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Polypropylene (PP) is one of the most used polymeric materials worldwide, either as a neat material or as a matrix for composite manufacture employing a molding process. Fused deposition modeling (FDM) 3D printing is an alternative process that offers the potential for manufacturing value‐added products from PP. However, using neat PP for FDM is challenging because 3D‐printed PP warps and shrinks when cooled, and the mechanical properties of PP are poor. PP‐based composites with different fillers (e.g., glass, carbon, and natural fibers) have shown improved properties using FDM processes. An alternative filler for 3D‐printed PP‐based composites is basalt fiber (BF). The objective of this work was to assess the potential and impacts of BF as a filler for BF‐PP composites using FDM processes. PP was compounded with 15, 25, 35, and 45 wt% BF to produce filaments for 3D printing without adding any compatibilizer. Results of rheology studies, morphology, and mechanical and thermal properties of the 3D printed specimens showed that BF positively impacts Young's modulus (E), thermal stability, and dimensional stability of the composite. All composites, when processed at high shear rates (i.e., above 100 1/s), show approximately similar rheological behavior. E is almost doubled in the composite with 25 wt% BF and increased fourfold in the composite with 35 and 45 wt% BF, compared to neat PP. The Izod impact resistance of the formulations containing 35 and 45 wt% BF is ~70% that of neat PP. BF process easily and adequately reinforces PP composites manufactured via FDM. Highlights: Neat PP's poor mechanical properties are improved by adding basalt fiber (BF).Up to 45 wt% BF was used to reinforce PP‐based composites.PP‐BF composites are easier to process via DFM compared to neat PP.BF improves PP‐based composite's thermal and dimensional stability. [ABSTRACT FROM AUTHOR]

A growing concern of climate change and waste pollution is causing a shift in products towards green materials. The automotive industry is exploring environmentally friendly alternatives to glass fibers (GF). This research focuses on understanding interactions between constituents of biocomposites made up of basalt fiber (BF) and hemp hurd particle fiber (HF) reinforced polypropylene (PP), and statistically comparing the mechanical properties. The addition of a coupling agent has significantly improved the performance and fiber-matrix interactions in the biocomposite blends. The elastic modulus of some BF/HF/PP mixtures were comparable to the GF/PP composite; however, the GF still outperformed in strength. Rotational and capillary rheometer analysis determined the viscosities of all formulations displaying that basalt composites were consistently lower in viscosity than the glass fiber composite, indicating easier processing conditions. [ABSTRACT FROM AUTHOR]

The primary objectives of the study were to characterize the critical properties of wood flour produced using highly deteriorated beetle-killed spruce for wood-plastic composite (WPC) production and evaluate important mechanical and physical properties of WPC extruded using an industry standard formulation. Chemical composition analysis indicated no significant differences in wood constituents between highly deteriorated and sound wood. Preliminary investigation with Fourier transform infrared spectroscopy (FTIR), however, indicated partial degradation or depolymerization of carbohydrate components in highly deteriorated effects of these changes could be seen in cell collapse and poor interaction between thermoplastic matrix and deteriorated wood fiber. Physical and mechanical properties of extruded WPCs manufactured from highly deteriorated material were comparable to WPC properties produced using pine wood flour that served as a control material. POLYM. ENG. SCI., 49:129-136, 2009. (c) 2008 Society of Plastics Engineers, INTRODUCTION In Alaska, the most damaging natural occurrence to the forests south of the Alaska Range, is the spruce bark beetle (SBB), which attacks white (Picea glauca (Moench) Voss), sitka [...]

Cellulose micro/nanofibrils were successfully extracted from softwood Douglas fir in three distinct stages. Initially raw Douglas fir wood chips were subjected to a hot water extraction (HWE) treatment. Then HWE treated cellulosic fibers underwent a bleaching process followed by a mild ultrasonication. Chemical composition analysis according to ASTM standards confirmed that most of hemicelluloses and nearly all lignin were removed during the first two stages, respectively. Microscopy studies showed formation of nanofibrils during the ultrasonication process, and increasing ultrasonication time led to generation of greater percentage of nanofibrils. With the removal of the matrix materials, the crystallinity of the cellulosic fibers was increased, whereas thermal stability was maintained. HWE opened up the cell wall structure, thereby facilitating the subsequent fractionation into micro/nanofibrils. The obtained cellulose micro/nanofibrils could serve as reinforcing material in composite products or raw material for other applications, such as filtration membrane. [ABSTRACT FROM AUTHOR]

The process named 'sulfite pretreatment to overcome recalcitrance of lignocellulose' (SPORL) is designed for the digestion of softwoods within the framework of the biorefinery concept. 'Hot water extraction (HWE)' is an environmentally benign and low-cost pretreatment, which only needs water as a reagent. In the present study, HWE has been investigated as a pre-process prior to SPORL with Douglas fir as feedstock. The SPORL parameters, namely, temperature and treatment time, were in the range 135-155°C and 40-120 min, respectively, while the sulfuric acid concentration was 0.2-0.4% (v/v). The aim was to maximize the enzymatic digestibility of the treated wood. The severity of SPORL at different pretreatment conditions was characterized by the combined severity factor (CSF). The HWE pre-process led to a two-fold increase in specific surface area of the substrate. More hemicellulosic-derived simple sugars were dissolved in the spent liquor (SL) as the CSF increased from 1.23 to 1.82. A maximum enzymatic digestibility of 64.3% was attained when SPORL was conducted at 155°C for 120 min with a sulfuric acid concentration of 0.4% (v/v). A considerably high enzymatic digestibility (~55-60%) is still achievable by incorporating HWE prior to SPORL, even if the SPORL severity is reduced, namely to a lower temperature (145°C), a shorter time (80 min), and a lower acid volume (0.3% v/v). [ABSTRACT FROM AUTHOR]

Hot water extraction (HWE) partially removes hemicelluloses from wood while leaving the majority of the lignin and cellulose; however, the lignin partially migrates to the inner surfaces of the cell wall where it can be deposited as a layer that is sometimes visible as droplets. This lignin-rich material was isolated via Soxhlet extraction with dichloromethane to investigate its rheological behavior in blends with high-density polyethylene (HDPE), a common material in wood plastic composites (WPCs). Pyrolysis gas-chromatography/mass spectrometry (Py-GC/MS) and electrospray ion mass spectrometry (ESI/MS) confirmed that the isolated material is constituted mainly of low-molecular-weight lignin oligomers. The blends of HDPE/isolated lignin, in varying ratios, were tested by means of dynamic rheology. A 'shoulder' was found in plots 'shear storage moduli (G′) vs. frequency sweep' and a shift of the terminal zone to lower frequencies was observed. Apparently, this shoulder is caused by the elastic contribution of the interfacial tension between the blend components. The rheology of WPCs produced from HWE wood and HDPE shows a similar shoulder in G′ plots, suggesting that the HDPE/lignin blends are in part responsible for the shape of the G′ curves. [ABSTRACT FROM AUTHOR]