dzj_sunkeycn
见习生
"likekd 发表：
likekd兄，按照您所提供的分子直径，好像按照分子直径来看应该是H2O>N2>O2>CO2>He啊，你的单位是NM？
不过真空绝热行业目前在气体的阻隔性能上主要考虑的还是水蒸气的阻隔性能，大部分厂家在吸气剂材料上也是多采用干燥剂为主
我们认为影响材料阻隔性能的因素很多，如材料结构，不同的薄膜材料对水蒸气和氧气的阻隔性能差异很大，如BOPA的阻氧性能好隔水性差，PET隔水性能好于阻氧性能。
"likekd 发表：常见气体的分子直径，水分子的直径为0.3um，STP板可以阻断水的渗透，就可以阻断其他的无机气体，我觉得关键的问题是内部吸气剂的成分，及内部材料所释放出来的气体是否能被化学反应掉。
请教楼上：BOPA/PET/PE/AL等材料（单体、复合）隔气性能有准确的指标吗？相关标准？为什么国外用3层铝箔+PET+PE的复合膜，没有BOPA（芯材吸气剂以定情况下，号称可以保证30年，2层铝箔的是20年）？"dzj_sunkeycn 发表：likekd兄，按照您所提供的分子直径，好像按照分子直径来看应该是H2O>N2>O2>CO2>He啊，你的单位是NM？
不过真空绝热行业目前在气体的阻隔性能上主要考虑的还是水蒸气的阻隔性能，大部分厂家在吸气剂材料上也是多采用干燥剂为主
我们认为影响材料阻隔性能的因素很多，如材料结构，不同的薄膜材料对水蒸气和氧气的阻隔性能差异很大，如BOPA的阻氧性能好隔水性差，PET隔水性能好于阻氧性能。
是否可以翻译成中文哟，对这个我看不懂哟"captain_203 发表：A vacuum insulated panel (VIP) is a form of thermal insulation consisting of a nearly gas-tight enclosure surrounding a rigid core, from which the air has been evacuated. It is used in building construction to provide somewhat better insulation performance than conventional insulation materials.
By removing air from fiber, powder, or foam core materials VIPs achieve high thermal performance at a fraction of the thickness of cut-to-fit insulation materials. VIP products are made-to-fit architectural details, with specified service lives for floor, wall, and roof constructions. Quality control of component manufacture is important.
A VIP uses the insulating effects of a vacuum to produce much higher thermal resistance than conventional insulation. Conventional insulation produces anR-value of eight or less per inch (fiberglass being towards the lower end and foam panels towards the higher end). VIPs are commonly as high as R-30 per inch, and have achieved commercially viable levels of R-50 per inch.[citation needed]
VIPs consist of:
The near-vacuum inside VIP's greatly reduces conduction and convection of heat. This is similar to the way in which a vacuum flask works, but without the reflective metal coatings, as the core material reduces infrared radiation.
- Membrane walls, used to prevent air from getting into the vacuum area
- Core material, used to hold the vacuum inside the membrane while preventing the membrane walls from collapsing. (e.g.fumed silica, aerogel, glass fibers or foams)
- Chemicals to collect gases leaked through the membrane or offgassed from the membrane materials are added to VIP with glass fibers or foams cores, as core with bigger pore size requires vacuum level lower than about 1 mbar during the planned service life. (Getter)
VIPs offer very high R-value by thickness (30-50R value per inch compared with 5-8R/in for various foams and a lower 2-3.54R/in for common fiberglass batting), but by cost and lifespan it is less competitive. Compared to more conventional insulating materials VIPs have a high cost/r-value ratio. Unlike fiberglass (although foam insulation does age), VIPs age as it is impossible to completely keep air from filling the vacuum. As air leaks in and pressure of the panel normalizes with its surrounding air its R-value deteriorates.
Although their higher cost compared with fiberglass and foam generally keep them out of traditional housing situations, their spectacular R/in values make them useful in situation where high insulation requirements or space constraints make traditional insulation impractical. (Foam sheets are used over fiberglass often for the same goal of higher R/in, despite higher cost for the same R value).
"发泡大侠 发表：请教楼上：BOPA/PET/PE/AL等材料（单体、复合）隔气性能有准确的指标吗？相关标准？为什么国外用3层铝箔+PET+PE的复合膜，没有BOPA（芯材吸气剂以定情况下，号称可以保证30年，2层铝箔的是20年）？
产品的燃烧性能，从膜材本身来说是铝塑复合，虽然外层的玻璃纤维和铝箔为不燃材料，当长时间将板材正中央置于火焰上方时，铝箔后方的塑料（PET/PA/PE)会迅速融化层液体状，并直接破坏真空板的密封导致产品漏气失效。如果将火焰直接面对封边时，其中的塑料成分在没有玻璃纤维和铝箔的保护下会直接燃烧，这也许是困惑各大厂家的一个问题。"发泡大侠 发表：会的。因为表面的隔气复合膜有有机的塑料膜和粘合剂，会燃烧的。但是它们量很小，约0.1MM左右（复合膜一般厚度0.25MM左右），加上表面有玻璃纤维布的防护及自己有一定的阻燃性能及多层铝箔的隔绝（空气），还是可以达到国家相关防火要求的。其系统的防火安全性能还有表面的防护砂浆（一般厚度3-5MM）那、、、
分析的很全面。"毛毛四世 发表：最后再说一下吸气剂。
吸气剂，也是VIP核心技术之一，作用就是吸附外部渗透的气体和内部释放的气体以维持VIP内部的真空度。现在的VIP用吸气剂基本上都是被意大利的赛斯给垄断了，为什么垄断，因为的确有技术含量（在常温低压条件下启动，能与多种常见气体反应，而且反应前后都是稳定物质，那些吸水用的氧化钙只是干燥剂，并不是真正意义上的吸气剂），垄断结果，那就是价格高，特别是用在建筑材料市场。目前很多宣传使用吸气剂的建筑VIP都是噱头，因为如果芯材和阻隔膜选材不好的话，即使使用吸气剂也没什么意义，因为吸气剂的气体吸附量远远小于外部渗透的气体和内部释放的气体的总量。
关于吸气剂的使用，主要是用在玻璃纤维类材料作为芯材的VIP，因为玻璃纤维材料对气压的敏感度比较高，而用气相二氧化硅作为芯材的VIP，则不需要使用吸气剂，因为对气压的敏感度比较低。这点可以参考我前面提供的那篇文献内容。