三聚甲醛

The flame retarding mechanism of MCA on POM was that formaldehyde and formate acid were absorbed by melamine resulting from melamine cyanurate pyrolysis and temperature of burning materials was reduced because melamine cyanurate sublimation absorbed heat and thermalplastic polyurethane absorbed formaldehyde and enhanced stability of POM composites.

热失重、红外和气质联用分析表明，MCA／TPU复合阻燃剂对聚甲醛的阻燃作用是由于三聚氰胺氰尿酸盐高温分解并吸热，降低材料燃烧区域的温度；另一方面MCA高温分解生成的三聚氰胺可吸收聚甲醛分解产生的甲醛和甲酸；此外，TPU可提高聚阻燃甲醛的热稳定性，有利于阻燃。

The effect of different reaction conditions,such as catalyst concentration,molar ratio of reactants,reaction temperature,reaction time,on the coupling reaction of trioxane and methyl formate synthesizing methyl glycolate and methyl methoxy acetate using sulfuric acid as catalyst has been studied.Through the analysis for the yield of products and system pressure,and comparison with other different acidity catalysts,we considered that the activation of formaldehyde was the control step of reaction rate to the...

以硫酸为催化剂，研究了三聚甲醛与甲酸甲酯偶联合成乙醇酸甲酯和甲氧基乙酸甲酯的反应中，催化剂浓度、原料配比、反应温度、反应时间等条件对反应过程的影响，通过对产物收率和系统压力变化的分析，并结合与其它不同酸强度催化剂的对比，得到甲醛的活化是偶联反应的速率控制步骤，催化剂的酸强度决定其对甲醛的活化能力，是影响偶联反应的主要因素。

Acid catalyst and H + catalysis in the acid catalysts were studied for synthesis of methyl glycolate via coupling of methyl formate and trioxane in a microform high-pressure autoclave(120mL).

在微型高压反应釜中(12 0ml)，考察了酸催化三聚甲醛和甲酸甲酯制备羟基乙酸甲酯的偶联反应，并对酸催化剂中H+的作用进行了研究。

The sythesis of methyl glycolate by methyl formate coupled with triformaldehyde with the catalyst of superphosphoric acid is exploring researched in this thesis. The point of exertion is the capacity of the new catalysts.

本研究主要对以过磷酸为催化剂催化甲酸甲酯与三聚甲醛偶联合成乙醇酸甲酯进行考查，通过对以过磷酸、浓硫酸及过磷酸与浓硫酸混合酸催化剂时反应现象、乙醇酸甲酯产率等的对比，研究以过磷酸为催化剂偶联合成乙醇酸甲酯反应的催化活性。

In this paper, methylal and diethoxymethane were used as end capping agents to improve the thermal stability of the product in molten copolymerization of trioxane with ethylene oxide or with dioxolane.

为此研究了在三聚甲醛与环氧乙烷或三聚甲醛与二氧五环熔融共聚体系中，通过封端剂甲缩醛或二乙氧基甲烷的使用，对热碱稳定的共聚甲醛的收率提高了3％左右。

In the rotation diagram of polytrioxane obtained by γ-irradiation of trioxane there appear some new diffraction spots in addition to that for ordinary polyoxymethylene.

在辐照聚合制得的聚三聚甲醛的迴转图上，除出现普通聚甲醛的衍射点外，还存在着一些新的衍射斑点。

High molecular weight polyoxymethylene was obtained from trioxane crystal by solid state polymerization with γ-irradiation from Co80 source.

用Co~(60)γ射线辐照三聚甲醛晶体固相聚合得到高分子量的聚甲醛。

Polyoxymethylene with wry high degree of erystallinity cain be obtained by γ-irradiation of trioxane single crystals with Co60 source.

三聚甲醛单晶经Co60γ射线辐照可以得到一种结晶度很高的聚三聚甲醛。

The crystal structure of trioxane was accurately determinated. By using the crystal structure model of trioxane, the ring-opening polymerization mechanism of trioxane by γ-irradiation may be fairly well explained. Polyoxymethylene obtained by solid state polymerization of trioxane may have two types of molecular chains with different orientations, one parallel to the C...

我们精确测定了三聚甲醛的晶体结构，利用三聚甲醛晶体结构模型，可以很好地阐明三聚甲醛在受到γ射线辐照后开环聚合的机理，由三聚甲醛晶体固相聚合得到的聚三聚甲醛，应该有两种不同取向的分子链，一种与三聚甲醛的c轴平行；另一种与c轴成75°37′的交角。

A series of SiW_(12)/AC catalysts with different silicotungstic acid loadings supported on acti- vated carbon which was treated with 10% HNO_3 solution were prepared by an impregnation method and the catalytic performance of SiW_(12)/AC for the synthesis of trioxane were investigated.

以10%硝酸溶液处理过的活性炭为载体，采用不同质量分数的硅钨酸SiW_(12溶液为浸渍液，制备了不同负载量的SiW_(12)/AC催化剂，考察了催化剂在合成三聚甲醛中的催化性能，并用XRD、FT-IR、NH_3- TPD、BET、TG-DSC等手段对SiW_(12)/AC催化剂晶粒大小、催化剂表面的酸量及酸强度、比表面积及热稳定性等微观特性进行了表征。

Do you know, i need you to come back

你知道吗，我需要你回来

Yang yinshu、Wang xiangsheng、Li decang,The first discovery of haemaphysalis conicinna.

1〕 杨银书，王祥生，李德昌。安徽省首次发现嗜群血蜱。