在保持β-半水石膏(β-H)试件吸水性能的基础上,提高β-H试件的机械强度是石膏模具行业亟待解决的难题之一.以部分水解的聚醋酸乙烯酯(PHPVAc)为添加剂,考察了不同水解度的PHPVAc对β-H试件抗折强度、抗压强度和吸水率的影响,并初步探讨了PHPVAc对β-H水化进程的影响.研究发现,水解度为65% ~ 99%的PHPVAc均能提高β-H试件的机械强度,但其吸水率有所降低.当PHPVAc的水解度为91% ~99%时,可使β-H试件的抗折、抗压强度提高7% ~8%,吸水率降低2% ~3%;水解度为78%的PHPVAc (PHPVAc78)可使β-H试件在吸水率少量降低的同时,最大幅度地提高β-H试件的抗折强度和抗压强度;PHPVAc78掺量为0.05wt%的β-H试件的抗折、抗压强度分别较未添加大分子的石膏试件者提高了26%和4%,吸水率仅降低2%.此外,PHPVAc改性β-H的水化度和电导率实验的结果表明,PHPVAc可以加速β-H的水化进程.
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