Statistical Model for Impact and Energy Absorption of 3D Printed Coconut Wood-PLA

Fused deposition modeling(FDM)-3D printing has been the favored technology to build functional components in various industries.The present study investigates infill percentage and infill pattern effects on the printed parts’impact properties through the 3D printing technique using coconut wood-filled PLA composites.Mathematical models are also proposed in the present study with the aim for future property prediction.According to the ASTM standard,fifteen specimens with different parameter combinations were printed using a low-cost FDM 3D printer to evaluate their impact properties.Statistical analysis was performed using MINITAB to validate the experimental data and model development.The experimental outcomes reveal the honeycomb pattern with 75%infill density achieves the highest energy absorption(0.837 J)and impact energy(5.1894 kJ/m^(2)).The p-value from statistical analysis clearly shows that all the impact properties are less than the alpha value of 0.05,suggesting all the properties are vital to determine the impact properties.The validation process affirms that the generated mathematical model for the energy absorbed and the impact energy is reliable at an acceptable level to predict their respective properties.The errors between the experimental value and the predicted value are 3.98%for the energy absorbed and 4.06%for impact energy.The findings are expected to provide insights on the impact behavior of the coconut wood-filled PLA composites prepared by FDM-3D printing and a mathematical model to predict the impact properties.

海南椰子木维管束形态特征及其与物理力学性能的关系

维管束是椰子木组织构造的重要组成部分,作为承重单元,维管束的形态特征影响椰子木的宏观物理力学性能。以树龄40 a的海南高种椰子木(Cocos nucifera)为材料,以径向和高度方向为考察因素,分析维管束的分布密度、直径、横切面面积和总面积占比在株内的变异规律,并探究维管束总面积占比与密度、顺纹抗压强度等物理力学性能指标的相关性。结果表明:不同树株间,除了维管束总面积占比、抗弯强度有显著差异外,维管束其他形态特征和物理力学性能指标差异均不显著。在径向从内部向外部,椰子木维管束的分布密度、直径、横切面面积和总面积占比逐渐增大,与径向位置呈高度线性正相关;椰子木的密度和顺纹抗压强度等物理力学性能亦逐渐增大,与维管束总面积占比呈高度线性正相关。在高度方向从底部向上,维管束的直径和横切面面积逐渐减小,分布密度和总面积占比先增加后减少,与高度位置呈显著或高度相关。基于维管束总面积占比指标建立椰子木物理力学性能的模型,模型预测结果可为椰子木下锯方法和锯材质量分等提供依据。

利用废弃椰木制备B和N共掺杂碳微纳结构及其电磁波吸收性能

5G通信技术为社会发展和日常生活提供了极大的便利,但同时也带来严重的电磁波污染。为了减轻这种污染产生的危害,设计轻量化和环保的宽带电磁波吸收材料已成为研究热点。本文利用椰木做前驱体制备了一种具有竹节管状一维结构的B和N共掺杂碳材料,B和N共掺杂优化了生物质衍生碳的组成,改善了材料的阻抗匹配,一维的竹节中空结构有利于电磁波进入材料内部。制备的材料具有优异的电磁波吸收性能,最低反射损耗(RL)在14.12 GHz时达到-59.64 dB,有效吸收带宽(EAB)宽度范围为5.88 GHz,所需厚度仅为2.1 mm。研究结果表明这种材料优异的电磁波吸收性能来自于电磁波在材料中的多重折射和散射、偶极子极化、界面极化及电导极化等方面的共同作用。

Granular Activated Carbon from Wood Originated from Tropical Virgin Forest

This research investigates several woods originated from trees of tropical virgin forest as raw material for the production of granular activated carbon. Mechanical strength of the activated carbons produced was related to wood hardness and lignin content but not to cellulose-lignin ratio. One of the eight woods studied (Dividivi) produced an activated carbon with a high mechanical strength similar to that produced from coconut shell, taken as a standard. Dividivi is also suggested as promissory for desert greening.

椰子树和棕榈树人造板研究情况简介

介绍了国外椰子树和棕榈树人造板研究现状,供国内同行参考。

木器漆涂料耐候性影响因素研究

为了提高木器漆涂料涂膜的耐候性,必须关注主体树脂、固化剂以及添加的选择。笔者选用豆油改性醇酸树脂、椰子油改性醇酸树脂、合成脂肪酸改性醇酸树脂与其他原料组成PU白漆甲组份,不同配比的HDI三聚体与TDI三聚体组成PU实色漆乙组份作为固化剂,紫外线吸收剂等光稳定剂作为添加剂,测试不同树脂、不同固化剂配比、紫外线吸收剂对涂膜耐候性及硬度的影响。通过分析实验结果,指出椰子油改性醇酸树脂、HDI三聚体、紫外线吸收剂配合使用的木器漆涂料拥有良好的耐候性能,有效地抑制了涂膜的黄变,保持了涂膜的持久耐用性以及良好的装饰美观性,可以满足人们对木器漆涂料户外使用的需求。