Pine Fibers Research Articles

Fiber Pretreatment and Its Effects on Wood Fiber Reinforced Polypropylene Composites

ABSTRACT This study investigates the effect of pretreatment of fiber with NaOH and coupling with maleated polypropylene (MAPP) on the physical and mechanical properties of composites, based on radiata pine (Pinus Radiata) fiber, produced with a polypropylene matrix, using a twin-screw extruder followed by injection molding. Prior to reinforcement, the fiber was treated with NaOH. The effect of treatment was assessed using zeta potential, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Tensile testing, SEM, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) were carried out to assess the effect of modification on composite properties. An increase of 106% for strength and 302% for Young's modulus were obtained by using 60 wt% fiber and 2 wt% MAPP, compared to the unreinforced matrix. Fiber pretreatment with NaOH reduced strength but improved Young's modulus (370% compared to unreinforced matrix) of resulted composite.

Corn gluten meal as a biodegradable matrix material in wood fibre reinforced composites

This study was undertaken to investigate corn gluten meal (CGM) as a biodegradable matrix material for wood fibre reinforced composites. CGM was used alone, as well as hybridized with polypropylene, and reinforced with radiata pine ( Pinus Radiata) fibre using a twin-screw extruder followed by injection moulding. Tensile testing, scanning electron microscopy and differential scanning calorimetry were carried out to assess the composites. For composites from CGM and wood fibres, extrusion was carried out with the aid of the following plasticizers: octanoic acid, glycerol, polyethylene glycol and water. Windows of processability for the different plasticizers were obtained for all plasticizers. These were found to lie between 20 and 50 wt.% of plasticizer with a maximum of approximately 20% wood fibre reinforcement. The best mechanical properties were obtained with a matrix containing 10 wt.% octanoic acid and 30 wt.% water, which gave a tensile strength and Young's modulus of 18.7 MPa and 4 GPa, respectively. Hybrid matrix composites were compounded with a maleated polypropylene coupling agent and benzoyl peroxide as a cross-linking agent. The highest tensile strength and Young's modulus obtained from hybrid matrix composites were 36.9 MPa and 5.8 GPa with 50 wt.% fibre.

The Effect of Poly[methylene(polyphenyl isocyanate)] and Maleated Polypropylene Coupling Agents on New Zealand Radiata Pine Fiber–Polypropylene Composites

The effects of poly[methylene (polyphenyl isocyanate)] (PMPPIC) and maleated polypropylene (MAPP) coupling agents, separately and combined, on the strength and Young’s modulus of New Zealand radiata pine-reinforced polypropylene (PP) composites were assessed. A modest improvement compared to the unreinforced matrix strength of 4% and much greater improvement of 123%, substantially greater than reported elsewhere in the literature, were obtained using PMPPIC and MAPP respectively. Young’s modulus improvements compared to the unreinforced matrix of 77 and 177% were obtained using PMPPIC and MAPP respectively. The MAPP coupling agents with the longest chain lengths and lower functionality gave the greatest benefit, supporting chain entanglement as the major mechanism for enhanced bonding with PP. Relatively high moulding temperatures and low injection pressures, bringing about enhancement of fiber orientation in the test direction, also appear to have contributed to such large improvements in composite properties in the current work. Combination of PMPPIC and MAPP coupling agents produced mixed results: benefits were obtained by combining PMPPIC and MAPP with the longest chain lengths which can be explained by PMPPIC bonding with hydroxyl groups not accessible to further coupling with MAPP once saturation is achieved.

Tensile properties, morphology, and thermal behavior of PVC composites containing pine flour and bamboo flour

AbstractComposites of unplasticized poly(vinyl chloride) (PVC) blended with bamboo flour and pine flour, respectively, were prepared in a batch mixer followed by compression molding. The effects of wood flour fillers on the morphology, static mechanical properties, and thermal properties of the composites were investigated. Compared with neat PVC resin, the introduction of both bamboo flour and pine flour significantly improved the stiffness of the composites, while decreasing the tensile strength to some extent. Tensile tests showed that pine flour–filled composites exhibited better mechanical properties than those filled with bamboo flour with the same particle size at the same loading level. Scanning electron microscopic examination revealed good dispersion and alignment tendency of short pine fiber within the composites at a lower loading level. Moreover, experimental results indicated that both bamboo flour and pine flour additions showed no obviously adverse effect on the thermal stabilities of these composites. Based on the comprehensive properties, these composites meet the need of woodlike material for use as wood structures. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1804–1811, 2004

New thermoplastic materials reinforced with cellulose based fibers

AbstractThe preparation of new cellulose fiber reinforced thermoplastics is described, and the mechanical properties and water absorption of these materials are measured.In order to improve the compatibility between cellulosic and plastic materials, different amounts of coupling agents, such as organotitanate compounds, maleic anhydride copolymers and their combinations, are studied. As a filler, pine fiber, rose, carnation or coffee husk is used. Furthermore, the influence of the composition of the composites and the particle size of the filler on the material properties of the thermoplastics are investigated. The surface of the fractured samples is analyzed using scanning electron microscopy (SEM). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3466–3472, 2003

The effect of silane coupling agents on radiata pine fibre for use in thermoplastic matrix composites

Abstract Gamma-aminopropyltriethoxysilane (GS) and dichlorodiethylsilane (DCS) were employed for surface modification of radiata pine ( Pinus radiata ) wood fibre. Levels of fibre moisture were carefully controlled to optimise chemical and hydrogen bonding with these silane coupling agents. The effect of pre-treatment using 2% sodium hydroxide, shown to be effective in assisting silane coupling for other natural fibres [Composites, Part B: Engng 30 (1999) 321], was also investigated. X-ray photoelectron spectroscopy and nuclear magnetic resonance (NMR) were used to characterise modification of the wood fibre. Concentrations of up to 3.2 wt% Si were obtained on the fibre surface due to silane coupling, however, pre-treatment was found to dramatically reduce this value. NMR provided evidence that coupling had occurred between the fibre and DCS by reaction producing ether linkages between the hydroxyl groups on the wood fibre and silane. Pre-treatment and treatment were found to have an insignificant effect on fibre strength. Composite sheets were produced by blending fibre (5, 10 and 20 wt%) with polyethylene followed by extrusion. An increase in strength was obtained at fibre contents of 5 wt% for all treatments compared to composites with untreated fibre. This is believed to be mainly due to increased compatibility of the fibre surface to polyethylene. However, there was no such improvement obtained at higher fibre contents. Evidence suggests that the production of voids is limiting composite strength.

Medium Density Fibreboard Manufactured from Blends of White Cypress Pine and Non-Durable Wood Species Shows Increased Resistance to Attack by the Subterranean Termite C. lacteus

Summary Medium density fibreboards consisting of blends of the naturally durable wood species white cypress pine (Callitris glaucophylla) and non-durable wood species were manufactured in a commercial plant and subjected to a bioassay using the subterranean termite species, Coptotermes lacteus. A board composed of 30% cypress pine, 30% slash pine (Pinus elliottii) and 40% of the naturally durable hardwood species spotted gum (Corymbia maculata) was also manufactured and bioassayed against C. lacteus. The aims were to determine (i) whether boards containing cypress pine possessed increased resistance to termite attack compared to a control manufactured entirely from non-durable wood species; (ii) the relationship between the cypress pine content of boards and their resistance (if any) to termite attack; (iii) whether the termite resistance of boards containing cypress pine could be further enhanced by the addition of spotted gum fibre. There was an inverse relationship between the cypress pine content of MDF specimens and mass losses of the specimens during the bioassay; the percentage mass losses of specimens containing 11.4, 16.2 and 34.2% cypress pine being 20.3, 13.4 and 8.8%, respectively, compared to 32.8% for the control, which consisted of non-durable slash pine (80%) and hoop pine (Araucaria cunninghamii) (20%) fibre. There was strong evidence that the inverse relationship between the cypress pine content of boards and mass losses during the bioassay was linear, although a statistically significant quadratic (curvilinear) effect was also apparent. The addition of spotted gum fibre to boards did not increase their resistance to termite attack. Cypress pine heartwood contains a variety of extractives that are either toxic or repellent to termites, and the increased termite resistance of MDF containing cypress pine compared to the control is probably due to the insecticidal effect of such chemicals on C. lacteus. The incorporation of cypress pine fibre into MDF shows promise as an alternative to chemical biocides for increasing the resistance of MDF to termites. However, the response of termites to heartwood extractives varies between species, and therefore further experimentation is needed to test the resistance of MDF containing cypress pine fibre to attack by greater range of wood destroying termites under test conditions that more closely simulate field conditions.

Einfluß der Lagerung von Industrierestholz der Klefer und Fichte auf seine Eignung für die Herstellung von Spanplatten und mitteldichten Faserplatten (MDF)

Particle- and medium density fibreboards (MDF) were prepared from chips of spruce and pine, a byproduct of sawing wood in a saw mill with a profiling unit. The wood residues were stored in piles of 40 m 3 volume for different time periods. The physical-technological properties of the particle- and fibreboards prepared therefrom were evaluated and the formaldehyde release of the boards was assessed. The results reveal: In general, there is a positive influence of storage on the thickness swelling and internal bond strength of UFbonded particleboards; the bending strength of UF-bonded particleboards showed no pronounced response to storage. The positive influence of storage on the thickness swelling and internal bond strength was much higher in case of boards made from pine chips than in case of spruce boards. On using PMDI as a binder for particleboards no significant influence of storage on the thickness swelling, internal bond strength and bending strength was detected. The influence of storage on the thickness swelling of UF-bonded MDF from pine fibres was much less pregnant than on that of UF-bonded particleboards. On UF-bonded MDF from spruce the influence of storage, if any, was negligible. On using PMDI as a binder for MDF there was no detectable change in the thickness swelling due to storage. The internal bond strength of UF-bonded MDF experiences only subtle positive change due to storage of pine wood chips. However, no notable change was detected in case of MDF from spruce. Storage has almost no influence on the chemical properties of boards.

Einfluß der Lagerung von Industrierestholz der Kiefer und Fichte auf seine Eignung für die Herstellung von Spanplatten und mitteldichten Faserplatten (MDF)

The residues of a saw mill with a profiling unit were stored in piles of about 40 m 3 for different time periods. From time to time wood material was taken from the piles and disintegrated to chips using a ring flaker or pulped using the thermomechanical process and defibrated. Both chips and fibres were analysed chemically to detect any change in adhesion relevant properties, especially in pH-value, buffering capacity, amount of volatile acid content in the extractives. Moreover, the formaldehyde release and the emanation of volatile acids were assessed using the flask-method technique. The results led to the following conclusions : the pH-value of cold and hot water extractives of chips and fibres derived from saw mill residues increased slightly on seasoning of the residues. The hot extractives showed, however, lower pH-values and higher alkaline buffering capacities than the cold water extractives. The results of measuring the volatile acid content in extractives are in harmony with those of pH-value and buffering capacity. The content of volatile acids of fibres and flakes decreased on seasoning of saw mill residues as well as the release of volatile acids from flakes and fibres. Likewise, storage decreased the formaldehyde release from the chips on seasoning the saw mill residues. Pine flakes and fibres showed always lower pH-value, higher alkaline buffering capacity compared to spruce chips and fibres. Moreover, the release of volatile acids from pine flakes and fibres was much higher than from spruce wood. The changes in adhesion related properties in saw mill residues of pine wood were much pregnant than in spruce.

Structure of mixed pine and hardwood stands 12 years after various methods and intensities of site preparation in the Georgia Piedmont

In the Georgia Piedmont (U.S.A.), size, abundance, and species diversity of trees were quantified in a plantation of Pinustaeda L. 12 years after various methods and intensities of site preparation. In clear-cut only versus site-prepared plots, greater hardwood abundance (27% vs. 8% of the total basal area) and size (8.6 vs. 7.4 m in height) were associated with reduced pine volume (73 vs. 123 m3/ha) and increased Simpson and Shannon diversity indices. Tree-species richness was greater in plots where residual trees from clear-cutting had been removed with a chainsaw versus large machinery (10 vs. 7 species). With increasing site-preparation intensity, reductions in basal area of volunteer pines coincided with proportionate increases (R2 = 0.80) in basal area of planted pines. As a result of this compensatory effect, total volume of all pines varied little (122–134 m3/ha) among site-preparation intensities. Research results suggest that site-preparation treatments can be selected to facilitate the development of a variety of stand structures, including those that favor evenness (clear-cut only) or richness (manual cutting) of tree species, low-cost production of pine fiber (manual cutting), and stand uniformity for management of pine sawtimber (mechanical and herbicide).

Twisting energy of holocellulose fibers

AbstractFreely drying fibers exhibit collapse and twist behavior that is only infrequently observed in the formation of a paper web. Anisotropic fiber shrinkage models are employed that enable calculation of the twisting energy of a freely drying fiber as well as the reverse case (dry to wet). The twisting energy appears to be highly significant in relation to the fiber and bond energies associated with paper strength. Some experimental results with southern pine fibers have been obtained using specially designed testing devices.