Mixtures comprising organosilicon compounds of the general formula R 3-a-b (OR 1) a R 2 b Si[OSiR 2] p [OSiRR 2] q [OSiR 2 2] r OSiR 3-a-b (OR 1) a R 2 b, wherein R may be identical or different and is a monovalent, optionally substituted, SiC-bonded hydrocarbon radical, R 1 may be identical or different and is a hydrogen atom or a monovalent, optionally substituted hydrocarbon radical, R 2 is a SiC-bonded unit of the general formula R 3 -X-[CO- n]-X-R 4 - where X may be identical or different and is -O- or -NR x -, R 3 may be identical or different and denotes monovalent, optionally substituted hydrocarbon radicals having at least 6 carbon atoms, R 4 are divalent, optionally substituted hydrocarbon radicals having 1 to 40 carbon atoms, wherein individual carbon atoms may be replaced by oxygen atoms or -NR z -, R x may be identical or different and is a hydrogen atom or monovalent, optionally substituted hydrocarbon radicals having 1 to 20 carbon atoms, wherein individual carbon atoms may be replaced by oxygen atoms, R z may be identical or different and is a hydrogen atom or monovalent, optionally substituted hydrocarbon radicals having 1 to 20 carbon atoms, wherein individual carbon atoms may be replaced by oxygen atoms, n is 0 or 1, a is 0, 1, 2 or 3, b is 0 or 1, p is an integer from 1 to 1000, q is 0 or an integer from 1 to 100 and r is 0 or an integer from 1 to 100, with the proviso that a+b is ≤ 3 and at least one R 2 radical is present, organic fibres, thermoplastic polymers and optionally polyolefins substituted by carboxylic acid anhydride groups. organosilicon compounds of the general formula R 3-a-b (OR 1) a R 2 b Si[OSiR 2] p [OSiRR 2] q [OSiR 2 2] r OSiR 3-a-b (OR 1) a R 2 b, wherein R may be identical or different and is a monovalent, optionally substituted, SiC-bonded hydrocarbon radical, R 1 may be identical or different and is a hydrogen atom or a monovalent, optionally substituted hydrocarbon radical, R 2 is a SiC-bonded unit of the general formula R 3 -X-[CO- n]-X-R 4 - where X may be identical or different and is -O- or -NR x -, R 3 may be identical or different and denotes monovalent, optionally substituted hydrocarbon radicals having at least 6 carbon atoms, R 4 are divalent, optionally substituted hydrocarbon radicals having 1 to 40 carbon atoms, wherein individual carbon atoms may be replaced by oxygen atoms or -NR z -, R x may be identical or different and is a hydrogen atom or monovalent, optionally substituted hydrocarbon radicals having 1 to 20 carbon atoms, wherein individual carbon atoms may be replaced by oxygen atoms, R z may be identical or different and is a hydrogen atom or monovalent, optionally substituted hydrocarbon radicals having 1 to 20 carbon atoms, wherein individual carbon atoms may be replaced by oxygen atoms, n is 0 or 1, a is 0, 1, 2 or 3, b is 0 or 1, p is an integer from 1 to 1000, q is 0 or an integer from 1 to 100 and r is 0 or an integer from 1 to 100, with the proviso that a+b is ≤ 3 and at least one R 2 radical is present, organic fibres, thermoplastic polymers and optionally polyolefins substituted by carboxylic acid anhydride groups. R may be identical or different and is a monovalent, optionally substituted, SiC-bonded hydrocarbon radical, R 1 may be identical or different and is a hydrogen atom or a monovalent, optionally substituted hydrocarbon radical, R 2 is a SiC-bonded unit of the general formula R 3 -X-[CO- n]-X-R 4 - where X may be identical or different and is -O- or -NR x -, R 3 may be identical or different and denotes monovalent, optionally substituted hydrocarbon radicals having at least 6 carbon atoms, R 4 are divalent, optionally substituted hydrocarbon radicals having 1 to 40 carbon atoms, wherein individual carbon atoms may be replaced by oxygen atoms or -NR z -, R x may be identical or different and is a hydrogen atom or monovalent, optionally substituted hydrocarbon radicals having 1 to 20 carbon atoms, wherein individual carbon atoms may be replaced by oxygen atoms, R z may be identical or different and is a hydrogen atom or monovalent, optionally substituted hydrocarbon radicals having 1 to 20 carbon atoms, wherein individual carbon atoms may be replaced by oxygen atoms, n is 0 or 1, a is 0, 1, 2 or 3, b is 0 or 1, p is an integer from 1 to 1000, q is 0 or an integer from 1 to 100 and r is 0 or an integer from 1 to 100, with the proviso that a+b is ≤ 3 and at least one R 2 radical is present, X may be identical or different and is -O- or -NR x -, R 3 may be identical or different and denotes monovalent, optionally substituted hydrocarbon radicals having at least 6 carbon atoms, R 4 are divalent, optionally substituted hydrocarbon radicals having 1 to 40 carbon atoms, wherein individual carbon atoms may be replaced by oxygen atoms or -NR z -, R x may be identical or different and is a hydrogen atom or monovalent, optionally substituted hydrocarbon radicals having 1 to 20 carbon atoms, wherein individual carbon atoms may be replaced by oxygen atoms, R z may be identical or different and is a hydrogen atom or monovalent, optionally substituted hydrocarbon radicals having 1 to 20 carbon atoms, wherein individual carbon atoms may be replaced by oxygen atoms, n is 0 or 1, a is 0, 1, 2 or 3, b is 0 or 1, p is an integer from 1 to 1000, q is 0 or an integer from 1 to 100 and r is 0 or an integer from 1 to 100, with the proviso that a+b is ≤ 3 and at least one R 2 radical is present, organic fibres, thermoplastic polymers and optionally polyolefins substituted by carboxylic acid anhydride groups.