Polypropylene Tubing in Teaching Laboratories The substitution of polyethylene tuhing for glass has several benefits in teaching laboratories.' However, polyethylene is limber and cannot replace glass in many situations. In contrast to polyethylene, polypropylene tuhing is more rigid and retains its rigidity over a broader temperature range. I t does not, for example, hecome flaccid at steam temperatures. Its rigidity and its workability in a flame make it a more suitable substitute for glass in constructions requiring only simple hcllds. Wc,rking with pulvpropylenc, although unfamiliar, rs simple. Tocut thr tuhing, smre it with a single firm slice of s knife: gmsp the tubing on hgrth s ~ d e of s the score,and quickly hend the tubing away from the mark. The tubing hreakq cleanly with a snap; fire-poliihing is unnecessary. Tubing nor scored uill collapse when bent. When coated with a thin film ofsilimne grease, the tuhing :s easrlv inserted through stoppers. The tuhing hends easily in a Runren flame: it hends easiest in the direction of the rur\,ature devrloped hy coiling fm shiomcnt. Attach a wme-tor, - . t,, the burner. Adimt thegar wachiew a flame which hnsn small luminousedge. While krepmg a modest bending force on the tubing, slowljand repeatedly pass the segment to be hent through the flame. The tubing becomes almost transparent just above the lowest convenient working temperature. Adjustments can be made for quite same time after the heated segment is removed from the flame. While holding the tuhing in the desired position, cool it rapidly in a basin of water or under the tap. When cold the hent segment will again he rigid. Several laboratory sections have used %-in. polypropylene tubing instead of glass tubing. In none of these were there any burns or cuts oftentimes associated with laboratory sessions where glass is manipulated. Constructions are completed in less than half the time required with glass tuhing. 'Long, K. P., J. CHEM. EDUC., 51,789 (1974). University of Connecticut Storrs, 06268
Frederick W. Wassmundt
Volume 53, Number 10, October 1976 / 669
