聚氨醋改性后的單組分聚氨酯密封膠的低溫性...
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低分子量聚異丁烯對硅烷改性聚氨酯密封膠的影響
- 發(fā)布時間 : 2023-3-12 18:38:58
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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.
低分子量聚異丁烯對硅烷改性聚氨酯密封膠的影響
(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 : 2023-3-12 18:38:58
- Views:
Information
由4.2.2所測數(shù)據(jù)可知，隨配方中基體所用中分子量聚異丁烯分子量的下降，硅烷改性聚氨酯密封膠模量與粘度均有下降。如同前文的論述，壓敏膠的剝離強度與模量呈負(fù)相關(guān)，但分子量過低也會增加每份聚異丁烯中的端位雙鍵含量，對硅烷改性聚氨酯密封膠本體強度造成不利影響，如下圖4-25，為中分子量聚異丁烯分子量對硅烷改性聚氨酯密封膠T型剝離強度的影響。
由上圖上表可知，聚異丁烯分子量的降低，使硅烷改性聚氨酯密封膠剝離強度明顯增加，但對本體強度存在不利影響。使用PIB8350的配方，剝離過程發(fā)生內(nèi)聚破化。中分子量聚異丁烯分子量對持粘性的影響本節(jié)對于初粘性不再做討論，因為將PIB8950替換為P1B8550和PIB8300后硅烷改性聚氨酯密封膠的模量和粘度都明顯降低，按照國標(biāo)GB/T 4852-2002測量初粘性都超過了量程。因而本節(jié)主要討論中分子量聚異丁烯的分子量對持粘性的影響。
由上圖4-26可知，若中分子量聚異丁烯的分子量降低過多，硅烷改性聚氨酯密封膠在測試持粘性的過程會發(fā)生內(nèi)聚破壞。雖然在T型剝離強度測試中未發(fā)現(xiàn)過多影響本體強度，但在持粘性測試中會發(fā)現(xiàn)，由于端位雙鍵地增多，硅烷改性聚氨酯密封膠大分子鏈段活動能力的強，中分子量聚異丁烯分子量的降低亦會較嚴(yán)重地影響硅烷改性聚氨酯密封膠地本體強度和抗冷流性，弛豫時間因此縮短。另外，二者測試過程中作用力速度的不同也是導(dǎo)致二者結(jié)果產(chǎn)生差異的原因。
由于陽離子引發(fā)體系和反應(yīng)溫度等條件的不同，聚異丁烯分子鏈末端雙鍵的空間位置會有所不同，根據(jù)分子鏈末端碳碳雙鍵的位置的差異，末端結(jié)構(gòu)是。烯占比較高的聚異丁烯被稱之為反應(yīng)性聚異丁烯，或高活性聚異丁烯，本課題采用的軟化劑或粘度調(diào)節(jié)劑正是數(shù)均分子量2300的反應(yīng)性聚異丁烯。低分子量聚異丁烯具有極強的粘性，且與基體材料中分子聚異丁烯和丁基橡膠具有相同的結(jié)構(gòu)單元，故相容性較好，有文獻表明，對比其他種類軟化劑，聚異丁烯對硅烷改性聚氨酯密封膠表面粘性增強作用效果更加明顯。本節(jié)依照配方2-7以低分子量聚異丁烯PIB2300的用量為變量制備硅烷改性聚氨酯密封膠試樣并進行以下測試。www.kubee.cn
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