不同初始含水率湿天然橡胶微波干燥特性研究

对不同初始含水率的湿天然橡胶(NR)微波干燥特性进行了研究。结果表明,湿天然橡胶微波干燥的全过程可分为加速、减速、相对恒速干燥三个阶段;湿天然橡胶快速干燥和较快速干燥阶段为物料干燥的主要阶段;不同的初始含水率对湿天然橡胶的干燥过程和产品表观质量影响较大,胶料初始含水率越高,干燥速率越快,但干燥时间较长,且产品表观质量较差,初始含水率越低,干燥时间短,产品表观质量较好;湿天然橡胶微波干燥较佳初始含水率范围为10%～20%。     

纳米CeO_2/天然橡胶复合材料干燥特性的研究

采用自行研制的动态称量微波干燥设备对纳米CeO2/天然橡胶复合材料进行干燥试验,研究了复合材料的微波干燥特性;采用扫描电子显微镜研究了微波干燥纳米CeO2/天然橡胶复合材料的表面微观结构,并与传统的热空气干燥方式进行了对比。研究表明,纳米CeO2/天然橡胶复合材料的微波干燥过程主要包括失水率加速期、失水率减速期和失水率相对恒定期三个阶段,且干燥初期复合材料的失水率随含水率的降低而增加,随后,失水率随含水率的降低而减小,微波干燥可以显著缩短干燥时间,干燥后的复合材料无发粘和未干透现象发生。     

干燥方式对天然橡胶性能的影响

探讨直接烘干、絮胶烘干、微波烘干和烟熏烘干4种干燥方式对天然橡胶(NR)性能的影响。结果表明:微波烘干时间远远短于其他3种干燥方式,且几乎不存在夹生胶现象;微波烘干NR纯胶、炭黑和白炭黑填充NR硫化胶物理性能均较优,絮胶烘干NR次之;絮胶烘干炭黑填充NR硫化胶的损耗因子(tanδ)最小,微波烘干NR白炭黑填充配方硫化胶的tanδ最小。     

干燥方式对NR耐老化性能的影响

研究热空气和微波两种干燥方式对NR耐老化性能的影响。结果表明,与热空气干燥相比,微波干燥对NR分子链破坏程度较轻,微波干燥的NR热稳定性较好,塑性初值、塑性保持率和门尼粘度较高,耐热空气老化性能显著提高。     

用橡胶加工分析仪研究微波干燥天然橡胶的性能

用橡胶加工分析仪对微波干燥的天然橡胶进行了应力松弛扫描、温度扫描和应变扫描,并与热空气干燥的天然橡胶进行了对比。结果表明,热空气干燥的天然橡胶应力松弛较快,而微波干燥的天然橡胶拉伸诱导结晶表现尤为明显。     

干燥工艺参数对颗粒状氯化天然橡胶干燥过程的影响

通过氯化天然橡胶的穿透干燥试验,探讨风温、风速以及粒径对CNR干燥速率的影响规律,通过对数据正交分析,寻找最佳干燥工况及参数,揭示影响干燥速率的规律。     

不同干燥因素对天然橡胶微波干燥过程的影响

使用动态称量微波干燥设备研究了不同微波功率密度、不同胶样厚度和不同初始含水率3种因素对湿天然橡胶微波干燥过程及表观质量的影响。结果表明,3种因素对湿天然橡胶微波干燥过程和胶样表观质量的影响较大;微波功率密度越大,失水速率就越大,干燥时间就越短,胶样易出现干燥发粘现象;胶样厚度越厚,失水速率越小,干燥时间就越长,易出现部分夹生和发粘现象;初始含水率越高,失水速率就越大,干燥时间就越长,胶样易出现部分发粘现象。微波干燥湿天然橡胶较为合适的微波功率密度、胶样厚度和初始含水率分别为30.14-34.2W/dm3,5~15mm和10%-20%。     

微波干燥天然橡胶含水量与干燥速率关系研究

为探讨湿天然橡胶微波干燥新技术,利用自制的微波干燥试验测试系统,对湿天然橡胶进行了不同干燥温度下的微波干燥试验,测试分析了微波干燥过程中湿天然橡胶含水率与失水率的关系,并探讨了不同干燥温度下湿天然橡胶含水率与失水率的关系。研究结果表明,不同干燥温度下湿天然橡胶失水速率随干基含水率的变化曲线呈一致趋势;失水率随含水率的升高先增大后减小;干燥温度越高,湿天然橡胶相同失水率下对应的含水率就越高。     

两种干燥方式天然橡胶的表观超微结构及热氧降解反应动力学

笔者采用SEM和TG-DTG方法研究微波和热风干燥方式处理的NR的表观超微结构以及热氧降解反应动力学。结果表明,采用微波干燥的NR胶粒表面粗糙,而热风干燥的NR胶粒表面熔融平滑;两种干燥方式处理的NR热氧降解过程均为两步反应,用微波干燥的湿NR热氧稳定性较高。     

颗粒状氯化天然橡胶穿透式干燥动力学模型

本试验通过氯化天然橡胶的薄层干燥试验,探讨风温、风速以及粒径对CNR含水量的影响规律,建立薄层干燥方程。试验结果表明,预测值与实测值一致性较好,所建数学模型可用于描述氯化天然橡胶的薄层干燥。     

Effect of three drying methods on the drying characteristics and quality of okra

The objective of this study was to compare the drying characteristics and quality of dried okra obtained by vacuum freeze drying (VFD), microwave vacuum drying (MVD), and pulse-spouted microwave vacuum drying (PSMVD). The quality parameters include color (L*, a*, and b*), texture (hardness and fracturability), shrinkage ratio (SR), nutrient retention (chlorophyll, flavonoids, and vitamin C), and sensory score was investigated. Vacuum freeze drying maximally preserved the original properties of samples. And the samples dried by PSMVD showed higher quality and more uniformity compared to MVD. Considering of all aspects comprehensively, such as cost-effectiveness, practicability, and scale-up, PSMVD was a promising technique which would match results obtained by vacuum freeze drying.     

Effects of different drying methods on the microstructure and thermal oxidative aging resistance of natural rubber

In this work, the wet natural rubber granules were dried by hot air and by microwave at 115°C, respectively; the morphological structures of dried natural rubber granules were studied by using a scanning electronic microscope, whereas the thermal oxidative properties of dried natural rubber granules were investigated by comparison of variation in properties before and after aging, and the changes in the thermal oxidative decompose temperatures. The results showed that it needed 13.47 min for microwave drying and 210.00 min for hot air drying to reduce the moisture content of wet natural rubber to the required value. The granules of natural rubber dried by microwave were of rough surfaces and the cutting traces produced during the processing of wet natural rubber remained on the natural rubber surface; whereas, the natural rubber granules dried by hot air were of smooth surfaces, and the cutting traces produced during the processing of wet granules disappeared. The thermal oxidative resistance of vulcanized natural rubber dried by microwave improved significantly. The initial plasticity (P₀), plasticity retention index, and thermo‐oxidative decomposition temperature of natural rubber dried by microwave were higher than those of natural rubber dried by hot air. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

应用涂装设备改善水性木器涂料的干燥瓶颈

从不同条件及各种涂装现场的角度来探讨水性木器涂料与不同涂装干燥设备的搭配的效果,寻找出适合水性木器涂装的设备,改善水性木器干燥瓶颈,促使水性木器涂料能广被采用。     

内蒙古某褐煤干燥特性的实验研究

利用热风干燥实验装置对内蒙古某褐煤进行不同温度、不同风速、不同粒度的干燥特性研究。结果表明：降低褐煤的粒度可有效缩短干燥时间;热风风速对褐煤的干燥速率影响很小,干燥适宜温度为150~165℃,在此温度区间内干燥时间较理想,进一步提高风温虽然有助于提高干燥效率,但有发生自燃的危险。     

小颗粒“胶乳法”氯化天然橡胶穿透干燥试验

通过氯化天然橡胶(CNR)的穿透干燥试验,探讨风温、风速以及粒径对“胶乳法”CNR干燥速率的影响规律,结果表明,温度和风速对含水量的下降速率影响较大,而粒度对其影响较小。建立了穿透干燥方程,对实验数据进行了拟合,结果显示其吻合性较好。红外光谱分析以及物理性能测试结果表明,“胶乳法”CNR物料的干燥温度应控制在100℃以下。     

城市污泥热风与微波干化特性研究

采用热风和微波加热两种方式对城市污泥进行薄层干化实验研究,分别考察污泥薄层厚度和其他操作条件对污泥干燥特性及能耗的影响。研究发现:在热风干燥过程中,由于污泥的塑性,污泥表面容易结壳,从而严重阻碍了水分向外迁移,使得干燥速率呈阶梯状下降。微波干燥污泥具有时间短、干燥速率大,同时节省能源。     

A comparative study of drying methods on physical characteristics,nutritional properties and antioxidant capacity of broccoli

Abstract

Broccoli is considered one of the attractive raw materials for dehydrated vegetables owing to its high nutritional value. However, information about how drying methods affect the physicochemical and nutritional properties of broccoli is limited. In this study, broccoli pieces were subjected to freeze drying (FD), hot air drying (HAD), microwave vacuum drying (MVD), vacuum drying (VD), MVD combined with HAD (MVD?+?HAD), and MVD combined with VD (MVD?+?VD). Quality attributes of dehydrated broccolis were contrasted in terms of color, texture, volume shrinkage, nutritional components, antioxidant activity, and rehydration capacity. Results demonstrated that FD better preserved the nutrients while HAD displayed the worst effect. The combination of MVD?+?HAD and MVD?+?VD resulted in higher retention of nutritional compositions, better antioxidant activity, and lower energy consumption than that of HAD. Furthermore, combined drying processing exhibited similar rehydration capacity but lower hardness compared to that of HAD.     

Comparison of physical and mechanical properties of NR/carbon black/reclaimed rubber blends vulcanized by conventional thermal and microwave irradiation methods

This work experimentally monitored the physical and mechanical properties of natural rubber/carbon black/reclaimed rubber blends vulcanized by microwave (MW) irradiation and conventional thermal (CT) systems, and the curing mechanisms are addressed in conjunction with the vulcanizate properties. The microwave oven for rubber blend vulcanization was specially designed and constructed in this work. The results suggested that the tensile modulus and the hardness of the vulcanizates could be enhanced by increasing the reclaimed rubber (RR) content, whereas the tensile stress, elongation at break, and tear strength decreased with the RR loading. The mechanical properties of the vulcanizates from the CT method were higher than those from the MW method. The vulcanizates from the MW method had higher resistance to toluene penetration than those from the CT method. The differences in the properties of the vulcanizates from the CT and MW methods became smaller at higher RR contents. The sensitivity in property changes of the vulcanizates due to addition of the RR content was greater for the CT method than for the MW method. The differences in the results between these two curing systems could be explained in terms of the density and the types of crosslinks present in the vulcanizates. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 5039–5048, 2006     

Effects of intermittent microwave drying on quality characteristics of pistachio nuts

In this research, the effect of intermittent microwave drying (IMD) on drying time and quality characteristics for three varieties of Iranian pistachio nuts was investigated and compared with the sun drying method. The quality parameters, such as chemical characteristics, physical parameters, and sensory evaluation were considered. Three varieties, Kal-Khandan, Kaleh-Bozi, and Ghermez, were dried in an 800-W, 2,450-MHz domestic microwave oven. Experiments were conducted in three material loads of 50, 100, and 150?g under intermittent method at 6?s of power-on and 70?s of power-off with three replications. The total drying time was in the range of 114.03–266.07?min, depending on material loads and varieties. The higher the material load, the longer the drying time. The results showed that the effect of drying method on the shell splitting size was very significant (p?p?相似文献