纳米结晶纤维素改善脲醛树脂胶黏剂游离甲醛的研究

为了降低脲醛树脂胶黏剂的游离甲醛释放量,以俄罗斯落叶松浆粕为原料,利用酸水解,硅烷偶联剂改性等制备获得表面改性纳米结晶纤维素(M-NCC),并将M-NCC作为吸附材料用于脲醛树脂基材制备胶合板,研究M-NCC对脲醛树脂胶黏剂游离甲醛的吸附效果和机理。结果表明:透射电镜(TEM)检测可知,制备的NCC颗粒长度约为100~200 nm、直径约为20~30 nm,结晶度为57.3%,相比原始纤维素提高了41.1%;硅烷偶联剂3-(2-氨乙基)-氨丙基甲基二甲氧基硅烷(MCPS)使NCC的浸润性显著增强,当MCPS用量为8%时M-NCC接枝率达到27.2%,M-NCC对脲醛树脂的接触角为65.7°,下降32.7%;由扫描电镜(SEM)照片可观测到,表面改性显著改善了低浓度NCC颗粒在脲醛树脂基材中的分散状态,当M-NCC质量分数2%时,纳米颗粒的分散性能明显下降;M-NCC可有效吸附脲醛树脂基材中的游离甲醛,当M-NCC质量分数1.5%时可致游离甲醛比对照组(0.51 mg/L)下降50.9%。

Reduction of Free Formaldehyde Emission from Urea-formaldehyde Resin Adhesive by Use of Modified Nanocrystalline Cellulose

In this study,a modified nanocrystalline cellulose ( M-NCC) was used to reduce the free formaldehyde emission from urea-formaldehyde resin adhesive. M-NCC was prepared by a procedure that Russian larch pulp was hydrolyzed by acid, followed by the modification of 3-(2-aminoethyl)-aminopropylmethyldimethoxysilane (MCPS). The effects of M-NCC on the emission of free formaldehyde from urea-formaldehyde resin adhesive were analyzed. The results indicated that from the TEM images, the length of the nanocrystalline cellulase ( NCC) particles prepared by acid hydrolysis was 100-200 nm,and the diameter was 20-30 nm. Compared with the original cellulose,the crystallinity degree of NCC was improved by 41. 1 %. The wetting property of M-NCC was enhanced by the graft of MCPS. The contact angle between M-NCC and urea-formaldehyde resin adhesive was decreased by 32. 7% when the grafting ratio was 27. 2%. The SEM images showed that the disperse state of M-NCC particles under low concentrations was improved significantly and the dispersity of nano-partides decreased obviously as the M-NCC was 2%. Free formaldehyde was absorbed by the M-NCC and 1. 5% M-NCC led to a 50. 9% decline of the emission of free formaldehyde.