Experimental and numerical modelling comparison of thermal performance of expanded polystyrene and corrugated plastic packaging for fresh fish

Experiments were carried out to compare the thermal performance of wholesale fresh fish boxes made of corrugated plastic (CP) and expanded polystyrene (EPS). Free standing boxes containing whole, fresh fillets were exposed to dynamic thermal loads. The chilling effect of frozen ice packs was studied by including them in some of the boxes. The frozen ice packs proved efficient for protecting fresh fish fillets against temperature abuse. Furthermore, the results show that the insulating performance of EPS is significantly better than the insulating capacity of CP. Maximum fish temperature of 16.1 °C (CP) and 11.0 °C (EPS) were recorded inside the thermally abused boxes without ice packs, initially at 1.9 to 2.1 °C and stored for 6.1 h at a mean ambient temperature of 19.4 °C. The fish temperature distributions during thermal abuse were studied with a numerical model for both packaging types, applying effective thermal properties of the sandwich-structured CP box. The purpose of the model was to cost effectively improve the packaging design. A satisfactory agreement between numerical results and experimental results was obtained.     

可折叠水产品运输保温包装箱结构设计

目的 开发可折叠水产品运输保温包装箱。方法 借鉴纸包装结构设计中的可折叠设计思想, 以塑料中空板为箱体材料, 结合保温材料, 得到可折叠水产品运输保温包装箱结构设计方案, 将其与普通塑料泡沫箱进行物流成本对比分析, 通过抗压试验测定分析不同类型水产品运输保温包装箱的抗压强度。结果 该包装箱实现了空箱储运时可折叠, 降低了物流成本; 箱子抗压强度好, 优于市场上常用的水产品塑料泡沫箱, 同时可通过调整外箱体材料及保温材料来优化包装箱的各方面性能; 在采用该包装箱进行水产品包装时, 需在内包装中增加塑料袋来满足水产品物流运输过程中防水渗漏的要求。结论 该可折叠水产品运输保温包装箱的结构设计方案可行, 力学性能好。     

Evaluation of a biodegradable foam for protective packaging applications

Green Cell^® foam (GCF) is a biodegradable foam packaging material produced from a proprietary cornstarch blend. It is commercially available in a variety of laminations and constructions. Cushioning ability and thermal resistance (R‐value) are the fundamental properties needed to compete against synthetic foams. Since GCF is starch based and biodegradable, a concern was that moisture would likely affect its physical properties. Cushioning characteristics and insulation R‐values of 1 and 2 inch foams were determined as a function of temperature and moisture content. The ASTM method D1596 was used to determine the cushioning properties and an ice melt test was used to determine the thermal resistance. Moisture sorption isotherms were developed at three temperatures (20, 25 and 30°C) to determine its moisture sensitivity. The 1‐inch‐thick foam had lower G values at lower static stresses than synthetic foams, but had higher G values at higher static stresses. The 2‐inch‐foam had G values similar to that of synthetic foam materials. Dimensional changes were observed at higher relative humidity (RH) conditions, especially at 30°C. The R‐values at higher humidities were also less than that of synthetic materials. Copyright © 2007 John Wiley & Sons, Ltd.     

纳米纤维素基泡沫材料在包装领域的研究进展

纳米纤维素作为天然可降解材料,具有优良的力学性能、高比表面积、大长径比等特性。为研究基于纳米纤维素开发的泡沫材料在包装领域的应用,对近年来纳米纤维素基泡沫材料的制备方法及其缓冲、隔热、阻燃、抗菌、疏水等性能进行总结,概括了纳米纤维素泡沫材料在纳米纤维素制备、湿泡沫发泡和泡沫成型干燥等领域的进展。但由于现阶段纳米纤维素制备工艺的复杂性,以及干燥过程中较高的能耗和较长的周期,作为包装材料的关键性能指标还有进一步提升的空间,实现规模化生产仍有一些问题有待解决。通过综述纳米纤维基泡沫材料在包装领域的研究进展,以期为可持续包装材料的发展提供理论支持。     

Contribution to the gas chromatographic analysis for both refrigerants composition and cell gas in insulating foams – Part II: Aging of insulating foams

In part I, a simple analysis protocol for refrigerant substances has been proposed for use in refrigerating plants or as blowing agents for insulating foams. The present work proposes original results obtained with that method to study the aging of insulating foams. The characteristics of insulating foam panels have been studied including the initial composition and heterogeneity of cell gases, as well as the aging of both unprotected and protected insulating panels. A special focus has been laid on aging at the junctions in refrigerated trucks panels. Indeed, insulation boxes for refrigerated trucks are usually made of various foam panels covered by a single gas-tight facing. A quicker aging was observed under the facing in the foam panels' junction areas, and we could assert that the global aging of the refrigerated trucks box mainly results from the aging of the assemblies (sides and junctions).     

蓄冷箱在疫苗冷链中的研究进展

每年疫苗产品损耗的主要因素之一是冷链运输的失效,在运输过程中使用最为普遍的设备是蓄冷箱。影响蓄冷箱保温性能的因素主要包括保温箱体的绝热性能、蓄冷材料的蓄冷能力及保温包装方式的设计。本文综述了蓄冷箱在疫苗冷链中的研究进展,分析了疫苗蓄冷箱常用保温材料及相变蓄冷材料的选择和应用,并讨论了箱体热阻的计算及蓄冷箱温度的监控。在此基础上指出整体包装和开发相变蓄冷材料的研究方向。     

复合材料包装箱模块化设计与成型技术研究

目的 为了满足复合材料包装箱在交通运输方面的更多需求,本文研究出一种轻质、高强、耐腐蚀、防霉、安装轻便快捷的复合材料包装箱制造技术。方法 本文通过包装箱设计与仿真分析、产品表征等工序开展研究,将包装箱设计成4种16块单元面板,通过材料筛选、模具设计、单元件成型工艺研究,完成面板制作,并进行单元件质量称量、力学性能表征试验。结果 包装箱总质量较同规格金属箱子质量减少70%以上,力学测试结果显示实际弯曲强度较理论值高85.41%,泡沫加强筋平拉强度较理论值高出15.08%。结论 研究结果表明模块化复合材料包装箱满足设计要求。     

前驱体热解氮化硼/碳化硅复相泡沫陶瓷的抗氧化与高温隔热性能研究

以聚碳硅烷(PCS)和三甲胺基环硼氮烷聚合前驱体(PBN)进行共聚合制得复合前驱体, 以此为原料采用高压裂解发泡技术制备了一种氮化硼/碳化硅(BN/SiC)复相开孔泡沫陶瓷. 由包含不同比例组分的起始前驱体所制得的泡沫陶瓷的孔隙直径在1~5 mm, 体积密度在0.44~0.73 g/cm³之间. 对该陶瓷材料的微观结构和性能的研究表明, 由于BN相的引入使得BN/SiC复相泡沫陶瓷在800~1100℃的抗氧化性能有了显著的提高; 其压缩强度随着引入BN比例的增加而提高, 约为纯SiC泡沫陶瓷的5~10倍. 其中以组分重量比为1:1的起始复合前驱体所制备BN/SiC复相多孔陶瓷在1500℃时的导热系数仅为4.0 W/(m·K); 对其进行隔热性能测试, 材料热面中心温度为1400℃时, 其背面中心温度仅为280℃; 采用有限差分法数值模拟背部升温历程, 将其有效导热系数代入计算模型, 得到材料背部中心温度升温历程的数值模拟结果, 与实际升温历程基本一致.     

隔热疏水功能涂料研究进展

目的 归纳隔热疏水涂料的功能实现方法,分析疏水隔热功能涂料在包装中的潜在的应用价值,为新型多功能涂料的制备及其在纸包装领域的应用提供参考和借鉴。方法 梳理并归纳阻隔型、反射型、辐射型等3种类型隔热涂料的工作原理及实现方式,系统介绍几种常见的疏水表面形成机理模型以及制备方法,综述疏水隔热功能涂料的应用研究进展。结果 涂料的制备以及涂布技术已经成熟,疏水隔热功能涂料可涂布于瓦楞纸箱、白卡纸等表面用于食品保温包装。结论 将隔热疏水功能涂料用于纸包装箱,用来保护温敏食品品质和节约冷链运输成本,具有巨大的潜力和广阔的发展前景。     

夏黑葡萄电商物流品质评价及影响因素分析

目的 对不同电商物流包装,不同产区夏黑葡萄的运输品质构建规范化评分模型,进一步完善运输过程中葡萄的品质评价体系,同时为不同运输包装的组合利用提供理论依据。方法 以云南、江苏、天津等地的5个产区的夏黑葡萄为研究对象,采用4种典型电商包装进行48 h实物寄递试验。运用相关性和主成分分析,对夏黑葡萄的电商物流品质进行综合评价,筛选出适宜的电商包装方式,并进一步分析运输过程中造成品质差异的环境影响因素。结果 主成分分析提取了3个主成分,累计贡献率达89.096%,对3个主成分得分进行权重相加和建立果实品质评分(Y)模型：Y=0.562Y₁+0.186Y₂+0.143Y₃。结果表明处理组1(瓦楞纸箱/泡沫箱/冰袋/袋中袋)内夏黑运输品质最优且更稳定,其他3个处理组品质波动较大。通过分析运输过程中环境温度及振动的变化,发现EPS泡沫箱保温性能最好,冰袋辅助降温可以有效降低包装箱内温度,提高葡萄商品性;提高包装量是削弱Z轴振动对产品影响的有效手段。结论 本研究建立了一套综合性的果实品质评分模型,利用该模型能够较为客观、准确地反映出夏黑...     

Evaluation of silica aerogel-reinforced polyurethane foams for footwear applications

In this work, a simple way to create a nanocellular structure within polyurethane (PU) foam was developed by the incorporation of silica aerogels, and the resultant foams were evaluated for footwear applications. To protect the brittle aerogels from breakage, the softness of PU foams was first tailored by changing the ratio of glycerol and polypropylene glycol. Different amounts of silica aerogels (0–15 wt%) were then loaded into a selected PU foam and analyzed in terms of compressive mechanical properties, shock attenuation performance, and thermal insulation. After incorporation of the aerogels, the compressive modulus, the compressive stress, and the deformation recovery of the foams improved, while the excellent flexibility was preserved. For simulated gait experiments, the shock attenuation capability of the foams was shown to increase with an increase in the aerogel content. These findings can probably be attributed to the improved elasticity of the solid phase and the changed morphology of the gaseous phase as observed from the SEM images. Moreover, the thermal insulation of the developed foams was also investigated, showing an increased trend with the aerogel content.     

Characterization of rigid polyurethane foams containing microencapsulated Rubitherm? RT27. Part I

Rigid polyurethane foams (RPU foams) and phase change materials (PCMs) are widely used in buildings for thermal insulation and thermal storage, respectively. The combination of both materials could increase energy savings, leading to more energy efficient housing. In this work, PU foams were produced incorporating different percentages of microcapsules containing Rubitherm^? RT27. Microcapsules added to the foam had a high influence on the foaming process and also on the foam properties. It was observed that the increase of foam microcapsules content decreases the final foam height but increases its density and thermal energy storage (TES) capacity. On the other hand, an increase of the foam microcapsules content up to 5 wt% led to decrease the reduced compressive strength (RS) and modulus (RE) in 7 and 25%, respectively. Higher contents had a sharply negative impact on mechanical properties.     

玻璃纤维增强体形式对酚醛泡沫性能的影响

针对酚醛泡沫脆性大、强度低等缺点,采用3种不同增强形式的玻璃纤维增强体,即短切玻璃纤维(SGF)、酚醛树脂浸渍固化的玻璃纤维针(GFN)及三维间隔连体织物,对酚醛泡沫进行增强.研究了纤维含量和纤维长度对酚醛泡沫压缩性能的影响规律,对比了不同增强形式纤维增强酚醛泡沫复合材料的压缩性能与保温性能.结果表明:当SGF长度为3 mm,与基体质量比为5%时,SGF增强酚醛泡沫的比压缩强度最佳,较纯泡沫的提高了21%;GFN(长度5 mm,与基体质量比为25%)增强酚醛泡沫的比强度提高8%;三维间隔连体织物增强酚醛泡沫的比强度虽略有下降,但其压缩强度(0.239 MPa)达到了承重类酚醛泡沫的要求.SGF和GFN增强的酚醛泡沫的热导率与纯酚醛泡沫的相比略有上升,但仍符合高效保温材料的要求;三维间隔连体织物增强酚醛泡沫的热导率上升明显.     

Investigation of the effect of thermal insulation materials on packaging performance

This investigation evaluates thermal insulation performance of a typical shipping container with different insulation materials. A mathematical model developed from our previous work was used to analyse the effect of packaging characteristics on insulative performance. A number of materials were employed as a liner to insulate a typical cardboard box, and the effect of these materials on package insulative performance was evaluated through experimental tests and the transistent thermal model. The results showed that application of aluminium foil to the internal liner surface of polyethylene gave 46% increase in the package insulative performance compared with the original polyethylene-insulated packages. An improvement of 79% and 106% in insulative performance per unit liner thickness was obtained from packages insulated with a polyisocyanurate board and aerogel blanket compared with the polystyrene-insulated package. The results also indicated that temperature surrounding the package played a significant role in the maximum insulation time. Furthermore, an excellent agreement was obtained between the mathematical model and the experimental results across all packaging aspects studied in this work.     

应用于包装领域的明胶泡沫性能研究

目的 制作和表征基于明胶的生物基可堆肥降解泡沫材料,并应用于包装领域。方法 明胶泡沫通过机械发泡和在周围环境中干燥制成。研究明胶含量、表面活性剂含量以及发泡温度对泡沫最大发泡倍率(MER)、收缩、密度、结构以及压缩性能的影响。此外,研究不同明胶含量样品的导热率。结果 研究的3个因素对泡沫性能和结构有显著影响。MER值和收缩是黏度相关,并极大地影响泡沫密度、力学性能以及热导率。增加明胶含量制造出了密度和压缩强度更高的泡沫(由于MER值更低)。表面活性剂质量分数从0.75%增加到1.5%由于发泡性提升造成泡沫密度轻微下降。然而,进一步将表面活性剂质量分数提升至3%造成黏度显著增加、MER值下降,从而导致泡沫密度增加。更高的发泡温度可以得到更高的MER,但是由于液态泡沫稳定时间更长,收缩程度更大,泡沫密度更大。结论 明胶泡沫展现出作为低密度传统塑料泡沫(密度小于30 kg/m³)环保替代品极具潜力的性能。研究成功实现了明胶泡沫的低热导率〔0.038～0.039 W/(m.K)〕和相对较低的收缩程度。     

瓷砖产品的全瓦楞纸板缓冲包装设计

以某品牌瓷砖产品为研究对象,用瓦楞纸板替代传统的EPS泡沫塑料,对瓷砖产品进行全瓦楞纸板缓冲包装的优化设计。以原包装的EPS泡沫塑料衬垫和瓦楞纸板的缓冲性能数据为基础,对所选择的材料与结构进行了初步的性能校核。研究表明,从材料性能、成型工艺和成本等方面考虑,采用全瓦楞纸板衬垫取代EPS衬垫进行瓷砖产品的包装是可行的。     

Finite element analysis (FEA) applied to polyethylene foam cushions in package drop tests

Two designs of polyethylene (PE) foam cushions were compared, using a rigid ‘product’ of mass 5.6 kg, and an outer corrugated fibreboard box. The acceleration–time history for the product was measured when the box was dropped flat from 1 m onto a rigid floor. The data was processed to calculate the impact force as a function of the packaging deformation. Finite element analysis (FEA) predictions of the impact force vs. package deflection were accurate for end‐cap designs using Ethafoam, but underestimated the slope of the experimental force vs. deflection relation for corner‐cap designs. The corner‐cap design is more efficient in reducing the peak product acceleration for multiple impacts. The contribution of the corrugated board box to the impact response appears to be small. The FEA results were compared with those from the cushion curve design method and were found to better predict the performance of complex shaped cushions. Copyright © 2004 John Wiley & Sons, Ltd.     

Liquid nucleating additives for improving thermal insulating properties and mechanical strength of polyisocyanurate foams

The effects of liquid-type nucleating silane additives on the cell structure, mechanical strength, and thermal insulating properties of the polyisocyanurate (PIR) foams have been studied. The PIR foams synthesized with hexamethyldisilazane (HMDS) as a silane additive showed the smaller average cell size and lower thermal conductivity than those of the PIR foams prepared with the hexamethyldisiloxane, dimethoxydimethylsilane, and hexadecyltrimethoxysilane. When HMDS was added, average cell size of the PIR foam was becoming smaller due to lower surface tension of the polyol solution, thereby the nucleation rate and number of bubbles produced were increased and then the cell size becomes smaller. The additives likely act as nucleating agents during the formation of PIR foams. The smaller cell size appears to be one of the major reasons for the improvement of thermal insulation properties and mechanical properties of the PIR foams. From the results of cell size, thermal conductivity, and mechanical strength of the PIR foams, it is suggested that the HMDS may be the efficient liquid-type additive for the reduction of cell size and improvement of the thermal insulation property of the PIR foams.     

基于常温干燥法的纤维素基泡沫制备及性能分析

传统的石油基泡沫难以降解,因而带来环境污染和安全问题。纤维素基泡沫借助其可生物降解的天然特性,逐渐成为研究热点。然而,目前的成型技术在很大程度上依赖于干燥条件（如冷冻干燥和超临界干燥）,存在干燥耗时长、成本高的问题,因而难以实现泡沫的规模化生产。为解决此问题,提出一种常温干燥制备可再生纤维素基泡沫的新方法。以纸浆纤维为主料、纳米纤维素为黏结剂、聚乙烯醇作为纤维分散剂和泡沫助剂,经过充分混合、发泡、排水和干燥后,制成纤维素基泡沫。最后,测试泡沫密度、孔隙率,分析导热性能、力学性能。结果表明：制备的纤维素基泡沫具有密度低（(0.015±0.002)~(0.028±0.004) g/cm3）、孔隙率高（>98%）、热导率低（(0.060±0.003)~(0.069±0.003) W/(m·K)）等特点。纤维素基泡沫在80%应变下的最大应力值为59.366 kPa,比其他文献报道的类似纳米纤维素基泡沫高37.1%。未来,纤维素基泡沫有望替代石油基泡沫,在冷链运输过程中对产品进行缓冲保护和隔热保温。