Microcapsules with low content of formaldehyde: preparation and characterization
Microcapsules with low content of formaldehyde: preparation and characterization
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DOI：
10.1039/b902832c
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发表时间：
2009-01-01
影响因子：
--
通讯作者：
Preece, Jon A.
中科院分区：
文献类型：
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作者：
Long, Yue;York, David;Preece, Jon A.
在这里报道的研究中，原位聚合过程已被用于生产含有油基工业前体的三聚氰胺甲醛微胶囊。这里的微胶囊生产低甲醛与三聚氰胺的摩尔比（0.20 - 0.49）相比，以前的文献报道（2.30-5.50）。对微胶囊的形貌、粒径及分布、壁厚、机械强度和包封率等性能进行了表征，发现微胶囊的壁厚和机械性能随甲醛与三聚氰胺（F/M）摩尔比的变化而变化。通过透射电子显微镜（TEM）测量的微胶囊的壁厚从80 +/- 1.9增加到308 +/- 1.7 nm当F/M摩尔比从0.20增加到0.49时，（增加285 +/- 2.4%）（增长145%），微囊的标称破裂应力由1.3 ± 0.1 MPa增加到4.2 ± 0.4 MPa（223 +/- 11.5%增长）。当F/M摩尔比从0.49增加到2.30（369%）时，微胶囊壁厚仅增加14个垂直于0.8%的方向，微胶囊的名义破裂应力仅增加66个垂直于12.8%的方向。因此，已经表明，从先前的文献报道中可以显著降低甲醛含量的水平，同时仅略微降低机械性能，并且仍然保持类似于75%的包封效率。
In the research reported here, an in situ polymerization process has been used to produce melamine formaldehyde microcapsules containing an oil-based industrial precursor. Here the microcapsules were produced with a low formaldehyde to melamine molar ratio (0.20 0.49) compared to previous literature reports (2.30-5.50). The properties of the microcapsules such as morphology, particle diameter and distribution, wall thickness, mechanical strength, and encapsulation efficiency were characterized, and it was found that the wall thickness and mechanical properties of microcapsules were modulated as a function of formaldehyde to melamine (F/M) molar ratio. The wall thickness of the microcapsules measured by transmission electron microscopy (TEM) increased from 80 +/- 1.9 to 308 +/- 1.7 nm (285 +/- 2.4% increase) when the F/M molar ratio was increased from 0.20 to 0.49 (145% increase), and the nominal rupture stress of the microcapsules measured by a micromanipulation technique increased from 1.3 +/- 0.1 to 4.2 +/- 0.4 MPa (223 +/- 11.5% increase). In contrast, when the F/M molar ratio increased from 0.49 to 2.30 (369%), the wall thickness of microcapsules only increased by 14 perpendicular to 0.8% and the nominal rupture stress of the microcapsules only increased by 66 perpendicular to 12.8%. Thus, it has been shown that significant reduction in the levels of formaldehyde content is possible from previous literature reports, whilst only marginally reducing the mechanical properties, and still maintaining the encapsulation efficiency of similar to 75%.