Shorter peptides are less likely to exhibit secondary structure. Secondary structure prediction programs often require at least 20AA peptides to predict any secondary structure. Short peptides tend to have unordered structure and this could be why you observed alpha-helical formation in the 32mer
Not even with the addition of TFE will it show secondary structure? I found that low temperature has some minor effect, but still more apparent as random coiling. Thanks for your help nonetheless!