinary excretion of albumin and glucose, although there were significant differences between the LS and both high-flow sevoflurane groups (HSP, HS). Conclusions Low-flow sevoflurane, which produces a sevenfold higher compound A exposure than high-flow sevoflurane, resulted in significant increases of several biochemical markers in half of the patients. Probenecid appears to provide protection against these renal effects.

Studies on mechanical properties of thermoplastic composites prepared from flax-polypropylene needle punched nonwovens

2018 ◽  
Vol 25 (3) ◽  
pp. 489-499 ◽  
Author(s):  
V.R. Giri Dev ◽  
A.K.P. Dhanakodi
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Natural Fiber ◽  
Thermoplastic Composites ◽  
Flexural Properties ◽  
Process Variables ◽  
Molding Process ◽  
Impact Properties ◽  
Dummy Variable ◽  
Weight Proportion

Abstract Natural fiber reinforced thermoplastic composites using flax and polypropylene were prepared using compression molding process. Needle punched nonwovens were used as preforms for preparing the composites. Three variables namely fiber weight proportion, areal weight of the mat, and needling density were chosen for the study. Modified Taguchi L18 experimental design with dummy variable was chosen for the study and the effect of the above variables on tensile, flexural, and impact properties of the composites were studied. By altering the fiber weight proportion and areal weight of the mat, tensile and flexural properties improved. An increase in 34% of tensile strength and 40% of flexural strength has been observed. Impact properties of the composites were significantly altered by modifying the process variables. Increasing the needling density led to a decrease in overall mechanical properties of the composites.

scholarly journals Effect of Wood-Fiber Geometry Size on Mechanical Properties of Wood-Fiber from Neolamarckia Cadamba Species Reinforced Polypropylene Composites

2021 ◽  
Vol 1 (1) ◽  
pp. 42-50
Author(s):  
Mohd Sukhairi Mat Rasat ◽  
Razak Wahab ◽  
Amran Shafie ◽  
Ahmad Mohd Yunus AG. ◽  
Mahani Yusoff ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Wood Species ◽  
Renewable Resources ◽  
Wood Fiber ◽  
Wood Particle ◽  
Thermoplastic Composites ◽  
Polypropylene Composites ◽  
Natural Wood ◽  
Particle Geometry

Using natural wood-fiber as reinforcement in commercial thermoplastics is gaining momentum due to its high specific properties and renewable resources. In this study, the effect of wood particle geometry size on mechanical properties of thermoplastics composite was investigated. The wood species that has been chosen is Kelempayan species (Neolamarckia cadamba) and reinforced with polypropylene using fiber geometry size of 75 and 250 ?m. Thermoplastic composites were produced from two types of ratio (30:70 and 10:90) between wood-fiber and polypropylene. Static bending and tensile strength were tested. The result showed that wood-fiber from 75 ?m geometry sizes with ratio of 30:70 between wood-fiber and polypropylene was most suitable in producing thermoplastic composites. The geometry sizes of wood particle as well as the ratio between wood-fiber and polypropylene were found to influence the mechanical properties of the thermoplastic composites.

Natural Fibre/Polypropylene Wrap Spun Yarns and Preforms for Structured Thermoplastic Composites

2011 ◽  
Vol 675-677 ◽  
pp. 427-430 ◽  
Author(s):  
Jin Hua Jiang ◽  
Ze Xing Wang ◽  
Nan Liang Chen
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Hot Pressing ◽  
Mechanical Performance ◽  
Great Influence ◽  
Natural Fibre ◽  
Thermoplastic Composites ◽  
Flax Fibres ◽  
Fibre Composites ◽  
Spun Yarns

In the past decade, natural fibre composites with thermoplastic matrices had attracted many composites manufactures for the superiority of lightweight and low-cost. A major challenge for natural fibre composites was to achieve high mechanical performance at a competitive price. Composites constructed from yarn and fabric structure preforms were better than composites made from random nonwoven mats. However, the twist structure of conventional ring spun yarns prevented the full utilization of fibre mechanical properties in the final composites. In this paper, the wrapped yarns were produced by wrap spun method with flax and polypropylene (PP), in which all flax fibres were twistless, then woven to be fabric preforms. The PP fibres served as a carrier for flax fibres during processing and became the polymer matrix in the final composites. The homogenous distribution of fibre and thermoplastic matrix in preforms could be achieved before hot pressing, so that not lead to impregnate difficultly, and prevented damage to the reinforced nature fibres during processing. Composites made from the wrapped yarn demonstrated significant tensile and peeling properties. The fabric structures (include plain, twill, and basket weave) and yarn tensile orientation (in 0°, 90°, 45°), had great influence on tensile strength and elongation of preforms. The cavity thickness of hot pressing mould had different influence on the tensile strength and peeling strength of thermoplastic composites, and the mechanical properties were superior when the thickness was 0.8-1.2 mm. The microstructure of thermoplastic composites showed uniform infiltration between layers, and had good bonding interface between flax fibre and PP matrix in composites.

Effect of Preheating and Fatiguing on Mechanical Properties of Bulk-fill and Conventional Composite Resin

2019 ◽  
Vol 45 (4) ◽  
pp. 387-395
Author(s):  
AA Abdulmajeed ◽  
TE Donovan ◽  
R Cook ◽  
TA Sulaiman
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Flexural Strength ◽  
Composite Resin ◽  
Statistical Significance ◽  
Composite Resins ◽  
Significant Difference ◽  
Diametral Tensile Strength

Clinical Relevance Bulk-fill composite resins may have comparable mechanical properties to conventional composite resin. Preheating does not reduce the mechanical properties of composite resins. SUMMARY Statement of Problem: Bulk-fill composite resins are increasingly used for direct restorations. Preheating high-viscosity versions of these composites has been advocated to increase flowability and adaptability. It is not known what changes preheating may cause on the mechanical properties of these composite resins. Moreover, the mechanical properties of these composites after mastication simulation is lacking. Purpose: The purpose of this study was to evaluate the effect of fatiguing and preheating on the mechanical properties of bulk-fill composite resin in comparison to its conventional counterpart. Methods and Materials: One hundred eighty specimens of Filtek One Bulk Fill Restorative (FOBR; Bulk-Fill, 3M ESPE) and Filtek Supreme Ultra (FSU; Conventional, 3M ESPE) were prepared for each of the following tests: fracture toughness (International Organization for Standardization, ISO 6872), diametral tensile strength (No. 27 of ANSI/ADA), flexural strength, and elastic modulus (ISO Standard 4049). Specimens in the preheated group were heated to 68°C for 10 minutes and in the fatiguing group were cyclically loaded and thermocycled for 600,000 cycles and then tested. Two-/one-way analysis of variance followed by Tukey Honest Significant Difference (HSD) post hoc test was used to analyze data for statistical significance (α=0.05). Results: Preheating and fatiguing had a significant effect on the properties of both FSU and FOBR. Fracture toughness increased for FOBR specimens when preheated and decreased when fatigued (p=0.016). FOBR had higher fracture toughness value than FSU. Diametral tensile strength decreased significantly after fatiguing for FSU (p=0.0001). FOBR had a lower diametral tensile strength baseline value compared with FSU (p=0.004). Fatiguing significantly reduced the flexural strength of both FSU and FOBR (p=0.011). Preheating had no effect on the flexural strength of either FSU or FOBR. Preheating and fatiguing significantly decreased the elastic modulus of both composite resins equally (p>0.05). Conclusions: Preheating and fatiguing influenced the mechanical properties of composite resins. Both composites displayed similar mechanical properties. Preheating did not yield a major negative effect on their mechanical properties; the clinical implications are yet to be determined.

Microstructure and Mechanical Properties of TRIP-Aided Steels with Different Heat Treatments

2015 ◽  
Vol 817 ◽  
pp. 439-443 ◽  
Author(s):  
Rui Dong ◽  
Ai Min Zhao ◽  
Ran Ding ◽  
Jian Guo He ◽  
Han Jiang Hu
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Total Elongation ◽  
Heat Treatments ◽  
Second Phase ◽  
Soft Matrix ◽  
Significant Difference

The microstructures, mechanical properties and retained austenite characteristics of TRIP-aided steels with three different heat treatments were studied in this paper. The results indicated that the designed annealing treatments resulted in completely different matrices and the morphologies of second phase, and a significant difference in mechanical properties. The TAM steel was found to have fine annealed martensite lath matrix and inter lath acicular retained austenite, and possessed an excellent combination of strength and elongation which attributed to the highest retained austenite volume fraction and carbon concentration. For TPF steel, the higher instability and lower carbon content of retained austenite and the soft matrix resulted in the lowest ultimate tensile strength and total elongation. While in TBF steel, the stability of retained austenite was lower than that in TAM steel but higher than that in TPF steel. The ultimate tensile strength of TBF was significantly higher than the TAM and TPF steels, but the ductility of TBF steel was lower than TAM steel.

scholarly journals Investigation of optimal lamination condition of CFRTP by compression molding method and a comparison of mechanical properties with CFRTS

2020 ◽  
Vol 12 (12) ◽  
pp. 168781402098625
Author(s):  
Dae Won Kim ◽  
Chul Kyu Jin ◽  
Min Sik Lee ◽  
Chung Gil Kang ◽  
Hyung Yoon Seo
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Carbon Fiber ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Compression Molding ◽  
Molding Method ◽  
Pressure Time ◽  
Die Temperature ◽  
Lower Tensile Strength

The variables of die temperature, pressure, time, lamination method, and forming count are applied to fabricate thermosoftening CFRP (CFRTP) with compression molding method. The mechanical properties of CFRTP are compared with those of thermosetting CFRP (CFRTS). The first lamination method is that one hotmelt is inserted into carbon fiber (five carbon fibers and four hotmelts). The optimal lamination conditions are the die temperature of 220°C, pressure of 6 MPa, and pressurization time for 10 min. The tensile strength of CFRTP of this lamination method is 400 MPa. For higher tensile strength value, the second lamination method was applied. CFRTP prepreg was prepared with one hotmelt and one carbon fiber by applying die temperature at optimal lamination conditions. Five CFRTP prepregs were laminated under the same conditions. When the CFRTP sheet was three formings, the tensile strength of 494 MPa could be obtained. CFRTS are prepared by laminating the epoxy prepregs at 140°C with the compressive pressure of 0.5 MPa for 30 min. CFRTP sheet has the lower tensile strength than CFRTS sheet by 223 MPa, but the flexural strength was higher by 61 MPa and by 1.0 J/cm2 for Charpy impact test.

Effects of the Frequency and Duration of Cyclic Stress on the Mechanical Properties of Cultured Collagen Fascicles From the Rabbit Patellar Tendon

2005 ◽  
Vol 127 (7) ◽  
pp. 1168-1175 ◽  
Author(s):  
Ei Yamamoto ◽  
Daisuke Kogawa ◽  
Susumu Tokura ◽  
Kozaburo Hayashi
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Patellar Tendon ◽  
Load Condition ◽  
Peak Stress ◽  
Cyclic Stress ◽  
Control Group ◽  
Significant Difference

The effects of frequency or duration of cyclic stress on the mechanical properties of collagen fascicles were studied by means of in vitro tissue culture experiments. Collagen fascicles of approximately 300μm in diameter were obtained from rabbit patellar tendons. During culture, cyclic stress having the peak stress of approximately 2MPa was applied to the fascicles at 1Hz for 1hour∕day (1Hz-1h group), at 1Hz for 4hours∕day (1Hz-4h group), or at 4Hz for 1hour∕day (4Hz-1h group). The frequency of 4Hz and the duration of 1hour∕day are considered to be similar to those of the in vivo stress applied to fascicles in the intact rabbit patellar tendon. After culture for 1 or 2weeks, the mechanical properties of the fascicles were determined using a micro-tensile tester, and were compared to the properties of non-cultured, fresh fascicles (control group) and the fascicles cultured under no load condition (non-loaded group). The tangent modulus and tensile strength of fascicles in the 4Hz-1h group were similar to those in the control group; however, the fascicles of the 1Hz-1h and 1Hz-4h groups had significantly lower values than those of the control group. There was no significant difference in the tensile strength between the 1Hz-1h and non-loaded groups, although the strength in the 1Hz-4h group was significantly higher than that of the non-loaded group. It was concluded that the frequency and duration of cyclic stress significantly affect the mechanical properties of cultured collagen fascicles. If we apply cyclic stress having the frequency and duration which are experienced in vivo, the biomechanical properties are maintained at control, normal level. Lower frequencies or less cycles of applied force induce adverse effects.

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