麻秆芯缓冲包装材料静态缓冲特性和蠕变性能研究

对研发的麻秆芯缓冲包装材料进行了静态压缩和蠕变性能试验研究.比较分析结果表明:麻秆芯缓冲包装材料是一种优良弹性材料,有适宜的硬度和抗压性能,受外力作用时,无明显的屈服点,不出现材料的溃散,在很宽的应力范围内皆可表现出突出的缓冲特性;材料受到多次冲击后仍能保持良好的缓冲特性.麻秆芯缓冲包装材料具有优良的抗蠕变特性.相比较而言,在试验初期(1h前)材料蠕变相对较大,且变化率较快,后期(24h后)的变化率较慢,曲线几乎呈直线状态;材料最大蠕变率、残余应变皆随着静应力的增大而增大.测试压缩载荷分别为13.5kg(静应力52.92kPa),19kg(静应力74.48kPa),30kg(静应力117.6kPa)条件下,材料的最大蠕变率分别为0.0367%,0.0417%,0.050%.试验卸载24h后材料的残余应变分别仅为0.0210%,0.0245%,0.0323%.     

多轴向经编玻璃纤维织物增强复合材料的蠕变特性研究

玻璃纤维增强复合材料在长期服役条件下的蠕变行为会导致结构件发生形变,进而对材料稳定性产生很大的影响,因此对其蠕变性能的研究很有必要。分别以三轴向和四轴向经编玻璃纤维织物为增强体,环氧树脂为基体,采用真空辅助树脂传递模塑(vacuum assisted resin infusion, VARI)成型方法制备复合材料试样。研究不同应力水平下复合材料试样的弯曲蠕变规律,对蠕变曲线进行线性拟合,预测材料蠕变寿命。基于试样断裂失效形貌图,分析蠕变损伤情况,揭示蠕变特性。结果表明,当施加小于弯曲断裂强度值80%的应力时,复合材料蠕变历经2个阶段,减速蠕变阶段,应变随时间延续而增加,但增速逐渐减小;匀速蠕变阶段,应变随时间延续而匀速增加。当施加大于弯曲断裂强度值80%的应力时,2种复合材料在历经减速蠕变和匀速蠕变阶段后,进入加速蠕变阶段,此阶段应变随时间延续而快速增加,直至试样破坏失效。通过蠕变试验,验证复合材料在弯曲断裂强度值80%的应力水平下蠕变寿命预测结果的准确性。结果显示,三轴向和四轴向复合材料试样分别在施加应力2.83 h和37.40 h后发生蠕变断裂,蠕变寿命预测结果与试验结果的误差较小...     

MPP微孔发泡材料缓冲性能研究

为降低对产品的冲击,对新型MPP(Microcellular Polypropylene foam)材料的性能进行研究。通过对MPP材料的试验,利用MATLAB对数据进行分析处理,得到其不同发泡倍数的应力-应变曲线;通过换算,得出其应力-缓冲系数的分布图。试验数据表明,缓冲系数随着应力的增大,呈现出先增大后减小,再增大趋势;缓冲系数随着发泡倍数的增加而减小,且缓冲系数最大时对应的应力为0.3~0.6 MPa。结果表明:MPP作为一种新型缓冲材料,根据其缓冲系数-应力曲线图,可以计算出对应所需材料的厚度,对其在缓冲包装设计时提供了设计依据,同时对以后的相关试验和优化具有重要的参考意义。     

压力和水分对苦荞米花气流膨化倍数的影响

以苦荞麦为原料,研究不同压力和水分添加量对苦荞米花膨化倍数的影响。结果表明:压力和水分添加量对苦荞米花膨化倍数均有影响;在试验条件范围内,随着水分添加量的增大,苦荞米花膨化倍数先增大后减小;随着压力的增大,苦荞米花膨化倍数逐渐增加;在水分添加量为3.4%、压力为1.2 MPa时,苦荞米花的膨化倍数理论最大值为28.7,试验验证值为28.4。     

不同含量发泡剂制备的纤维发泡材料的性能研究

以玉米秸秆粉末和废瓦楞纸板为主要原料,通过微波发泡研制出了一种环境友好的新型环保缓冲包装材料,并探讨了不同发泡剂含量制备植物纤维微波发泡缓冲包装材料的力学性能和微观性能。结果表明,AIBN发泡剂的不同含量对材料的静态压缩性能及回弹率影响显著,随着AIBN发泡剂含量的增多,在相同的应变条件下,材料的应力随之减小,材料的缓冲性能有所增强,回弹率先上升后下降。另外,借助电子扫描显微镜,研究了不同添加量的发泡剂对材料孔结构的影响。最后,采用FTIR对材料的分子结构进行了分析。     

EPE缓冲材料的静态压缩性能试验研究

目的:研究聚乙烯发泡结构材料的静态压缩性能,为缓冲包装设计提供数据支持。方法:选用EPE缓冲材料,依据《包装用缓冲材料静态压缩试验方法》对EPE的缓冲性能进行测试,对比分析EPE缓冲包装材料的压缩形变性能、载荷—位移曲线试验数据。结果:EPE发泡结构材料,回复能力较强,回复率均达到80%以上,能够适应多次压缩。EPE载荷—位移曲线存在两个明显的变形区域,一是厚度压缩率为0%-75%之间,载荷变化范围较窄,位移量变化较大;二是厚度压缩率约在75%以上,位移量变化较小,载荷急剧上升。结论:EPE发泡结构材料的压缩恢复性能、压缩率与EPE的厚度有密切关联,载荷—位移曲线的趋势基本一致,随着厚度的增大,材料承受的载荷增加,缓冲性能增强。     

白炭黑增强蔗髓缓冲包装材料的性能研究简

本实验以蔗髓为原料,亚硫酸氢镁制浆废液为胶黏剂,并向其中添加沉淀法白炭黑制备新型缓冲包装材料.采用SEM对不同类型白炭黑形貌进行表征.实验分析了白炭黑的种类、用量和比表面积对缓冲包装材料的表观密度和静态压缩强度的影响.结果表明,白炭黑加入量对蔗髓缓冲包装材料（BPCPMs）的表观密度影响不大;加入0.5wt％的白炭黑即可显著提高BPCPMs静态压缩强度;随白炭黑用量增加,BPCPMs的压缩应力呈现先增大后减小的趋势,蔗髓包装材料在较大应力条件下的缓冲效率得到提高;随白炭黑比表面积的增加,BPCPMs的压缩应力增加,而且在高应变条件下,压缩应力的增幅有所提高.     

白炭黑对蔗髓/红液包装缓冲材料力学性能的影响

研究了白炭黑比表面积和用量对蔗髓/红液包装缓冲材料力学性能的影响。实验结果表明:加入质量百分比用量0.5%的白炭黑即可以显著提高包装缓冲材料的静态压缩强度,随白炭黑比表面积增加,包装材料的压缩强度增大;包装材料的压缩应力随白炭黑添加量增加,呈先增大后减小趋势,在白炭黑添加量为7.5%时,材料应力值最小。     

白炭黑增强蔗髓缓冲包装材料的性能研究

本实验以蔗髓为原料,亚硫酸氢镁制浆废液为胶黏剂,并向其中添加沉淀法白炭黑制备新型缓冲包装材料。采用SEM对不同类型白炭黑形貌进行表征。实验分析了白炭黑的种类、用量和比表面积对缓冲包装材料的表观密度和静态压缩强度的影响。结果表明,白炭黑加入量对蔗髓缓冲包装材料(BPCPMs)的表观密度影响不大;加入0.5wt%的白炭黑即可显著提高BPCPMs静态压缩强度;随白炭黑用量增加,BPCPMs的压缩应力呈现先增大后减小的趋势,蔗髓包装材料在较大应力条件下的缓冲效率得到提高;随白炭黑比表面积的增加,BPCPMs的压缩应力增加,而且在高应变条件下,压缩应力的增幅有所提高。     

蜂窝夹层结构消音板平压试验研究

通过对蜂窝夹层结构消音板压缩试验研究,建立蜂窝结构压缩应力随压缩应变变化曲线,得到不同位移载荷下芯材的变形特点,试验结果曲线验证了蜂窝纸板压缩过程经历的4个阶段,与理论曲线吻合。从试验结果来看,该芳纶纤维增强蜂窝夹层结构复合材料作为某新机用风扇消音板材料满足力学性能要求。     

损伤条件下聚氯乙烯涂层膜结构材料拉伸蠕变特性

为进一步研究膜结构材料的力学特性,以机织聚氯乙烯涂层膜结构材料为研究对象,对其无损及单边切口试样的短期拉伸蠕变性能进行测试,分析切口尺寸及蠕变应力对蠕变性能的影响,并对其拉伸蠕变特性进行研究。实验结果表明：无损及切口试样的蠕变曲线均体现了初始蠕变和等速蠕变阶段的特征。在同等净切口蠕变应力条件下,切口试样的蠕变量小于无损试样,且随着切口尺寸的增加而降低。相对于Findley 模型,4 元件Burger 模型较适合描述聚氯乙烯涂层膜结构材料的短期蠕变行为。同时,基于4元件Burger 模型拟合系数,分析了蠕变应力及切口尺寸对初始蠕变应变、缓弹性变形和黏性变形的影响。     

酱香高温大曲贮存期质量变化规律的分析研究

对不同季节生产的酱香高温大曲在不同贮存期质量变化进行研究,通过理化指标、感官质量、损耗率及主要微生物数量分析,结果发现,高温大曲在贮存前期水分下降较快,后期下降较慢,酸度变化和水分变化呈正相关,糖化力变化幅度不大,贮存时间越长损耗率越大,主要微生物随着贮存时间的延长,优胜劣汰,种类和数量发生改变。综上,酱香高温大曲夏季曲储存时间4~6个月为宜,冬季曲储存时间5~8个月为宜。     

Impact of mechano-sorptive creep to the long-term strength of timber

An engineering method is presented for the analysis of creep deformation in wood due to changing moisture content. The method is applied to the analysis of stresses in timber during long-term loading. It is concluded that the larger variation of moisture content at the surface layer of timber makes its creep rate higher than in the middle of the cross-section. As a result, an increasing portion of the load will be carried by the inner part of the material during sustained loading. This uneven stress distribution may explain to a great extent why the strength of wood is lower under a long-term load than under a short-term load.     

Viscoelastic Characterization of Sage Seed Gum

Wild sage seed is a small, rounded, and mucilaginous seed, which comes from Salvia macrosiphon. The viscoelastic behavior of sage seed gum, at different concentrations (0.5–2%, w/w), was examined by measuring the transient (in-shear structural recovery and creep/recovery tests) and dynamic (stress and frequency sweeps) rheological properties. The mechanical spectra showed typical weak gel behavior at all concentrations, with storage modulus higher than loss modulus, and little variation with frequency. Both moduli greatly increased with increasing the concentration, and the concentration dependency was well described by the power-law model. The loss tangent was increased slightly with increasing the frequency in the range of 0.25–0.67, although it was not affected by an increase in gum concentration. Moreover, the complex viscosity was found to increase with the increase of sage seed gum concentration and to decrease linearly with the increase of frequency. All samples showed typical viscoelastic response to stress in creep/recovery tests, with recoverable strain increasing in direct proportion to sage seed gum concentration. Creep curves were adequately fitted with a Burger model of four parameters. The elastic and viscous contributions to the general viscoelastic behavior were analyzed through the obtained parameters. The concentration had no specific effect on the in-shear recovery properties of sage seed gum gels, and the gel structure was highly recovered after applying shear. The results of this article indicated that sage seed gum may offer an excellent alternative for commercial gums as a thickening/gelling agent.     

Compression creep behaviour of polyester needle-punched nonwoven fabrics

This present study deals with the compression creep behaviour of polyester needle-punched nonwoven fabrics. Polyester fibres of three different cross-sectional shapes (round, circular hollow and trilobal) have been selected for this study. An instrument has been designed and fabricated to measure the compression creep property of needle-punched fabrics. The effect of duration of compression load, fabric weight, fibre cross-sectional shapes and reinforcing material on percentage compression creep has been studied. It has been observed that initially, compression creep decreases rapidly and with increase in time, decrease of percentage creep becomes minimal. After about 8500?min of application of the same compression load, no change in compression creep is noticed. The percentage compression creep decreases with the increase in fabric weight irrespective to fibre cross-sectional shapes of polyester needle-punched nonwoven fabrics. Trilobal cross-sectional fabric shows maximum amount of percentage compression creep at all levels of fabric weight followed by round and hollow cross-sectional polyester samples, respectively. The percentage compression creep is higher in case of fabric samples made without reinforcing material compared to the samples with reinforcing material. Hollow cross-sectional polyester fibre can be successfully used as raw material for the preparation of needle-punched nonwoven fabrics with or without reinforcing material carpet or floor mats. However, normal round cross-sectional polyester fibre only with reinforcing material can be used for the said application. Compression creep values of these selected polyester needle-punched fabric samples are much lesser in comparison with commercial market polypropylene needle-punched carpet samples.     

高温水分散体系交联马铃薯淀粉的非晶化现象研究

研究了用三偏磷酸钠为交联剂高交联马铃薯淀粉的制备方法,采用偏光显微镜和广角X-射线衍射对交联马铃薯淀粉由多晶态向非晶态的渐变过程进行了详细报道发现了随着温度的升高交联马铃薯淀粉逐渐非晶化现象,提出在高温条件下交联马铃薯淀粉存在着只含无定型结构的非晶颗粒态,并用扫描电镜对非晶颗粒态马铃薯淀粉的结构进行了详细研究。     

添加酿酒酵母的切达干酪风味研究

随着干酪市场的日益增长,开发新型风味干酪成为新的趋势.根据前期实验结果,研究选定了3种制作添加酿酒酵母的切达干酪(KY组、KH组、KC组)加工工艺,通过顶空固相微萃取和气相色谱-质谱联用技术、聚类分析及感官评价对干酪中挥发性风味化合物进行测定及分析,以此来评价酿酒酵母在切达干酪中的应用前景.干酪成熟过程中,3组干酪中挥...