长寿命产品退化筛选试验方法研究

 传统的可靠性筛选方法以产品是否失效为筛选判据,对于高可靠长寿命产品,必须将产品长时间置于筛选应力下,对于一批产品中的合格品会产生较为严重的不良影响.针对退化失效型产品,研究了不合格品与合格品的性能退化规律:在筛选应力下,相对于合格品,不合格品性能参数的变化速率相对较快,从而使得性能参数在试验检测过程中形成明显的双峰分布.论文提出了基于产品性能退化特性的可靠性筛选技术,在保证筛选成品率和产品可靠度的前提下,通过合理选取筛选试验持续时间和筛选阈值,实现了缩短试验时间和减少筛选应力对合格品的不良影响的目的,最后通过实例说明了方法的有效性.     

吉林市特色产品外宣现状与外宣传播问题研究

吉林特色产品是富有东北特色的精品,是东北的民族风格和地域特点的凝练,从方方面面反映出了东北劳动人民的生活形态。这些特色产品的外宣是其扩大国际知名度,走向国际市场的基本前提。长期以来,由于种种原因,在外宣过程中存在忽视受众的思维习惯、对文化冲突重视不够等问题,加上受到西方绿色壁垒的禁锢,使得我们的宣传未能达到预期效果。在贸易保护主义日趋抬头的当下,探索积极的外宣手段和科学的外宣策略对吉林特色产品的推广和普及具有重要的意义。     

Poly(lactic acid)–thermoplastic starch–cotton composites: Starch-compatibilizing effects and composite biodegradability

Poly(lactic acid) (PLA) is a biodegradable, brittle, and high-cost polymer, which can be applied over structural components and green packaging. In this study, we reinforced PLA with natural cotton (10 wt %) and thermoplastic starch (TPS; 3 wt %) to obtain a biodegradable and lower cost composite. TPS was incorporated in three distinct ways: it was blended, coated, and blended and coated. In this study, we investigated the compatibilization of TPS in the improvement of matrix-reinforcement adhesion and increase in the tensile behavior without a compromise in biodegradation. The samples were investigated with thermal analysis, dynamic mechanical thermal analysis, tensile testing, scanning electron microscopy, confocal laser scanning microscopy, and hydrolytic degradation. The results show that the coupling effect was more pronounced in the PLA_TPS–cotton_TPS (hybrid system with PLA and cotton) hybrid system. This formulation presented a higher glass-transition temperature, thermal stability, storage modulus, wettability, and ductility. The TPS addition improved the adhesion between the matrix and starched cotton fiber and retarded abiotic biodegradation. These properties will allow for green applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47490.     

Preparation and analysis of poly(l-lactic acid) composites with oligo(d-lactic acid)-grafted cellulose

α-Cellulose extracted from jute fiber was grafted with oligo( d -lactic acid) (ODLA) via a graft polycondensation reaction in the presence of para-toluene sulfonic acid and potassium persulfate in toluene at 130 °C for 9 h under 380 mmHg. ODLA was synthesized by the ring-opening polymerization of d -lactides in the presence of stannous octoate (0.03 wt % lactide) and d -lactic acid at 140 °C for 10 h. Composites of poly( l -lactic acid) (PLLA) with the ODLA-grafted α-cellulose were prepared by the solution-mixing and film-casting methods. The grafting of ODLA onto α-cellulose was confirmed by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The analysis of the composites was performed with FTIR spectroscopy, SEM, wide-angle X-ray diffraction, and thermogravimetric analysis. The distribution of the grafted α-cellulose in the composites was uniform and showed better compatibility with PLLA through intermolecular hydrogen bonding. Only homocrystalline structures of PLLA were present in the composites, and the thermal stability increased with increasing percentage of grafted α-cellulose. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47424.     

Predicting trends in structural and physical properties of a model polymer with embedded natural fibers: Viability of molecular dynamics studies for a bottom up design

The effects of relatively high- and low-shear processing on the macroscopic and microscopic porosities of a standard packaging polymer—linear low density polyethylene (LLDPE) and its composites with pine flour are studied. The macroscopic porosities, represented by deviations of observed density from the theoretical density, primarily drive the trends in mechanical and solvent uptake properties. The microscopic porosities of the system, however, are independent of the processing method and pine flour concentration. Furthermore, by using molecular dynamics (MD), molecules of LLDPE and pine flour were constructed. The material properties of the molecules, specifically microporosity and elastic moduli, were compared to experiment. A semiempirical modeling approach was used to fit the simulated data to the experimental composite moduli. The model of Halpin and Tsai was found to be the most efficacious for this system, and the benefits of the combined MD-semiempirical modeling for bottom up design are discussed. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48189.     

注塑成型光学制品折射率分层模拟与实验研究

与玻璃制造光学制品相比,高分子注塑光学制品具有质量轻、易加工、抗冲击性好等优点,在航空航天、精密透镜等高端领域得到广泛应用。然而受注塑过程复杂压力场、温度场的耦合作用,注塑透明制品折射率通常呈非均匀的分布,存在角偏差、光畸变等光学缺陷。因此,开展注塑工艺对其折射行为影响的模拟与实验研究,对实现折射率可控光学制品的成型具有重要意义。基于Hele Shaw注塑理论和Lorentz Lorenz物理光学理论,构建了注塑光学制品厚度方向折射行为分层预测模型,开发了相关模拟程序,基于自主研发的注塑模软件Z-Mold实现了注塑过程与折射率分布的一体化模拟。以聚碳酸酯注塑平板件为例,利用Brewster法对折射率模拟结果进行了验证。该方法成功应用到神舟系列航天舱外服面窗的研制。     

提高熔铸耐火材料制品冒口补缩效率途径的探讨

通过分析熔铸耐火材料制品冒口的补缩原理和冒口的设计,认为浇铸冒口是浇铸工艺的重要组成部分,为提高熔铸耐火材料制品冒口补缩效率提出:合理加高冒口,提高冒口内熔液的补缩压力;采用加热冒口,延长冒口的凝固时间;实行二次补浇铸,增加冒口热能;控制制品铸件保温工艺,增长冒口补缩距离。     

超高压技术对低盐肉制品降盐机制及品质改良的研究进展

低盐肉制品的开发是当前肉类食品的发展趋势,但降低钠盐的添加量会引起肉品品质的劣变。超高压技术作为一种新型的非热加工技术,可以降低肉制品中的食盐使用量,改善肌肉蛋白质的功能特性,改进低盐肉制品的品质。本文从高压处理对低盐肉制品保水性、蒸煮损失、咸味、颜色以及微生物安全性5 个方面出发,综述了超高压技术在低盐肉制品品质改良应用中的研究进展,并在此基础上论述了超高压技术对低盐肉制品的降盐机制,指出该技术在低盐肉制品应用中存在的局限性,并对其未来的发展前景进行展望,以期为超高压技术在低盐肉制品中的应用和推广提供理论参考。     

鱼类加工副产物的食用化及其在鱼肉重组制品中的应用

在鱼类加工过程中会产生大量的副产物,其中具有多种生物活性物质,如胶原蛋白、明胶、甲壳素、脂肪酶、蛋白酶及生物活性多肽等。本文介绍了鱼类加工副产物的营养保健功能和风味特征,列举了常见副产物的基本营养成分和氨基酸组成,并系统归纳了具体副产物中含有的生物活性成分,同时概括了鱼肉重组制品的分类及其重组技术,综述了副产物在鱼肉重组制品中的应用现状,并结合实际展望了鱼类加工副产物的发展与应用前景。以期为高效利用鱼类加工产生的副产物提供借鉴,并为其进一步开发利用提供有益参考。     

乳液凝胶替代动物脂肪在肉制品中应用的研究进展

随着消费者越来越注重饮食与健康之间的关系,如何替代肉制品中含有大量饱和脂肪酸的动物脂肪已经成为肉品科学领域研究的热点问题。然而,单纯地过多降低动物脂肪使用量会大大降低肉制品的风味和柔嫩多汁的口感。近年来,利用具有独特结构和功能特性的乳液凝胶作为一种新型的动物脂肪替代物越来越受到重视。本文在国内外相关研究的基础上,全面综述了乳液凝胶的制备方法、品质特性和在低脂肉制品中的应用情况,以期为乳液凝胶替代动物脂肪在肉制品中的应用提供良好的理论依据,也为生产高附加值的新型健康低脂肉制品提供创新性技术指导。