全自動(dòng)封膠機(jī)廠家提示大家，影響膠粘劑粘接強(qiáng)度的化學(xué)要素主要指分子的極性、分子量、分子外形(側(cè)基幾及大小)、分子量散布、分子的結(jié)晶性、分子對(duì)環(huán)境的穩(wěn)定性(轉(zhuǎn)變溫度和降解)以及膠粘劑和被粘體中其它組份性質(zhì)PH值等。
The manufacturer of automatic sealing machine reminds us that the chemical factors affecting the bonding strength of adhesives mainly refer to the polarity, molecular weight, molecular shape (side group number and size), molecular weight dispersion, molecular crystallinity, molecular stability to the environment (transition temperature and degradation), and the properties of adhesives and other components in the adhesives, such as PH value.
1、極性。膠粘劑和被粘體分子的極性影響著粘接強(qiáng)度，但并不意味著這些分子極性的增加就一定會(huì)進(jìn)步粘接強(qiáng)度。從極性的角度動(dòng)身為了進(jìn)步粘接強(qiáng)度，與其改動(dòng)膠粘劑和被粘體全局部子的極性，還不如改動(dòng)界面區(qū)外表的極性。例如聚乙烯、聚丙烯、聚四氟乙烯經(jīng)等離子外表處置后，外表上產(chǎn)生了許多極性基團(tuán)，如羥基、羰基或羧基等，從而顯著地進(jìn)步了可粘接性。
1. Polarity. The polarity of adhesives and adhesives affects the bonding strength, but it does not mean that the increase of the polarity of these molecules will certainly improve the bonding strength. In order to improve the bonding strength, it is better to change the exterior polarity of the interface area than to change the polarity of the adhesive and the global part of the adhesives. For example, polyethylene, polypropylene and polytetrafluoroethylene (PTFE) have been treated by plasma. Many polar groups, such as hydroxyl, carbonyl or carboxyl groups, have been produced on the surface, which greatly improves the bondability.
2、分子量。聚合物的分子量(或聚合度)直接影響聚合物分子間的作用力，而分子間作用力的大小決議物質(zhì)的熔點(diǎn)和沸點(diǎn)的上下，決議聚合物的玻璃化轉(zhuǎn)變溫度Tg和熔點(diǎn)Tm。聚合物無論是作為膠粘劑還是作為被粘體，其分子量都影響著粘接強(qiáng)度。
2. Molecular weight. Molecular weight (or degree of polymerization) of polymers directly affects the intermolecular forces of polymers, and the magnitude of intermolecular forces determines the melting point and boiling point of materials, and the glass transition temperature (Tg) and melting point (Tm) of polymers. Whether polymer is used as adhesives or as adhesives, its molecular weight affects the bonding strength.
3、側(cè)鏈。長(zhǎng)鏈分子上的側(cè)基是決議聚合物性質(zhì)的重要要素。從分子間作用力思索，聚合物支鏈的影響是，當(dāng)支鏈小時(shí)，增加支鏈長(zhǎng)度，降低分子間作用力。當(dāng)支鏈到達(dá)一定長(zhǎng)度后，開端結(jié)晶，增加支鏈長(zhǎng)度，進(jìn)步分子間作用力。這應(yīng)當(dāng)是降低或進(jìn)步粘接強(qiáng)度的緣由。
3. Side chain. The side groups on long chain molecules are important factors to determine the properties of polymers. Considering the intermolecular forces, the effect of polymer branched chains is to increase the length of branched chains and reduce the intermolecular forces when the branched chains are small. When the branched chain reaches a certain length, it begins to crystallize, increases the length of the branched chain, and improves the intermolecular force. This should be the reason for reducing or improving the bonding strength.
4、PH值。關(guān)于某些膠粘劑，其PH值與膠粘劑的適用期有較為親密的關(guān)系，影響到粘接強(qiáng)度和粘接壽命。普通強(qiáng)酸、強(qiáng)堿，特別是當(dāng)酸堿對(duì)粘接資料有很大影響時(shí)，對(duì)粘接常是有害的，特別是多孔的木材、紙張等纖維類材更容易受影響。

4, pH value. As for some adhesives, their PH value has a close relationship with the application life of the adhesives, which affects the bonding strength and bonding life. Ordinary strong acid and alkali, especially when acid and alkali have a great impact on bonding data, are often harmful to bonding, especially porous wood, paper and other fibers are more vulnerable.
由于像熱固性的酚醛樹脂和脲醛樹脂的固化過程受PH值的影響很大，常常請(qǐng)求酸度較大。例如，固化時(shí)在酚醛樹脂中參加對(duì)甲苯磺酸或磷酸，在脲醛樹脂中參加氯化銨或鹽酸。因而，在不希望酸度大又要粘接的場(chǎng)所，選用中性的間苯酚甲醛樹脂是適合的。
Because the curing process of phenolic and urea-formaldehyde resins, such as thermosetting resins, is greatly affected by the PH value, the acidity is often requested. For example, p-toluene sulfonic acid or phosphoric acid is added to phenolic resin during curing, and ammonium chloride or hydrochloric acid is added to urea-formaldehyde resin. Therefore, it is suitable to use neutral m-phenol formaldehyde resin in places where acidity is not expected to be high and adhesion is required.
將木材外表預(yù)先用堿處置，普通可得到結(jié)實(shí)的接頭。但還必需留意膠層的PH值，它對(duì)膠層比對(duì)被膠接外表更有影響。
The wood appearance can be pre-treated with alkali, and generally a strong joint can be obtained. However, it is necessary to pay attention to the PH value of the adhesive layer, which has more influence on the surface of the adhesive layer than on the bonded surface.
5、填料。在膠粘劑中配合填料有如下作用：(1)增加膠粘劑的內(nèi)聚強(qiáng)度；(2)調(diào)理黏度或工藝性(例如觸變性)；(3)進(jìn)步耐熱性；(4)調(diào)整熱收縮系數(shù)或收縮性；(5)增大間隙的可填充性；(6)給予導(dǎo)電性；(7)降低價(jià)錢；(8)改善其他性質(zhì)。
5. Filling. The fillers in the adhesives have the following functions: (1) increasing the cohesive strength of the adhesives; (2) adjusting the viscosity or technological properties (such as thixotropy); (3) improving the heat resistance; (4) adjusting the thermal shrinkage coefficient or shrinkage; (5) increasing the fillability of the gap; (6) giving conductivity; (7) reducing the price; (8) improving other properties.
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