Preparation and characterization of polypropylene/wood flour/nanoclay composites

In this study, the effects of coupling agent and nanoclay loading on the mechanical properties and water absorption of composites are investigated. Composites based on polypropylene (PP), wood flour, nanoclay, and maleated polypropylene (MAPP) were made by melt compounding and then injection molding. The mechanical analysis showed that the biggest improvement of the tensile and flexural strengths can be achieved for the nanoclay loading at 3%. However, further increasing of the loading of nanoclay resulted in a decrease of all the mechanical properties. The maximum tensile and flexural strengths (increase of ??46%, compared to the pure PP) were achieved in the composites when 7.5% MAPP was used as coupling agent in the manufacture of the composites. Finally, it was found that addition of nanoclay or MAPP reduced the water absorption property of the composites. However, the extent of improvement in the water absorption is more prominent with MAPP.     

Effect of temperature, plastic type and virginity on the water uptake of sawdust/plastic composites

Water absorption of wood plastic composites (WPCs) manufactured from sawdust and virgin and recycled plastics (HDPE and PP) was studied. Wood flour was prepared from sawdust and mixed with different virgin or recycled plastics at 50% by weight fiber loading. The mixed materials were compression molded into panels. Water absorption of manufactured WPCs was determined after 2 and 24 h immersion in distilled water at different temperatures (25, 50 and 70 °C). WPCs containing recycled plastics exhibited higher water absorption especially when the two recycled plastics were mixed together. Immersion temperature had a significant effect on water absorption.     

Enhanced water resistance of extruded wood–polypropylene composites based on alternative wood sources

Polypropylene wood flour composites made from short-rotation coppice (SRC) and low valued beech wood (Fagus sylvatica) were investigated with respect to their suitability for use in the production of wood–polymer composites (WPC). An industrial wood source consisting of spruce wood flour (Picea abies) was used as reference material. All composites were compounded on a co-rotating twin screw extruder containing either 60 or 70 wt% wood flour. Consolidation was done by profile extrusion. Mechanical and physical properties of the composites were investigated. The wood sources were characterized concerning their particle length and shape by the use of a dynamic optical particle analysis system. X-ray microtomography (µ-CT) was used to study the dispersion of wood particles and the internal composite structure. However, all composites based on alternative wood sources showed an equivalent performance regarding mechanical properties compared to the composite reference. Composites containing beech wood flour showed notably reduced water absorption rates, whereas the composites based on SRC wood flour revealed significantly reduced moisture content compared to reference composites. A different particle length distribution was depicted between the industrial wood source and three other investigated wood sources. Moreover, all wood flour sources were characterized by a mean aspect ratio up to 3:1. The X-ray microtomography illustrated morphological differences between composites. Based on the X-ray images, an alignment along the melt flow and a decent encapsulation by polypropylene were shown.     

Fabrication optimization of polypropylene composites reinforced with steam-exploded wood flour by wet process

To take advantage of the unique characteristics of the wood flour by combining them with plastic in conventional panel pressing methods, a wet process was developed to make composites using polypropylene and steam-exploded (SE) flour from small-diameter loblolly pine. Wet-laid wood flour/polymer composites were fabricated using a standard TAPPI handsheet method followed by compression molding. The variables that may affect the product properties were investigated using an orthogonal test design. The results revealed that the modulus of elasticity (MOE) of composites increased, while modulus of rupture (MOR) decreased with increasing SE wood flour content. Both MOE and MOR of the composites increased with maleic anhydride grafted polypropylene content. Dynamic mechanical analyzer and differential scanning calorimetry measurement gave insight into the structure of these composites, and scanning electron microscope was used to characterize the interfacial adhesion.     

Exploring the potential of milkweed stalk in wood plastic manufacture

The physical and mechanical properties of milkweed composites based on different loads of milkweed flour and maleic anhydride grafted polypropylene (MAPP) using polypropylene as matrix are investigated in this study. There levels of milkweed fibers (30, 40, and 50 wt.%), one level of mixed milkweed flour (20:20 wt.% fiber:bark), and two levels of MAPP (4 and 6 wt.%) were used to prepare natural fiber-reinforced composites. Physical and mechanical properties including flexural, tension, impact, and thickness swelling were evaluated according to ASTM standards. The result demonstrated that addition of milkweed flour fluctuates mechanical properties of reinforced composite. However, the optimum load of milkweed flour was different in each test. Generally, 40 wt.% mixed flour composite in comparison with 40 wt.% milkweed composite showed lower mechanical results and higher thickness swelling. MAPP as a coupling agent improved physical and mechanical properties of milkweed-filled composites in most properties. The results of this study depicted positive effects of lignocellulose fibers and coupling gent and also negative effect of bark flour as a function of lower cellulose and higher extractive contents on physical and mechanical properties of milkweed-reinforced composites.     

Reinforcement of Polypropylene Composites Based on Recycled Wool or Cotton Powders

This article addresses the preparation and characterization of polymer composites of polypropylene (PP) containing recycled wool or cotton micro-powder. The PP composites were produced in a lab-scale twin-screw extruder. The recycled wool or cotton powder was obtained from wool and cotton waste fibers (from textile industry) by freeze milling technique. The amount of powder (wool or cotton) was varied from 1% to 10 %. Cotton and wool powders were homogenously distributed in the polymer matrix, as observed from scanning electron microscopic (SEM) images. Thermal, physical, and mechanical properties of the obtained composites were investigated by differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA), tensile strength, dyeability as well as the moisture uptake behavior is also explored. The overall results clarify that wool or cotton powders could be used as effective reinforcing materials for the production of PP composites with enhanced properties.     

Preliminary study of the stiffness enhancement of wood–plastic composites using carbon nanofibers

Vapor-grown carbon nanofibers (CNFs) were compounded into polypropylene (PP) with southern pine wood flour (WF) by high shear melt blending to investigate the reinforcement effects of CNFs on the stiffness of conventional wood flour/plastic composites. CNF loadings of 1, 2 and 5 parts by weight per 100 parts of PP were employed with three WF levels (20, 40 and 60 parts). Maleated polypropylene (MAPP) was used as a coupling agent to improve WF to PP compatibility. The incorporation of CNFs significantly increased the modulus of elasticity of these nanocomposites with MAPP addition. The presence of 0.61 wt?% of CNF within a 36.6%WF/1.83%MAPP/61%PP composite exhibited a modulus (7590 MPa) that was 59% greater than its counterpart without CNF (36.8%WF/1.84%MAPP/61.4%PP) (4783 MPa) and 90% greater than pure PP. The origin of this enhancement is not yet understood.     

Hybrid Composites Made from Jute/Coir Fibers: Water Absorption,Thickness Swelling,Density, Morphology,and Mechanical Properties

The action of water in natural fiber-reinforced composite material was studied so as to produce great swelling with resultant changes in the fine structure, dimensional stability, and mechanical properties. Water absorption and thickness swelling test reveal that hybrid composite shows water absorption moderately, which is 15.3% for hybrid coir/jute/coir composite and 11.2% for hybrid jute/coir/jute composite. The thickness swelling, water absorption, and mechanical properties of the hybrid composites slightly increased as the layering pattern of hybrid composites changed. Hybridization of coir fibers composites with jute fibers can improve the dimensional stability, extensibility and density of pure coir composites. Microstructures of the composites were examined to understand the mechanisms for the fiber-matrix interaction in relation to mechanical properties.     

木纤维-聚丙烯原料及复合材料的热解特性研究

利用热重分析仪对木纤维-聚丙烯(PP)复合材料及其两种主要原料在静态空气中的热解特性进行了研究.试验结果表明:木纤维在热解过程出现两次失重峰,在第一燃烧阶段,活化能比较稳定,平均72.83 kJ/mol;燃烧第二阶段热解复杂.聚丙烯属于单峰失重,初始热解活化能为127.77 kJ/mol,随着温度上升活化能降低,甚至低于木材活化能,但综合比较热稳定性聚丙烯比木纤维高.木纤维-聚丙烯复合材料表现出两种原料共同促进了热解、燃烧的现象.     

Influence of chemical modification of wood on the crystallisation of polypropylene

The mechanical properties of wood/polypropylene composites depend strongly on interfacial adhesion between components. However, the application of chemical modification to improve compatibility can influence the supermolecular structure of polypropylene matrix. The experimental material comprised two most common Polish timber species pine wood (Pinus silvestris L.) as a softwood species and beech wood (Fagus silvatica L.) as a hardwood species. The size of wood sawdust ranged from 0.5 to 1.0 mm. Three different types of wood/PP mixture were prepared: (1) PP – untreated wood, (2) PP – NaOH treated wood and (3) PP – esterified wood with maleic anhydride. In this work, the kinetic parameters of crystallization of PP by differential scanning calorimetry were investigated. It is interesting that crystallisation of PP depends on the kind of wood. The chemical treatment of wood caused changes of crystal conversion and half crystallisation time of polypropylene matrix.     

Microfoaming of flax and wood fibre reinforced polypropylene composites

Natural and wood fibre reinforced plastics as a relatively new group of environmental friendly materials have been extensively applied in interior, building applications and in the automobile industry. Among others, natural and wood fibre reinforced foamed polymer materials are of high significance because of the possibility of their reducing the density of automotive components which have a cellular structure. However, the properties of these materials have not been fully investigated and described. Microcellular composites of polypropylene containing natural and wood fibre was prepared using an injection moulding process. In the present work, the manufacturing technology of natural and wood fibre reinforced polymer microfoams was developed and the influence of fibre and microvoid content on its property spectrum was systematically investigated. The forming of microvoids and the degree of foaming related to the variation of the processing parameters in connection with manufacture technology was characterised. Measurement of density, cell size, tensile and flexural properties of the prepared composites was carried out. The cell structure is dependent on flow direction of foaming. The density of microfoamed wood fibre-PP composites was reduced by about 24% and decreased by as much as 0.77 g/cm³.Light microscopy showed that the cells are circular and it was also observed that the maximum cell sizes are between 10–50 μm. Water absorption and scanning electron microscopy of the composites were also investigated. Considering the experimental results, it can be deduced that the microcellular composites exhibit a possible combination of relatively good engineering properties and lower density for different technical applications.     

An Experimental and Numerical Investigation on the Mechanical Properties of Addition of Wood Flour Fillers in Red Banana Peduncle Fiber Reinforced Polyester Composites

ABSTRACT

In this work, eco-friendly red banana peduncle fiber reinforced polymer composites (RBPF) and wood flour are added as a filler (RBWF) were prepared using compression molding process. These composites were analyzed by testing of properties such as tensile strength, flexural strength, impact strength, and water absorption. Tensile and flexural properties of the composites are verified using ANSYS. The chemical functional group of the composites was analyzed by Fourier transform-infrared spectroscopy (FT-IR). Microscopic examinations were conducted using the scanning electron microscopy (SEM) analysis. Crystallinity index (CI) and Crystalline Size (CS) of the composites were found by conducting X-ray diffraction (XRD) analysis. Results indicated their appropriateness in lightweight applications in automobile, construction and aviation industries.     

Effects of Wood Particle Size and Mixing Ratios of HDPE on the Properties of the Composites

The main goal of this research is to innovate wood-plastic composites by using various wood particle sizes and different mixture ratios (weight ratio) of HDPE (High Density Polyethylene). After mixing the wood particles (recycled wood waste) and the plastic powder, we use a molding and pressing process to make composites with a thickness of 12 mm. By doing so, the wood particle content can be increased to 75%. This kind of composite provides excellent dimensional stability, its moisture content is under 2.5%, and the thickness swelling rate after 24 hr water absorption is under 7.5%. The maximum static bending strength of this composite reaches 20.7 N/mm², and is better than that of general commercial particleboards. The composite made of larger sized wood particles has better strength properties. In addition, when the plastic content ratio increases, the dimensional stability of the composite will increase as well. After the soaking process in boiling water, the static bending strength of wet composite remained at 50%; this shows the good weather resistance of the composite. The surface veneer overlaid peeling strength of the composite showed 1.02–1.63 N/mm. After the evaluation of processing, cost of material and strength properties of the composite, we would suggest that the use of 70% of wood particles and 30% of plastic powder is practical to produce proper sized composites.     

Physical modification of polypropylene fibers used in construction

One of the applications of polypropylene fibers (PP) is in construction like reinforcement in concretes. Research on the use of PP fibers in silicate composites already has fairly long history. But there are some disadvantages, which must be eliminated. Observed, low affinity between the fibers and cement matrix is associated with nonpolar, hydrophobic, physical, and chemical inactive polyolefinic character of this polymer. The increase in adhesion of PP fibers to matrix could be achieved with the physical modification of PP fibers with inorganic additive. The most importance inorganic additive into concrete is silica fume. The aim of our paper is the presentation of the influence of modification on properties of PP fibers. There will be evaluated the optimization of composition (contents of nanoadditive and dispersant) of prepared PP fibers based on the mechanical and thermomechanical properties, the sorption moisture as well as on the macromorphological structure of PP surface.     

木塑复合材料力学性能影响因素研究

采用木材刨花与LDPE、HDPE.和PP等热塑性高分子聚合物,经热压复合工艺制成木塑复合板材,研究了塑料基质种类、刨花用量与偶联剂种类对木塑复合材料力学性能的影响。结果表明:相较于LDPE和PP,由HDPE制成的木塑复合材料力学性能更佳;所使用的三种偶联剂,以硅烷偶联剂的效果最好;随着刨花用量的增加,木塑复合材料的抗弯曲性能逐步提高,但内结合强度逐渐下降。     

Relationship between dye sorption and morphology in polypropylene/poly (butylene terephthalate) microfibrillar blend nanocomposite fibers

In this research work, the relation between microstructural enhancement and dyeing behavior of immiscible blend nanocomposite fibers was investigated using scanning electron microscopy, transmission electron microscopy, X-ray diffraction patterns, and rheometric mechanical spectrometer along with quantitative analysis of dye sorption. A novel microfibrillar morphology blend fiber, in which poly (butylene terephthalate) nanocomposite fibrils uniformly distributed in the cross section of polypropylene matrix, was successfully developed using melt compounding process. Preferred location of nanoclay had improving effect on poly (butylene terephthalate) fibril formation such that there was an organoclay concentration above that fiber with fine microfibrillar morphology could hardly be produced. It was demonstrated that nanoclay melt intercalation and partitioning controlled the activation energy of dyeing. The maximum sorption rate was achieved by utilizing compatibilizer to transfer part of nanoclay platelets into the polypropylene matrix.     

Use of starch granules melting to control the properties of bio‐flour filled polypropylene and poly(butylene succinate) composites: Mechanical properties

The feasibility and industrial potential of using bio‐flours from tropical crop residues, in particular starch containing bio‐flours, for the manufacture of bio‐composites was investigated. Polypropylene (PP) and poly(butylene succinate) (PBS) were compounded with bio‐flours from pineapple skin (P) and from non‐destarched (CS) and destarched (C) cassava root by twin‐screw extrusion. In CS composites, two levels of starch granules melting were achieved by adjusting the extrusion temperature, enabling control of morphological and mechanical properties. The use of bio‐flours reduced tensile strength by 26–48% and impact strength by 14–40% when the proportion of bio‐flour was increased to 40% w/w, while flexural strength initially increased upon addition of bio‐flours, before decreasing at higher loads. The use of compatibilizers, in particular maleic anhydride‐polypropylene (MAPP) in PP composites with 30% bio‐flour resulted in tensile strength similar to non‐compatibilized composites with 10% bio‐flour (34–35 MPa). MAPP also increased flexural strength to higher levels than pure PP, resulting in a stronger, but less flexible material.     

Effectiveness of polypropylene film as a barrier to migration from recycled paperboard packaging to fatty and high-moisture food.

The capability of a polypropylene (PP) film barrier to prevent migration of residual contaminants from recycled paperboard into food simulants was studied. Anthracene, benzophenone, methyl stearate and pentachlorophenol were chosen as chemical surrogates to represent classes of contaminants likely to be found in recycled paper/paperboard. Each surrogate was spiked into a test specimen made of seven thin virgin paper layers at concentrations of 1-50 mg kg(-1). Test specimen were dried, stacked and sandwiched with PP films, laminated with PP film and then subjected to migration experiments using a compression cell maintained at 100 degrees C for 2 h. The concentration of the surrogates in the test specimen and in 95% ethanol, isopropanol and 10% ethanol food-simulating solvents was determined by gas chromatography with flame ionization and electron capture detection. The results show that although the concentrations of the surrogates in the food simulants decreased with an increase in PP film thickness, they were still high and generally resulted in dietary concentrations >0.5 microg kg(-1), the level that US Food and Drug Administration would equate with negligible risk for a contaminant migrating from food packaging. Only at the lowest spiking level (1 mg kg(-1) benzophenone) did migration from the paperboard through a 0.127-mm PP film result in a dietary concentration of 相似文献   

Characterizing the migration of antioxidants from polypropylene into fatty food simulants

The migration (diffusion and equilibrium) processes of antioxidants (AOs) from polypropylene (PP) films of different thicknesses into n-heptane and 95% ethanol as fatty food simulants were analysed at 20, 37 and 60°C. Heptane fully extracted the AOs from the polymer while a partition equilibrium described the migration to ethanol. The kinetics of migration were also studied via the diffusion coefficients. As expected, diffusion was found to be faster when the polymer was in contact with heptane, due to polymer swelling by the solvent. The kinetics of the process in ethanol was described by different theoretical expressions which are discussed. Equations disregarding partition equilibrium failed to describe the process and the diffusion coefficient values obtained through them were much smaller than the actual ones and dependent on film thickness. The results also showed the significance of food simulant selection in the analysis of food-packaging interactions and migration variability with thickness.     

Improving the UV and water-resistance properties of Scots pine (Pinus sylvestris) with impregnation modifiers

Wood modification is commonly used to alter and improve wood properties. This study investigates the effects of impregnation modification with four environmentally nontoxic agents on the UV-resistance and water absorption properties of solid wood. Scots pine (Pinus sylvestris) was impregnated with modifiers by pressure device. The solid wood specimens were treated with water glass, silicone, melamine, and tall oil. The modified samples were analyzed by SEM microscopy, and thickness swelling, water absorption and UV resistance were determined. The penetration of the studied modifiers differed. The melamine-treated samples were found to exhibit the best impregnation, which also affected the wood properties favorably. The melamine-treated solid pine wood samples absorbed half of the water absorbed by wood treated with the other solutions and attained the best results in thickness swelling and weathering tests. It is concluded that impregnation modification of Scots pine is dependent on the nature of the modifier and based on the results of this study, melamine solution treatment is found to have a positive effect on the properties of solid pine wood.