基于醋酸乙烯酯的大分子添加劑對模具石膏機械性能的影響
發(fā)布時間：2018-07-31 08:24
【摘要】：在保持模具石膏試件吸水性能的基礎(chǔ)上,提高試件的機械強度是石膏模具行業(yè)亟待解決的難題之一。文中以含有醋酸乙烯酯單元的大分子(不同水解度的聚乙烯醇PVA和聚醚聚酯型磺酸基大分子PES)為添加劑,考察了其對模具石膏的抗折、抗壓強度和吸水率的影響,以獲得能夠在不降低石膏吸水率的前提下提高其機械強度的理想外加劑。另外研究了外加無機鹽、拌合水p H和養(yǎng)護時間對大分子改性β-半水石膏(β-H)的影響,最后研究了大分子添加劑對β-H的水化進程及晶體形貌的影響。具體研究內(nèi)容及主要結(jié)論如下:1.通過控制聚醋酸乙烯酯(PVAc)的水解反應(yīng)條件,得到了不同水解度(65%~99%)的PVA,并研究了不同水解度PVA對α、β-H試件的機械強度和吸水率的影響。結(jié)果表明,水解度為65%~99%的PVA均能在不同程度上提高石膏試件的機械強度,但其吸水率有所降低。其中,水解度為78%的PVA(PVA78)可使得α、β-H試件在吸水率少量降低的同時,最大幅度地提高其抗折強度和抗壓強度。當PVA78摻量為0.05wt.%時,可使得β-H試件的抗折、抗壓強度較未添加大分子的石膏試件分別提高了26%和4%,吸水率僅降低了1%。0.1 wt.%的PVA78可使得α-H試件的抗折、抗壓強度分別較未添加大分子的石膏試件提高了21%和5%,吸水率提高了1%。最后,測定了PVA78改性β-H的水化度、凝結(jié)時間、水化溫度和體系的電導(dǎo)率,發(fā)現(xiàn)PVA78可以加速β-H的水化進程。2.研究了養(yǎng)護時間、拌合水p H、外加無機鹽對PVA78改性β-H試件的影響。結(jié)果表明,PVA78的加入使β-H的p H使用范圍由7~9擴大至5~9。而外加鹽的存在則會降低PVA78改性的β-H試件的機械強度,其降低的程度與無機鹽的種類有關(guān)。具有較強促凝作用的Na2SO4和具有較強緩凝作用的CH3COONa和Na2CO3對PVA78改性的β-H試件的機械強度降低程度較大,而Na NO3和Na Cl對PVA78改性β-H試件的強度降低程度較小。另外,外加鹽對β-H試件機械強度的降低作用是通過改變其晶體形貌來實現(xiàn)的:外加鹽使得二水硫酸鈣的晶體變短,晶體之間的連接點減少,使強度降低。3.以醋酸乙烯酯(VAc)、甲基丙烯磺酸鈉(SMS)和大分子單體甲基烯基聚氧乙烯聚氧丙烯嵌段共聚醚(608)為原料,采用水相自由基共聚法合成了聚醚聚酯型磺酸基大分子(PES)。通過單因素實驗和正交試驗篩選出PES性能最優(yōu)的配方為:nSMS:n608:nVAc=1:5:14,WAPS=1.5 wt.%,溫度為80 oC。PES的最佳摻量為0.1wt.%時,PES改性β-H試件的抗折強度較空白提高5%,抗壓強度降低2%,吸水率較空白提高2%。4.通過測定PES改性β-H的水化度、水化溫度和體系的電導(dǎo)率,發(fā)現(xiàn)PES對β-H的水化進程并無明顯影響;而通過電鏡分析其晶體形貌發(fā)現(xiàn),PES的摻入使得石膏的晶體形貌由大片狀變?yōu)橹鶢罨蛐∑瑺?增加了晶體結(jié)構(gòu)的緊密程度,改善了β-H試件的機械強度。
[Abstract]:On the basis of maintaining the water absorbency of gypsum test piece, improving the mechanical strength of the specimen is one of the problems to be solved urgently in gypsum mould industry. In this paper, the effects of macromolecules containing vinyl acetate units (polyvinyl alcohol PVA and polyether polyester sulfonic acid macromolecule PES) on the bending, compressive strength and water absorption of gypsum were investigated. In order to obtain the ideal admixture which can improve the mechanical strength of gypsum without reducing its water absorption. In addition, the effects of inorganic salts, mixing water pH and curing time on the modification of 尾 -hemihydrate gypsum (尾 -H) were studied. Finally, the effects of macromolecular additives on the hydration process and crystal morphology of 尾 -H were studied. The specific research contents and main conclusions are as follows: 1. By controlling the hydrolysis conditions of polyvinyl acetate (PVAc), different degree of hydrolysis (65%) was obtained, and the effects of different degree of hydrolysis (PVA) on mechanical strength and water absorption of 偽, 尾 -H specimens were studied. The results show that the mechanical strength of gypsum specimens can be improved by PVA with hydrolysis degree of 65% and 99%, but the water absorption is decreased. Among them, PVA (PVA78) with a hydrolysis degree of 78% can increase the flexural strength and compressive strength of 偽, 尾 -H specimens at the same time that the water absorption rate decreases slightly. When the content of PVA78 is 0.05wt.%, the bending resistance of 尾 -H specimen can be increased by 26% and 4% than that of gypsum specimen without macromolecular addition, respectively, and the water absorption of 偽 -H specimen can be reduced by only 1.0.1 wt.% PVA78, and the bending strength of 偽 -H specimen can be increased by 26% and 4%, respectively, when the addition of PVA78 is 0.05wt.%, the bending resistance of 偽 -H specimen can be improved. The compressive strength was increased by 21% and 5%, respectively, and the water absorption was increased by 1% compared with the gypsum specimen without macromolecular addition. Finally, the hydration degree, setting time, hydration temperature and conductivity of 尾 -H modified by PVA78 were measured. It was found that PVA78 could accelerate the hydration process of 尾 -H. The effects of curing time, mixing water pH and inorganic salt on PVA78 modified 尾 -H specimens were studied. The results showed that the pH range of 尾 -H was expanded from 7- 9 to 5g 9 with the addition of PVA78. The mechanical strength of 尾 -H specimens modified by PVA78 was decreased by the presence of added salt, and the degree of reduction was related to the type of inorganic salts. The mechanical strength of 尾 -H specimens modified by PVA78 was decreased greatly by Na2SO4 with stronger coagulation-promoting effect and by CH3COONa and Na2CO3 with stronger retarding effect, while the strength of 尾 -H specimens modified by PVA78 was reduced by Na NO3 and NaCl to a lesser extent. In addition, the effect of added salt on the mechanical strength of 尾 -H specimen is achieved by changing the crystal morphology: the addition of salt makes the crystal of calcium sulfate dihydrate shorter, the connection point between crystals decreases, and the strength decreases by 0.3. Polyether polyester sulfonic group macromolecule (PES). Was synthesized by water phase free radical copolymerization of vinyl acetate (VAc),) sodium methpropylene sulfonate (SMS) and macromolecular monomer methylenyl polyoxyethylene polyoxypropylene block copolymer (608). Through single factor experiment and orthogonal test, the optimum formula of PES performance is: 1: 608: n VAc1: 5: 14 WAPSX 1.5 wt. and the optimum temperature of 80 oC.PES is 0.1 wt.%. The bending strength of 尾 -H modified by PES is increased by 5%, the compressive strength is reduced by 2%, and the water absorption is increased by 2. 4% compared with the blank. By measuring the hydration degree, hydration temperature and conductivity of 尾 -H modified by PES, it was found that PES had no obvious effect on the hydration process of 尾 -H. By electron microscope analysis, it was found that the crystal morphology of gypsum was changed from large sheet to columnar or small sheet with the addition of PES, which increased the compactness of crystal structure and improved the mechanical strength of 尾 -H specimen.
【學(xué)位授予單位】：江南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TQ174.62;TQ177.37
本文編號：2154996
[Abstract]:On the basis of maintaining the water absorbency of gypsum test piece, improving the mechanical strength of the specimen is one of the problems to be solved urgently in gypsum mould industry. In this paper, the effects of macromolecules containing vinyl acetate units (polyvinyl alcohol PVA and polyether polyester sulfonic acid macromolecule PES) on the bending, compressive strength and water absorption of gypsum were investigated. In order to obtain the ideal admixture which can improve the mechanical strength of gypsum without reducing its water absorption. In addition, the effects of inorganic salts, mixing water pH and curing time on the modification of 尾 -hemihydrate gypsum (尾 -H) were studied. Finally, the effects of macromolecular additives on the hydration process and crystal morphology of 尾 -H were studied. The specific research contents and main conclusions are as follows: 1. By controlling the hydrolysis conditions of polyvinyl acetate (PVAc), different degree of hydrolysis (65%) was obtained, and the effects of different degree of hydrolysis (PVA) on mechanical strength and water absorption of 偽, 尾 -H specimens were studied. The results show that the mechanical strength of gypsum specimens can be improved by PVA with hydrolysis degree of 65% and 99%, but the water absorption is decreased. Among them, PVA (PVA78) with a hydrolysis degree of 78% can increase the flexural strength and compressive strength of 偽, 尾 -H specimens at the same time that the water absorption rate decreases slightly. When the content of PVA78 is 0.05wt.%, the bending resistance of 尾 -H specimen can be increased by 26% and 4% than that of gypsum specimen without macromolecular addition, respectively, and the water absorption of 偽 -H specimen can be reduced by only 1.0.1 wt.% PVA78, and the bending strength of 偽 -H specimen can be increased by 26% and 4%, respectively, when the addition of PVA78 is 0.05wt.%, the bending resistance of 偽 -H specimen can be improved. The compressive strength was increased by 21% and 5%, respectively, and the water absorption was increased by 1% compared with the gypsum specimen without macromolecular addition. Finally, the hydration degree, setting time, hydration temperature and conductivity of 尾 -H modified by PVA78 were measured. It was found that PVA78 could accelerate the hydration process of 尾 -H. The effects of curing time, mixing water pH and inorganic salt on PVA78 modified 尾 -H specimens were studied. The results showed that the pH range of 尾 -H was expanded from 7- 9 to 5g 9 with the addition of PVA78. The mechanical strength of 尾 -H specimens modified by PVA78 was decreased by the presence of added salt, and the degree of reduction was related to the type of inorganic salts. The mechanical strength of 尾 -H specimens modified by PVA78 was decreased greatly by Na2SO4 with stronger coagulation-promoting effect and by CH3COONa and Na2CO3 with stronger retarding effect, while the strength of 尾 -H specimens modified by PVA78 was reduced by Na NO3 and NaCl to a lesser extent. In addition, the effect of added salt on the mechanical strength of 尾 -H specimen is achieved by changing the crystal morphology: the addition of salt makes the crystal of calcium sulfate dihydrate shorter, the connection point between crystals decreases, and the strength decreases by 0.3. Polyether polyester sulfonic group macromolecule (PES). Was synthesized by water phase free radical copolymerization of vinyl acetate (VAc),) sodium methpropylene sulfonate (SMS) and macromolecular monomer methylenyl polyoxyethylene polyoxypropylene block copolymer (608). Through single factor experiment and orthogonal test, the optimum formula of PES performance is: 1: 608: n VAc1: 5: 14 WAPSX 1.5 wt. and the optimum temperature of 80 oC.PES is 0.1 wt.%. The bending strength of 尾 -H modified by PES is increased by 5%, the compressive strength is reduced by 2%, and the water absorption is increased by 2. 4% compared with the blank. By measuring the hydration degree, hydration temperature and conductivity of 尾 -H modified by PES, it was found that PES had no obvious effect on the hydration process of 尾 -H. By electron microscope analysis, it was found that the crystal morphology of gypsum was changed from large sheet to columnar or small sheet with the addition of PES, which increased the compactness of crystal structure and improved the mechanical strength of 尾 -H specimen.
【學(xué)位授予單位】：江南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TQ174.62;TQ177.37
【參考文獻】
相關(guān)期刊論文 前10條
1 張高科,謝毅,朱瀛波,牟善彬;減水劑對石膏微觀結(jié)構(gòu)及性能的影響[J];非金屬礦;2003年05期
2 黃芯紅;;我國陶瓷業(yè)現(xiàn)狀及展望[J];佛山陶瓷;2010年06期
3 王福諄，，劉可如;精鑄技術(shù)在模具制造中的應(yīng)用[J];廣東機械學(xué)院學(xué)報;1994年04期
4 傅樂峰;鄧最亮;張毅;鄭柏存;于建國;;聚羧酸類超塑化劑分子結(jié)構(gòu)對石膏分散性能的影響[J];高分子學(xué)報;2011年03期
5 康永;高建峰;;新型懸浮法制備低醇解度聚乙烯醇的研究[J];化工技術(shù)與開發(fā);2009年10期
6 許東穎,李月鳳,蘇濤;聚醋酸乙烯酯的醇解研究[J];廣西師范學(xué)院學(xué)報(自然科學(xué)版);2003年04期
7 趙敏;彭家惠;魏桂芳;朱登玲;;成型工藝對陶瓷模具石膏性能的影響[J];硅酸鹽通報;2013年01期
8 惠泊寧;劉東輝;李樺軍;;強度增強型石膏專用聚羧酸系高性能減水劑[J];硅酸鹽通報;2013年02期
9 趙敏;彭家惠;朱登玲;李志新;;陶瓷模具石膏增強技術(shù)研究[J];材料導(dǎo)報;2013年04期
10 王平林;;高醇解度聚乙烯醇的制備方法研究[J];安徽科技;2013年07期
相關(guān)碩士學(xué)位論文 前5條
1 豐霞;β型模具石膏的增強研究[D];廣西大學(xué);2007年
2 杜勇;建筑磷石膏改性研究與應(yīng)用[D];重慶大學(xué);2010年
3 魏桂芳;陶瓷模具石膏的增強及耐溶蝕性研究[D];重慶大學(xué);2013年
4 朱登玲;注漿成型陶瓷模具石膏改性研究[D];重慶大學(xué);2014年
5 毛玉成;聚羧酸大分子的合成及其在模具石膏中的應(yīng)用[D];江南大學(xué);2014年
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