I would have to question the type of relaxer you are using. If you has a sensitive scalp and are using a no-lye relaxer, then it is possible this is drying your hair out, especially if it’s a retail brand. There are currently only 2 no-lye relaxers on the market that do not cause dryness and they are both professional products; the Affirm Moisturizing No-lye relaxer and the Mizani No-lye. Both of these products are only available in salons and they are the best no-lye technology currently available in the country. If you are using a normal sodium hydroxide relaxer, then you should check to make sure that 1. The relaxer is the right strength according to the texture of your hair and 2. That you or your hair stylist are not pulling the relaxer through to the ends of the hair. This last bit is very important because this practice will dry the hair out, make the hair shaft thinner and eventually cause it to break off.
Another possible reason for dryness could be the use of hair food on the scalp and hair. Many people use hair food thinking this will help them with their dryness problem, but nothing could be further from the truth! Hair foods tend to be very heavy and waxy, and clog the hair and scalp rather than nourish them. My personal test to determine whether or not a product is suitable is to take a little bit of it, put it on the back of your hand, and rub it in. If the product is absorbed into the skin without leaving a shiny film and makes the skin soft, and feeling moisturized, then you can try that one. If it leaves that shiny film and sits on top of the skin then that is what it will do to your hair; not a good choice.
The key to having shiny, silky hair is to add moisture to it. Limit the amount of heat appliances you use (blow dryers, straighteners and tongs), because heat appliances remove moisture from the hair. Rather mold or set the hair, and sit under a hood dryer. You can also get steam treatments to add more moisture as well as using sulphate-free shampoos and moisturizing conditioners, and treatments.
Remember, less is better when it comes to product usage. Start off using less of a product and add more if you feel the need, but don’t overload the hair and scalp with any product, even if it is a good one. You will waste the product, and clog the hair and scalp if you do.