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This research aims to improve the flame-retardant properties of wood–plastic composites with different recycled plastics. Acrylonitrile butadiene styrene (ABS) and polyvinyl chloride (PVC), flame-retardant materials, and recycled polypropylene (PP) were used as matrix in this research. Recycled ethylene propylene diene monomer (EPDM) with flame-retardant properties was also added to mix with rubberwood flour (RWF) to improve mechanical properties. The rubberwood flour, coupling agent (MAPP), and lubricant are fixed at 44.5%, 4%, and 1%, respectively, whereas recycled plastics and EPDM rubber contents are in the range of 30.5–50.5% and 0–20%, respectively. The composite materials were manufactured into panels using a twin-screw extruder and hot press machine. The experimental results were statistically analyzed by analysis of variance (two-way ANOVA) at a 95% confidence level. The highest values of the mechanical parameters of wood–plastic composites reinforced with recycled polypropylene (RWF44.5PP50.5) were 15.89 MPa, 42.26 MPa, 41.79 MPa, and 0.0202 J for tensile strength, flexural strength, compression strength, and impact strength, respectively. An increasing EPDM rubber content of wood–plastic composites provided better thermal properties. The thermogravimetric analysis and differential scanning calorimetry of hybrid composites with recycled ABS (RWF44.5ABS30.5EPDM20) obtained the highest value with thermal stability in the range of 255–284 °C. For the flammability properties, the hybrid composites with high EPDM rubber content were less flammable. Recycled PVC with content of RWF44.5PVC50.5 outperformed hybrid composites reinforced made from ABS and PP in terms of UL-94 and the limiting oxygen index with values of 25.73%. [ABSTRACT FROM AUTHOR]

Natural fibers are an alternative to reduce the use of synthetic materials in acoustic products. Such fibers have the benefits of being inexpensive, environmentally benign, biodegradable, and safe for human health. The influence on sound absorption coefficient of different natural fibers including rubberwood, coconut coir, and oil palm empty fruit bunches was investigated. The samples were composed of three kinds of natural fibers, three different fiber sizes, and two different kinds of adhesives. The porosity values of the samples were found in the range of 4.58-8.84% whereas the lowest water absorption value was found on the sample with rubberwood fiber in the range of 57.62-127.83%. Impedance tube testing was used for the sound absorption tests following ISO 10534-2. The experimental result revealed that the natural fibers have good performance associated with the fiber length. The longer fiber performs the better sound absorption than that of the short fiber. All kinds of natural fiber plates tested had sound absorption of 50% above 3.5 kHz whereas the oil palm fiber gave the highest absorption coefficient at 95%. The fiber size fraction approved that those fibers could improve the peak values of sound absorption. The small fiber size gave higher peak values than that of the large fiber size. The type of adhesive influences sound absorption coefficient on the sample with small fiber size (80 mesh) than that of the large fiber size (40 mesh). The output of this study reveals the waste plant fibers could adopt to develop sound absorber building materials. [ABSTRACT FROM AUTHOR]

Mixture design method of experiments was used to determine the compositions of wood-plastic composite samples manufactured from recycled polypropylene (rPP), rubberwood flour (RWF), and calcium carbonate (CC). Factors were determined the mixture compositions rPP, RWF, CC, maleic anhydride-grafted polypropylene (MAPP), ultraviolet (UV) stabilizer, and lubricant (Lub) on properties of the samples, namely tension, compression, surface roughness, water absorption (WA), thickness swelling (TS), and thermogravimetric analysis (TGA). The specimens were produced by extrusion and compression molding methods. The analysis of variance and response surface methodology were employed for the analysis and optimization of the compositions. Optimal composition for overall response was 51.8 wt% rPP, 35.9 wt% RWF, 7.2 wt% CC, 3.9 wt% MAPP, 0.2 wt% UV stabilizer, and 1.0 wt% Lub with desirability score combining their output value of 0.757. The addition of CC content increased the mechanical properties but decreased the WA and TS. A high RWF content increased WA and TS with longer immersion times. The TGA of composites mainly depends on the chemical components of RWF and rPP types. The scanning electron microscope morphology in the composites with different amount of CC increased their densities due to good dispersion of CC as filler and good contact between the RWF reinforcement and rPP matrix. [ABSTRACT FROM AUTHOR]

Rubberwood (Hevea brasiliensis) is a major raw material used in furniture factories in southern Thailand. Proper kiln drying of the lumber plays a significant role on the efficient utilization of the final product. Overall quality-reducing defects in such a materials are inevitable, unless a correct and proper drying process is used. Therefore, the objective of the present study was to develop a three-dimensional numerical model of heat and moisture transfer during the drying process and to conduct physical experiments in order to compare the results between the two approaches. For this purpose, an innovative kiln dryer was designed in the laboratory which will also contribute to the prevention of defects in the wood. The results show that the samples dried at a temperature of 120 °C experienced faster decreases in their moisture content compared to those dried at temperatures of 100 °C and 80 °C. The drying temperature and moisture content of the samples were successfully predicted by the simulation model created in this investigation and the two approaches demonstrated good agreement for temperature and moisture with root mean square errors of 0.50 and 0.19, standard errors of 0.38 and 0.16, and mean absolute errors of 0.94 and 2.18, respectively. These results will help rubberwood drying facilities prevent wood deformation while reducing the drying time required. [ABSTRACT FROM AUTHOR]

Rubberwood flour (RWF) was treated by alkaline, silane, and alkaline–silane, and consequently, reinforced recycled polypropylene (rPP) composites. The wood–plastic composites (WPCs) were prepared with 40 wt% RWF content using a twin-screw extruder, followed by compression molding. Silane treatment was applied at various concentrations and treatment times to evaluate the effect of treatment conditions on water absorption, mechanical properties, thermal properties, and morphological characterization of WPCs. The results indicated that alkaline–silane treatment of RWF exhibits higher properties in comparison to silane or alkaline only. In addition, silane concentrations significantly affected water absorption, mechanical strength, and hardness, while treatment times remained relatively unaffected by these properties. The best water resistance, mechanical strength, and hardness of WPCs were achieved by alkaline–silane treatment with 5% silane concentration for 2 h, which improved the interfacial adhesion of RWF and rPP as well as increased the crystallinity in the WPCs. [ABSTRACT FROM AUTHOR]

This study aimed to determine the equilibrium moisture content and to develop an indirect measurement technique for the moisture content (MC) by observing temperature and vapor pressure during hot air drying. The temperature and gas pressure were recorded during hot air drying at several points within wood sample specimens conforming to ASTM D 143 and AOAC, 1990. The moisture content was estimated from measured temperature and pressure. The accuracy of MC estimates was validated by oven-drying method. For validation, nine experiments at different temperatures of hot air drying were run and the indirect measurement was found to provide a good accuracy. The obtained statistics were R2 = 82.5%, standard error (SE) ranging from 0.15 to 0.43, root mean square error (RMSE) ranging from 0.16 to 0.38 and mean absolute error (MAE) ranging from 0.4 to 1.1 respectively. It can be concluded that the air in wood was removed completely, especially when the MC was below the fiber saturation point. We have demonstrated an alternative moisture content monitoring method for potential adoption by the rubberwood industries. [ABSTRACT FROM AUTHOR]

The influences of plastic matrix on mechanical properties (flexural and tensile properties) of wood-plastic composites (WPCs) were investigated. WPCs were prepared with five types of plastic as the matrix phase, namely high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP), polyvinyl chloride (PVC), and polystyrene (PS). Rubberwood flour was used as reinforcing filler. Additionally, maleic anhydride, UV-stabilizer, and paraffin wax were used as coupling agent, ultraviolet stabilizer and lubricant, respectively. The WPCs were produced in two stages: mixing in an internal mixer, and compression molding. WPCs from PS and PP exhibited higher mechanical properties whereas LDPE, HDPE, and PVC gave lower values. In particular LDPE gave consistently the poorest mechanical properties to WPCs. Moreover, the WPCs with PS and PP had the smallest losses of mechanical properties from natural weathering, while LDPE would again be the poorest choice in this respect. These results indicate that WPCs from PP and PS are the best alternatives for applications requiring resistance to natural weathering (exposure to ultraviolet and humidity) or with high mechanical loading (stresses). [ABSTRACT FROM AUTHOR]

The mechanical and physical properties of wood-plastic composites (WPCs) were determined as function of different contents of nanoclay, talcum, and calcium carbonate as filler. It appears that the specimens made with 7 wt% calcium carbonate content resulted in the highest strength values. The modulus of rupture of the samples linearly increased with increasing amount of filler. The WPCs specimens having 9 wt% nanoclay showed the lowest dimensional stability in the form of water absorption and thickness swelling. An addition of 3 wt% talcum content also presented the highest cooling temperature and crystallization. Content of 7 wt% of calcium carbonate was determined as optimum level of filler regarding overall mechanical and physical properties of WPCs specimens. [ABSTRACT FROM AUTHOR]

The present study aims to investigate the moisture absorption of polypropylene (PP)/rubberwood flour (RWF) composites and its effects on dimensional stability. The compositions included different grades of plastic, and the amounts of wood flour, maleic anhydride-grafted polypropylene (MAPP), and ultraviolet (UV) stabilizer were varied. The composite materials were manufactured into panels by a twin-screw extruder. Long-term water absorption (WA), long-term thickness swelling (TS), and degradation of flexural properties of the composites were studied for a range of water immersion times. The WA and TS of the samples increased with RWF content and immersion time. Recycled PP gave higher WA and TS than virgin PP, for the composites with 45 wt% RWF. Increasing MAPP content from 3 to 5 wt% had no significant effect on WA and TS, whereas the addition of 1 wt% UV stabilizer increased them. A MAPP content of 3 wt% is recommended for moisture resistance, while the amount of UV stabilizer should be kept as low as possible. Flexural strength and modulus of composites also decreased with moisture uptake; however, <3% WA did not significantly affect the flexural strength. In contrast, the maximum strain of composites consistently increased with WA. [ABSTRACT FROM AUTHOR]

The mechanical properties of composites from recycled waste plastic and waste sawdust are of interest in trying to convert these waste streams to useful products. The development of these composites from natural fiber is therefore receiving widespread attention due to the growing environmental awareness. The effects of compositions were investigated including different grades of plastic (virgin and recycled) and amounts of wood flour, coupling agent, and ultraviolet (UV) stabilizer on mechanical and physical properties of polypropylene/rubberwood flour (RWF) composites. Virgin polypropylene gave better mechanical properties than recycled (recycled polypropylene (rPP)), both in composites and as unfilled plastic. RWF content exceeding 25 wt% enhanced the strength of RWF-reinforced rPP composites. The modulus and hardness of composites increased linearly with wood flour loadings. Maleic anhydride-grafted polypropylene (MAPP) as a coupling agent increased the strength, modulus, and hardness of the composites. However, addition of 1 wt% UV stabilizer degraded the mechanical properties. Therefore, 4 wt% MAPP content is recommended to achieve good mechanical properties of rPP/RWF composites, while the amount of UV stabilizer should be as small as possible to avoid its negative influence. [ABSTRACT FROM AUTHOR]

Composites of rubberwood flour (RWF) and recycled polypropylene (rPP) were produced into panel samples by using a twin-screw extruder. The effects on creep behavior of mixture fractions of rPP, RWF, maleic anhydride-grafted polypropylene (MAPP), and ultraviolet (UV) stabilizer were studied in a D-optimal mixture design. Creep was significantly affected by the composition. Increasing the fraction of RWF decreased creep, while MAPP and UV stabilizer increased it. The models fitted were used to optimize a desirability score that balanced multiple creep characteristics. The model-based optimal formulation 50.5 wt% rPP, 44.9 wt% RWF, 3.5 wt% MAPP, 0.1 wt% UV stabilizer, and 1.0 wt% lubricant was experimentally validated to have low creep closely matching the model predictions. [ABSTRACT FROM PUBLISHER]

The effects of time, temperature, and stress on the flexural creep of composites from recycled polypropylene (rPP) and rubberwood flour (RWF) were experimentally investigated and numerically modeled. Creep of rPP/RWF composites increased with an increase of time, temperature, and stress. A critical temperature of rPP composites containing 44.5wt% RWF is 65°C. Burger, Power law, and HRZ models fit the creep profiles well in general, but at high temperature and stress levels the Power law and HRZ models performed poorly. However, the HRZ model interpolated creep well across the applied stresses, or across the temperatures. The time-temperature superposition (TTS) and time-stress superposition (TSS) principles were used to model long-term creep. The master curves from TTS and TSS principles were in good agreement with each other. They predicted that the lifetime limitation by long-term creep exceeds 10years for 15MPa stress at 25°C. All these results pertain to a specific formulation of rPP/RWF composites. [ABSTRACT FROM AUTHOR]

Wood–plastic composites (WPCs) have been proposed as an alternative to natural wood due to their physical and mechanical properties. Development of these composites from natural fibers is receiving widespread attention partly because of growing environmental awareness. To dispose of produced waste from industry, low-value fiber resources could be converted into high-value products. This research studies the combination of polyvinyl chloride (PVC) to rubberwood (RBW) fiber, to palm oil trunk fiber, and to palm oil shell (POS) fiber. Composite performance optimization, material option comparison, basic engineering performance improvement, and durability of WPCs have been investigated. A two-stage process consisting of compounding and forming to produce WPCs using 40%–60% natural fiber reinforcements was carried out. Physical and mechanical properties of the WPCs were studied. The results showed that WPCs consisting of 60% RBW fiber and 40% PVC yielded the highest modulus of elasticity and modulus of rupture, which are approximately 90,130 MPa and 433 MPa, respectively. The ultimate compressive strength with a value of approximately 316 MPa was achieved from 60% POS fiber and 40% PVC. Reinforcing 40% POS fiber in 60% PVC exhibited the lowest water absorption rate. The overall result indicates an improvement of engineering performance, making better use of industrial wastes and indirectly assists environmental conservation endeavor along the process. [ABSTRACT FROM AUTHOR]

Highlights: [•] Composites based virgin PP had smaller loss of MOR and MOE than based recycled PP. [•] Composites with 1wt% UV stabilizer had smaller loss of MOR and MOE than without. [•] Increase of rubberwood flour content in composites increased loss of MOR and MOE. [Copyright &y& Elsevier]

D-optimal mixture experimental design was used to determine the optimal mixture of composites from rubberwood (Hevea brasiliensis) flour and recycled polypropylene and to systematically analyze the effects of composition, namely recycled polypropylene, rubberwood flour, maleic anhydride-grafted polypropylene, and ultraviolet stabilizer fractions. Panel samples were extruded, and their properties were characterized. The overall compositions significantly affected water absorption, thickness swelling, flexural strength and modulus, and maximum strain. Water absorption and thickness swelling increased with the fraction of rubberwood flour. At long immersion times, flexural strength and modulus decreased, but maximum strain increased with high fraction of rubberwood flour. The fraction of maleic anhydride-grafted polypropylene only slightly affected water absorption and flexural properties, while the ultraviolet stabilizer fraction had a clear negative effect increasing water absorption and decreasing flexural properties. The models fitted were used for optimization of a desirability score, substituting for the multiple objectives modeled. The optimal formulation found was 68.9 wt% recycled polypropylene, 25.0 wt% rubberwood flour, 5.0 wt% maleic anhydride-grafted polypropylene, 0.1 wt% ultraviolet stabilizer, and 1.0 wt% lubricant. This formulation of the composites can be used for most suitable applications based on the moisture resistance. [ABSTRACT FROM PUBLISHER]

Abstract: A mixture design was used in experiments, to determine the optimal mixture for composites of rubberwood flour (RWF) and reinforced recycled polypropylene (rPP). The mixed materials were extruded into panels. Effects were determined of the mixture components rPP, RWF, maleic anhydride-grafted polypropylene (MAPP), and ultraviolet (UV) stabilizer, on the mechanical properties. The overall composition significantly affected flexural, compressive, and tensile properties. The fractions of recycled polypropylene and rubberwood flour increased all the mechanical material properties; however, increasing one fraction must be balanced by decreasing the other, and the rubberwood flour fraction had a higher effect size. The fraction of MAPP was best kept in mid-range of the fractions tested, while the UV stabilizer fraction overall degraded the mechanical properties. Our results suggest that the fraction of UV stabilizer should be as small as possible to minimize its negative influences. The models fitted were used for optimization of a desirability score, substituting for the multiple objectives modeled. The optimal formulation found was 50.3wt% rPP, 44.5wt% RWF, 3.9wt% MAPP, 0.2wt% UV stabilizer, and 1.0wt% lubricant; the composite made with this formulation had good mechanical properties that closely matched the model predictions. [Copyright &y& Elsevier]

It is important for furniture manufacturers to develop an effective organization, produce high-quality products, and develop new product designs which correlate with customer requirements to obtain more satisfactory output. Quality function deployment (QFD) was employed to design and produce new types of prototype plywood wardrobe. Customer product requirements were transformed into House of Quality of QFD. These require applied techniques to design the new forms of the product through changes in, for example, product shape, pattern, color, functionality, and quality of materials used. Product satisfaction was evaluated by customers composing of groups of product users and sales agent stores. The results revealed that the average satisfaction value of the new prototype increased from 2.71 to 4.08 points over the current products (an increase of about 54.87%). Hypothesis testing of customer satisfaction between the current and the new designs was found to significantly increase with regard to the QFD approach. [ABSTRACT FROM AUTHOR]

Cross-sectional moirè interferometry technique is a very commonly applied one for the characterization of electronic packages. While the technique is popular, its use has not been accompanied by rigorous evaluation of its measurement accuracy. Such an evaluation, necessary because the cross-sectioning destructively modifies the original geometry, is the goal of the current paper. In the present study, a five-layer specimen with intact axi-symmetry as well as one in which the symmetry is destroyed through cross-sectioning are chosen as the vehicles for developing an understanding of the effect of cross-sectioning. We present a rigorous validation of an analytical elasticity model of axi-symmetric package-like structures in which the model prediction is shown to be accurate to within 1% of experimental measurement. The validated analytical model is used to estimate a reduction in radial stress of approximately 40% due to the cross-sectioning of the circular specimens, while the radial strains were virtually unaffected by cross-sectioning; These results suggest that cross-sectional moirè interferometry is likely to yield accurate strains, but not stresses. Since damage under cyclic loading is a function of both stress and strain, the use of moirè interferometry for studying the evolution of strains in packages under cyclic loading is likely to be grossly in error. [ABSTRACT FROM AUTHOR]

The effective coefficient of thermal expansion (CTE) of printed circuit boards (PCBs) have a great deal of influence on the reliability of solder joints in microelectronic packages. In this paper we carryout a systematic characterization of nineteen circuit board samples using strain gages, further validated by moirè interferometry, to understand the impact of CTE variation on the reliability of solder joints. It is shown that the measured effective coefficient of thermal expansion varied in a wide range by as much as 5 PPM about the commonly used value of 17 PPM. This is shown to cause a significant reliability impact for a representative plastic ball grid array package assembly. The comparison between strain gage and moirè interferometry showed good overall correlation, but differed from each other by as much as 2.73 parts per million (PPM). The possible sources of error in each technique are identified and discussed. [ABSTRACT FROM AUTHOR]

• Mixture experiment design was applied to optimize a formulation of particleboard. • RWS, PFF and TS significantly affected the MOR, IBS and WA characteristics. • IBS increased with an increase of tapioca starch content in range of 10 to 15%. • The measured averages deviate less than 6.02% from model prediction values. • Particleboard produced from an optimal formulation met JIS requirements in Type 8. Optimizing a formulation of particleboard, contained rubberwood sawdust (RWS), palmyra fruit fiber (PFF) and tapioca starch (TS), was done by applying the mixture experiment design to achieve the maximum modulus of rupture (MOR) and internal bond strength (IBS), and minimum water absorption (WA). The materials were processed into particleboard panels using a hot compression machine. Analysis of variance revealed that all compositions significantly affected the MOR, IBS and WA characteristics. The increasing additions of palmyra fruit fiber in the particleboard increased the MOR and WA values but decrease the IBS. The MOR and WA characteristics were improved with an increase of the tapioca starch content. An optimal formulation of particleboard was found to be 64% RWS, 20% PFF and 16% TS. The particleboard produced from the optimal formulation apart from meeting the Japanese Industrial Standard requirements in Type 8 can also be processed efficiently as wooden boxes for food containers. [ABSTRACT FROM AUTHOR]