Inhibition of the thermal degradation of rigid poly(vinyl chloride) using poly(N‐[4‐(N′‐phenyl amino carbonyl)phenyl]maleimide)

Poly(N‐[4‐(N′‐phenyl amino carbonyl)phenyl]maleimide), poly(PhPM), has been investigated for the inhibition of the thermal degradation of rigid poly(vinyl chloride) (PVC) in air, at 180°C. Its stabilizing efficiency was evaluated by measuring the length of the induction period, the period during which no detectable amounts of hydrogen chloride gas could be observed, and also from the rate of dehydrochlorination as measured by continuous potentiometric determination, and the extent of discoloration of the degraded polymer. The results have proved the greater stabilizing efficiency of poly(PhPM) relative to that of the DBLC commercial stabilizer. This is well demonstrated by the longer induction period values and by the lower rates both of dehydrochlorination and discoloration of the polymer during degradation relative to those of the DBLC reference stabilizer. The greater stabilizing efficiency of the poly(PhPM) is most probably attributed not only to its possession of various centers of reactivity that can act as traps for radical species resulting during the degradation process, and replacement of labile chlorine atoms on PVC chains by relatively more thermally stable poly(PhPM) moieties, but also due to the ability of its fragmentation products to react with the evolved hydrogen chloride gas. A radical mechanism is suggested to account for the stabilizing action of this polymeric stabilizer. A synergistic effect is achieved when the poly(PhPM) was blended in various weight ratios with DBLC. This synergism attains its maximum when poly(PhPM) and DBLC are taken at 3 : 1 weight ratio. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Photothermal stability of encapsulated Si solar cells and encapsulation materials upon accelerated exposures

We have conducted a series of accelerated exposure test (AET) studies for various samples of crystalline-Si (c-Si) and amorphous-Si (a-Si) cells that were encapsulated with different superstrates, pottants, and substrates. Transmittance, fluorescence, color indices, impedance spectroscopy, laser optical beam induced current (OBIC), and light and dark current–voltage (I–V) measurements were used to characterize the samples. Nonuniform browning patterns of ethylene vinyl acetate (EVA) pottants were observed for glass/EVA/glass-encapsulated c-Si cell samples under solar simulator exposures at elevated temperatures. The EVA discolored gradually into a yellow–brown color when exposed under 7.5 ultraviolet (UV) suns at a black panel temperature (BPT) of 85°C, and very rapidly into a dark brown color when exposed under 9.0 UV suns at a BPT of 145°C. The latter conditions also caused extensive delamination of a polyolefin-based thermoplastic pottant laminated between two borosilicate plates. No visible color change of EVA could be observed for the c-Si cell samples heated in an oven at 85°C or exposed under 1.2 UV suns at BPT=60–65°C or 80–85°C. Under 1.2 UV suns exposure at a BPT of 60–65°C, the thin layers of EVA or silicone in the lightweight c-Si cell samples, which were laminated in a polymer/solar cell/polymer configuration with Tedlar or Tefzel films, did not discolor because of photobleaching reactions. In comparison, the polyester or nylon superstrate films turned yellow on laminates of polymer/a-Si/polymer minimodules, and significant delamination was observed for the polyester/EVA layers. For all c-Si cell samples tested, irregular changes in the I–V parameters were observed that could not be attributed only to transmittance changes of the superstrate/pottant layers. Under UV-transmitting polymer superstrate films, current/efficiency losses were greater for the c-Si and a-Si cells that were laminated with silicone-type adhesives than with EVA or polyethylene pottants.     

包装食品新鲜度指示卡的研究

食品新鲜度指示卡作为包装的一部分,可直接指示包装食品的质量状况。而大部分食品一旦发生变质,就会代谢出大量的CO2气体,故包装环境中CO2气体含量可作为这一类食品是否腐败变质的重要衡量指标。本实验以玉米淀粉膜为基材,通过添加复合酸碱指示剂、缓冲溶液等主要成分,制得包装食品新鲜度指示卡。     

Carbon Monoxide in Modified Atmosphere Packaging Affects Color, Shelf Life, and Microorganisms of Beef Steaks and Ground Beef

ABSTRACT— Color and microbiology of steaks and ground beef stored in 0.4% CO, 30% CO2, and 69.6% N2 (but removed from the modified atmosphere before display) were compared with product displayed immediately after packaging in polyvinyl chloride film (only atmospheric oxygen). Storage of ground beef, loineye, inside round, and tenderloin steaks for up to 35 d in 0.4% CO resulted in typical initial bloomed color. Compared with product exposed to only oxygen, storage of ground beef and loineye steaks in 0.4% CO decreased color stability, whereas color life increased for tenderloin and inside semimembranosus muscles. No steaks having acceptable color had spoilage levels of microbes (≥log 7). Thus, carboxymyoglobin formed from 0.4% CO did not mask microbial spoilage.     

甲基锡及其复合热稳定剂在PVDC中的应用

用变色法测定了甲基锡、甲基锡/环氧大豆油和甲基锡/硬脂酸钙3种热稳定剂对PVDC的热稳定作用.结果表明:3种热稳定剂对PVDC的热稳定作用是甲基锡/硬脂酸钙＞甲基锡/环氧大豆油＞甲基锡,甲基锡/环氧大豆油复合热稳定剂的最佳组成为(1:1)～(2:1),甲基锡/硬脂酸钙复合热稳定剂的最佳组成为1:3.     

电气设备镀银面变色机制分析与处理

实际应用中发现镀银后的铜排出现严重变色问题,影响电气设备的可靠运行.对制造过程发现的问题进行深入分析,指出其形成原因是与镀银工艺、储存防护不当和项目管理密切相关,最后提供了具体处理方案.     

Discoloration of Hydrotreated Naphthenic Rubber Base Oil at High Temperature

Abstract

In this article, the reasons for discoloration of hydrotreated naphthenic rubber base oil under high temperature were studied in detail. In order to define compositional factors associated with the color deterioration, firstly liquid-solid chromatography was used to separate hydrotreated naphthenic rubber base oil into five different fractions, i.e., saturates, monoaromatics, diaromatics, polyaromatics, and polars. Then color change of each fraction was evaluated under high temperature. The results of the test indicate that polyaromatics and polars are the main precursor of color and deposits, respectively, and the composition of polyaromatics was characterized by elemental analysis, gas chromatography mass spectrometry (GC-MS) and atmospheric pressure chemical ionization mass spectrometer (APCI/MS).     

锦氨纤维高温模压色变问题的改善

探讨了采用尼龙抗热色变整理剂NK 001改善锦氨白坯布及染色布高温热压模色变问题的应用工艺及效果。结果表明,浸轧20~40 g/L尼龙抗热色变整理剂NK 001后,锦氨白坯布的ASTM白度下降率由原先的43.32%降低至20%左右;配合菲诺酸性B LV系列染料,可将压模前后总色差值控制在1.0,最大力份差在7%以内,可满足浅色系的匀染性和压模热变色需求。此外,浸轧NK 001不会影响染色样的耐水洗色牢度。     

淀粉热变色性质的研究

研究了淀粉在直接加热、与水组合后加热时的色泽变化。淀粉的热变色温度范围为190~210℃,水浸胀后,淀粉的热变色温度范围下降。