Rees J E, Rue P J
J Pharm Pharmacol. 1978 Oct;30(10):601-7. doi: 10.1111/j.2042-7158.1978.tb13340.x.
Three techniques were used to compare the time-dependent deformation of microfine cellulose (Elcema G250), anhydrous lactose, dicalcium phosphate dihydrate (Emcompress), modified starch (Sta-Rx 1500) and sodium chloride. (1) In stress-relaxation experiments using a reciprocating tablet machine, none of the materials behaved as a Maxwell body in contrast to recent published work (David & Augsburger, 1977). Possible reasons for this disagreement are discussed. (2) Heckel plots showed that increasing the time for which a material was under compression (contact times of 0.17 and 10 s) had no effect on dicalcium phosphate compacts but increased the consolidation of other materials in the rank order sodium chloride less than lactose less than cellulose less than starch. (3) Deformation tests on preformed compacts were carried out in diametral compression by loading compacts to 75% of their breaking force at four different strain rates between 0.05 and 6.5 mm min-1. The deformation of Sta-Rx compacts was time-dependent. Sodium chloride compacts exhibited brittle behaviour in the diametral compression test and in the 10 s contact time experiment. This was apparently due to work-hardening, following the extensive plastic deformation of crystals during compaction as indicated by the stress relaxation results.
采用了三种技术来比较微晶纤维素（Elcema G250）、无水乳糖、二水磷酸氢钙（Emcompress）、变性淀粉（Sta-Rx 1500）和氯化钠随时间的变形情况。（1）在使用往复式压片机进行的应力松弛实验中，与最近发表的研究（David和Augsburger，1977年）不同，没有一种材料表现为麦克斯韦体。讨论了这种不一致的可能原因。（2）赫克尔图表明，增加材料受压的时间（接触时间为0.17秒和10秒）对磷酸氢钙压片没有影响，但会增加其他材料的固结程度，固结程度由低到高依次为氯化钠小于乳糖小于纤维素小于淀粉。（3）对预制压片进行径向压缩变形测试，通过在0.05至6.5毫米/分钟的四种不同应变速率下将压片加载至其断裂力的75%。Sta-Rx压片的变形与时间有关。氯化钠压片在径向压缩试验和10秒接触时间实验中表现出脆性。如应力松弛结果所示，这显然是由于压实过程中晶体发生广泛塑性变形后产生的加工硬化所致。
