麻纤维增强完全可降解复合材料的制备及性能研究

以亚麻落麻纤维、聚乳酸纤维为原料,采用非织造结合模压成型工艺制备了完全可降解复合材料.研究了增强纤维体积分数及纤维长度对复合材料弯曲、冲击性能的影响,采用扫描电镜(SEM)研究了复合材料中纤维与树脂之间的界面结合状况.结果表明:材料的弯曲、冲击强度均随纤维长度的增加而增大,当纤维长度为72mm时,体积分数为40%的材料具有最好的弯曲性能,纵横向弯曲强度分别为55.15、42.02MPa;体积分数为50%的材料具有最好的冲击性能,纵横向冲击强度分别为19.714、14.012kJ/m2;裁切断口处的SEM表明增强纤维与基体树脂之间存有一定数量的空隙,两相之间的界面结合强度有待进一步改善.     

竹原纤维/可生物降解塑料复合材料的性能研究

通过热压成型制备了竹原纤维增强可生物降解塑料复合材料,研究了材料的力学性能、热稳定性、断裂面的微观结构等,以及复合材料的微生物降解性能。研究结果表明,复合材料的拉伸强度和弯曲强度随竹原纤维含量增加而增加,当竹原纤维质量分数为16.67%时,复合材料的拉伸强度和弯曲强度较纯可降解塑料分别增加46.9%和93.1%,但断裂伸长率和冲击强度随着竹原纤维含量增加而降低。复合材料的热稳定性比纯可降解塑料和竹原纤维更好。在土壤微生物的作用下,复合材料在20 d时间的降解率可达19.4%。     

羟基磷灰石/外消旋聚乳酸复合材料的制备、力学性能及体外降解

采用液相吸附法制备了羟基磷灰石/外消旋聚乳酸[hydroxyapatite/poly-D,L(racemic)lactic acid,HA/PDLLA]复合材料,通过材料实验机和体外模拟试验研究了复合材料的力学性能和体外降解性能.对材料的力学测试表明,由于加入了质量分数为10%的HA颗粒,复合材料的力学性能得到了改善,复合材料的弯曲强度达146.2 MPa,弯曲模量为2.5 GPa,与纯PDLLA材料相比,弯曲强度提高了9.4 MPa,弯曲模量提高了0.2 GPa,同时其拉伸强度下降并不明显.体外降解模拟试验结果表明,HA含量为10%的复合材料在前6周的质量损失小于1%,在第12周的最终质量损失为5.4%,其在降解中后期的质量损失比纯PDLLA材料低约2%～3%.     

黄麻纤维接枝聚醚增强UP复合材料研究

采用经过氢氧化钠和甲苯二异氰酸酯-聚醚二元醇(TDI-PPG)表面处理的黄麻纤维织物作为增强体,以191#通用不饱和聚酯树脂(UP)作为基体,通过模压成型的方法制备了黄麻纤维增强UP复合材料。傅立叶变换红外光谱及X射线光电子能谱分析表明,TDI-PPG接枝于黄麻纤维上;通过热分析确定了复合材料的加工温度为160℃,根据生产经验确定成型压力为2 MPa;用短梁弯曲法测试了黄麻纤维接枝前、后UP复合材料的层间剪切强度,后者大于前者;随着黄麻纤维体积分数的增加,接枝黄麻纤维增强UP复合材料的力学性能得到提高,当黄麻纤维体积分数为54.44%时,接枝黄麻纤维增强UP复合材料的拉伸强度、弯曲强度和冲击强度分别为112.31 MPa,109.32 MPa和14.85 k J/m2。     

聚丙烯纤维/表面改性黄麻纤维复合膜的制备及性能

以聚丙烯(PP)纤维为基体,经碱、偶联剂表面改性处理后的黄麻纤维为第二组分,采用非织造-模压工艺制备了PP纤维/表面改性黄麻纤维复合膜,探讨了经表面改性处理后的黄麻纤维含量对复合膜的力学性能、吸水性能以及复合膜的断面形貌的影响。结果表明:随着黄麻纤维含量的增加,复合膜的拉伸强度呈先增大后减小趋势,但变化不明显,当黄麻纤维质量分数为10%时,拉伸强度达到最大为60.5MPa,复合膜的拉伸模量、弯曲强度、弯曲模量也呈先增大后减小趋势,当黄麻纤维质量分数为30%时,复合膜力学性能最优,其拉伸模量、弯曲强度、弯曲模量分别为6.4 GPa,80.7MPa,5.0 GPa;复合膜的吸水率(W)随黄麻纤维含量的增加而增大,当黄麻纤维质量分数为40%时,复合膜的W最大为6.6%;当复合膜中黄麻纤维质量分数小于等于30%时,PP纤维与黄麻纤维之间界面粘合良好,黄麻纤维与PP纤维紧密相连,相互交叉形成网状结构。     

PP/甘蔗皮纤维复合材料的拉伸性能

采用热压工艺制造聚丙烯(PP)/甘蔗皮纤维复合材料,并研究其拉伸性能。研究热压温度为175℃、压力为2 MPa、时间15 min工艺条件下纤维粒径大小和质量分数对复合材料拉伸强度和拉伸弹性模量的影响。结果表明:在甘蔗皮纤维质量分数为40%条件下,复合材料拉伸性能随着粒径减小呈现先增加后减少的趋势,当纤维粒径为40~60目(0.45~0.3 mm)时材料拉伸强度最大,为8.58 MPa,此时弹性模量为2.44 GPa;在相同纤维粒径40~60目条件下,纤维质量分数为40%时PP复合材料拉伸强度最大,纤维质量分数为50%时PP复合材料拉伸弹性模量最大,达到2.65 GPa。根据实验结果,甘蔗皮纤维增强PP复合材料在纤维粒径为40~60目、质量分数在40%时综合拉伸性能最佳。     

废弃混纺纤维/聚乳酸复合材料的制备及力学性能研究

以废弃涤/棉(65/35)混纺纤维作为增强材料,聚乳酸颗粒作为基体材料制备复合材料,并且采用正交及单因素试验对其成型工艺进行优化。结果表明:最优成型工艺条件为涤/棉混纺纤维质量分数40%、热压温度180℃、热压压力12 MPa,该条件下的复合材料的拉伸强度和弯曲强度分别是59.56 MPa和48.75 MPa。     

苎麻落麻纤维增强TPS全降解复合材料力学性能的研究

以苎麻落麻纤维为增强体,甘油/尿素/山梨醇为复合增塑剂塑化的淀粉为基质,制备全降解复合材料,并研究了纤维长度和纤维含量对复合材料的力学性能的影响。结果表明,苎麻纤维和TPS具有良好的界面结合,复合材料的拉伸强度和模量随着苎麻纤维长度和含量的增加而增加,达到25.14 MPa和1 136.36 MPa,接近于未加入纤维时的2倍,断裂伸长率明显下降,但是纤维含量的增加对断裂伸长率的影响不大。弯曲强度和模量与拉伸强度和模量呈现相似的增长趋势。     

长玻纤增强聚丙烯在汽车翼子板上的应用

对不同玻纤质量分数的LFT-PP粒料国标注塑样条,进行拉伸、弯曲、冲击等性能测试分析,结果表明:玻纤试样的拉伸强度、弯曲强度以及冲击强度均随玻纤质量分数的增加而提高;样品断裂延伸率随玻纤质量分数变化不明显,弯曲挠度随玻纤质量分数增加而减小;其中质量分数40％的玻纤试样拉伸强度达到145 MPa,弯曲强度高达170 MPa,简支梁缺口冲击强度为27 kJ/m2,表现出优异的力学性能.将质量分数40％玻纤的长纤粒料注塑成汽车翼子板制件,制品通过了汽车塑料制品各项测试并完成装配.     

竹原纤维增强低熔点聚酯复合材料的制作及其性能研究

采用非织造加工工艺将经适当脱胶处理的竹原纤维与低熔点聚酯(LMPET)纤维制成混合纤维预成型件,经模压成型制成竹原纤维增强LMPET复合材料板材。研究表明,当模压温度、时间及压力分别为170℃、20 m in及30 MPa,竹原纤维的质量分数为40%时,制得的复合材料的纵、横向拉伸强度分别为136.0、87.6 MPa;纵、横向弯曲强度分别为534.0、470.0 MPa。竹原纤维增强LMPET复合材料初步确定可用于汽车、建材等领域。     

Novel ceramic matrix composites with tungsten and molybdenum fiber reinforcement

Ceramic matrix composites usually utilize carbon or ceramic fibers as reinforcements. However, such fibers often expose a low ductility during failure. In this work, we follow the idea of a reinforcement concept of a ceramic matrix reinforced by refractory metal fibers to reach pseudo ductile behavior during failure. Tungsten and molybdenum fibers were chosen as reinforcement in SiCN ceramic matrix composites manufactured by polymer infiltration and pyrolysis process. The composites were investigated with respect to microstructure, flexural- and tensile strength. The single fiber strengths for both tungsten and molybdenum were investigated and compared to the strength of the composites. Tensile strengths of 206 and 156 MPa as well as bending strengths of 427 and 312 MPa were achieved for W/SiCN and Mo/SiCN composites, respectively. The W fiber became brittle across the entire cross section, while the Mo fiber showed a superficial, brittle reaction zone but kept ductile on the inside.     

Evaluation of biomass residue: 1. Briquetting waste paper and wheat straw mixtures

Studies have demonstrated that waste paper and wheat straw or their mixtures can be compressed to a relative density greater than unity, and stabilized at that density without binder material. A reduction in the volume of the material also provides a technological benefit, so the material could be transported and stored more economically than is possible at present. The effects of the briquetting pressure on the density, moisture content, and bending and compressive strengths of the briquettes were determined at six different pressures of 300, 400, 500, 600, 700 and 800 MPa. The optimum moisture contents and compressive strengths were found to be respectively 18.0% and 38.2 MPa for waste paper, 22.0% and 22.4 MPa for wheat straw, and 18.0% and 32.0 MPa for a 20.0% by weight of waste paper and straw mixture. The effect of the temperature and time on the briquette density of wheat straw was examined.     

Properties and manufacturing of a new starch plastic

Environmental awareness has strongly stimulated the introduction of biodegradable materials based on renewable resources of natural origin. This paper describes the properties and manufacturing of such a bioplastic. In a counter‐rotating twin screw extruder, starch and polystyrene were mixed. To enhance material properties such as tensile strength and impact strength, two routes were followed. First, the starch was altered by grafting polystyrene onto the starch backbone using a counter rotating twin screw extruder. The newly formed material was blended with polystyrene in difierent ratios. Tensile strengths of 10 to 35 MPa were obtained while notched impact strengths varied from 0.5 J m^?1 to 1.5 J m^?1. Soaking the material for a certain time in water end measuring the tensile strength of the wet material revealed that the tensile strength remained more the less the same for blends containing more than 30 wt% PS. Second, polystyrene grafted starch was used as a compatibilizer. A homogenous blend could bobtained (according to scanning electronic microscopy pictures) by adding the compatibilizer to a starch, polystyrene, and water mixture. Again, tensile and impact strengths were measured for different ratios of the polymers used. The tensile strength and the impact strength were of the same magnitude as they were with the blended material. X‐ray diffraction and DSC measurements revealed a highly ordered system. When the fraction of polystyrene was above 60 wt% of the blend, the amylose part of the starch crystallized.     

PVAL/改性淀粉复合发泡材料的制备及性能

以玉米淀粉为原料,通过丙烯酸塑化改性法制备玉米改性淀粉。以柠檬酸和NaHCO_3作为复合发泡剂,甘油、二乙醇胺和山梨醇作为复合增塑剂改性聚乙烯醇(PVAL),与改性淀粉辅以其它加工助剂,利用模压成型发泡制备了一种可生物降解的PVAL/改性淀粉复合发泡材料。重点探究了改性淀粉含量对复合发泡材料生物降解性能和发泡形态的影响,NaHCO_3发泡剂含量对复合材料耐水性能、力学性能和发泡性能的影响,助剂滑石粉含量对复合材料发泡性能的影响。结果表明,当改性淀粉质量分数为40%,复合发泡剂NaHCO_3、滑石粉及柠檬酸质量分数均为4.0%时,所得发泡材料的生物降解性能较好,拉伸强度为2.134 MPa,断裂伸长率为79.1%,泡孔分布均匀,泡孔结构良好,形状较规整。     

生物可降解山麻杆韧皮纤维增强PBS复合材料的性能研究

以山麻杆韧皮纤维为增强体,其与PBS颗粒按质量比20∶80模压成型制备了4种板材,探讨了表面处理对纤维微观结构与物理性能的影响,分析比较了板材力学性能及生物降解性。结果表明, 采用物理化学相结合方法预处理后,表面依然存留一定量的果胶等物质;预处理纤维进一步碱处理后表面出现“S”形凹槽,预处理纤维进一步偶联剂处理后表面凹槽连续性好、深度深;碱处理、偶联剂处理后纤维拉伸强度分别提高5.08 %和降低3.58 %;相比纯PBS,偶联剂处理后纤维复合材料拉伸强度与弯曲强度各提高48.32 %和25.97 %,拉伸模量与弯曲模量各提高146.45 %和128.30 %;3种纤维复合材料生物可降解性变化趋势一致,但偶联剂处理后的材料失重率变化幅度最小。     

Preparation and Characterization of Bioblends from Gelatin and Linear Low Density Polyethylene (LLDPE) by Extrusion Method

Abstract

Bioblends are composites of at least one biodegradable polymer with a non-biodegradable polymer. Successful development of bioblends requires that the biodegradable polymers be compatible with other component biodegradable/synthetic (non-biodegradable) polymers. Bioblends from LLDPE and gelatin were prepared by extrusion and hydraulic heat press technique. The gelatin content in the bioblends was varied from 5 to 20 wt%. Various physico-mechanical properties such as tensile, bending, impact strength (IS), thermal ageing and soil degradation properties of the LLDPE/gelatin bioblends with different gelatin contents were evaluated. The effect of thermal ageing on mechanical properties was studied. The mechanical properties such as tensile modulus (TM), bending strength (BS), bending modulus (BM) were found to increase with increasing gelatin content up to 20 wt%, however tensile strength (TS) and elongation at break (%E _b) were decreased with increasing gelatin content. Impact strength value increased with increasing gelatin content up to 10 wt% and then decreased slightly with increasing gelatin content. The blend containing 20 wt% gelatin showed relatively better mechanical properties than other blends. The values of TS, TM,%E _b, BS, BM and IS for the bioblend with 20 wt% gelatin content are 5.9MPa, 206.3MPa, 242.6%, 12.1MPa, 8 MPa and 13.7 J/cm², respectively. Water uptake increases with increasing soaking time in water and weight loss due to soil burial also increases with increasing gelatin content in the blends but both are significantly lower than that of pure gelatin sheet. Weight loss values after thermal ageing increase with time, temperature and increasing gelatin content in the blend but are much lower than pure gelatin. Mechanical properties such as TS, TM are increased and %E _b is decreased after thermal ageing at 60°C for 30 min. Consequently, among all of the bioblends prepared in this work the blend having 20% gelatin content yields properties such that it can be used as a semi-biodegradable material.     

Composite ceramic materials with SiC fiber

The technology and mechanical characteristics of composite ceramic materials strengthened by discrete and continuous fibers of silicon carbide are described. The introduction of an 8% volume fraction of continuous SiC fibers into cordierite increases its strength by almost a factor of 2. Among composites strengthened by SiC whisker the highest density is exhibited by materials with a matrix of Al₂O₃ - ZrO₂ (580 MPa). Materials with matrices of Al₂O₃ and synthetic mullite have mean ultimate bending strengths of 460 and 420 MPa, respectively. The microstructures of the materials are described.Translated from Ogneupory, No. 8, pp. 3 – 6, August, 1995.     

Fabrication of Surlyn ionomer fibers using a novel coextrusion approach and mechanical property characterization

We report the fabrication of poly (ethylene-co-methacrylic acid) sodium-neutralized ionomer (Surlyn 8940) fibers via a forced-assembly coextrusion and layer multiplication process with polystyrene (PS) as the matrix material. The PS separating materials were removed by toluene extraction to yield independent Surlyn fibers. The tensile properties of Surlyn fiber strands were studied under different strain rates. Surlyn fibers were oriented to 300% strain at different temperatures to study the effect of orientation on the tensile properties. The oriented Surlyn fibers were annealed after orientation to further enhance the mechanical properties. Further drawing of these oriented fiber mats to a draw ratio of 4 at 60 °C followed by annealing at 60 °C can afford moduli in excess of 350 MPa and tensile strengths in excess of 70 MPa. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48046.     

高支化f-CTBN/PEG聚氨酯的合成与降解性能研究

采用逐步聚合的方法,以功能化丁腈橡胶(f-CTBN)与不同相对分子质量(Mn)聚乙二醇(PEG)共聚合得到一系列高支化嵌段聚氨酯(f-CTBN/PEG)高分子材料。通过对材料溶胀性,模拟生物环境降解,以FT-IR对基团变化分析和ESEM形貌观察,以及力学性能的测试。结果表明:材料的降解速率随时间延长呈减慢趋势,且随PEG含量的增大材料降解越快;拉伸强度(超过18MPa)和杨氏模量(超过40MPa)相对较高。有望根据需求来调节f-CTBN/PEG的比例大小,从而用于医用防护材料的生产。     

增强增韧抗静电尼龙612材料的制备及性能

采用熔融共混法制备了增强增韧抗静电尼龙(PA)612材料,探讨了抗静电剂种类及用量对PA612材料抗静电性能的影响,同时研究了玻璃纤维(GF)和增韧剂三元乙丙橡胶接枝马来酸酐用量对材料力学性能的影响。抗静电性能测试结果表明,石墨烯、碳纳米管在表面电阻方面的渗流阀值明显小于导电炭黑,即石墨烯、碳纳米管对PA612的抗静电效果优于导电炭黑;高用量下,添加碳纳米管的材料表面电阻比添加石墨烯的低一个数量级,但碳纳米管的成本较高。力学性能测试结果表明,GF能大幅提高材料的拉伸与弯曲强度,增韧剂能大幅提高材料的冲击性能,当增韧剂质量分数不高于10%时,材料的拉伸与弯曲强度下降幅度较小。当抗静电剂石墨烯、GF及增韧剂质量分数分别为3%,40%和10%时,制得的PA612材料具有较好的综合性能,其拉伸强度为120 MPa,弯曲强度为210 MPa,常温缺口冲击强度为10 k J/m~2,-45℃缺口冲击强度为9.6 k J/m~2,表面电阻为1×1011Ω,可满足PA612在储存、运输和使用过程中的抗静电要求。