The Effect of Compatibilizer on the Properties of Impact Poly(propylene)-Wood Composites

The effect of two compatibilizers, polypropylene graft maleic anhydride (PPgMA) and ethylene vinyl alcohol (EvOH), on the physical properties of wood polymer composites were studied. The composites were prepared with pine wood and two different impact polypropylene polymers, where the polymers varied according to ethylene content. These compatibilizers, when used together and pre-reacted to create a joint compatiblizer of PPgMA and EvOH, significantly improved control over the repeatability of the physical properties tested, compared to when the compatibilizers were used individually. The impact values were slightly reduced, however the standard deviation of these values showed that the variation in the impact properties were significantly minimized when EvOH was also introduced. It appears that the joint compatiblizer provides better control over the hardness to impact balance of these composite materials and some of these physical properties were improved depending on the ratio between PPgMA and EvOH used, in the joint compatibilizer. Due to the difference in chemistry between PPgMA and EvOH, we expected PPgMA to interact more with the crystalline polypropylene matrix of the impact polymer and the EvOH with the amorphous, rubbery part and yield interesting results.     

Analytical pyrolysis vs. classical wet chemical analysis to assess the decay of archaeological waterlogged wood

The macromolecular complexity of wood limits the possibility of obtaining complete chemical information on its alteration in archaeological objects. This paper compares the results obtained in the characterisation of the components of archaeological wood by a classical wet chemical method and by an instrumental method based on pyrolysis in presence of hexamethyldisilazane coupled with gas chromatography/mass spectrometry, Py(HMDS)–GC/MS. We compare the results obtained with the two methods quantitatively. This enables us to evaluate the efficiency of Py(HMDS)–GC/MS in assessing the chemical composition and the state of conservation of degraded wood. The material analysed consisted of reference sound wood and waterlogged wood from the ?ó?te historical site, located on a small island on Lake Zarańskie in Poland. The samples are from the remains of settlements dating to a period between the 9th and the 12th centuries AD.     

Effect of Wood Flour on the Curing Behavior,Mechanical Properties,and Water Absorption of Natural Rubber/Wood Flour Composites

The preparation of natural rubber/wood flour (NR/WF) composites and the influence of WF content, modification, and particle size on the vulcanizing behavior, mechanical properties, and water absorption of NR/WF composites are described. Results show that the addition of WF into NR delayed the scorching time and vulcanizing time of NR. The appropriate WF contents can improve the mechanical properties of NR. However, the overloading of WF destroys the mechanical properties of NR. The addition of WF increased the water absorption of NR. The silicone couple agents that were used to modify the WF had little effect on the water absorption of NR/WF composites. Decreasing the WF particle size enhanced the water absorption of NR/WF composites because the water-absorbing surface area increased with decreasing WF particle size. The water absorption of sisal-fiber-filled NR-based composites was larger than that of the WF-filled NR-based composites. A useful equation, w=ktⁿ , was inferred from the water absorption results to calculate the water absorption (w) of the NR/WF composites as a function of time (t), where k was a constant concerning the compounds’ character that was primarily determined by the WF's character and n was the power of time that was related to the NR's inherent character, such as cross-linking density, and primarily determined the water absorption rate.     

Moisture Migration in Wood Under Heating Measured by Thermal Neutron Radiography

The article addresses the transport of moisture due to high-temperature gradients resulting from heating by means of thermal neutron radiography. Moisture migration due to heating is quantified along the orthotropic directions of two wood species, spruce and beech, with high spatial and moisture content resolution. As the heat wave is propagating into the wood, the moisture content in the heated zone rapidly decreases, and moisture is transported due to the high-temperature gradient ahead of the heated zone, resulting in a zone with higher moisture content. Both the drying and the moisture accumulation areas evolve non-uniformly, depending on wood microstructure and orientation.     

VALUING A TIMBER HARVEST CONTRACT AS A HIGH‐DIMENSIONAL AMERICAN CALL OPTION VIA LEAST‐SQUARES MONTE CARLO SIMULATION

Abstract Industrial timberland ownership in the United States has shifted substantially in the last 20 years. Having sold their fee‐owned timberlands, forest products companies relied heavily on the open market for raw timber. To reduce their exposure to market risks, however, forest products companies have been using a number of supply chain instruments, such as timber harvest contracts. As these vehicles become increasingly important to the forest industry, it is necessary and important to determine their economic values. In this study, we treated a 3‐year timber harvest contract on a 30‐year‐old loblolly pine plantation as a high‐dimensional American call option and calculated its value by the least‐squares Monte Carlo simulation technique. The estimated values of such a contract ranged from $1,693/ac to $1,984/ac under two timber price assumptions. With reasonable starting timber prices and strike price in the simulation, random timber prices led to higher contract values. Results from this study can help private landowners, timber brokers, and forest products companies better manage their business risks.     

Assessment of historic Tilia codrata wood by solid-state C CPMAS NMR spectroscopy

Historic lime (Tilia cordata Mill.) wood samples, differing by their provenance, conservation status and period have been investigated by solid-state carbon-13 cross polarization magic angle sample spinning nuclear magnetic resonance (¹³C CPMAS NMR) spectroscopy. Structural and chemical modifications were assessed by comparing the historic samples with a reference wood sample. The conventional NMR measurements followed by the ¹³C resonance integral intensities of the wood samples have been carried out in order to acquire information of the chemical changes due to the natural ageing process taking place over the years. The main results concern the decrease of the carbohydrates moiety, especially the decrease of the hemicelluloses and amorphous cellulose signals, while the signals for aliphatic and methoxyl carbons from lignin present and increase of the intensity up to 120 years then start to decrease. At the same time a slight widening of the amorphous carbohydrate signals was observed, which may evidence the occurring of some chemical rearrangements, with the formation of new chemical species. These lead in the ¹³C NMR spectra to the line broadening of the signals induced by their chemical shifts dispersion.     

SA-PBT-SVM的实木表面缺陷近红外光谱识别

针对实木板材表面存在的活节、死节、裂纹与虫眼4类缺陷,提出了基于近红外光谱分析的定性识别模型。随机选取50个样本组成训练集,30个样本组成测试集,在室内温度20 ℃、相对平均湿度50%环境下,采用900~1 700 nm的近红外光谱仪采集样本表面光谱,并利用SNV方法进行光谱数据预处理,以消除固体颗粒大小、表面散射及光程变化对漫反射光谱的影响;然后,采用偏二叉树双支持向量机(PBT-SVM)构建缺陷分类模型,运用模拟退火算法(SA)对4类核函数、参数及波长特征进行全局寻优;寻优过程以97个波长吸收度为输入特征,运用顺序前向法依次加入新特征,当分类器准确率达到90%时,得到核参数及波长特征;最后,通过确定的核函数、参数与波长构建了缺陷分类模型,并对测试样本集进行了分类验证。实验结果表明,SNV预处理方法使相同缺陷的近红外光谱具有较好的一致性,其中,活节与死节光谱差异显著,但死节、裂纹与虫眼的光谱趋势相近;当PBT-SVM分类器采用多项式核函数、参数在γ=28.63,coef=18.69,d=1,C=12.03时,缺陷识别效果最好,裂纹和活节的识别率达到了100%,虫眼为93.33%,死节为93.33%,平均准确率达到了96.65%,平均识别时间仅为0.002 s。利用近红外光谱分析的方法能够快速、有效地完成4类实木板材缺陷的识别。     

Synthesis and characterization of ZnS:Ni-NPs loaded on AC derived from apple tree wood and their applicability for the ultrasound assisted comparative adsorption of cationic dyes based on the experimental design

The applicability of ZnS:Ni nanoparticles loaded on activated carbon derived from apple tree wood (ZnS:Ni-NPs-ACATW) for the adsorption of Methylene Blue (MB) and Janus Green B (JGB) dyes in single system from water solution has been described. The synthesized adsorbent characterized and identified by UV–Vis, FE-SEM, EDX, TEM, FTIR and XRD. The influences of operation parameters including initial MB or JGB concentration (9.0–33.0 mg L⁻¹), pH (4.0–10.0), extent of adsorbent (0.08–0.12 g) and sonication time (4.0–8.0 min) investigated and subsequently best operational condition optimized by central composite design (CCD) combined with response surface methodology (RSM) and desirability function (DF) using STATISTICA 10.0 software. At optimum conditions, maximum MB and JSB adsorption onto ZnS:Ni-NPs-ACATW, i.e. 99.57% ± 1.34 and 98.70% ± 2.01, respectively was achieved pH of 7.0, 0.11 g adsorbent, 14 and 28 mg L⁻¹ of MB and JSB concentration respectively and 8 min sonication time. Experimental data were modelled by Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) isotherms. Langmuir isotherm and monolayer adsorption capacity of MB and JSB was found to be 21.79 and 28.01 mg g⁻¹ respectively. The regression results strongly support more contribution of pseudo-second-order model for more accurate and repeatable representation of kinetic data. These results reveal that ZnS:Ni-NPs-ACATW could be useful as agents to efficiently remove dyes (JGB and MB) from contaminated water and can be very well recommended for wastewater remediation and control of environmental pollution.