Hydroxypropylmethylcellulose (HPMC) ist eine mit Propylenoxid substituierte Methylcellulose. Sie kommt in verschiedenen Polymerisationsgraden und unterschiedlichen Substitutionsgraden auf den Markt.
As a seed coating material, HPMC gel can enhance the uniformity of seed coating and provide protection against environmental stresses.
The cello, with its deep and resonant sound, is a captivating instrument that has the ability to touch the hearts of listeners. One important aspect of playing the cello is the size of the instrument, known as cello size. The versatility of redispersible polymer powders extends beyond their applications in construction and adhesivesBut, there are some potential disadvantages that are not immediately obvious. HPMC is listed as a food ingredient — E464 — which means that recommended daily maximum quantities must be defined. HPMC undergoes a rigorous manufacturing process involving the synthetic — and not natural — alteration of cellulose. During production, various highly reactive, harmful or toxic substances are used that must be removed and disposed after production, including propylene oxide (which is considered to be carcinogenic) and chloromethane.
Substitution of cellulose with ethyl-, methyl-, hydroxypropyl-, hydroxypropyl-methyl- and carboxymethyl groups may increase the resistance of cellulose to degradation. Resistance increases with the degree of substitution and is greatest when the substituent groups are evenly dispersed along the polymer chain. Most cellulose of the additive under assessment will therefore pass the intestine undigested and will excreted unchanged via faeces. Even when a high cellulolytic activity is present, as in the rumen, ethyl cellulose remains sufficiently resistant to degradation to be used as enteric coatings designed to protect methionine from rumen release (EFSA FEEDAP Panel, 2012c). Subsequent degradation in the post-ruminal tract is most likely to lead to high molecule weight breakdown products, with little probability of absorption.
The substitution pattern—whether the methoxyl and hydroxypropyl groups are distributed uniformly or are block-wise—also influences the performance of HPMC