Biobased flexible polyurethane foams manufactured from lactide-based polyester-ether polyols for automotive applications

In this study, biobased polyester-ether polyols derived from meso-lactide and dimer acids were evaluated for flexible polyurethane foams (PUF) applications. Initially, the catalyst concentration was optimized for the biobased PUF containing 30% of biobased polyol (70% petroleum-based polyol). Then, the same formulation was used for biobased PUF synthesis containing 10%–40% of biobased polyols. The performance of biobased PUF was compared with the performance of the control foam made with 100% petroleum-based polyol. The characteristic times (cream, top of the cup, string gel, rise, tack-free) of biobased PUF were determined. The biobased PUF were evaluated for the mechanical (tensile and compressive) and morphological properties. As the wet compression set is important for automotive applications, it was measured for all biobased PUF. The thermal degradation behavior of biobased PUF was also evaluated and compared with the control foam. The effect of different hydroxyl and acid values of polyols on the mechanical properties of biobased PUF is also discussed. The miscibility of all components of PUF formulations is crucial in order to produce a foam with uniform properties. Thus, the miscibility of biobased polyols with commercial petroleum-based polyol was studied.     

Effect of a Small Amount of Synthetic Fiber on Performance of Biocarbon-Filled Nylon-Based Hybrid Biocomposites

Advanced hybrid biocomposites are engineered from nylon 6, waste wood biosourced carbon (biocarbon) with a low content of synthetic fiber for lightweight auto-parts uses. The novel engineering process through direct injection molding of only 2 wt% synthetic fibers in the form of masterbatch with 20 wt% biocarbon, results outstanding performance of the resulting nylon biocomposites. Such uniquely developed biocomposites show tensile strength of 105 MPa and tensile modulus of 5.14 GPa with a remarkable heat deflection temperature (HDT) of 206 °C. The direct injection molding of synthetic fiber retains the length ≈3 times higher as compared to traditional extrusion and injection molding; resulting greater degree of entanglement and composite reinforcement effectiveness in the hybrid biocomposites. Highly dimensionally stable nylon 6 biocomposites with a very low coefficient of linear thermal expansion results through reinforcing ability of the sustainable biocarbon and small amount of synthetic fiber.     

Polyamide 6–Cellulose Composites: Effect of Cellulose Composition on Melt Rheology and Crystallization Behavior

Melt rheology and crystallization behavior of polyamide 6 (PA 6) and microcrystalline cellulose (MCC) composites were systematically studied in this research. The incorporation of MCC into the PA 6 matrix resulted in higher complex viscosities (|η*|), storage modulus (G′), and shear viscosities than those of neat PA 6, especially at low frequencies. The orientation of rigid molecular chains in the composites introduced by the addition of MCC induced a strong shear thinning behavior with an increase in MCC loading. The non‐isothermal crystallization kinetics of PA 6 and MCC composites were investigated by differential scanning calorimetry. The Avrami and Tobin model were applied to describe the process of non‐isothermal crystallization and to determine the crystallization parameters of the composites. Analysis of the crystallization kinetics indicated that the Avrami (n_a) and Tobin exponent (n_t) was altered by the MCC. It was also found that the Avrami and Tobin equations fit the empirical data well. POLYM. ENG. SCI., 54:739–746, 2014. © 2013 Society of Plastics Engineers     

Contextual Information Requirements of Cost Estimators from Past Construction Projects

Past project data sources provide key information for construction cost estimators. Previous research studies show that relying only on one’s own experience during estimation results in estimators’ bias. Having and referring to historical databases, containing objective information on what happened in past projects, are essential for reducing estimators’ biases. The first step toward development of useful project history databases is to understand what information estimators require from past projects. The research described in this paper targets estimators’ information needs identified through interviews, brainstorming sessions, task analyses, and card games conducted with estimators with different experience levels and specialized in heavy/civil and commercial construction projects, and exploration of historical and standard databases available in companies to determine what is being currently represented. Findings show that estimators need contextual information, depicting the conditions under which specific production rates were achieved, so that they can identify which production rate would be more realistic to use during the production rate estimation of an activity in a new bid. Comparison of the contextual information needs identified in this research with information items available in historical data sources (such as company cost reports, RSMeans, previous studies) highlighted some gaps and important opportunities for improvements in those sources. The identified contextual information items are significant for practitioners in developing ways to augment their existing project history databases to make them more beneficial for estimators.     

Optimization of dry powder deposition parameters for production of large substrates using functionally graded ceramics

The ability to control the spatial variation in three dimensions of dielectric properties is known to play a crucial role in achieving novel electromagnetic performance such as miniaturization and high gain of broadband antennas. To address this need, the objective in this paper is to use earlier proposed Dry Powder Deposition to produce large substrates of Functionally Graded Materials with spatially controlled CaTiO₃‐MgTiO₃‐Mg₂TiO₄ dielectrics. We present an in‐depth analysis and optimization of critical processing parameters such as compaction pressure, sintering temperature, and dwell time. Using the optimized compaction and co‐sintering process, spatially varying large (8.2 cm × 8.2 cm) substrates were produced without the presence of any significant cracks and warping. In addition to these structural functionalities, sintered ceramic constituents of the designed substrate display targeted dielectric permittivity values of a miniaturized broadband Satellite Communication Ultra High Frequency antenna at the optimized conditions. This optimized route opens up possibilities for multifunctional metrics to be addressed for other applications calling for different spatial distributions of large Functionally Graded Materials possibly with the same family of ceramic constituents.     

Influence of Micro- and Nanonatural Fillers on Mechanical and Physical Properties of Foamed SMA Composites

This study is to investigate the reinforcing effects of fillers on mechanical and physical properties of foamed styrene-maleic anhydride (SMA) composites. According to the results, the best foaming was determined for starch reinforced SMA composite. The best result of expansion ratio was found as 22.75% to SMA/starch composites. Stereo light microscopy results demonstrated that the foamed cell distribution is heterogeneous and composed of two sections. The minimum density was found as 0.64 g/cm³ for foamed SMA/starch composites. Mechanical properties of all foamed composites were found to be low as compared to neat SMA composite.     

Nanoclay reinforced polyethylene composites: Effect of different melt compounding methods

Nanoclay (NC) reinforced high‐density polyethylene (HDPE) composites were prepared by different melt compounding methods using (1) a single screw extruder (SSE), (2) twin screw extruder (TSE), (3) a combination of SSE and extensional flow mixer (EFM), and (4) a bowl mixer masterbatch method (MB). PE‐grafted maleic anhydride (PE‐g‐MA) was used as a compatibilizer. EFM increased complex melt viscosity (η*) of the HDPE/NC composites as compared to the neat HDPE and also provided a better interaction between HDPE and NC to create slightly lower melt η* as compared to MB and PE‐g‐MA composites. The low viscosity melt behavior of the pure HDPE changes to more solid like melt behavior in the PE‐g‐MA HDPE/NC composites in the low frequency (ω) region. PE‐g‐MA + EFM method exhibited better impact strength compared to the other HDPE/NC composites. Using the PE‐g‐MA and masterbatch compounding methods had a beneficial role in improving mechanical properties. POLYM. ENG. SCI., 57:324–334, 2017. © 2016 Society of Plastics Engineers     

Cellulose NANOFIBER‐polyethylene nanocomposites modified by polyvinyl alcohol

The uniform dispersion of cellulose nanofibers (CNFs) in non‐polar polymer matrices is a primary problem to overcome in creating novel nanocomposites from these materials. The aim of this study was to produce CNF‐polyethylene (PE) nanocomposites by melt compounding followed by injection molding to investigate the possibility of using polyvinyl alcohol (PVA) to improve the dispersion of CNF in the PE matrix. The tensile strength of CNF‐ filled composites was 17.4 MPa with the addition of 5 wt % CNF–PVA, which was 25% higher than the strength of neat PE. The tensile modulus of elasticity increased by 40% with 5% CNF–PVA addition. Flexural properties also significantly increased with increased CNF loading. Shear viscosity increased with increasing CNF content. The elastic moduli of the PE/CNF composites from rheological measurements were greater than those of the neat PE matrix because of the intrinsic rigidity of CNF. Melt creep compliance decreased by about 13% and 45% for the composites with 5 wt % CNF and 10 wt % CNF, respectively. It is expected that the PVA carrier system can contribute to the development of a process methodology to effectively disperse CNFs containing water in a polymer matrix. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42933.