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聚四氟乙烯(PTFE)针刺滤料的寿命与蠕变失效密切相关。为预测其长期蠕变行为,在200~260℃范围内进行梯度蠕变实验,借助时温等效原理得到滤料的蠕变曲线,并进一步探究后处理工艺对PTFE针刺滤料蠕变性能的影响。结果表明:在恒定拉应力下PTFE滤料发生了蠕变和其他多种形变,长时间尺度内蠕变起主要作用,预测滤料的高温蠕变寿命在3年左右。此外,时移因子与温度的关系曲线满足WLF方程,意味着时温等效原理描述PTFE滤料的高温蠕变行为是适用的。在试验周期内,松弛热定形增加了滤料的蠕变应变量,定长热定形、浸渍整理、覆膜整理降低了滤料的蠕变应变量,其中覆膜整理滤料的抗蠕变性能最佳。 相似文献
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为研究滤料清灰性能的不同影响因素,选取4种聚苯硫醚(PPS)纤维滤料,即未经后处理、烧毛、聚四氟乙烯(PTFE)乳液浸渍和PTFE 微孔膜覆膜处理的滤料为试样,采用滤料动态过滤性能测试仪测试了4种聚苯硫醚纤维滤料的清灰性能,通过扫描电镜观察了过滤前后滤料的表观形貌。测试结果表明:在试验周期内,这4种滤料中,覆膜滤料经粉尘过滤后剩余压差最低,清灰周期最长,清灰性能最为优异;未经处理滤料清灰性能次之;PTFE乳液浸渍滤料由于表面纤维间充满着PTFE 乳液固状物,其清灰性能较差;烧毛处理滤料表面留有面积较大的PPS 纤维烧焦物质,其清灰性能最差。 相似文献
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通过采用SEM探索玻纤布覆膜滤料、玻纤毡覆膜滤料的微观结构,分析了覆膜滤料的表面特点,从微观上对覆膜滤料的过滤机理进行了探索,并探索了覆膜滤料的膜裂现象.认为覆膜布与覆膜毡的烟气过滤主要依靠来与基体结合的聚四氟乙烯膜进行,减少覆膜滤料表面聚四氟乙烯膜与基材的结合点和结合面积是提高滤材产品性能的有效措施. 相似文献
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聚酯/天丝混纺织物在服用舒适性和耐久性方面性能优越,这是因为天丝具有很好的水分调节性能。与公认的聚酯/棉混纺相比,优越的水分调节性能可使聚酯/天丝混纺纱在不影响服装舒适性的基础上增加聚酯的含量,从而获得更好的耐久性。天丝的应用及纺纱技术的合理选择可延长工作服使用寿命,从而增加效益。 相似文献
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Priscilla M. Clarkson 《Critical reviews in food science and nutrition》1995,35(1-2):131-141
Performance of strenuous physical activity can increase oxygen consumption by 10‐ to 15‐fold over rest to meet energy demands. The resulting elevated oxygen consumption produces an “oxidative stress” that leads to the generation of free radicals and lipid peroxidation. A defense system of free radical scavengers minimizes these dangerous radicals. Indirect measurements of free radicals generated during exercise include assessing products of lipid peroxidation that appear in the blood (e.g., malondialdehyde and conjugated dienes) or expired in the breath (pentane). Changes in antioxidant scavengers and associated enzymes (e.g., glutathione, tocopherol, glutathione peroxidase) also provide clues about demands on the defense system. Physical training has been shown to result in an augmented antioxidant system and a reduction in lipid peroxidation. Supplementation with antioxidants appears to reduce lipid peroxidation but has not been shown to enhance exercise performance. The “weekend athlete” may not have the augmented antioxidant defense system produced through continued training. This may make them more susceptible to oxidative stress. Whether athletes or recreational exercisers should take antioxidant supplements remains controversial. However, it is important that those who exercise regularly or occasionally ingest foods rich in antioxidants. 相似文献
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研究了妊娠期长毛兔母兔饲喂不同蛋氨酸含量的饲粮对其繁殖性能和仔兔生产性能的影响。结果表明,随着长毛兔母兔妊娠期饲粮蛋氨酸含量增加,长毛兔母兔的产活仔数,断奶仔兔和初生仔兔窝重极显著提高(P<0.01),对母兔血清总蛋白、白蛋白和尿素氮影响差异不显著(P>0.05),提高了仔兔断奶重、毛纤维直径和2月龄体重(P>0.05),仔兔2月龄产毛量显著增加(P<0.05)。结果提示,蛋氨酸可促进妊娠期长毛兔母兔体内蛋白质营养利用,提高母兔繁殖性能和仔兔的生产性能;长毛兔妊娠饲粮中蛋氨酸质量分数以不超过0.71%为宜。 相似文献