Permeation of hydrocarbons through organosilane crosslinked LDPE

The importance of polymeric transportation systems has been steadily increasing over the years. It is a useful material in numerous applications, such as packaging, oil and gas pipes, and household items. One particular aspect of polyethylene (PE) is the permeability of small molecules, such as low‐molecular‐weight hydrocarbons. In the present study, PE sheets were crosslinked by grafting and subsequent hydrolysis of organosilanes during a reactive extrusion process. The formation of a network structure was characterized by sol/gel analysis and by rheological measurements. It is shown that as a result of crosslinking the permeation of linear alkanes through the PE is reduced. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45374.     

Degradation of low density polyethylene during extrusion. III. Volatile compounds in extruded films creating off‐flavor

This study was aimed at finding a correlation between the experienced off‐flavor in packaged foods and the presence of specific degradation products in PE packaging films. The possibility to trap degradation products by chemical reactions with scavengers, that is, zeolites and maleic anhydride grafted LLDPE, were investigated. This trapping would prevent the degradation products from migrating to the polymer film surface and further into food in contact with the film. This work concludes that off‐flavor in water packed in LDPE‐films depends on extrusion temperature and the content of oxidation products in the polymer film. At lower extrusion temperatures, reactive additives to the LDPE material could control the release of off‐flavor giving components. Adsorbents, such as zeolites, which are able to adsorb degradation products, are effective also at higher extrusion temperatures. The amount of oxidized degradation products in the films correlated well to the perceived off‐flavor in the packed water. The presence of aldehydes and ketones have a clear impact on the off‐flavor. The best correlation between off‐flavor and oxidized components were found for C₇? C₉ ketones, and aldehydes in the range of C₅ to C₈. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 847–858, 2005     

不同包装处理对花生仁贮藏品质影响研究

研究包装处理对花生仁保鲜效果的影响。分别对花生仁进行普通包装、真空包装、充氮包装,监测存储期间花生仁水分含量、过氧化值、酸价的变化,对比3种包装花生仁的贮藏品质。结果表明:包装处理能够明显改善花生仁的贮藏品质,其中包装的阻隔性对花生仁的保鲜效果影响显著,真空包装和充氮包装花生仁的过氧化值和酸价分别低于普通包装31%~50%、26%~47%,对两重要品质指标的劣化有明显的抑制作用,说明阻隔性包装能够有效提高花生仁的贮藏品质。     

Thermal and catalytic pyrolysis of a synthetic mixture representative of packaging plastics residue

A synthetic mixture of real waste packaging plastics representative of the residue from a material recovery facility (plasmix) was submitted to thermal and catalytic pyrolysis. Preliminary thermogravimetry experiments coupled with Fourier transform infrared spectroscopy were performed to evaluate the effects of the catalysts on the polymers’ degradation temperatures and to determine the main compounds produced during pyrolysis. The thermal and catalytic experiments were conducted at 370°C, 450°C and 650°C using a bench scale reactor. The oil, gas, and char yields were analyzed and the compositions of the reaction products were compared. The primary aim of this study was to understand the effects of zeolitic hydrogen ultra stable zeolite Y (HUSY) and hydrogen zeolite socony mobil-5 (HZSM5) catalysts with high silica content on the pyrolysis process and the products’ quality. Thermogravimetry showed that HUSY significantly reduces the degradation temperature of all the polymers—particularly the polyolefines. HZSM5 had a significant effect on the degradation of polyethylene due to its smaller pore size. Mass balance showed that oil is always the main product of pyrolysis, regardless of the process conditions. However, all pyrolysis runs performed at 370°C were incomplete. The use of either zeolites resulted in a decrease in the heavy oil fraction and the prevention of wax formation. HUSY has the best performance in terms of the total monoaromatic yield (29 wt-% at 450°C), while HZSM5 promoted the production of gases (41 wt-% at 650°C). Plasmix is a potential input material for pyrolysis that is positively affected by the presence of the two tested zeolites. A more effective separation of polyethylene terephthalate during the selection process could lead to higher quality pyrolysis products.     

Ultraviolet protection of recycled polyethylene terephthalate

Polyethylene terephthalate (PET) is commonly used for food packaging due to its high clarity, high resistance to water vapor, oxygen and carbon dioxide permeation, and good mechanical properties. However, its high transmittance in the ultraviolet‐A (UVA) region leaves food susceptible to UV‐induced degradation reactions. Incorporating post‐consumer recycled (PCR) PET into virgin PET increased UVA absorption 100% when utilizing 100% PCR‐PET, thus, increasing the protection potential of food packaging by reducing UVA‐induced degradation reactions. Comparison of the current data with previous work demonstrated the reproducibility of UVA protection independent of the PC flake source. The thickness‐normalized absorbance at 350 nm was a reliable predictor of the UVA protection potential regardless of composition and manufacture date. Raman, fluorescence, and attenuated total reflectance‐Fourier transform infrared spectroscopy analyses provided support that the UVA absorbing moiety was a quinone derivative formed during degradation reactions that are known to occur during melt processing/re‐processing. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45181.     

塑料包装与环境保护

评述了塑料包装材料面临环境问题的挑战,国内外对治理塑料包装废弃物对环境污染问题的主要途径和对策强调指出,加强塑料废弃物的综合治理,采取减量,回收,降解等防与治相结合的方针,确保塑料包装工业顺利,迅速,健康地发展,作者还目前国内“以纸代塑”的舆论导向进行了科学的分析,认为纸与塑各具特点,在未来的包装市场将仍然是纸塑并存,各得其所。     

Recycling of multilayer packaging using a reversible cross-linking adhesive

Plastic-based multilayer packaging has an important function on the packaging market, but is currently not recyclable as the polymer layers used are usually thermodynamically immiscible. This work therefore follows the approach to prepare separable multilayer packaging using a packaging adhesive modified with thermally unstable adducts, and proposes a corresponding recycling process. For this purpose, typical multilayer structures (polyethylene (PE)// polyethylene terephtalate (PET), PET//aluminum, and PE//aluminum) were prepared by curing furan-/maleimide-functionalized polyurethane (PU)-prepolymers with a three-functional cross-linking agent. Adhesions of up to over 3N per 15 mm test specimen were measured or substrate failures of PET films were observed. However, heating in dimethylsulfoxide, the retro-Diels–Alder reaction takes place and the cross-linked adhesive turns thermoplastic and dissolves in the solvent. Thus, the laminate separates and the pure PE, PET, and aluminum foils can be recovered without any PU residue.     

Accelerated and environmental weathering studies on polyethylene–starch blend films

Biodegradable polymers are desirable for a variety of applications, such as in packaging, agriculture, and medicine. Polyethylene (PE) blended with starch is already found to be a potential candidate to replace nondegradable thermoplastics in the areas of packaging. Films of polyethylene (PE)–starch blends with and without vegetable oil as a compatibilizer were prepared. The degradation of the films under thermooxidative treatment, ultraviolet light exposure, high temperature, high humidity, and natural ambience (soil burial) were monitored. It is seen that vegetable oil as an additive has a dual role: as a plasticizer, it improves the film quality; as a prooxidant, it accelerates degradation of the film. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2251–2257, 1998     

反应型聚氨酯胶黏剂的最近进展与发展趋势

本文阐述了近期聚氨酯胶黏剂的技术创新和发展趋势,如用于制备软包装材料的层压聚氨酯胶黏剂,它同时具有低有害单体(芳香族异氰酸酯和胺)迁移率和"智能固化"的特点(固化潜伏期或者固化速率可调);基于表面钝化固体异氰酸酯的潜伏型单组分体系为热熔胶和水基聚氨酯分散体系开拓了新的发展空间;新一代Purmelt MicroEmissionTM胶黏剂中MDI单体的含量少于0.1%,从而显著减少了使用过程中有毒异氰酸酯气体的挥发,大大提高了其操作安全性.在适应新工艺、新产品、以及日益严格的安全与环保要求下,聚氨酯胶黏剂又一次向我们展示了其独特的生命力.     

REVIEW OF VOLATILE ORGANIC COMPOUNDS DERIVED FROM POLYETHYLENE

The formation of volatile organic compounds (VOCs) in polyethylene (PE) is a topic of concern to industries involved in the packaging of items such as foodstuffs and pharmaceuticals that are sensitive to organoleptic contamination. This article reviews the available literature on VOCs that originate from PE during its manufacture, processing, storage, and service life. The package–product interactions that may occur between PE and packaged foodstuffs are also considered together with the wide range of methods for the analysis of VOCs. The following analytical methods are discussed: (i) sensory evaluation, (ii) chromatographic techniques and their associated sampling techniques, including the “hot-jar” method and dynamic headspace sampling, (iii) gas chromatography–olfactory sensing, and (iv) artificial olfaction or “electronic nose” technology.     

PVA,PVA Blends,and Their Nanocomposites for Biodegradable Packaging Application

This review exclusively addresses material systems primarily based on poly(vinyl alcohol) (PVA), one of the most popular water-soluble biopolymers, for their use in packaging applications with the primary objective of reducing petrobased plastic waste. In addition, some typical PVA blends and nanocomposites are discussed as comparative studies for material packaging. Structural characteristics, mechanical, thermal, and barrier properties, in addition to biodegradation of these multiple material systems are summarized in a systematic manner. Finally, associated fabrication processing methods together with the most popular theoretical models used for the permeability of PVA nanocomposites are also reviewed in detail.     

Preparation and characterization of antistatic packaging for electronic components based on poly(lactic acid)/carbon black composites

Poly(lactic acid) (PLA) is a biodegradable aliphatic polymer obtained from renewable sources; its main application is in the packaging sector. Electronic components require the use of antistatic packaging that prevents damage and electric shock. As PLA has no conductive characteristics, it requires the addition of allotropic carbon forms such as conductive carbon black to make the polymer less resistive as the dissipative material and making it suitable for the manufacture of antistatic packaging. In this study, PLA was melt blended with 5, 10, and 15 wt % of carbon black. The composites were prepared using a high-speed mixer. Samples were characterized by Izod impact resistance tests, scanning electron microscopy, thermal properties, electrical characterization, and biodegradation tests in garden soil. The addition of carbon black in the PLA matrix increases the temperature of degradation and decreases the crystallinity degree and the impact resistance of the composites. However, carbon black is a great option to increase the electrical conductivity of PLA. The addition of carbon black in PLA makes the composite less resistive and suitable for use as antistatic packaging for the transportation and storage of electronic components. Furthermore, this composite does not cause damage to the environment as the carbon black does not interfere in the degradation mechanism of PLA. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47273.     

Mechanical and barrier properties of cardboard and 3D packaging coated with microfibrillated cellulose

Microfibrillated cellulose (MFC) is increasingly used with cellulosic substrates and especially with paper materials. Its use with cardboard remains not reported and the study of mechanical and barrier properties of MFC‐coated cardboard has been investigated in this article. The influence of coating process as well as the effect of MFC have been highlighted by comparing different MFC‐coated cardboard samples with PE‐coated cardboard samples. MFC was coated using bar coating process. Their distribution and homogeneity onto cardboard was observed using techniques such as SEM and FE‐SEM. Tests such as oxygen and air permeability, bending stiffness, and compressive strength have been carried out. The coating process used impacts significantly cardboard properties by two opposite ways: on one hand it damages the structure cohesion of cardboard decreasing its compressive strength; on the other hand it increases its bending stiffness by increasing considerably the samples thickness. The addition of MFC counterbalances the negative effects of the coating process: bending stiffness and compressive strength are indeed improved by 30% in machine direction. On the contrary, MFC does not enhance much cardboard barrier properties, although it considerably increases their water absorption. Within a framework of packaging application, MFC will rather have consequent effects on cardboard's properties as blend or as part of the multilayer structure. Other applications have to be considered for its use as top layer. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40106.     

变频器在粒碱包装输送系统的应用

针对粒碱包装输送过程中控制下料的闸板阀故障率高、下料量不准确问题,采用变频器实现旋转阀的无级调速以控制旋转阀下料量,提高了粒碱全自动包装的运行效率,降低了系统故障率.     

Recent Developments in Food and Agricultural uses of Ozone as an Antimicrobial Agent-Food Packaging Film Sterilizing Machine using Ozone

Recent food putrefaction with new strains of microorganisms, such as Lactic acid bacteria and disinfectant-resistant strains of gram-negative bacteria, mold, yeast have increased interest in exploring different disinfection techniques for food sanitation. In Japan, food processing companies consider Lactic acid bacteria and gram-negative bacteria, mold, yeast, to be of greatest concern because of the severity and number of food putrefaction they cause. We supplied a laboratory machine that sterilizes for food packaging film and preformed cups using ozonated water and ozone gas. UV-ray sterilizing can be used for support. Ozone should be useful in reducing the degree of microbial contamination caused by inadequate disinfection against new resistant strains. There is growing tendency to use ozone in food industry as an effective means of disinfection without any additives. Many types application equipment have been developed. Based on the properties of ozone as a strong germicidal agent, conversion of factories to use ozone for sterilization of food packaging film is being implemented.     

Recent Advances in Lipid Derived Bio-Based Materials for Food Packaging Applications

The utilization of lipids is presently in the spotlight of food industry as they are one of novel renewable and sustainable raw materials. Lipids derived materials are considered as a promising alternate to petro-based polymers as they are sustainable, biorenewable, biodegradable, and environmentally benign. These unique attributes draw the attention of scientific community for the use of lipids in food packaging applications with a potential to compete with fossil fuel derived polymers. This paper reviews recent advances in the use of lipids and their effect on the barrier, antimicrobial, antioxidant, and mechanical properties of films, coating and nanocomposites for food packaging applications. Modification of lipids and its chemical interactions with other biopolymers during processing for the synthesis of different materials are also discussed. Global patents and research trend in use of lipids for the preparation of biocomposites are also described. The role of lipids in the circular economy is highlighted and life cycle assessment of lipids derived products is outlined with examples. The review is concluded with synoptic view of existing and forthcoming potential use of lipids in various food packaging applications.     

来自塑料包材的化妆品安全性隐患

塑料内常含有残留单体、添加剂、低聚体、加工助剂等化学物,在其与产品接触过程中可能发生迁移而污染产品,从而对人体健康产生潜在的危害。介绍了来自塑料包装材料的存在安全隐患的迁移物及其危害,讨论了迁移的理论基础以及迁移过程的预测模型。指出了对包装材料安全监管和深入研究的必要性、监管和进一步研究的重点方向,以及化妆品生产企业确定包装材料时应该关注的重点。     

The effect of temperature on the pulsed current processing behaviour and structural characteristics of porous ZSM-5 and zeolite Y monoliths

Hierachically porous monoliths of ZSM-5 and Y zeolites have been prepared by pulsed current processing (PCP). The densification behaviour and structural characteristics during rapid thermal treatment of the zeolites have been determined and related to the influence of the Si:Al ratio on the thermal stability of the zeolites. Monoliths of macroscopic shape can be prepared with an insignificant loss of surface area and micropore volume when the PCP-treatment was performed at temperatures below a critical maximum PCP temperature (T_PCP). Full-profile fittings of the powder X-ray diffraction patterns showed that the lattice strain of zeolite Y increases rapidly above the critical T_PCP while the ZSM-5 zeolites undergo a phase transition from orthorhombic to monoclinic. The use of a novel ceramic processing route for the production of the zeolite monoliths that do not significantly influence the structural characteristics and surface area of the starting materials has a potential to be of importance in catalysis and gas separation applications.     

Polylactic acid and its blends with petroleum‐based resins: Effects of reprocessing and recycling on properties

Environmental and economic reasons make the use of bioplastics and biocomposites increasingly coveted in sectors other than packaging. Recycling of all wasted or rejected durable plastics is highly desired and biobased plastics are no exception. Therefore, the investigation of pre‐ and post‐consumer recycling of products made from biobased plastics is of great interest. Polylactic acid (PLA) and its blends have been chosen for this study because it is an excellent representative of mass‐produced bioplastics for industrial applications. As part of the “Sustainable Recycling of ‘Green’ Plastics” project, the current study addresses the durability issues related to the reprocessing and post‐consumer recycling of a PLA virgin resin and two commercially available blends of PLA namely one with polycarbonate (PC) and one with polyethylene (PE). The materials were investigated using methods that simulate post‐processing and post‐consumer recycling. Accelerated ageing was performed at elevated temperature and humidity to simulate the usage period of the materials. The materials were analyzed using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and their mechanical strength was evaluated by tensile and impact testing. The flow properties of the materials were characterized by the melt flow index (MFI). Multiple processing of pure PLA did not affect the impact strength or the glass transition temperature (T_g), but caused crystallization and increase in the MFI, indicating that degradation occurred during processing. DSC thermograms of the blends revealed that the components in the blends were not miscible. Multiple processing of the blends did not significantly affect the elastic modulus of the materials, but affected the elongation at break. The results indicated that multiple processing of the PLA/HDPE blend caused increased dispersion and thus increased elongation at break, while the dominating mechanism in the PLA/PC blend was degradation that caused a decrease in elongation at break. Post‐consumer recycling of the PLA/PC blend was simulated and the results clearly showed that ageing corresponding to one year of use caused a significant degradation of PLA. Pure PLA was severely degraded after only one ageing cycle. Although the PLA/PC blend showed some improved mechanical properties and resistance to degradation compared with pure PLA, one ageing cycle still caused a severe degradation of the PLA and even the PC was degraded as indicated by the formation of small amounts of bisphenol A. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43916.     

Lipid autoxidation in fishery products postharvest: Is cold to freezing oxygen‐free packaged storage the better remedy?

The progress of lipid oxidation in fishery products is complex, as it involves a whole lot of reactions that deter product quality. On the other hand, the use of modified atmosphere packaging (MAP) has, over the years, been effective in improving food product safety and nutritional quality. In addition, as an oxygen‐free and protective food packaging technique, MAP has been shown to effectively minimize overall lipid damage. In this article we discuss how cold to freezing/sub zero‐temperatures could be promising for reducing the development of lipid oxidation in fishery products.