新疆绿洲生态区袋栽黑木耳催耳芽技术

【目的】开发有效的袋栽黑木耳催耳芽方法,为袋栽黑木耳栽培提供理论基础和技术支持。【方法】 采用小孔出耳和集中催芽方法,对菌床菌袋的不同遮盖物和通风方式进行对比试验。【结果】主动通风和保湿性好的催芽方式出芽率最高,为93.28%;自然通风和具有一定保湿性的催芽方式出芽率也较高,可达80%以上;而通风差,保湿性好的催芽方式出芽率最差,在45%以下,且污染率和烧菌程度高。【结论】袋栽黑木耳催耳芽效果受湿度、温度、通风等多个因素的影响,在温度、湿度适宜的条件下,通风流畅可以明显提高出芽率和整齐度,降低污染率和烧菌程度。     

贡嘎山东坡亚高山土壤生物有效磷的时空分异

采用湿化学浸提法测定了贡嘎山东坡亚高山带不同海拔(2 628 m、2 781 m、3 044 m和3210m)峨眉冷杉林的土壤生物有效磷(Bio-PL)含量,并利用原位树脂袋包埋法测定了土壤生物有效磷(Bio-PS)供给量,以阐明土壤生物有效磷的垂直分异和季节变化特征及其主要影响因素。研究发现:(1)土壤Bio-PL库及Bio-PS均随海拔升高呈增大趋势,低海拔地区生物有效磷因淋溶大量流失是形成这种梯度变化的主要原因。(2)随土层深度增加,Bio-PL库及Bio-PS显著降低,有机质层(O层)Bio-PL库约占土壤剖面的75%且该层的Bio-PS全年均为正值。O层中较高的有机磷含量和较强的磷酸酶活性是O层生物有效磷富集的重要原因。(3)2 781 m样点O层Bio-PS在9月最高,而3 044 m和3 210 m样点的Bio-PS在6月和9月出现两个高值。各样点矿质土层的Bio-PS全年多低于0,在8月时最低。Bio-PS的季节变化主要受生物吸收及径流流失控制。     

丹东河口艳红桃可降解纸袋套袋对果实品质的影响

通过对比试验研究了丹东河口艳红桃可降解纸袋套袋对果实品质的影响,结果表明:艳红桃采用可降解纸袋套袋,能有效防治虫害和桃锈病对果实的危害并能防治裂果病。在果实快速生长期进行套袋和在着色期脱袋增加了果实色泽,提高了其商品性能。     

含炭量对木炭/聚丙烯复合材料性能的影响

为了改善聚丙烯(polypropylene,PP)的力学性能,该文以木炭、聚丙烯(polypropylene,PP)为主要原料,采用双螺杆挤出机制备木炭/PP复合材料。并利用X射线衍射仪(X-ray diffractometer, XRD)、差式扫描量热仪(differential scanning calorimeter, DSC)、电子万能力学试验机、动态热机械分析仪(dynamic mechanical analyzer, DMA)、场发射扫描电镜(scanning electron microscope, SEM)等仪器对复合材料进行性能特性的表征分析。试验结果表明,PP基体在高温下以流体的形式流入木炭的孔隙,并与木炭相互缠绕、粘结,形成一种界面较为致密的结构,这种结构使得复合材料具有较好的静态力学性能(拉伸强度最高为25.47 MPa)与动态力学性能(储能模量最高为4 921.92 MPa)。研究结果可为木炭在生物基材料方面的应用提供新的思路。     

Comparison of water absorption and mechanical properties of wood–plastic composites made from polypropylene and polylactic acid

Abstract

This study focuses on the water absorption and mechanical properties of composites made from softwood sawdust and plastics, such as virgin and recycled polypropylene and polylactic acid (PLA). The composites were processed by extrusion, and their properties were investigated by a water immersion test, mechanical tests and a cyclic test for moisture resistance. Scanning electron microscopy was used to study the morphology of the fracture surfaces of the composites. The composites made with recycled polypropylene had the lowest water absorption and thickness swelling of the studied composites. The PLA composites made with heat-treated sawdust showed the highest flexural strength. Of the polypropylene based composites, virgin polypropylene resulted in composites with higher flexural strength. The Charpy impact strength of the composites was found to have an inverse trend compared to flexural strength. Cyclic treatment of the studied composites resulted in 20–60% loss of flexural strength, depending on type of composite.     

Chemical modification of isotactic polypropylene by melt blending

The branched polypropylene (b-PP) was prepared by melt blending process with initiator, antioxidant, and functional monomers to improve the melt strength through the melt grafting. The melt flow index (MFI) of theb-PP was increased with increasing the initiator content. On the introduction of the alkylamine as the branching agents the MFI of theb-PP was increased, while that of theb-PP with the pentaerythritol triacrylate (PT) was decreased. It may be caused by the chain scission of thei-PP backbone due to the reduced thermal stability of thei-PP on the melt blending. The MFI of theb-PP without the antioxidant was increased due to the chain scission occurred during the melt processing, while on the introduction of the antioxidant, the MFI of theb-PP was decreased. The crystallization temperature of theb-PP was higher than that of PP, which was attributed to the branched chain structure. It was found that the PT was the most effective functional monomers for enhancing the melt properties of theb-PP.     

剑麻纤维/聚丙烯木塑复合材料耐磨性能研究

采用熔融共混、模压成型方式制备剑麻纤维(SF)/聚丙烯(PP)木塑复合材料,探讨剑麻纤维对复合材料耐磨性能的影响;考察SF的表面处理方式、用量以及同玻璃纤维(GF)混杂增强与复合材料耐磨性能的关系;通过扫描电镜(SEM)对复合材料磨损的表面形态结构进行了研究。结果表明:SF的表面处理方式和用量对材料耐磨性能有一定影响;SF与GF混杂后材料的耐磨性能随SF用量的增加而增加;纯PP树脂的摩擦以磨粒磨损和粘着磨损为主,SF/PP复合材料磨损以磨粒磨损为主,SF/GF/PP复合材料的磨损是磨粒磨损和粘着磨损共同承担的结果。     

聚丙烯纤维对渠道矿渣混凝土力学性能影响的研究

为降低渠道衬砌混凝土的脆性,将聚丙烯纤维、粒化高炉磨细矿渣、聚羧酸系超塑化剂加入普通混凝土中。共采用体积含量占混凝土的0.1%、0.2%、0.3%、0.4%、0.5%、0.6%、0.7%和0.8%八个掺量的聚丙烯纤维,以及矿渣替代水泥量的35%、45%、55%、65%、75%五个掺量的矿渣组成的21个混凝土配合比。试验结果表明,掺加矿渣和聚丙烯纤维使硬化混凝土密度减小;对于大多数配合比的矿渣混凝土,聚丙烯纤维降低了抗压强度,提高了抗折强度和劈拉强度;其中0.2%~0.4%的聚丙烯纤维和45%~55%的矿渣是最优掺量。进一步以电镜扫描图(SEM)显示的混凝土基体微观结构解释了其宏观力学性能。