有機硅改性單組分聚氨酯密封膠
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不同R值對MS密封膠性能的影響
- 發(fā)布時間 : 2025-4-14 16:37:20
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(Summary description)Customized SILICONE STRUCTURAL SEALANT from China manufacturer refers to the adhesive with high strength, can bear large load, aging resistance, fatigue resistance and corrosion resistance, and has stable performance within the expected life. It is suitable for bearing the bonding of strong structural parts. Non structural adhesive has low strength and poor durability. It can only be used for bonding, sealing and fixing of ordinary and temporary properties, and cannot be used for structural adhesive bonding. NEUTRAL SILICONE WETHERPROOF SEALANT from China manufacturer is a structural adhesive with waterproof function. Silicone glue refers to the adhesive based on silicone rubber. According to different functions, it can be divided into structural adhesive, potting adhesive, sealant, thermal conductive adhesive, flame retardant adhesive and so on.
不同R值對MS密封膠性能的影響
(Summary description)Customized SILICONE STRUCTURAL SEALANT from China manufacturer refers to the adhesive with high strength, can bear large load, aging resistance, fatigue resistance and corrosion resistance, and has stable performance within the expected life. It is suitable for bearing the bonding of strong structural parts. Non structural adhesive has low strength and poor durability. It can only be used for bonding, sealing and fixing of ordinary and temporary properties, and cannot be used for structural adhesive bonding. NEUTRAL SILICONE WETHERPROOF SEALANT from China manufacturer is a structural adhesive with waterproof function. Silicone glue refers to the adhesive based on silicone rubber. According to different functions, it can be divided into structural adhesive, potting adhesive, sealant, thermal conductive adhesive, flame retardant adhesive and so on.
- 發(fā)布時間 : 2025-4-14 16:37:20
- Views:
Information
水分含量的影響水分來源主要是PBA3000中所含的水，另外還有空氣中的水分、反應器具中殘留的水分等。水分主要影響預聚體赫度、貯存穩(wěn)定性及最終產(chǎn)品性能。水產(chǎn)生的2個副作用是:①與MS密封膠反應生成腮基，使預聚物赫度增大;②以腮基為支化點進一步與MS密封膠反應，形成縮二腮支鏈或交聯(lián)而使預聚物的穩(wěn)定性下降甚至發(fā)生凝膠，導致預聚物的赫度增大，易產(chǎn)生氣泡，流動性差，難以與擴鏈劑混合均勻，最終影響制品的力學性能。R-NCO+HOHRNHz+COztRNHz+R-NCOR-NH-CO-NH-R從反應式可看出，異氰酸醋與水反應很快分解成胺和COzo18g水就能消耗0.5mol的IPDI，產(chǎn)生22.4L的COz。水的存在十分有害，為確保預聚體的質(zhì)量，必須嚴格控制聚醋水分含量，一般低于質(zhì)量分數(shù)0.05%時影響較小。實驗所用聚醋的含水質(zhì)量分數(shù)初測為0.070/O,100一120℃下真空脫水2.0h后下降至0.03%，可保證實驗順利進行。異氰酸酉旨指數(shù)的影響異氰酸酷指數(shù)即R值(NCO與OH物質(zhì)的量比)對MS密封膠的相對分子質(zhì)量、表面張力、貯存穩(wěn)定及粘接強度等有較大影響。表3列出了不同R值對MS密封膠性能的影響。從表3可看出，隨著R值的增大，MS密封膠的赫度逐漸增大，初粘強度和終粘強度也增大。這是因為隨R值增大，MS密封膠的相對分子質(zhì)量和MS密封膠的赫度同時增大，一般情況下，R值選擇0.95-1.08較合適。這是因為聚醋和擴鏈劑中存在少量水分及IPDI純度等的影響。R0值過小，則MS密封膠的赫度和內(nèi)聚強度較小，達不到粘接要求;R值過大，MS密封膠赫度太高，在使用中對材質(zhì)的浸潤性較差，影響剝離強度。當R值超過1.08時MS密封膠的粘接性能下降，這是由于隨著R值增加，多余的一NCO與線性大分子主鏈上的一NHCOO一形成腮基甲酸醋交聯(lián)鍵，增大了剛性鏈間的距離，妨礙了剛性鏈的氫鍵締合，使大分子鏈間的聚集作用減弱，因而導致了MS密封膠粘接性能下降。由表3可看出，R值選用1.05時最為合適。http://ago-games.com/
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上一篇: 單組分聚氨酯密封膠的過程中確定反應溫度
上一篇: 單組分聚氨酯密封膠的過程中確定反應溫度
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