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1.
Leather manufacturing involves a crucial energy-intensive drying stage in the finishing process to remove its residual moisture and generates important heat gradients. The numerical model presented in this study has been developed to describe the drying process of porous medium: bovine leather that undergoes deformation due to shrinkage. The mathematical formulation of fundamental heat, mass and momentum transfers’ phenomena during drying summarizes a two-dimensional model considering elastic behavior of bovine leather. The evolution of moisture content, temperature, and mechanical stresses during drying was discussed. The model was validated with experimental results. Numerical simulations show good agreement with experimental results. The study shows that the elastic model keeps the stress sign at the final stage of drying. The deformations induce tensional stresses near the surface equilibrated by compressive stresses within the product. They reached their maximum for normal stresses equal to 5.97 and 3.52?MPa at around 2145 and 868?s, respectively, for normal stresses along x and y directions and then decrease. 相似文献
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A series of polyethylene glycol-linked Gemini fatty alcohol phosphate surfactants (GFAP) were prepared with long chain n-alkanol (C = 8, 12, 16, 18), polyethylene glycol (PEG-200, PEG-400, PEG-600, PEG-800, PEG-1000) and phosphorus oxychloride (POCl3). The structure of the prepared surfactants was characterized by Fourier transform infrared spectrometer (FT-IR). The surfactants were employed for the modification of chrome-tanned leather. The morphological changes of chrome-tanned leather and modified chrome-tanned leather were observed by scanning electron microscopy (SEM). The relationship between the alkyl chain length and molecular weight of the PEG and the hydrophobicity, softness, mechanical strength of modified chrome-tanned leather was also discussed. The experimental results showed that the mechanical strength and softness of modified chrome-tanned leather were enhanced with an increase of alkyl chain length, while the hydrophobicity, mechanical strength and softness were decreased with an increase of molecular weight of the PEG. The hydrophobicity, mechanical strength and softness of modified chrome-tanned leather were optimized for an alkyl chain length of 16. Therefore, 16–200 Gemini phosphate surfactants with an alkyl chain length of 16 and a PEG molecular weight of 200 have a good comprehensive modification effect on Chrome-tanned leather, the tensile strength, tear strength and softness of modified chrome-tanned leather are 57.07 N mm−2, 79.49 N mm−1, 9.73 mm, respectively. 相似文献
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GB/T 30398-2013《皮革和毛皮化学试验致敏性分散染料的测定》中规定了皮革和毛皮中的致敏性分散染料的测定方法,按照GB/T 30398-2013标准用HPLC法测定皮革中可萃取致敏性分散染料,以分散黄3为例,分析了测试过程中不确定度的来源,对各不确定度分量进行评定及合成,并计算得出合成不确定度和扩展不确定度。结果表明,对本测试方法影响较大的不确定度分量是标准物质配制。在重复测定的条件下,测定结果的不确定度仅与溶液中的致敏性分散染料浓度有关。 相似文献
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Pig leather industry contributed significantly to the life of people all over the world, but serious water environmental problems have arisen. Investigation in tanneries with green pig hides in China showed that pollution resulted mainly from beamhouse operations. Assessment indicated that wastewater from pig‐hides processing had: (1) wide variations of pH, (2) high levels of sulfide (S2?) and chromium, (3) high levels of neutral salts and ammonia nitrogen (NH 4+‐N), (4) high levels of suspended solids (TSS) and oil & grease, and (5) low biodegradability. A tannery processing 10 000 pig hides per day generated chemical oxygen demand (COD) of 3.81–12.31 tonnes and NH 4+‐N 0.27–1.06 tonnes, respectively. The pollution loads were equivalent to those of a city of 60 000–120 000 inhabitants, which has a COD of 3.9–10.56 tonnes/day and NH 4+‐N of 0.462–1.164 tonnes/day, respectively (SEPAC). And nearly 30% of the tanneries discharged their wastewater by screening only or by primary treatment like coagulation–sedimentation, while the rest of them discharged directly into surface waters without any treatment. 相似文献
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Senem Kamiloglu Esra Capanoglu 《International Journal of Food Science & Technology》2014,49(4):1027-1039
In this study, to evaluate the in vitro bioaccessibility of eight different pekmez and pestil samples, total phenolics, flavonoids, proanthocyanidins, anthocyanins and antioxidant capacity were determined at different phases of simulated gastrointestinal (GI) digestion. For the analysis of antioxidant activity, four different methods were used including 2,2‐azinobis(3‐ethylbenzothiazoline)‐6‐sulfonic acid, 1,1‐diphenyl‐2‐picrylhydrazil, ferric reducing antioxidant power and cupric ion reducing antioxidant capacity. The results revealed that the dialysed fraction (IN) represented 12–50%, 3–17% and 3–72% of the total phenolics, flavonoids and proanthocyanidins, respectively. Moreover, total antioxidant capacity of IN fraction was 2–57% of the initial values obtained for pekmez and pestil samples. To identify the influence of simulated in vitro GI digestion on total anthocyanins, only black mulberry molasses (pekmez) and plum leather (pestil) were analysed and according to the results no anthocyanins were detected in the IN fraction for both samples. The present study presented a detailed insight of bioaccessibility of polyphenols in various pekmez and pestil samples. 相似文献
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针对目前容栅数显皮革测厚仪在测量过程中的测量准确度不高的现状,对测厚仪的工作原理进行分析后,找出误差的影响因素,提出了一种分别从硬件、软件2个方面进行改进的办法.在机械加工和安装方面,通过添加半圆形限位片以及弹簧片的方法进行改进.在软件方面进行优化,即编写测量出错提示以及定时5 s后在LCM06XK上进行锁定当前显示的经过数字滤波算法求平均的厚度值的软件程序以提高测量准确度.最后通过实验数据证明改进后的仪器具有测量准确度高、稳定性好、抗干扰能力强等优点. 相似文献